WO2024173252A1 - Electrode structure by dry manufacturing - Google Patents

Abstract

An example electrode fabricated using a solvent-free process is provided. The electrode includes a substrate including a dry mixture of active materials, binder, and conductive additives electrostatically sprayed onto the substrate, thermally activated, and bonded to the substrate. The binder and the conductive additives form conductive binder agglomeration clusters. The binder and the conductive additives uniformly cover a surface of the active materials. The binder is uniformly distributed in a thickness direction of the electrode. The electrode includes pores between the active materials that are both microsize pores and submicron- size pores. The micro-size pores are open pores that allow electrolyte to diffuse.

Description

Attorney Docket No.137174.00034 ELECTRODE STRUCTURE BY DRY MANUFACTURING CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of a co-pending, commonly assigned U.S. Provisional Patent Application No.63/445,204, which was filed on February 13, 2023, the entire content of the foregoing application is incorporated herein by reference in its entirety. STATEMENT OF GOVERNMENT SUPPORT [0002] This invention was made with government support under Grant No. DE- EE0006250 awarded by the U.S. Department of Energy. The government has certain rights in the invention. BACKGROUND [0003] The highly frequent extreme weather phenomena that occurred in recent years has alerted us to the power of climate change, and the urgent need to control greenhouse gases emission. In response to the United Nations Paris climate agreement (2015), the major emission countries and institutions, such as the United States, the European Union, and China, have claimed their net-zero pledge. (See, e.g., Rogelj, J. et al., Three ways to improve net-zero emissons targets. Nature 591, 365-368 (2021)). These policies have accelerated the Li-ion batteries (LIBs) market surge, and the boost could last for decades. As a result, the LIBs market will expand from about 160GWh in 2018 to about 1200GWh by 2030 based on forecasts. (See, e.g., Pillot, C., The Rechargeable Battery Market and Main Trends 2018-2030. International Congress for Battery Recycling (2019)). In the LIBs market, electrical vehicles (EVs) make up the largest market share and have huge potential. Due to the limitation of charging time and the cost of organic solvent in the electrode manufacturing process, the development of EVs is slowed. Current electrode manufacturing technology uses a slurry of active materials, conductive carbon, binders, and organic solvent coated on a metallic substrate. However, the typical organic solvent is flammable, toxic, and expensive, necessitating the use of dry and recovery systems, which further improves the cost of electrode manufacture. In addition, to meet the fast-charging demand from the EV market, the U.S. Department of Energy (DOE) has published the targets for extreme fast charging (XFC) batteries, which require charging 80% of the capacity within 15 minutes. However, the e-of-art battery technology has multiple difficulties for the fast-charging application. First, the graphite anode has a low operation 1 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 potential plateau (<0.25V vs. Li⁺/Li), which could cause Li plating on the surface by the overpotential. (See, e.g., Gao, T. et al., Interplay of Lithium Intercalation and Plating on a Single Graphite Particle. Joule 5, 393-414.10.1016/j.joule.2020.12.020 (2021); Cai, W. et al., The Boundary of Lithium Plating in Graphite Electrode for Safe Lithium-Ion Batteries. Angew Chem Int Ed Engl 60, 13007-13012.10.1002/anie.202102593 (2021)). Second, the electronic conductivity of the electrodes and the ion diffusivity in the electrolyte and solid phases (active materials) can limit the electron and Li⁺ transportation. (See, e.g., Weiss, M. et al., Fast Charging of Lithium‐Ion Batteries: A Review of Materials Aspects. Advanced Energy Materials 11. 10.1002/aenm.202101126 (2021)). Third, the high tortuosity electrode microstructure could prolong the Li⁺ diffusion path and cause poor contact between the electrolyte and active materials interface. (See, e.g., Heubner, C. et al., Understanding thickness and porosity effects on the electrochemical performance of LiNi0.6Co0.2Mn0.2O2-based cathodes for high energy Li-ion batteries. Journal of Power Sources 419, 119-126. 10.1016/j.jpowsour.2019.02.060 (2019); Parikh, D. et al., Correlating the influence of porosity, tortuosity, and mass loading on the energy density of LiNi0.6Mn0.2Co0.2O2 cathodes under extreme fast charging (XFC) conditions. Journal of Power Sources 474.10.1016/j.jpowsour.2020.228601 (2020)). [0004] To overcome these challenges, numerous new materials have been discovered. Most of these novel materials can be hard to scale up or apply in high-loading electrodes. (See, e.g., Pham, V.H. et al., Selenium-sulfur (SeS) fast charging cathode for sodium and lithium metal batteries. Energy Storage Materials 20, 71-79. 10.1016/j.ensm.2019.04.021 (2019); Cai, W. et al., Rapid Lithium Diffusion in Order@Disorder Pathways for Fast‐ Charging Graphite Anodes. Small Structures 1. 10.1002/sstr.202000010 (2020); Miroshnikov, M. et al., Made From Henna! A Fast-Charging, High-Capacity, and Recyclable Tetrakislawsone Cathode Material for Lithium Ion Batteries. ACS Sustainable Chemistry & Engineering 7, 13836-13844. 10.1021/acssuschemeng.9b01800 (2019)). Only a few studies are based on modifying the state-of-art battery system. The research that is based on the current commercial materials has the challenges to balance the cost and performance. The studies on developing the manufacturing technologies such as solvent- free manufacturing and aqueous binder, could reduce the production cost, improve throughput and lower energy consumption. (See, e.g., Liu, Y. et al., (2021). Current and Future Lithium-Ion Battery Manufacturing. iScience, 102332 (2021)). However, these innovations are typically accompanied by disadvantages, such as poor bonding strength, 2 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 side reactions, and even the sacrifice of energy density. (See, e.g., Bichon, M. et al., Study of Immersion of LiNi0.5Mn0.3Co0.2O2 Material in Water for Aqueous Processing of Positive Electrode for Li-Ion Batteries. ACS Appl Mater Interfaces 11, 18331-18341. 10.1021/acsami.9b00999 (2019); Lee, S.H. et al., Spray printing of self-assembled porous structures for high power battery electrodes. Journal of Materials Chemistry A 6, 13133- 13141. 10.1039/c8ta02920b (2018); Beneventi, D. et al., Pilot-scale elaboration of graphite/microfibrillated cellulose anodes for Li-ion batteries by spray deposition on a forming paper sheet. Chemical Engineering Journal 243, 372-379. 10.1016/j.cej.2013.12.034 (2014); Chen, K.H. et al., Enabling 6C Fast Charging of Li‐Ion Batteries with Graphite/Hard Carbon Hybrid Anodes. Advanced Energy Materials 11. 10.1002/aenm.202003336 (2020)). Other ways of modification, such as coating, doping, or developing special electrode structures, usually result in extra costs. Most methods like freeze drying, atomic layer deposition (ALD) and chemical vapor deposition (CVD) are high-cost and are hard to scale up. (See, e.g., Mu, Y. et al., Growing vertical graphene sheets on natural graphite for fast charging lithium-ion batteries. Carbon 173, 477-484. 10.1016/j.carbon.2020.11.027 (2021); Dang, D. et al., Freeze-dried low-tortuous graphite electrodes with enhanced capacity utilization and rate capability. Carbon 159, 133-139. 10.1016/j.carbon.2019.12.036 (2020); Wang, H.-Y. et al., Electrochemical investigation of an artificial solid electrolyte interface for improving the cycle-ability of lithium ion batteries using an atomic layer deposition on a graphite electrode. Journal of Power Sources 233, 1-5. 10.1016/j.jpowsour.2013.01.134 (2013)). The paradox of cost and performance has been the largest dilemma for the battery industry. [0005] As noted above, due to the rapidly increasing demand for energy storage, the lithium-ion battery market continues to expand. However, the conventional battery electrode manufacturing methods usually involve toxic organic solvent and energy- consuming drying/recovering processes. The evaporation of the solvent can lead to uneven material distribution and the electrodes’ microstructure could impede the fast-charging ability. As such, improved methods of battery electrode manufacturing are needed. SUMMARY [0006] Embodiments of the present disclosure provide a system and method for dry manufacturing of electrode structure and, particularly, roll-to-roll solvent-free manufactured electrodes for fast-charging batteries. The exemplary method is used to 3 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 achieve an electrode structure fabricated by dry or solvent-free manufacturing. The exemplary method includes a dry printing process to avoid the toxic solvent in the conventional slurry cast method, and skips the energy and time-consuming drying process. The total manufacturing cost (as compared to conventional methods) could be reduced by up to 15% and the roll-to-roll system has potential to be scaled up. The properties and the mechanism of the dry electrodes have been deeply studied, as discussed herein. The unique microstructure can benefit the electrode with an improved fast-charging ability and longer cycle life. The process therefore provides a more efficient way for battery manufacturing with higher-quality electrode products. [0007] With the ever-growing Lithium-ion battery (LIB) market, low cost, fast charging, and high capacity have become some of the essential requirements from customers, especially electric vehicle (EV) owners. In pursuit of low cost, increasing driving range, and reducing charging time, most of the efforts have been devoted to research on new materials for LIBs, which are usually far from industrialization. By contrast, innovations in manufacturing are usually expected to break the bottlenecks in a low-cost and high-efficiency way. The exemplary methods discussed herein demonstrate a solvent-free manufacturing technology that can avoid toxic organic solvents and form a unique electrode structure, resulting in low production cost and higher fast charging ability. The dry-printed (DP) cathode has almost 30% lower tortuosity (2.74 vs.3.8) than the slurry cast (SL) cathode. The unique electrode microstructure with more open pores between the active materials particles allows a shorter Li⁺ diffusion pathway in the electrodes, which leads to higher rate performance. As a result, the DP pouch cells show that superior capacity retention of 78% and 68% at 3C and 4C is significantly higher than the 66% and 52% capacity retention with SL cells at the same rates, which is consistent with the modeling prediction. Meanwhile, the coating layer on the surface of active materials can also prevent the excess side reaction between active materials and electrolytes, which prolongs the cycle life of the DP cells. The manufacturing process is a roll-to-roll system with immense potential to be scaled up, providing a more efficient and economical way of battery manufacturing. [0008] Based on the XFC demand, a scalable dry-printing manufacturing technology has been developed to produce fast-charging electrodes (e.g., charge 78% capacity in 20 min). Besides the higher performance of the electrodes, this technology can avoid toxic and expensive organic solvents and save drying energy consumption. (See, e.g., Ludwig, B. et 4 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 al., Solvent-Free Manufacturing of Electrodes for Lithium-ion Batteries. Sci Rep 6, 23150. 10.1038/srep23150 (2016)). The disclosure demonstrates the latest DP cells with the up-to- date commercial materials (NMC 622 and graphite), and the total manufacturing cost using the exemplary method can be reduced by 15% based on Argonne battery performance and cost (BatPaC) model. (See, e.g., Nelson, P.A. et al., Modeling the Performance and Cost of Lithium-Ion Batteries for Electric-Drive Vehicles, Third Edition. In U.S.D.o. Energy, ed. Third ed. (2019)). The single-layer DP pouch cells built from the roll-to-roll continuous system exhibit improved high-rate performance and higher cycling retention compared to the commercial SL cells. All of the control SL samples were prepared by Microvast Inc., using industrially relevant electrode processing. The specific microstructures of DP electrodes were studied by different characterization methods and demonstrated with pseudo-2D modeling. The experimentation results presented herein show a new path for the low-cost fast-charging battery and the implementation of advanced electrode design. [0009] The electrode structure manufactured by the exemplary dry method enables better rate and cycle performance. The capacity retention of dry electrodes is 78% and 68% at 3C and 4C, and is significantly higher than the 66% and 52% capacity retention with slurry cast electrodes. The dry manufacturing method enables lower cost, lower energy consumption, better performance as compared to convention electrode manufacturing. With the solvent-free dry printing technology, the electrodes have uniform binder/conductive carbon distribution and more open pores with lower tortuosity. These structural advantages can benefit the high-rate performance, especially the fast-charging ability. The surface binder/carbon coating layer can improve the cycle stability. [0010] In accordance with embodiments of the present disclosure, an exemplary method of battery electrode fabrication is provided. The method includes dry mixing active materials, binder, and conductive additives to form a dry mixture. The method includes electrostatically spraying the dry mixture onto a grounded current collector foil. The method includes thermally activating the dry mixture on the grounded current collector foil. The method includes bonding the dry mixture to the grounded current collector foil with rollers to form an electrode. [0011] The active materials include an anode active material and a cathode active material. The anode active material can be graphite. The cathode active material can be nickel-rich nickel manganese cobalt (NMC622). The binder can be polyvinylidene fluoride 5 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 (PVDF). The conductive additives can include Super C65 conductive carbon black. The dry mixture can include 90% by weight of the active materials, 5% by weight of the binder, and 5% by weight of the conductive additives. The grounded current collector foil can include a copper foil for anode fabrication and an aluminum foil for cathode fabrication. [0012] The method can include controlling spray time and spray rate of the dry mixture during electrostatically spraying of the dry mixture onto the grounded current collector foil. The method can include tuning an electrode porosity of the electrode by changing a gap between the rollers. The binder and conductive additives can form conductive binder agglomeration clusters to bridge the active materials in the electrode. The step of electrostatically spraying the dry mixture onto the grounded current collector foil is a solvent-free dry printing process. The electrode has a tortuosity of 2.74 for cathodes. [0013] In accordance with embodiments of the present disclosure, an exemplary electrode for a battery is provided. The electrode includes a grounded current collector foil defining a first surface and an opposing second surface, and a dry mixture of active materials, binder, and conductive additives electrostatically sprayed onto the grounded current collector foil. The dry mixture is thermally activated on the grounded current collector foil. The dry mixture is bonded to the grounded current collector foil with rollers to form the electrode. [0014] The active materials can include an anode active material including graphite. The active materials can include a cathode active material including nickel-rich nickel manganese cobalt (NMC622). The binder can be polyvinylidene fluoride (PVDF). The conductive additives can include Super C65 conductive carbon black. [0015] In accordance with embodiments of the present disclosure, an exemplary system for battery electrode fabrication is provided. The system includes a dry mixing assembly configured to receive and mix in a solvent-free manner active materials, binder, and conductive additives to form a dry mixture. The system includes a coating assembly configured to electrostatically spray the dry mixture onto a grounded current collector foil. The system includes an activation assembly configured to thermally activate the dry mixture on the grounded current collector foil. The system includes a bonding assembly including rollers configured to bond the dry mixture to the grounded current collector foil to form an electrode. 6 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 [0016] In accordance with embodiments of the present disclosure, an exemplary electrode fabricated using a solvent-free process. The electrode includes a substrate including a dry mixture of active materials, binder, and conductive additives electrostatically sprayed onto the substrate, thermally activated, and bonded to the substrate. The binder and the conductive additives form conductive binder agglomeration clusters. The binder and the conductive additives uniformly cover a surface of the active materials. The binder is uniformly distributed in a thickness direction of the electrode. The electrode includes pores between the active materials that are both micro-size pores and submicron-size pores. The micro-size pores are open pores that allow electrolyte to diffuse. [0017] The dry mixture of the conductive additives and the binder form a coating layer on the active materials. The pores between the active materials increase an electrolyte wettability and enhance a Li⁺ exchange contact interface between the active materials and electrolyte phases. The conductive binder agglomeration clusters formed by the binder and the conductive additives bridge the active materials. In some embodiments, the binder and the conductive additives uniformly covering the surface of the active materials form a coating layer thickness on the active materials of about 100 nm-200 nm, inclusive. In some embodiments, the binder and the conductive additives uniformly covering the surface of the active materials form a coating layer thickness on the active materials of about 200 nm or less. [0018] A cathode of the electrode has a tortuosity of about 2.74. An anode of the electrode has a tortuosity of about 3.28. The electrode exhibits a cycling stability with 77.6% capacity retained at a 400^th cycle. The electrode exhibits a charge capacity retention of 77.6% at 3C and 68.5% at 4C. The electrode exhibits less overpotential and polarization. [0019] The active materials include an anode active material and a cathode active material. The anode active material is at least one of graphite, or silicon. The cathode active material is at least one of nickel-rich nickel manganese cobalt (NMC622), lithium cobalt oxide (LCO), lithium nickel manganese cobalt oxide (NMC), lithium manganese oxide (LMO), lithium iron phosphate (LFP), or lithium nickel cobalt aluminum oxide (NCA). [0020] The binder is at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), or SBR. In some embodiments, the binder can be any other polymer or combinations thereof. The 7 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 conductive additives include Super C65 conductive carbon black, carbon nanotube, graphene, or a mixture thereof. In some embodiments, the dry mixture includes 90% by weight of the active materials, 5% by weight of the binder, and 5% by weight of the conductive additives. In some embodiments, the dry mixture includes >90% by weight of the active materials, <5% by weight of the binder, and <5% by weight of the conductive additives. [0021] Any combination and/or permutation of embodiments is envisioned. Other objects and features will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS [0022] To assist those of skill in the art in making and using the electrode structure by dry manufacturing, reference is made to the accompanying figures, wherein: [0023] FIGS.1A-1L are images of morphology of SL and DP electrodes, including an SEM image of cathode after dry mixing (FIG. 1A), F EDS image of cathode after dry mixing (FIG. 1B), SEM image of anode powder after dry mixing (FIG.1C), F EDS image of anode powder after dry mixing (FIG.1D), SEM image of the SL (FIG.1E), SEM image of the DP cathode surface (FIG.1F), ion polished cross-section SEM image of SL cathode (FIG. 1G), C element EDS mapping image of SL cathode (FIG. 1H), ion polished cross- section SEM image of DP cathode (FIG.1I), C element EDS mapping image of DP cathode (FIG. 1J), ion polished cross-section SEM image of DP cathode particle (FIG. 1K), and C element EDS mapping image of DP cathode image (FIG. 1L); [0024] FIGS. 2A-2D are graphs of electrodes property characterizations, including pore size distribution of the electrodes (FIG.2A), the electronic conductivity of the SL and DP electrodes (FIG. 2B), tortuosity of the SL and DP electrodes (FIG. 2C), and Nyquist impedance plots of the SL and DP electrodes symmetrical cells (FIG.2D); [0025] FIGS. 3A-3B are three-dimensional NMC electrode structures reconstructed from X-ray nanotomography for dry-printed electrode (FIG.3A), and slurry-cast electrode (FIG.3B), with a scale bar of 10 μm; 8 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 [0026] FIGS. 4A-4F are graphs of electrochemistry evaluations, including HPPC available power of DP and SL pouch cells with BSF factor (FIG.4A), HPPC resistance and OCV of DP and SL pouch cells (FIG.4B), cycle life test of DP and SL full cells at 1C (0.1C cycle checkpoint for every 50 cycles) (FIG. 4C), rate performance of the SL cathode- SL anode, DP cathode- SL anode, SL cathode- DP anode, and DP cathode- DP anode (FIG. 4D), differential capacity plots of the charge curves for different charging rates of DP cathode- DP anode cell (FIG. 4E) and SL cathode- SL anode cell (FIG. 4F); [0027] FIGS.5A-5F are pouch cell teardown analysis images, including SEM images of ion-polished electrode cross-section of cycled SL cathode (FIG. 5A) and cycled DP cathode (FIG.5B), ion-polished cross-section SEM image of the cycled SL cathode particle (FIG. 5C), HRTEM TEM image of the cycled SL cathode particle and the SAED pattern for the particle surface and interior (FIG. 5D), Ion-polished cross-section SEM image of the cycled DP cathode particle (FIG. 5E), and HRTEM TEM image of the cycled DP cathode particle and the SAED pattern for the particle surface and interior (FIG.5F); [0028] FIGS.6A-6B are graphs of surface layer characterization after cycle, including XPS of C1s, O1s, and F1s of the cycled cathodes (FIG.6A), and cycled anodes (FIG.6B); [0029] FIGS. 7A-7B are graphs of Simulated CC charging capacity of NMC/graphite full cells containing different types of cathodes and anodes (FIG. 7A), and lithium-ion concentration distribution in the electrolyte when the cells reach 4.2 V at the end of 4C charging (FIG. 7B); [0030] FIG.8 is a table of XRD refinement results for the SL and DP cathode after the cycle; [0031] FIG.9 is a table of P2D simulation parameters; [0032] FIGS. 10A-10B are schematics of the electrode microstructure of SL cathode (FIG.10A), and DP cathode (FIG.10B); [0033] FIGS. 11A-11P are photos of pouch cell size DP cathode and anode (FIGS. 11A-11B), C EDS mapping of SL (FIG.11I) and DP (FIG.11J) cathode, SEM images and C EDS mapping of SL cathode (FIGS. 11C-11D), and DP cathode cross-section (FIGS. 11K-11L), SEM images and F EDS mapping of SL anode (FIGS.11E-11F), and DP anode polished cross-section (FIGS. 11M-11N), SEM images of carbon & PVDF coating on NMC surface in DP cathode (FIG.11G) and Carbon Binder Domain (CBD) phase attached 9 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 to the NMC surface in SL cathode (FIG.11H), SEM images and C EDS mapping of NMC particle in SL cathode (FIGS.11O-11P); [0034] FIG.12 is a Raman spectroscopy of raw C65, NMC, and coated NMC; [0035] FIGS.13A-D are TGA graphs of cathodes (FIG.13A), and anodes (FIG.13C), and DSC heat flow of cathodes (FIG. 13B), and anodes (FIG.13D); [0036] FIG.14 is an SEM image of the CBD phase; [0037] FIG.15 is a table of tortuosity of the pure CBD sample; [0038] FIG.16 is a graph of charge curves of the DC-DA/SC-SA at different charging rates; [0039] FIG.17 is a graph of Coulombic efficiency of the cycling test; [0040] FIGS. 18A-18H are CV spectra of cathodes (FIG. 18A), and anodes (FIG. 18C), plot between peak current (I_p) and scan rate (v) for anionic peak and the cathodic peak of cathodes (FIG.18B), and anodes (FIG.18D), Li⁺ diffusion coefficients of cathode charging (FIG. 18E), and cathode discharging (FIG. 18F), anode delithiation (FIG. 18G), and anode lithiation (FIG.18H) as a function of voltage from GITT; [0041] FIG.19 is a table of internal resistance of different pouch cells; and [0042] FIGS. 20A-20D are graphs of XRD refinement of SL electrode (FIG. 20A), DP electrode (FIG. 20B), Cycled SL electrode (FIG. 20C), and Cycled DP electrode (FIG.20D). DETAILED DESCRIPTION [0043] Electrodes fabrication and morphology [0044] Targeting the fast-charging EV application (although applicable to other industries), the scaled-up DP electrodes were prepared for single-layer pouch cell tests. FIG. 10A shows the prepared DP cathode and anode electrodes, which have a flawlessly smooth surface and similar thickness and porosity as the control SL electrodes. The fabrication of DP electrodes starts with powder mixing. FIGS. 1A and 1C show the scanning electron microscopy (SEM) images of the well-mixed cathode and anode powders. Part of the C65 and PVDF particles are uniformly covered on the surface of the AM (Active Materials) particles, while others form micro-size agglomerations loosely attach to the AM particles. The energy-dispersive X-ray spectroscopy (EDS) mapping of 10 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 fluorine in FIGS. 1B and 1D also shows the uniform spatial distribution of PVDF. The presence of carbon in the surface coating layer is confirmed by the Raman spectrum in FIG. 12. After the electrostatic spraying, thermal activation, and calendaring, the surface morphology of the DP electrode shows a significant difference from the SL electrodes. (See, e.g., Ludwig, B. et al., Solvent-Free Manufacturing of Electrodes for Lithium-ion Batteries. Sci Rep 6, 23150.10.1038/srep23150 (2016); Liu, J. et al., Scalable Dry Printing Manufacturing to Enable Long‐Life and High Energy Lithium‐Ion Batteries. Advanced Materials Technologies 2. 10.1002/admt.201700106 (2017); Liu, J. et al., Strengthening the Electrodes for Li-Ion Batteries with a Porous Adhesive Interlayer through Dry-Spraying Manufacturing. ACS applied materials & interfaces 11, 25081-25089 (2019)). In FIG.1E, the surface of the SL cathode electrode is covered by large agglomerations of the carbon- binder domain (CBD), which is caused by solvent evaporation. (See, e.g., Font, F. et al., Binder migration during drying of lithium-ion battery electrodes: Modelling and comparison to experiment. Journal of Power Sources 393, 177-185. 10.1016/j.jpowsour.2018.04.097 (2018)). The EDS mapping also confirms the aggregates of carbon, which represents continuous large CBD covered on the surface of the AM particles (FIG.10B). In contrast, the AM particles can be seen clearly on the surface of the DP electrode in FIG.1F. The significant pores and gaps between the particles CAN increase the electrolyte wettability and enhance the Li⁺ exchange contact interface between the AM and electrolyte phases. [0045] FIGS. 1G and 1I show the detailed cross-section microstructure inside the electrode prepared by the ion polishing. The C65 and PVDF form the “conductive binder agglomeration” (CBA) clusters which bridge the AM particles in the DP electrode. (See, e.g., Ludwig, B. et al., Solvent-Free Manufacturing of Electrodes for Lithium-ion Batteries. Sci Rep 6, 23150. 10.1038/srep23150 (2016)). These CBA clusters can provide enough bonding strength for the DP electrode while not filling most of the space between the AM particles like in the SL electrode (FIG. 1I). (See, e.g., Ludwig, B. et al., Understanding Interfacial‐Energy‐Driven Dry Powder Mixing for Solvent‐Free Additive Manufacturing of Li‐Ion Battery Electrodes. Advanced Materials Interfaces 4, 1700570 (2017)). The C mapping also shows that the CBD phase fills in most of the space between the AM particles with few open pores in the SL cathode (FIGS. 1H and 1J). Similar microstructure differences could be observed from the ion-polished anode cross-section SEM images in FIGS. 11E and 11M. More open pores could be observed between the 11 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 graphite particles in the DP anode than in the SL anode. The C mapping for the cross- section of the LiNi_0.6Mn_0.2Co_0.2O₂ (NMC) particles in the DP electrode also confirmed that the C65 particles are uniformly covered on the surface of NMC particles after the spraying and thermal activation (Figure 1G). The extensive nano-size C65 powder on the surface works as a carbon coating layer, which could improve the local conductivity for the single particle and prevent the surface phase transformation during cycling. (See, e.g., Phattharasupakun, N. et al., Core-shell Ni-rich NMC-Nanocarbon cathode from scalable solvent-free mechanofusion for high-performance 18650 Li-ion batteries. Energy Storage Materials 36, 485-495. 10.1016/j.ensm.2021.01.032 (2021); Ren, D. et al., Ni-rich LiNi0.88Mn0.06Co0.06O2 cathode interwoven by carbon fiber with improved rate capability and stability. Journal of Power Sources 447. 10.1016/j.jpowsour.2019.227344 (2020); Chen, G. et al., A robust carbon coating strategy toward Ni-rich lithium cathodes. Ceramics International 46, 20985-20992. 10.1016/j.ceramint.2020.05.160 (2020)). FIG. 11G further shows that the coating layer thickness is around 100-200nm and perfectly fit the NMC particle surface. The outer surface of the coating layer has some gaps to allow the electrolyte wetting, and the dense interior could protect the NMC surface from side reaction and degradation. On the contrary, the AM particle in the SL electrode is surrounded by the CBD phase tightly, which could block the access of the Li⁺ to the AM particle surface (FIG. 11O). These microstructure differences are demonstrated in FIGS. 10A and 10B in a more vivid way. In FIG. 11C, the electrode cross-section SEM image demonstrated that the CBD phase is enriched around the surface of the SL cathode. The uneven binder distribution along the thickness side is also presented in the EDS image. The gradient binder distribution is caused by the capillary effect, which would force the binder migration during solvent evaporation. (See, e.g., Font, F. et al., Binder migration during drying of lithium-ion battery electrodes: Modelling and comparison to experiment. Journal of Power Sources 393, 177-185.10.1016/j.jpowsour.2018.04.097 (2018); Müller, M. et al., Investigation of binder distribution in graphite anodes for lithium-ion batteries. Journal of Power Sources 340, 1-5. 10.1016/j.jpowsour.2016.11.051 (2017).; Jaiser, S. et al., Microstructure formation of lithium-ion battery electrodes during drying – An ex-situ study using cryogenic broad ion beam slope-cutting and scanning electron microscopy (Cryo- BIB-SEM). Journal of Power Sources 345, 97-107. 10.1016/j.jpowsour.2017.01.117 (2017)). The accumulation of the binder at the electrode surface could lower the porosity at the top part of the electrode, blocking the contact between the AM particles and 12 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 electrolyte and impeding Li⁺ diffusion along the thickness direction. The corresponding depletion of the binder at the current collector side could lead to poor adhesion. It has been proved that the AM particles near the separator side have a higher state-of-lithiation (SoL) under high current density, which means the surface binder accumulation would further lower the electrode’s fast-charging ability. (See, e.g., Lu, X. et al., 3D microstructure design of lithium-ion battery electrodes assisted by X-ray nano-computed tomography and modelling. Nat Commun 11, 2079. 10.1038/s41467-020-15811-x (2020)). However, the DP electrode could potentially get rid of this issue due to the solvent-free manufacturing processes. FIG.11K presents the even distribution of AM particles, conductive carbon, and binder from the cross-section SEM view of the DP cathode and is confirmed with the carbon EDS mapping. [0046] Electrodes properties characterization [0047] The significant difference in the electrode microstructure could further affect the properties, which are related to the electronic conductivity, electrolyte wettability, diffusion, and safety, leading to the difference in performance. [0048] Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) were used to confirm the composition uniformity and thermal stability of the DP electrodes. In FIG. 13A, the DP and SL electrodes show 89.47% and 87.91% weight retention respectively after 700 ℃, which represents the ratio of active materials (NMC 622 is stable at 700 ℃) in the electrodes is similar. (See, e.g., Bai, Y. et al., Sustainable recycling of cathode scraps via Cyrene-based separation. Sustainable Materials and Technologies 25. 10.1016/j.susmat.2020.e00202 (2020)). The weight ratio of graphite in anodes cannot be identified by the TGA test, because the burning temperatures of graphite and C65 are overlapped (FIG.13C). For the DSC analysis in FIG.13B, the small heat flow peaks between 400℃ to 500℃ is corresponding to the decomposition of PVDF, while the higher peaks between 500℃ to 600℃ represent the burning of C65. (See, e.g., de C. Campos, J.S. et al., Preparation and characterization of PVDF/CaCO3 composites. Materials Science and Engineering: B 136, 123-128. 10.1016/j.mseb.2006.09.017 (2007); Freiberg, A.T.S. et al., Li2CO3 decomposition in Li-ion batteries induced by the electrochemical oxidation of the electrolyte and of electrolyte impurities. Electrochimica Acta 346.10.1016/j.electacta.2020.136271 (2020)). The DP cathode shows a delayed heat flow peak (564℃) compared to the SL cathode (551℃), which could be caused by the heat 13 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 exchange through the surface-coated C65 with the high heat capacity NMC particles. FIG. 13D shows the C65 peak is merged with the graphite peak in the DP anode, which is caused by the C65 coating on the surface of graphite particles and burned as an entirety. The graphite heat flow peak is significantly delayed in the DP anode (765℃) compared to the SL anode (706℃). (See, e.g., Ma, X. et al., High-Performance Graphite Recovered from Spent Lithium-Ion Batteries. ACS Sustainable Chemistry & Engineering 7, 19732-19738. 10.1021/acssuschemeng.9b05003 (2019)). The C65 agglomerations in the SL anode could ignite the graphite particles and accelerate the burnout process. Overall, the microstructure of DP electrodes could help to delay the thermal runaway with higher burning temperatures. (See, e.g., Song, L. et al., Review on Thermal Runaway of Lithium-Ion Batteries for Electric Vehicles. Journal of Electronic Materials 51, 30-46.10.1007/s11664-021-09281-0 (2021)). [0049] Mercury Intrusion Porosimetry (MIP) was applied to characterize the pore size distribution in the cathode electrodes. In FIG.2A, the SL cathode shows a significant peak between 0.1-0.2μm, which is corresponding to the nanopores in the slurry CBD phase. The peak near 1μm of the black line represents the open pores between the NMC and the CBD phase. However, the DP electrode exhibits a broader and lower peak at the sub-micro range and a higher amount of larger pores between 1-10μm. The large open pores (over 10μm) observed from the SEM images cannot be distinguished from the voids between samples (electrodes need to be cut into small pieces for the MIP test). (See, e.g., Radloff, S. et al., Characterization of structured ultra-thick LiNi0.6Co0.2Mn0.2O2 lithium-ion battery electrodes by mercury intrusion porosimetry. Materials Today Communications 28. 10.1016/j.mtcomm.2021.102549 (2021)). Overall, the SL cathode has more nano-size pores, while the DP cathode shows fewer small pores. Combined with the SEM images in FIGS. 1A, 1C, 1E, 1F, 1G, 1I, 1K, the DP cathode has more open pores between the particles than the SL cathode. [0050] Although the coating layer on the surface of active materials consumed some of the C65, the rest of the C65 bridged between the active material particles could provide comparable electronic conductivity for the DP electrodes. Both the DP cathode and anode show similar electronic conductivity with the corresponding SL electrodes in FIG. 2B. Besides the similar overall conductivity, the highly conductive surface coating layer can help to transfer the electrons to the whole particle surface for a uniform Li⁺ intercalation, which could release the local stress in the particles caused by the discontinuous contact 14 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 between the CBD phase and active materials in the SL electrode. (See, e.g., Zhu, Y. et al., A New Aspect of the Li Diffusion Enhancement Mechanism of Ultrathin Coating Layer on Electrode Materials. ACS Appl Mater Interfaces 11, 38719-38726. 10.1021/acsami.9b12740 (2019)). [0051] As an intrinsic property that can represent the actual flow path of the electrolyte in a porous electrode, the tortuosity factor is highly related to the Li⁺ diffusion and the rate performance of LIBs. The tortuosity of the dry and slurry electrodes is obtained from the electrochemical impedance measurements by the symmetrical cells in the blocking condition. (See, e.g., Landesfeind, J. et al., Tortuosity Determination of Battery Electrodes and Separators by Impedance Spectroscopy. Journal of The Electrochemical Society 163, A1373-A1387. 10.1149/2.1141607jes (2016)). This method has been well established and the accuracy has been confirmed with the 3D tomography characterization. (See, e.g., Nguyen, T.-T. et al., The electrode tortuosity factor: why the conventional tortuosity factor is not well suited for quantifying transport in porous Li-ion battery electrodes and what to use instead. npj Computational Materials 6.10.1038/s41524-020-00386-4 (2020)). In FIG. 2C, the experimental results show typical transmission-line model (TLM) behavior and could be fitted well by the TLM-Q model. Notably, the average tortuosity numbers calculated by Equation 3 indicate that the DP cathode has much lower tortuosity than the SL cathode (2.74 vs. 3.8). These tortuosity values are in accord with the electrode microstructure that more open-pores that are penetrating could be observed in the DP cathode. Meanwhile, the tortuosity numbers of the DP and SL anode are 3.28 and 3.75 respectively (FIG. 2D). The closer tortuosity between the DP and SL anode is caused by the compact stacking of the plate-shaped graphite particles, which hinders the Li⁺ diffusion along the thickness direction. [0052] To further discover the causation of the tortuosity difference, the tortuosity of DP and SL cathodes are independently measured from the electrode microstructures reconstructed from 3D nanotomography measurements (FIGS. 3A and 3B). Because carbon and PVDF are transparent to the hard X-ray used in tomography characterization, only AM is visible in the tomographic images. Therefore, the computed porosity and tortuosity reflect the property of the pore space between AM in the absence of CBD. The tortuosity in the electrode depth direction as measured from tomography is 1.325 and 1.48 for the DP and SL cathodes, respectively. They are much lower than the electrochemical impedance measurements and do not exhibit a large difference between the DP and SL 15 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 cathodes. Notably, the tortuosity values from tomography are in very good agreement with estimates based on the Bruggeman relation ^ = ^^{^^.^}, where ^ is porosity. The tortuosity of the pure CBD phase (slurry cast C65 and PVDF with a weight ratio of 1:1) was also separately measured (FIG. 14), which has a high value of 5.03 (FIG. 15). This number is much larger than the Bruggeman estimate. Such results provide convincing evidence that the presence of CBD causes a significant increase in the overall electrode tortuosity and deviation from the Bruggeman behavior, and the different spatial distributions of CBD in the DP and SL electrodes are responsible for their tortuosity difference. As the solvent induces the swelling of binder polymer chains during the slurry cast process, CBD occupies a larger volume in the pore region of the SL electrode than in the DP electrode, which impedes Li⁺ diffusion through the pore channels and reduces the rate performance of the former. (See, e.g., Daemi, S.R. et al., Visualizing the Carbon Binder Phase of Battery Electrodes in Three Dimensions. ACS Applied Energy Materials 1, 3702-3710. 10.1021/acsaem.8b00501 (2018)). [0053] Electrochemical evaluation [0054] The SL electrodes with the same parameters were adopted as the control in the electrochemical tests to prove the competitiveness of the DP electrodes. The single-layer pouch cells performance was evaluated following the United States Advanced Battery Consortium (USABC) testing protocols to prospect the commercial application potential. (See, e.g., Christopsen, J.P., Battery Test Manual For Electric Vehicles. INL/DE AC07- 05ID14517 Rev 3 (2015)). In addition, more electrochemical property tests were evaluated in coin-cell (half-cell vs. Li) configuration. [0055] The Hybrid Pulse Power Characterization (HPPC) test was applied to examine the realistic application scenario for the DP electrodes (FIGS. 4A and 4B). The DP cell exhibits higher available power (with Battery Size Factor (BSF) =335,000) than the SL during both the discharge and regen process at all degrees of the depth of discharge (DOD), which confirm the better rate capability for the DP electrodes under different test conditions. As shown in FIG. 4B, the DP cell has lower discharge and regen HPPC resistance, which is corresponding to the lower initial internal cell resistance (FIG.19). The open-circuit voltage (OCV) of both DP and SL cells share a similar trend following the change of DOD%. 16 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 [0056] All the combinations of the SL cathode/anode (SC/SA) and DP cathode/anode (DC/DA) were tested for rate performance. As an important index for fast charging, the CC (constant current) charging capacity retention (full capacity is calculated based on C/3 charging) at different rates (the full charging process includes CC+CV (constant voltage) charging) is chosen to evaluate the rate performance. In FIG. 4C, the DP full-cell DC-DA shows the highest CC charge capacity retention especially at 3C (77.6%) and 4C (68.5%), 11.7%, and 16.1% higher than the control SL full-cell SC-SA. Meanwhile, the performance of mix-and-match cells DC-SA (DP cathode/SL anode) and SC-DA (SL cathode/DP anode) set in between the DC-DA and SC-SA cells, further confirms that both DP cathode and anode have better rate capability than the control electrodes. The CC+CV charging curves in FIG. 16 show that the SL cell has significantly larger deviations than the DP cell from the low-rate potential as the charging rate increases. These plateau shifts are caused by the overpotential and polarization effect in the electrodes. The corresponding differential capacity (dQ/dV) plots are studied to demonstrate the aforementioned theory. In FIGS.4E and 4F, all charge curves and peaks shift toward the high voltage as the C-rates increase. The peak shifting between 0.33C and 4C is chosen to represent the polarization. The DC- DA cell has smaller peak shifting (0.255V) than the SC-SA cell (0.39V), which represents less polarization, better Li⁺ diffusion, and lower resistance in the DP cell. These rate performance results prove that the electrode structure features such as larger open pores space; lower tortuosity does show considerable benefit for the fast-charging ability. The pouch cell internal resistance also confirms that the DP electrodes have better electrolyte wettability. In the table of FIG. 19, the SC-SA cell shows 52% higher internal resistance compared to the DC-DA cell (1.3Ω vs. 0.86Ω). The DC-WA and WC-DA cells also have lower internal resistance than the WC-WA cell. FIG. 4D shows the DP and SL full-cell cycling performance with 1C charge and discharge. Both DP/SL cells have a constant first cycle coulombic efficiency around 86%. With the protection of the carbon/PVDF coating layer, the DP cells exhibited better cycling stability with 77.6% capacity retained at the 400^th cycle versus 72% capacity retained at the 350^th cycle for the SL cell. If using 80% capacity retention as the end-of-life determination condition, the DP cell can survive for 357 cycles while the SL cell will be terminated around 250 cycles. FIG.17 shows that the coulombic efficiency of the DP cell is more stable than the SP cell. The CV tests (FIGS. 18A, 18B, 18C, and 18D) and GITT (FIGS. 18E, 18F, 18G, and 18H) were conducted to identify the effect of the coating layer on the Li⁺ diffusivity. Both results show that the DP 17 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 cathode has a bit lower diffusivity than the control electrode while the DP anode shows similar diffusivity as the control electrode. The diffusivity results could be explained by the hindering of Li⁺ solid diffusion by the surface coating layer (especially for the spherical NMC particles). (See, e.g., Li, H. et al., Enhancing the performances of Li-ion batteries by carbon-coating: present and future. Chem Commun (Camb) 48, 1201-1217. 10.1039/c1cc14764a (2012)). Thus, the thickness control of the coating layer during mixing could be ameliorated in future research. [0057] Teardown Post-Mortem analysis [0058] After the cycling test, the cross-section of the DP and SL NMC particles was prepared by the Ar⁺ beam polishing. FIGS. 5A and 5B show that both SL and DP cathode show few cracks after the cycling test. The particle cross-section SEM image (FIG. 5E) shows that the carbon/PVDF surface coating layer keeps intact in the DP electrode after 400 cycles, while the cycled particle in the SL cathode (FIG. 5C) is partly detached from the CBD matrix. [0059] Transmission electron microscopy (TEM) was applied to study the surface structural degradation mechanism of the NMC particles after cycling. FIGS. 5D and 5F show the HRTEM images of SL and DP cathode particles after 400 cycles of the 1C/1D cycling test. The inner part of both samples exhibits consistent layer structure, which could be proved by the high magnification HRTEM lattice pattern and Selected Area Electron Diffraction (SAED) pattern. However, the significantly different lattice orientation with the bulk particle and the corresponding SAED pattern shows a typical disorder spinel structure on the surface of cycled SL cathode particles (FIG.5D). (See, e.g., Ma, X. et al., Recycled cathode materials enabled superior performance for lithium-ion batteries. Joule 5, 2955- 2970. 10.1016/j.joule.2021.09.005 (2021)). In contrast, the surface of the cycled DP cathode particle keeps the layer structure, proved by its consistent lattice orientation and the same SAED pattern as the bulk particle (FIG. 5F). From the TEM image, the close- coated carbon layer can also be observed on the surface of the DP cathode particle, which isolated the NMC surface from the electrolyte effectively and prevented the side reaction and further structural degradation. [0060] XPS measurement results of the cycled electrodes are shown in FIGS. 6A and 6B for the surface composition analysis. FIG. 6A demonstrates the XPS spectrum for the cathode CEI layer after cycling. The CF2 at ~688.3 eV in the F1s spectra represents the 18 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 PVDF binder on the surface, which is under the CEI layer. The DP cathode has a significantly higher CF₂ peak area (52.55%) than the SL cathode (28%), which comes from the PVDF in the surface coating layer. The DP cathode also shows a noticeably higher LiF: Li_xPO_yF_z ratio than the SL cathode, which represents a more stable CEI that can protect the cathode particles. (See, e.g., Phillip, N.D. et al., Influence of Binder Coverage on Interfacial Chemistry of Thin Film LiNi0.6Mn0.2Co0.2O2 Cathodes. Journal of The Electrochemical Society 167. 10.1149/1945-7111/ab78fc (2020)). The higher intensity of the CF2 peak at~291 eV was also detected in the C1s spectra for the DP cathode, which shows a good agreement with the CF₂ peak analysis in the F1s spectra. The transition metal oxide (M-O) signal from NMC particles results in a peak at ~529.7 eV in the O1s spectrum. The intensity of the M-O bond signal that penetrates through the CEI layer could indicate the thickness of the CEI layer. (See, e.g., Phillip, N.D. et al., Influence of Binder Coverage on Interfacial Chemistry of Thin Film LiNi0.6Mn0.2Co0.2O2 Cathodes. Journal of The Electrochemical Society 167. 10.1149/1945-7111/ab78fc (2020)). A significant M-O peak could be observed from the DP cathode even with the coating layer while there is no M-O signal could be detected for the SL cathode. This sharp contrast proves that the CEI layer in the DP cathode is thinner than the SL cathode, which is corresponding to better cycling stability. (See, e.g., Ahn, J. et al., Enhancing the cycling stability of Ni-rich LiNi0.83Co0.11Mn0.06O2 cathode at 4.5 V via 2,4-difluorobiphenyl additive. Journal of Power Sources 512.10.1016/j.jpowsour.2021.230513 (2021)). The composition of the SEI layer is also studied to analyze the stability of the anode (FIG.6B). The C1s and F1s spectra of both anodes show a similar trend. The high LiF: Li_xPO_yF_z ratio indicates that both anodes have a LiF-dominated SEI layer. The Li2CO3 peak at ~ 531.6 eV in the O1s spectra displayed a higher intensity in the DP anode than the SL anode, representing more of the inorganic compound in the DP anode SEI, which could benefit the stability of the SEI. (See, e.g., Bhattacharya, S. et al., Electrochemical cycling behaviour of lithium carbonate (Li2CO3) pre-treated graphite anodes – SEI formation and graphite damage mechanisms. Carbon 77, 99-112. 10.1016/j.carbon.2014.05.011 (2014); Qin, N. et al., Over‐Potential Tailored Thin and Dense Lithium Carbonate Growth in Solid Electrolyte Interphase for Advanced Lithium Ion Batteries. Advanced Energy Materials. 10.1002/aenm.202103402 (2022)). [0061] The XRD patterns of both SL and DP cathodes are carried out before and after cycling tests (FIGS. 20A-20D). The structural parameters calculated from the XRD 19 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 refinement are shown in the table of FIG.9. The lattice parameters are almost the same for both pristine electrodes as we use the same commercial cathode powder. After cycling, both DP and SL cathode show shrinkage along the a-axis and expansion along the c-axis compared with the pristine powder. (See, e.g., Ma, X. et al., A universal etching method for synthesizing high-performance single crystal cathode materials. Nano Energy 87. 10.1016/j.nanoen.2021.106194 (2021)). The DP cathode has a similar c-axis expansion rate compared with the SL cathode (1.67% vs 1.7%). However, the a-axis shrinkage of the DP cathode (1.43%) is smaller than the SL cathode (1.57%). The variation of lattice parameters could lead to a change in unit cell volume, increase the pressure between the primary particles, and further cause cracks in the cathode particles. (See, e.g., Ma, X. et al., Recycled cathode materials enabled superior performance for lithium-ion batteries. Joule 5, 2955-2970. 10.1016/j.joule.2021.09.005 (2021)). The less volume change and lattice distortion in the DP cathode particles are aligned with the better cycling stability and the less surface phase transformation in the TEM results. [0062] Modeling [0063] To gain additional insights into the correlation between electrode tortuosity and the cell charging performance, pseudo-2D simulations were performed for the charging process of NMC/graphite full cells consisting of different combinations of DP and SC electrodes. Among various electrode and electrolyte properties, the electrode porosity, tortuosity, particle size, and Li solid diffusivity are obtained from measurements while others are from literature. DP and SC electrodes only differ in their tortuosities in simulations. As shown in FIG. 7A, the cell consisting of the DP electrodes possesses the best CC charging capacity at all the C rates, the cell based on SC electrodes has the worst, and those with mixed DP and SC electrodes exhibit intermediate performance. The 4C fast charging capacities of the dry (DC-DA) and wet (SC-DA) cells show a notable difference (~10%), which is comparable to the experiment. FIG. 7B shows that the lower tortuosity of the DP electrodes results in smaller lithium salt concentration gradients within the dry cell, especially in the cathode region. This helps reduce the potential drop in the electrolyte and extend the CC charging process before reaching the cutoff potential (4.2 V). [0064] The process described herein was therefore used to develop the industry-level DP electrodes with the dry-printing roll-to-roll system. The DP electrodes produced by the high-efficiency solvent-free manufacturing method exhibit better performance than the 20 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 commercial standard SL electrodes. The analysis proves that the specific microstructure of the DP electrodes can lead to significantly lower tortuosity (2.74 vs.3.8 for cathodes) with a faster ionic diffusion path. These advantages helped the dry-printed battery to achieve almost 70% capacity at 4C constant current fast charging, which is much higher than the 52% from the slurry cast control cell. The surface PVDF/C65 coating layer can also protect the cathode surface from the erosion of the electrolyte side reactions, resulting in better cycle stability. Combining with the nanotomography and modeling results, is was discovered that the porous CBD phase caused by the swelling of binder polymer chains during drying (NMP evaporation) in the SL electrodes can lead to higher tortuosity and impede Li⁺ diffusion, while the open pores in the DP electrodes can provide a shorter Li⁺ pathway. Thus, the morphology of the CBD phase plays an important role in the electrode structure design, which proves the importance of the novel manufacturing methods beyond the conventional slurry cast method. Besides these electrode properties, dry-printing manufacturing is a cost-efficient and eco-friendly method and can be scaled up easily. The solvent-free manufacturing processes are also compatible with next-generation batteries, especially the solid-state battery (SSB), and have already attracted the focus of the industry. The dry-printing method can therefore lead a way for the industrial revolution in future battery production and provide more competitive battery products. [0065] EXPERIMENTAL PROCEDURES [0066] Materials availability: The study did not generate new unique reagents. Data and code availability: The study did not generate any datasets. [0067] Electrode preparation [0068] The fabrication process for DP anode and cathode is similar. The commercial graphite was used as the anode active material and the NMC622 was used as the cathode active material, for both anode and cathode. PVDF was used as the binder and Super C65 conductive carbon black was used as the conductive additives. The active materials (90% by weight), binder (5% by weight), and conductive additives (5% by weight) were dry mixed to form the mixture. The mixture powder was sprayed electrostatically onto the grounded current collector foil (copper foil for anode fabrication, aluminum foil for cathode fabrication). The electrode loading was controlled by spray time and spray rate, when the loading reached the desired value, as-deposited electrodes were thermally activated. The 21 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 bonding was improved, and for rollers pressing, electrode porosity was tuned by changing the gap between the two rollers to decrease the porosity. [0069] The slurry cast control group electrodes were from Microvast Inc. The slurry used N-Methyl-2-pyrrolidone (NMP) as solvent, and the materials, electrode loadings and properties were targeted to match the dry printed electrodes. [0070] Electrode characterization [0071] The structural parameters of the cathode before and after the cycle were tested by X-ray diffraction (XRD, PANalytical Empyrean Series 2) with Cu tube Kα radiation (45 kV, 40 mA) and then calculated by FullProf Suite software. The microstructure of the electrodes and surface morphology of the particles was measured by the scanning electron microscope (SEM, JEOL JSM 7000 F). XPS analysis was conducted using a PHI 5000 VersaProbe II System (Physical Electronics). The spectra were obtained using Al Ka radiation (ℎ_^= 1,486.6eV) (100 mm2 area, 25 W). The Raman spectra was measured by a Raman microscopy (Horiba Xplora). The ion-polished electrode cross-section was prepared with JEOL IB-19530CP Cross Section Polisher (Tokyo, Japan). The TGA/DSC were tested by an SDT650 (TA Instruments). 10mg of electrode materials were heated to room temperature to 900℃ by 10℃/min. The pore size distribution was tested with MicroActive AutoPore V 9600 mercury porosimeter. 1g of electrodes were cut into small pieces to fit in a 5.87mL penetrometer. The pressure range is from 0.1-50000 psia. [0072] Electrical conductivity test [0073] The electrical conductivity was tested through a two-point contact method. The resistance was first measured by the lab-assembled equipment. 3lbs was applied to a one- inch copper cylinder and the resistance of the electrode was measured by a high-sensitive resistance meter (EXTECH 380560). The conductivity σ was then calculated from Equation 1: ^ = ^{^} ^_∙^ (1) where ^ represents the thickness of the electrodes, ^ is the resistance, and ^ is the contact area. [0074] Tortuosity test [0075] Two pieces of 1x1 cm square electrodes were assembled in CR2032 coin cells in an argon-filled glovebox to form a symmetrical cell. 10 mM TBAClO4 (Sigma) in EC: 22 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 DMC (1:1 w: w) was used as a blocking electrolyte and a glass fiber (Whatman, GE) was adopted as the separator. The electrochemical impedance spectroscopy (EIS) was tested over the frequency range between 100 kHz and 10 mHz with an amplitude of 10 mV by a Bio-Logic VMP3 electrochemical analyzer. The EIS curves were then fitted with the simplified transmission-line model (TLM-Q) by EC-lab software with Equation 2 to calculate the ionic resistance of R_ion. Z = ^ ^{^^^^} ^_(^^)^ coth("#($%)^&R_^()) (2) where and

γ is w unit. [0076] The tortuosity τ of the electrode can be obtained by Equation 3: τ = ^{^^^^^,-} ._/ (3) where is the

area, mS/cm) and 3 is the porosity of the electrode. [0077] Tomography and tortuosity calculation [0078] Tomography characterization was conducted at beamline 18-ID of National Synchrotron Light Source II, Brookhaven National Lab. DP and SL cathodes were cut into strips of ~300 μm wide and ~10 mm long and mounted on the sample stage. The surface of the current collector is perpendicular to the X-ray beam direction, which helps to define the position of the electrode surfaces in the CCD camera field of view. The incident beam energy is 8.5 keV, which is above the Ni K edge (8.3 keV). Samples were rotated at a speed of 4 degrees per second over a range of 180 degrees; meanwhile, the projection images were recorded by the detector. Each scan provides a field of view of 40 × 40 × 40 μm³ and a pixel spatial resolution of 40 nm. Multiple scans were carried out along the electrode depth direction with an overlap of 30 μm to cover the entire electrode thickness (~100 μm) and also in the lateral direction to increase the total volume characterized.3D tomography images were reconstructed from the projection radiographs using the open-source Python library PyXAS. (See, e.g., Ge, M., and Lee, W.K. (2020). PyXAS - an open-source package for 2D X-ray near-edge spectroscopy analysis. J Synchrotron Radiat 27, 567-575. 10.1107/S1600577520001071 (2021)). Images from different scans are stitched together to form a representative electrode region of 0.9 – 1.2 × 10⁶ μm³. The reconstructed images 23 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 were pre-processed by a Gaussian blur filter (2 pixels) and then binarized into the active material vs pore regions using the Huang thresholding method. (See, e.g., Huang, L. et al., Image thresholding by minimizing the measures of fuzziness. Pattern Recognition Volume 28, Pages 41-51, https://doi.org/10.1016/0031-3203(94)E0043-K (1995)). [0079] The binarized images of DP and SL cathodes were visualized in Avizo. Features with fewer than 100 voxels are treated as noise and removed from the structures. Electrode porosity was calculated by counting the volume of the pore region against the total electrode volume. Tortuosity measurements were performed on the binarized image data using PyTrax, which calculates the tortuosity by simulating random walks in the pore space. (See, e.g., Tranter, T.G. et al., pytrax: A simple and efficient random walk implementation for calculating the directional tortuosity of images. SoftwareX 10. 10.1016/j.softx.2019.100277 (2019)). The electrode tortuosity along axis z is evaluated as Equation 4: ^₄ = ⁵ 3_{<82 4>} (4) where

of random walkers in the z-direction (assuming step size is equal to 1). The convergence of the computed tortuosity value was confirmed by increasing N and the number of random walkers in simulations. [0080] Electrochemical tests [0081] The anode and cathode for pouch cells were stacked in the ambient environment. Assembled pouch cells were transferred to a vacuum oven for overnight drying, followed by adding electrolyte (Gotion LP57, 1M LiPF6 in EC/EMC 3:7) and final sealing in the glove box. Arbin battery testing system with model number LBT21084 was used for all single-layer pouch cell testing at room temperature. The rate performance testing protocols include various C-rates charge (0.33C, 0.5C, 1C, 2C, 3C, 4C), followed by a CV 15min cut-off, and 0.33C discharge (2.7 - 4.3V). The 1C charge and discharge cycling (2.7 - 4.3V) was tested with 1C charging with a CV step until the current reached C/20 and then discharged at 1C. A 0.1C charge/discharge cycle was run every 50 cycles at the checkpoint. The HPPC test followed an ANL testing protocol (see SI) from 2.7-4.25 V. The HPPC power capability was calculated with a battery size factor (BSF) = 335,000 at 45kWh removed. 24 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 [0082] Pouch cell teardown analysis: The structural change after cycling was analyzed by high-resolution transmission electron microscopy (TEM, JEOL 2010F). [0083] Modeling [0084] A detailed description of P2D simulation has been discussed in the literature. (See, e.g., Fuller, T.F. et al., Simulation and Optimization of the Dual Lithium Ion Insertion Cell. Journal of The Electrochemical Society 141, 1-10 (1994); Doyle, M. et al., Modeling of Galvanostatic Charge and Discharge of the Lithium/Polymer/Insertion Cell. Journal of The Electrochemical Society 140, 1526-1533 (1993); Ferguson, T.R. et al., Nonequilibrium Thermodynamics of Porous Electrodes. Journal of The Electrochemical Society 159, A1967-A1985. 10.1149/2.048212jes (2012)). Electrode parameters used in this study are listed in the table of FIG. 9. Transport properties of electrolyte LiPF6 in EC/EMC 3:7 are concentration-dependent as measured by Landefeind and Gasteiger. (See, e.g., Landesfeind, J. et al., Temperature and Concentration Dependence of the Ionic Transport Properties of Lithium-Ion Battery Electrolytes. Journal of The Electrochemical Society 166, A3079-A3097. 10.1149/2.0571912jes (2019)). The analytical expressions of electrolyte diffusivity ;_<, conductivity 2, transference number =_> and thermodynamic factor ^{? @AB±} ? _{@A DE} are represented by Equations 5-8: ;_F = 1.01 × 10⁻⁷ · exp(1.01P_F) exp Q^{−1560 −487} T Uexp Q _T · P_FU (m²/s) (5)

^ab·cdeQ^fggg UU·D 2 = · + − · · ^{[^} _{h E} (S/m) (6)

= ^{= −12.8 − 6.12P + 0.0821T + 0.9 2 −4 2 + F 04PF +0.0318PF · T − 1.27 × 10 T +} _{0.0175P3 −3.12 × 10−3P2 · T − 3. −5 2 F F 96 × 10 PF · T} (7) m lnp_± = ^{25.7 − 45.1P −0.177T + 1.94P2 + 0.295P · −4 2 F F F T − 3.08 × 10 T +} × _{10−3P · T − 4. −4}

_{F 54 × 10 P ·} The simulation was run under an isothermal condition with T = 298K. [0085] The equilibrium potential of NMC was measured in a half-cell. The equilibrium potential of graphite was adopted from the literature (see Amin, R. et al., Characterization of Electronic and Ionic Transport in Li1-xNi0.33Mn0.33Co0.33O2(NMC333) and Li1- 25 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 xNi0.50Mn0.20Co0.30O2(NMC523) as a Function of Li Content. Journal of The Electrochemical Society 163, A1512-A1517.10.1149/2.0131608jes (2016)) as Equation 9: r_st,v)(w) = 0.124 + 1.5 exp( − 70w) − 0.0351 tanh( ^{y^^..k\ y^^.} ^_{.^k_} ) − 0.0045 tanh( <sup>`</sup> ^<sub>.[[`</sub>) − 0.035 tanh( ^{y^^.`` y^^.^ y^^.[`j} ^_.^^ ) − 0.0147 tanh(_{^.^_j}) − 0.102 tanh( _^.[j. ) − 0.022 tanh(

− 0.011 tanh( ^{y^^.[.j} ) + 0.0155 tan ^{y^^.[^^} ^_.^..\ h( _^.^.` ) (9) [0086] SUPPLEMENTAL INFORMATION [0087] ANL HPPC test protocols [0088] Charge the cell at C/3 rate to Vmaxop (4.25 V). Constant voltage charge until the current reaches the C/20 rate. [0089] Allow resting for 1 hr. [0090] Discharge the cell at C/3 rate to Vmin0 (2.7 V). [0091] Charge the cell at C/3 rate to Vmaxop (4.25 V). Constant voltage charge until the current reaches the C/20 rate. [0092] Allow resting for 1 hr. [0093] Perform the low-current HPPC test on all groups starting at Vmaxop (4.25 V) at 30°C. The test was performed using a peak 1C discharge. [0094] The HPPC pulse consists of: 1 C discharge (0.045 A) for 30 seconds, 40 second rest, and 0.75C (0.034 A) for 10 seconds. [0095] All HPPC pulses were followed by a remove 10% capacity step at C/3 and a 1- hour rest prior to the subsequent HPPC discharge step. [0096] While exemplary embodiments have been described herein, it is expressly noted that these embodiments should not be construed as limiting, but rather that additions and modifications to what is expressly described herein also are included within the scope of the invention. Moreover, it is to be understood that the features of the various embodiments described herein are not mutually exclusive and can exist in various combinations and 26 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 permutations, even if such combinations or permutations are not made express herein, without departing from the spirit and scope of the invention. 27 ^{ME1 47592150v.1}

Claims

Attorney Docket No.137174.00034 CLAIMS: 1. An electrode fabricated using a solvent-free process, the electrode comprising: a substrate including a dry mixture of active materials, binder, and conductive additives electrostatically sprayed onto the substrate, thermally activated, and bonded to the substrate; wherein the binder and the conductive additives form conductive binder agglomeration clusters; wherein the binder and the conductive additives uniformly cover a surface of the active materials; wherein the binder is uniformly distributed in a thickness direction of the electrode; wherein the electrode includes pores between the active materials that are both micro-size pores and submicron-size pores; and wherein the micro-size pores are open pores that allow electrolyte to diffuse. 2. The electrode of claim 1, wherein the dry mixture of the conductive additives and the binder form a coating layer on the active materials. 3. The electrode of claim 1, wherein the pores between the active materials increase an electrolyte wettability and enhance a Li⁺ exchange contact interface between the active materials and electrolyte phases. 4. The electrode of claim 1, wherein the conductive binder agglomeration clusters formed by the binder and the conductive additives bridge the active materials. 5. The electrode of claim 1, wherein the binder and the conductive additives uniformly covering the surface of the active materials form a coating layer thickness on the active materials of about 200 nm or less. 6. The electrode of claim 1, wherein a cathode of the electrode has a tortuosity of about 2.74. 7. The electrode of claim 1, wherein an anode of the electrode has a tortuosity of about 3.28. 8. The electrode of claim 1, wherein the electrode exhibits a cycling stability with 28 ^{ME1 47592150v.1} Attorney Docket No.137174.00034 77.6% capacity retained at a 400^th cycle. 9. The electrode of claim 1, wherein the electrode exhibits a charge capacity retention of 77.6% at 3C and 68.5% at 4C. 10. The electrode of claim 1, wherein the electrode exhibits peak shifting of about 0.255V. 11. The electrode of claim 1, wherein the active materials include an anode active material and a cathode active material. 12. The electrode of claim 11, wherein the anode active material is at least one of graphite, or silicon. 13. The electrode of claim 11, wherein the cathode active material is at least one of nickel-rich nickel manganese cobalt (NMC622), lithium cobalt oxide (LCO), lithium nickel manganese cobalt oxide (NMC), lithium manganese oxide (LMO), lithium iron phosphate (LFP), or lithium nickel cobalt aluminum oxide (NCA). 14. The electrode of claim 1, wherein the binder is at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), SBR, other polymer(s), or combinations thereof. 15. The electrode of claim 1, wherein the conductive additives include Super C65 conductive carbon black, carbon nanotube, graphene, or a mixture thereof. 16. The electrode of claim 1, wherein the dry mixture includes >90% by weight of the active materials, <5% by weight of the binder, and <5% by weight of the conductive additives. 29 ^{ME1 47592150v.1}