WO2020019036A1

WO2020019036A1 - Photo-rechargeable battery

Info

Publication number: WO2020019036A1
Application number: PCT/AU2019/050784
Authority: WO
Inventors: Yuxiang Hu; yang BAI; Lianzhou Wang
Original assignee: University of Queensland UQ
Current assignee: University of Queensland UQ
Priority date: 2018-07-26
Filing date: 2019-07-25
Publication date: 2020-01-30
Anticipated expiration: 2021-01-26

Abstract

A photo-rechargeable battery, including a photovoltaic component and a battery component. The photovoltaic component and the battery component are both formed on a common substrate and are integrated. The battery component includes a metal battery having a metal anode, and the photovoltaic component includes a plurality of perovskite photovoltaic cells interconnected in series to provide a relatively high voltage for charging the metal battery; and the photovoltaic component includes a metal electrode and is electrically interconnected to the metal battery by the metal electrode, which also constitutes the metal anode of the metal battery.

Description

PHOTO-RECHARGEABLE BATTERY

Background of the Invention

[0001] The present invention relates to photovoltaic technology and to rechargeable battery technology, and in particular to a photo-rechargeable battery, and a process for producing a photo-rechargeable battery.

Description of the Prior Art

[0002] The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as an acknowledgment or admission or any form of suggestion that the prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates.

[0003] The ever-increasing consumption of energy, environmental concerns, the widespread popularity of portable electronics and the Internet of Things (IoTs), and the increasing popularity of electric vehicles (EVs) are driving the pursuit of new-generation renewable power sources that have sustained and efficient output, mobility and flexibility, at practical cost. Despite the substantial progress achieved in the development of energy generation systems such as photovoltaic (PV) devices, fuel cells, and thermoelectric generators, and energy storage systems such as metal-ion batteries and supercapacitors, none of these systems alone is able to meet the diverse energy demands of society.

[0004] The integration of energy generation and energy storage systems is increasingly recognized as an ultimate solution to address the formidable challenges described above. Amongst the various integrated systems that have been investigated, photo-rechargeable batteries have been proposed as one of the most promising next-generation power sources with high sustainability and mobility, considering that solar energy is the most abundant and clean energy source on Earth kinder light illumination, photo-rechargeable batteries can continuously generate electricity using PV devices, and store the generated electrical energy in the batteries, which not only resolves the energy storage issues of PV devices, but also eliminates the energy source concerns of batteries. Although conceptually promising, critical issues such as low overall photoelectric conversion/storage efficiency (PCSE), particularly when illuminated under ambient or weak light, and poor cycling stability need to be solved before such integrated system can be widely adopted.

[0005] It is desired to provide a photo-rechargeable battery and process that alleviate one or more difficulties of the prior art, or that at least provide a useful alternative.

Summary of the Present Invention

[0006] In accordance with some embodiments of the present invention, there is provided a photo-rechargeable battery, including: a photovoltaic component; and a battery component; wherein the photovoltaic component and the battery component are both formed on a common substrate and are integrated; wherein the battery component includes a metal battery having a metal anode, and the photovoltaic component includes a plurality of perovskite photovoltaic cells interconnected in series to provide a relatively high voltage for charging the metal battery; and wherein the photovoltaic component includes a metal electrode and is electrically interconnected to the metal battery by the metal electrode, which also constitutes the metal anode of the metal battery.

[0007] In one embodiment the metal battery is at least one of: an aluminium battery; a lithium battery; a sodium battery; a magnesium battery; a zinc battery; and, an iron battery; and, the metal electrode is at least one of: an aluminium electrode; a lithium electrode; a sodium electrode; a magnesium electrode; a zinc electrode; and, an iron electrode.

[0008] In one embodiment the metal electrode and the metal battery include the same metal.

[0009] In some embodiments, the metal battery is an aluminium-ion battery, and the metal electrode is an aluminium electrode.

[0010] In some embodiments, the plurality of perovskite photovoltaic cells is three perovskite photovoltaic cells to provide the photovoltaic component with an output voltage in excess of 3.0 volts. [0011] In some embodiments, the common substrate is a glass substrate. In some embodiments, the common substrate is a flexible polymer substrate.

[0012] In some embodiments, the perovskite photovoltaic cells are formed from a stack of layers, including a patterned transparent and electrically conductive layer on a transparent substrate, a hole transport layer on the patterned transparent and electrically conductive layer, a perovskite layer on the hole transport layer, an electron transport layer on the perovskite layer, an insulating buffer layer on the electron transport layer, and a metal layer on the buffer layer.

[0013] In some embodiments, the hole transport layer is composed of poly(bis(4- phenyl)(2,4,6-trimethylphenyl)amine) (PTAA).

[0014] In some embodiments, the electron transport layer is composed of [6,6]-Phenyl C61 butyric acid methyl ester.

[0015] In some embodiments, the buffer layer is composed of bathocuproine.

[0016] In some embodiments, the photovoltaic component of integrated perovskite photovoltaic cells achieves a photovoltaic conversion efficiency (PCE) of at least 18.5%.

[0017] In some embodiments, the photo-rechargeable battery achieves an overall photovoltaic conversion/storage efficiency (PCSE) of at least 12%.

[0018] In some embodiments, the aluminium-ion battery has a graphite-based cathode, a discharge capacity at least 80 mAh g ¹ at 0.5 C-rate, and at least 75 mAh g ¹ at 20 C-rate.

[0019] In some embodiments, the aluminium-ion battery has an energy storage efficiency (ESE) of at least 79% at 0.5 C-rate.

[0020] In accordance with some embodiments of the present invention, there is provided a photo-rechargeable battery production process, including: forming a photovoltaic component and a battery component on a common substrate; wherein the battery component includes a metal battery having a metal anode, and the photovoltaic component includes a plurality of perovskite photovoltaic cells interconnected in series to provide a relatively high voltage for charging the metal battery; and integrating the photovoltaic component and the battery component by forming a metal electrode to electrically interconnect the photovoltaic component and the battery component, wherein the metal electrode constitutes both an electrical contact of the photovoltaic component and the metal anode of the metal battery.

[0021] In some embodiments, the plurality of perovskite photovoltaic cells is three perovskite photovoltaic cells to provide the photovoltaic component with an output voltage in excess of 3.0 volts.

[0022] In some embodiments, the step of forming the photovoltaic component and the battery component on the common substrate includes depositing a layer of metal and patterning the deposited layer of metal to form electrical interconnections between the perovskite photovoltaic cells and the metal battery.

[0023] In one embodiment the metal battery is at least one of: an aluminium battery; a lithium battery; a sodium battery; a magnesium battery; a zinc battery; and, an iron battery; and, the metal electrode is at least one of: an aluminium electrode; a lithium electrode; a sodium electrode; a magnesium electrode; a zinc electrode; and, an iron electrode.

[0024] In one embodiment the metal electrode and the metal battery include the same metal.

[0025] In some embodiments, the metal battery is an aluminium-ion battery, and the metal electrode is an aluminium electrode.

[0026] In some embodiments, the step of forming the photovoltaic component on the common substrate includes: forming a patterned transparent and electrically conductive layer on a transparent substrate; forming a hole transport layer on the patterned transparent and electrically conductive layer; forming a perovskite layer on the hole transport layer; forming an electron transport layer on the perovskite layer; forming a graphitic carbon layer on the electron transport layer; forming an electrically insulating buffer layer on the graphitic carbon layer; and forming a metal layer on the buffer layer.

[0027] In some embodiments, the hole transport layer is composed of poly(bis(4- phenyl)(2,4,6-trimethylphenyl)amine) (PTAA). [0028] In some embodiments, the electron transport layer is composed of [6,6]-Phenyl C61 butyric acid methyl ester and C60.

[0029] In some embodiments, the buffer layer is composed of bathocuproine.

[0030] In accordance with some embodiments of the present invention, there is provided a photo-rechargeable battery, including: a photovoltaic component; and a battery component; wherein the photovoltaic component and the battery component are both formed on a common substrate and are integrated; wherein the battery component includes an metal battery having a metal anode, and the photovoltaic component includes a plurality of photovoltaic cells interconnected to provide a voltage for charging the metal battery; and wherein the photovoltaic component includes a metal electrode and is electrically interconnected to the metal battery by the metal electrode, which also constitutes the metal anode of the metal battery.

[0031] In accordance with some embodiments of the present invention, there is provided a photo-rechargeable battery production process, including: forming a photovoltaic component and a battery component on a common substrate; wherein the battery component includes an metal battery having a metal anode, and the photovoltaic component includes a plurality of photovoltaic cells interconnected in series to provide a voltage for charging the metal battery; and integrating the photovoltaic component and the battery component by forming a metal electrode to electrically interconnect the photovoltaic component and the battery component, wherein the metal electrode constitutes both an electrical contact of the photovoltaic component and the metal anode of the metal battery.

[0032] In one embodiment the metal battery is at least one of: an aluminium battery; a lithium battery; a sodium battery; a magnesium battery; a zinc battery; and, an iron battery; and, the metal electrode is at least one of: an aluminium electrode; a lithium electrode; a sodium electrode; a magnesium electrode; a zinc electrode; and, an iron electrode.

[0033] In one embodiment the metal electrode and the metal battery include the same metal.

[0034] |In[YH l ][DCC2] some embodiments, the metal battery is an aluminium-ion battery, and the metal electrode is an aluminium electrode. [0035] It will be appreciated that the broad forms of the invention and their respective features can be used in conjunction and/or independently, and reference to separate broad forms is not intended to be limiting.

Brief Description of the Drawings

[0036] Various examples and embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

[0037] Figure 1 includes (a) a schematic illustration of a photo-rechargeable battery in accordance with an embodiment of the present invention; (b) a block diagram showing major components of the photo-rechargeable battery; and (c) a photograph of the actual photo- rechargeable battery;

[0038] Figure 2 includes a) a plan-view SEM image of a MAPbR film on a PTAA-coated ITO (Indium tin oxide) substrate; and b) a cross-sectional SEM image of a single photovoltaic cell;

[0039] Figure 3 includes a) a J-V curve and b) an EQE curve (the integrated current density is 22.45 mA cm ²) of a single photovoltaic cell;

[0040] Figure 4 is a plan view of a mask for patterning an ITO layer to define the ITO electrodes of the integrated photovoltaic module;

[0041] Figure 5 is a graph showing the steady-state photocurrent and efficiency at the maximum power point (2.62 V) of the integrated photovoltaic module;

[0042] Figure 6 includes histograms of the statistical distributions of a) photo conversion efficiency (PCE) and b) Foe of the described integrated photovoltaic modules (35 samples);

[0043] Figure 7 includes a) X-ray diffraction (XRD) and b) Raman spectra of graphitic cathode material;

[0044] Figure 8 includes a), b) Scanning electron microscopy (SEM) and c), d) transmission electron microscopy (TEM) images of a thin graphitic carbon film cathode; [0045] Figure 9 demonstrates the electrochemical performance of individual aluminium-ion battery and integrated photovoltaic module components of the photo-rechargeable battery, and includes: (a) a J-V curve of the perovskite solar module (PSM) system with the corresponding data (./.sc, Voc , fill factor (FF) and PCE), (b) lst, 5th, and 50th charge and discharge curves of AIB at a 0.5 C rate (41 mA g ¹), (c) Charge-discharge capacities and corresponding energy storage efficiency (ESE) of the aluminium-ion battery under increasing current density from 0.5 C to 20 C rate, and (d) Long-term cycling of charge-discharge capacities and ESE of the AIB at 10 C-rate;

[0046] Figure 10 demonstrates the performance of the integrated photo-rechargeable battery, and includes: (a) photo-charging curves (red) by PSM and galvanostatically discharging curves (black) of the battery within ten-times cycling (b) the PCE (rp) of the PSM and overall efficiency (PCSE, h₂) before and after cycling measurement (c) Overall efficiencies (PCSE, rp) comparison of reported solar harvest-storage devices, including dye-sensitized solar cell (DSSC)-supercapacitor (DSSC-SC), DSSC-LIB, Silicon solar cell-LIB (Silicon-LIB), PSCs- LIB, with the described photo-rechargeable battery;

[0047] Figure 11 includes a) J-V curves, b) Foe, c) fill factor of the cycling tested photovoltaic modules of the integrated device and d) discharging capacity of the battery of the integrated device during cycling measurement;

[0048] Figure 12 demonstrates the performance of the photovoltaic module and the integrated device subject to daily light intensity variations, and includes: (a) PCE of a certified silicon solar cell illuminated by different light intensities (blue line); the red line displays the metabolic sunlight intensity at different times of a selected day at the St Lucia Campus of the University of Queensland (inset figure); (b) overall PCSE of the integrated device (red line) and the PCE of the integrated photovoltaic module (blue line);

[0049] Figure 13 includes J-V curves of a) the photovoltaic module and b) a certified silicon solar cell under various light intensity;

[0050] Figure 14 includes a photovoltaic cell photo-charging curves (red) and galvanostatically discharging curves (black) of the integrated device under conditions of a) increased light intensities 20 mW cm ² (0.2 Sun), 50 mW cm ² (0.5 Sun), 75 mW cm ² (0.75 Sun), 100 mW cm ² (1.0 Sun) and d) reduced light intensities 75 mW cm ² (0.75 Sun), 50 mW cm ² (0.5 Sun), 20 mW cm ² (0.2 Sun);

[0051] Figure 15 is a histogram showing PCE (hi) and overall PCSE (h₂) variation of the integrated device under drastic changing light intensities.

Detailed Description of the Preferred Embodiments

[0052] Embodiments of the present invention include a photo-rechargeable battery that has unprecedented performance relative to prior art photo-rechargeable batteries by using interconnected perovskite photovoltaic cells as the energy source component, a metal battery as the energy storage component, and tightly integrating these components by forming and interconnecting them on a common substrate, wherein a contact electrode of the solar cells is formed from metal, and also constitutes the anode of the metal battery.

[0053] The perovskite photovoltaic cells can be formed from one or more perovskite materials, including organic-inorganic perovskites, inorganic perovskites, double perovskites, and/or lead-free perovskites, for example.

[0054] The metal battery can be any of a variety of different metal battery types, including batteries based on the metals aluminium, magnesium, zinc, or iron, for example, and may or may not be a metal-ion battery. For example, an aluminium-air/sulfur battery is not a metal- ion battery, but is a type of metal battery.

[0055] In one particular example, the photovoltaic cells include a series of perovskite photovoltaic cells, and the metal is aluminium. This combination of features is able to provide a photo-rechargeable battery with a power conversion efficiency of at least 18.5%, an overall photoelectric conversion/storage efficiency (PCSE) in excess of 12% under standard solar illumination (and even higher under weak illumination), and excellent rate capacity and cycling stability, as described below.

[0056] The components and operating principle of a photo-rechargeable battery in accordance with an embodiment of the present invention are illustrated in Figure 1. The battery includes a perovskite photovoltaic module 102 and an aluminium-ion battery 104. Unlike lithium-ion batteries, the aluminium-ion battery 104 is stable over a wide range of temperatures, and is able to handle the relatively high current densities generated by the perovskite photovoltaic module 102. To obtain a sufficient voltage for photo-charging the aluminium-ion battery 104, the photovoltaic module 102 is constituted by a series-connected stack of at least three nominally identical perovskite solar cells 106 to provide a relatively high output voltage of 3.28 V. In general, the photovoltaic module 102 can be constituted by any type or types of perovskite photovoltaic modules or cells that can provide sufficient output voltage for charging the battery 104, including simple perovskite solar cells and monolithic perovskite tandem solar cells, for example. The use of identical solar cells 106 in the stack improves the overall photovoltaic conversion efficiency of the photovoltaic module 102.

[0057] The aluminium ion battery 104 is tightly integrated with the photovoltaic module 102 by using their outermost aluminium electrode of the photovoltaic module 102 as the anode of the battery 104.

[0058] The charge transport pathway and related reactions that occur during the photo charging process are illustrated in Figure lb. During the photo-charging process (with switch Sl closed), the photovoltaic module 102 converts solar energy to electric energy for powering the battery 104. Specifically, electrons generated in the perovskite layer by incident sunlight transfer through an electron transporting material (ETM) and then the outmost metal electrode (dual -functional aluminium electrode) where the electrons directly participate in the anodic reaction of the aluminium-ion battery 104, as shown schematically in Figure lb. The corresponding photo-generated hole transfers through a hole transport material (HTM) to a transparent electrode of the photovoltaic module 102 and is finally neutralized by the electrons from the cathode of the battery 104.

[0059] In the described embodiments, the electron transport material is composed of P[6,6]- Phenyl C61 butyric acid methyl ester (PCBM); however, one or more other electron transport materials may be used in other embodiments, including CBM, C60, and/or ZnO, for example. Other suitable electron transport materials and combinations thereof will be apparent to those skilled in the art. [0060] In the described embodiments, the hole transport material is composed of poly(bis(4- phenyl)(2,4,6-trimethylphenyl)amine) (PTAA); however, one or more other hole transport materials may be used in other embodiments, including PEDOT:PSS, NiO, CuSCN, and/or CuGaCh, for example. Other suitable hole transport materials and combinations thereof will be apparent to those skilled in the art.

[0061] In the described embodiments, the transparent electrode is an Indium Tin Oxide (ITO) electrode, but one or more other transparent electrically conductive materials may be used in other embodiments, including FTO or flexible conductive materials such as ITO coated plastics such as Polyethylene naphthalate (PEN) or Polyethylene terephthalate (PET), for example. Other suitable transparent electrically conductive materials and combinations thereof will be apparent to those skilled in the art.

[0062] After photo-charging, the photo-rechargeable battery can be used as a normal battery to release the stored energy. A photograph of a fabricated embodiment of the photo- rechargeable battery is shown in Figure lc.

[0063] In the described embodiments, each of the perovskite photovoltaic cells has a planar heterojunction p-i-n structure consisting of the following stack of layers: indium-doped tin oxide (ITO) conductive electrodes/hole transport materials (HTMs)/perovskite/electron transport materials/metal electrode. The CFFNFFPbl·, (MAPbl·,) perovskite layers were formed on poly(triarylamie) (PTAA)-coated ITO substrates by an anti-solvent assisted one-step deposition method, as described in Chen, H. et al. A Defect-Free Principle for Advanced Graphene Cathode of Aluminium-Ion Battery. Adv Mater 29, doi: l0. l002/adma.20l605958 (2017). As shown in the Figure 2a, it forms smooth and compact perovskite films with average grain size larger than the film thickness. A typical cross-section scanning electron microscopy (SEM) image of the single PSC is shown in Figure 2b.

[0064] To fabricate the perovskite photovoltaic cells, poly(bis(4-phenyl)(2,4,6- trimethylphenyl)amine) (PTAA, to facilitate hole transport) was deposited on pre-patterned ITO/glass substrates by spin-coating 0.2 wt% PTAA in toluene at 4000 rpm for 30 s, followed by annealing at 100 °C for 10 min. A perovskite (MAPbE) precursor solution was prepared as described in Chen, B. et al. Efficient Semitransparent Perovskite Solar Cells for 23.0%- Efficiency Perovskite/Silicon Four-Terminal Tandem Cells. Adv. Energy Mater., doi: 10. l002/aenm.201601128 (2016). Then, the MAPb , precursor solution was spun onto the PTAA hole transport layer at 2000 rpm for 2 s and at 4000 rpm for 20 s. After 10 seconds of spin-coating, the substrates were washed with 300 pL of toluene. Subsequently, the films were annealed at 65 °C for 10 min and at 100 °C for 10 min. [6,6]-Phenyl C61 butyric acid methyl ester (PCBM, to facilitate electron transport) was coated by spin coating 2 wt% PCBM in di chlorobenzene at 6000 rpm for 35 s and then annealing at 100 °C for 30 min. The films were transferred to an evaporation chamber and 20 nm C60, 8 nm of bathocuproine (BCP, buffer layer) and Al were sequentially deposited under vacuum.

[0065] Although the buffer layer is composed of BCP in the described embodiments, it will be apparent to those skilled in the art that one or more other suitable materials can be used in other embodiments, including for example amorphous metal oxides, LiF, and other insulating materials and combinations thereof.

[0066] Figure 3a shows the current density-voltage (J-V) characteristics for a single perovskite photovoltaic cell, having a short-circuit current density (Jsc) of 23.1 mA cm ², an open-circuit voltage (Foe) of 1.1 V, and a fill factor (FF) of 75.4%, yielding a high PCE (rp) of 19.2%. The integral of the external quantum efficiency (EQE) spectrum shown in Figure 3b reached 22.45 mA cm ², which is in good agreement with that extracted from the J-V curve of Figure 3a). ETnlike the prior art approach of interconnecting multiple individual photovoltaic cells via external wires, an (at least nominally) optimal ITO pattern, as shown in Figure 4, was used to produce the high performance perovskite photovoltaic module 102, providing an output voltage over 3.0 V. The miniaturized photovoltaic module 102 was formed by interconnecting three identical perovskite photovoltaic cell formed from the same perovskite film on a common substrate. This strategy significantly improved the cell uniformity and reduced the performance mismatch between the photovoltaic cells in each photovoltaic module 102. In addition, it avoids additional Ohmic resistance as no external electrical wires are used. Benefiting from this low loss, the miniaturized perovskite photovoltaic module 102 delivered a high photovoltage of 3.28 V and a remarkable high PCE of 18.5% extracted from the J-V curve as exhibited in Figure 3a. The steady-state photocurrent and efficiency of the perovskite photovoltaic module 102 measured at the maximum power point (2.62 V) are presented in Figure 5, which confirms the performance parameters extracted from the J-V curve and verifies the absence of photocurrent hysteresis. The statistics of PCE and Voc distributions exhibited in Figure 6 demonstrate the reproducibility and reliability of the high performance photovoltaic module 102.

[0067] Owing to their advantages of enhanced rate-capacity, low-cost, high energy density, and long-cycling stability, graphite materials have been proven as one of the promising cathodes in AIBs. Thin graphitic carbon films (GCF) were prepared by chemical vapor deposition (CVD) and applied as a cathode material coated on gold-coated glasses/polyethylene terephthalate (PET) films. The graphitic carbon film was formed in a tube furnace with a gas supply unit that allows the introduction of liquid carbon sources during CVD growth. Prior to CVD, a Ni foil (thickness: 25 pm, purity: 99.99%, Alfa Aesar) was washed with water and acetone, and then cleaned in a reactive ion etching system (Prog 200 RIE) for 5 min.

[0068] The cleaned Ni foil was loaded into the tube furnace and heated up to 950°C at a rate of l0°C/min, and maintained for 30 min in a N₂/H2 atmosphere (N₂:Fl₂ =95:5 seem) to activate Ni grain growth. Subsequently, the CVD growth of carbon film was triggered by the addition of ethanol along with N₂/H₂ (95:5) at a rate of 100 seem under atmospheric pressure. After reaction for 5 min, the ethanol bubbling was stopped and the furnace was cooled to room temperature under Ar flow. After CVD growth, the as-grown carbon films were released from the Ni foil by chemical etching of Ni with a FeCF, (1 M) solution, followed by rinsing with DI water. The floating carbon film was transferred onto a suitable substrate, namely a Si0₂/Si substrate for characterization, and a gold coated glass or flexible (e.g., PET or other flexible polymer) substrate for electrode fabrication. To obtain higher areal loading, the graphite film was mixed with polytetrafluoroethylene (PTFE) (weight ratio of 9: 1) in DI water, followed by high-vacuum heating at 100 °C overnight.

[0069] The l-ethyl-3-methylimidazolium chloride ([EMIm]Cl, 98%, Sigma) was mixed with anhydrous aluminium chloride (99.99%, Sigma-Aldrich) (mole ratio of 1.3) to obtain the ionic liquid (IL) electrolyte. Glass fibre was applied as the separator (What-man). As described above, the anode electrode (aluminum layer) is also the electron transfer layer of the photovoltaic module 102, and is deposited in an evaporation chamber to ensure it has sufficient thickness.

[0070] The resulting photovoltaic module 102 samples were measured by X-ray diffraction (XRD) (Bruker, D8-Advance X-ray diffractometer, Cu Ka, l = 0.15406 nm). Raman spectra were obtained using a Renishaw Micro-Raman Spectroscopy System at a laser wavelength of 514 nm. Field-emission scanning electron microscopy (FE-SEM) (JEOL-7100), transmission electron microscopy (TEM) and high-resolution TEM (HR-TEM) (FEI F20 FEG-STEM) were applied to characterize the morphology of samples.

[0071] The electrochemical performance of the battery component 102 in isolation and the complete photo-rechargeable battery were tested using a battery tester (LAND-CT2001A). J- V curves of PSCs were evaluated by a Keithley model 2420 digital source meter with a solar simulator (Newport, Oriel Class AAA, 94063 A). The photo-rechargeable battery was photo- charged by a solar simulator. Different light intensities were used, as calibrated by a silicon reference cell with meter (Newport, 91150V) certified by NREL.

[0072] XRD, Raman spectroscopy, SEM, and TEM measurements were performed to characterize the morphology and crystalline structure of the graphitic carbon films, as shown in Figures 7 and 8. As described above, the aluminium electrode of the photovoltaic module 102 also functioned as the anode of the aluminium-ion battery 104. An ionic liquid (IL) electrolyte and glass fibre were applied as the electrolyte and separator, respectively, of the battery. The electrochemical performance of the aluminium-ion battery 104 is shown in Figure 9. The galvanostatic charge and discharge curves were displayed in Figure 9b. A reversible capacity of 82 mAh g ¹ can be achieved at current density of 0.5 C (equivalent to specific current of 41 mA g ¹). The negligible variation in charge-discharge curve of Figure 9b) after 50 cycles demonstrates the excellent reversibility of the battery 104.

[0073] Owing to the drastic shifts in current density under different light intensities, rate- performance is a significant parameter of the battery component in a solar-battery system. The rate-capacity of the aluminium-ion battery 104 was extraordinary stable (Figure 9c) with a retained capacity of around 76 mAh g ¹ under high current density (a“C-rate” of 20 C, being defined as the product of the current and time that the battery can provide when fully charged, in this case being 1640 mA g ¹). Meanwhile, the energy storage efficiency (ESE, h₃) of the battery component in a solar-battery system is critical to its overall photoelectric conversion/storage efficiency. Compared with other reported batteries, the aluminium-ion battery 104 exhibits one of the highest ESE (79% at 0.5 C-rate). Even at a high specific current of 1640 mA g ¹ (20 C), the energy storage efficiency was still maintained above 73%, which contributes to the high overall PCSE of the photo-rechargeable battery. Figure 9d shows long term cycling of the aluminium-ion battery 104 at a specific current of 10 C (or 820 mA g ¹). The charge-discharge capacity remains extraordinary stable during the measurement with a stable corresponding ESE of around 77%.

[0074] After evaluating the individual performance of the perovskite photovoltaic cells and modules 102 and the aluminium-ion battery 104 components above, the synergistic properties of the integrated photo-rechargeable battery was tested under a solar simulator (AM 1.5 G Hz, 100 mW cm ²). In Figure lOa, the aluminium-ion battery 104 was photo-charged by the perovskite photovoltaic module 102 for around 6 minutes (red curves in Figure 2a) over the potential range from around 1.85 V to 2.39 V with comparable stable specific current (7.43- 7.56 mA cm ² and 757-770 mA g ¹, Figure ld). After photo-charging with solar energy, this integrated system functioned as a normal battery for discharging (blue curves in Figure lOa) at a current density of 0.5 C-rate (41 mA g ¹).

[0075] The overall PCSE (h₂) is expressed as a percentage of the system’s output electric energy over the input solar energy, which is a critical evaluation criterion for solar-rechargeable batteries and other solar energy harvesting-storage systems. The overall PCSE is determined by both the solar-to-electricity conversion efficiency in the photovoltaic module 102 and the energy storage efficiency in the battery 104.

[0076] In this work, a high performance photovoltaic module 102 with a record high PCE of around 18.5% guarantees efficient energy conversion. Since the photovoltaic module 102 and battery 104 share the same aluminium electrode, the electric energy from the photovoltaic module 102 is directly delivered to the battery 104 with negligible loss during transmission. Furthermore, the comparable high ESE (h₃) of AIBs also contributes to the overall PCSE (h₂). The total energy conversion- storage efficiency (Figure lOb) of the integrated photo- rechargeable battery is as high as 12.04 %, outperforming other energy systems reported in the literature, including LIBs, Li-air batteries, supercapacitor integrated/series-jointed with various PV components.

[0077] Based on the PCE/PCSE comparison of reported representative solar storage- conversion systems shown in Figure 2c and listed in Table 1 below, the integrated photo- rechargeable battery described herein firstly achieves an overall PCSE above 10%.

[0078] Figure lOb shows the stability of the integrated device after ten cycles of repeated illumination and galvanostatic discharging. Even after ten cycles (AM 1.5 G Hz, 100 mW cm ²), the photovoltaic module 102 only has a slight degradation of its photovoltaic property (92% retention in PCE). The current density and voltage (J-V) curves of the cycled photovoltaic module 102 are shown in Figure 8a with corresponding Jc, Voc , and Fill factor (Figures 8b and 8c). The discharging capacity also remains stable during the cycling test (see Figure 8d). The overall PSCE (h₂) of the integrated device could still achieve 10.38% after ten cycles, corresponding to average of 0.18% reduction in h₂.

[0079] Most prior art reports of solar energy harvesting-storage system are only concerned with and evaluated under standard solar simulator conditions (AM 1.5 GHz, 100 mW cm ²). However, in reality the ambient light conditions dramatically change over time due to weather, climate, and many other factors. A real-time detection of the sunlight intensity on a rooftop of the St Lucia Campus of the University of Queensland (inset Fig. l2a), of the random-picked sunny day (December lst, 2017) is shown in Figure l2a (red curve). Based on these measurements, the light intensity would not only hundredfold change between early morning and midday, but also fluctuates drastically within time frames of only several minutes. Table 1 Comparison of representative reported solar storage-conversion systems.

[0080] The PCE of a certified silicon solar cell, which is widely utilized as a commercial PV device, under daily variational light intensity is shown in Figure l2a. Compared with the PCE of 12.1% under standard light intensity (1 sun, or 100 mW cm ²), the PCE is reduced by around 25 % under 20 mW cm ² light density (9.1%), which results in a substantial decrease of overall PCSE (h₂). In contrast to silicon solar cell and dye-sensitized solar cell (DSSC) based PV devices, whose efficiency is severely influenced by light intensity, perovskite solar cells exhibit much better PCE tolerance to variations in light intensity. Figure l2b) shows the influence of light-intensity on the overall PCSE of the integrated photo-rechargeable battery described herein. [0081] The efficiencies of the photovoltaic module 102 and the integrated photo-rechargeable battery were measured under daily variational light density. The blue line in Figure l2b shows the PCE of the photovoltaic module 102 with a small variation under light intensity of 20 mW cm ² (17.7 %, 109% retention of PCE) comparing with that of 100 mW cm ² (16.2 %). A similar variation of PCE also occurs when the light intensity reduces from 100 mW cm ² to 20 mW cm ² (17.3 %, 106% retention). This enhanced solar harvest efficiency performance guarantees a stable high energy input to the aluminium-ion battery 104.

[0082] Testing the integrated photo-rechargeable battery under different light intensities, the corresponding overall efficiency (h₂, red curve in Figure l2b) also remains high at around 11.8% (20 mW cm ²) with 7% retention increase comparing with the 11.0% (100 mW cm ²). The trend of PCSE is also reversible when the light intensity decreases from 100 mW cm ² to 20 mW cm ² (11.7%). The specific performance under different light densities are shown in Figures 13 and 14, and in Table 2 below. Even when the light intensity sharply increases (from 20 mW cm-2 to 100 mW cm ²) or decreases (from 100 mW cm ² to 20 mW cm ²), the overall PCSE remains stable, as shown in Figure 15.

[0083] Table 2 Photo-conversion efficiency of the integrated device and a commercial silicon solar cell under different light intensities

Light Intensity Silicon solar cell integrated device (hi, %) (rp, %)

17.0% 10.5%

50

100 16.2% 12.1%

50 16.8% 10.5%

[0084] As described above, the integrated photo-rechargeable battery described herein is able to achieve a record PCE efficiency of 18.5% and a record high PCSE of 12.04%. In particular, the shared electrode of the photovoltaic module 102 and the battery components 104 ensure a minimum energy loss during electron transfer.

[0085] In particular, in comparison with other light-susceptible solar-battery systems (25% efficiency decay with fivefold reduction of light intensity), the photovoltaic module 102 and the integrated photo-rechargeable battery described herein both maintain stable performance under substantial variations in light illumination with 109% (PCE) and 107% (PCSE) efficiency retention under same weaken light-intensity, respectively.

[0086] Whilst the above examples have focused on an aluminium battery and electrode, it will be appreciated that the techniques could be applied more broadly to other metal batteries and electrodes, including but not limited to a lithium battery, a sodium battery, a magnesium battery, a zinc battery, an iron battery, or the like, and a lithium electrode, a sodium electrode, a magnesium electrode, a zinc electrode, an iron electrode, or the like. In general however, the metal electrode and the metal battery include the same metal.

[0087] Throughout this specification and claims which follow, unless the context requires otherwise, the word“comprise”, and variations such as“comprises” or“comprising”, will be understood to imply the inclusion of a stated integer or group of integers or steps but not the exclusion of any other integer or group of integers. As used herein and unless otherwise stated, the term "approximately" means ±20%.

[0088] Persons skilled in the art will appreciate that numerous variations and modifications will become apparent. All such variations and modifications which become apparent to persons skilled in the art, should be considered to fall within the spirit and scope that the invention broadly appearing before described.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1) A photo-rechargeable battery, including:

a photovoltaic component; and

a battery component;

wherein the photovoltaic component and the battery component are both formed on a common substrate and are integrated;

wherein the battery component includes a metal battery having a metal anode, and the photovoltaic component includes a plurality of perovskite photovoltaic cells interconnected in series to provide a relatively high voltage for charging the metal battery; and

wherein the photovoltaic component includes a metal electrode and is electrically interconnected to the metal battery by the metal electrode, which also constitutes the metal anode of the metal battery.

2) The photo-rechargeable battery of claim 1, wherein:

a) the metal battery is at least one of:

i) an aluminium battery;

ii) a lithium battery;

iii) a sodium battery;

iv) a magnesium battery;

v) a zinc battery; and,

vi) an iron battery; and,

b) the metal electrode is at least one of:

i) an aluminium electrode;

ii) a lithium electrode;

iii) a sodium electrode;

iv) a magnesium electrode;

v) a zinc electrode; and,

vi) an iron electrode. 3) The photo-rechargeable battery of claim 2, wherein the metal electrode and the metal battery include the same metal.

4) The photo-rechargeable battery of any one of the claims 1 to 3, wherein the metal battery is an aluminium-ion battery, and the metal electrode is an aluminium electrode.

5) The photo-rechargeable battery of any one of the claims 1 to 4, wherein the plurality of perovskite photovoltaic cells is three perovskite photovoltaic cells to provide the photovoltaic component with an output voltage in excess of 3.0 volts.

6) The photo-rechargeable battery of any one of claims 1 to 5, wherein the common substrate is a glass substrate.

7) The photo-rechargeable battery of any one of claims 1 to 6, wherein the common substrate is a flexible polymer substrate.

8) The photo-rechargeable battery of any one of claims 1 to 7, wherein the perovskite photovoltaic cells are formed from a stack of layers, including a patterned transparent and electrically conductive layer on a transparent substrate, a hole transport layer on the patterned transparent and electrically conductive layer, a perovskite layer on the hole transport layer, an electron transport layer on the perovskite layer, an insulating buffer layer on the electron transport layer, and a metal layer on the buffer layer.

9) The photo-rechargeable battery of claim 8, wherein the hole transport layer is composed of poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine) (PTAA).

10) The photo-rechargeable battery of claim 8 or 9, wherein the electron transport layer is composed of [6,6]-Phenyl C61 butyric acid methyl ester. 11)The photo-rechargeable battery of any one of claims 8 to 10, wherein the buffer layer is composed of bathocuproine.

12) The photo-rechargeable battery of any one of claims 1 to 11, wherein the photovoltaic component of integrated perovskite photovoltaic cells achieves a photovoltaic conversion efficiency (PCE) of at least 18.5%.

13)The photo-rechargeable battery of any one of claims 1 to 12, wherein the photo- rechargeable battery achieves an overall photovoltaic conversion/storage efficiency (PCSE) of at least 12%.

14)The photo-rechargeable battery of any one of claims 1 to 13, wherein the aluminium-ion battery has a graphite-based cathode, a discharge capacity at least 80 mAh g ¹ at 0.5 C-rate, and at least 75 mAh g ¹ at 20 C-rate.

15)The photo-rechargeable battery of any one of claims 1 to 14, wherein the aluminium-ion battery has an energy storage efficiency (ESE) of at least 79% at 0.5 C-rate.

16) A photo-rechargeable battery production process, including:

forming a photovoltaic component and a battery component on a common substrate; wherein the battery component includes a metal battery having a metal anode, and the photovoltaic component includes a plurality of perovskite photovoltaic cells interconnected in series to provide a relatively high voltage for charging the metal battery; and

integrating the photovoltaic component and the battery component by forming a metal electrode to electrically interconnect the photovoltaic component and the battery component, wherein the metal electrode constitutes both an electrical contact of the photovoltaic component and the metal anode of the metal battery. 17) The photo-rechargeable battery production process of claim 16, wherein the plurality of perovskite photovoltaic cells is three perovskite photovoltaic cells to provide the photovoltaic component with an output voltage in excess of 3.0 volts.

18) The photo-rechargeable battery production process of claim 16 or 17, wherein the step of forming the photovoltaic component and the battery component on the common substrate includes depositing a layer of metal and patterning the deposited layer of metal to form electrical interconnections between the perovskite photovoltaic cells and the metal battery.

19) The photo-rechargeable battery production process of any one of the claims 16 to 18, wherein:

a) the metal battery is at least one of:

i) an aluminium battery;

ii) a lithium battery;

iii) a sodium battery;

iv) a magnesium battery;

v) a zinc battery; and,

vi) an iron battery; and,

b) the metal electrode is at least one of:

i) an aluminium electrode;

ii) a lithium electrode;

iii) a sodium electrode;

iv) a magnesium electrode;

v) a zinc electrode; and,

vi) an iron electrode.

20) The photo-rechargeable battery production process of claim 19, wherein the metal electrode and the metal battery include the same metal. 21)The photo-rechargeable battery production process of any one of claims 16 to 20, wherein the metal battery is an aluminium-ion battery, and the metal electrode is an aluminium electrode.

22) The process of any one of claims 16 to 21, wherein the step of forming the photovoltaic component on the common substrate includes:

forming a patterned transparent and electrically conductive layer on a transparent substrate;

forming a hole transport layer on the patterned transparent and electrically conductive layer;

forming a perovskite layer on the hole transport layer;

forming an electron transport layer on the perovskite layer;

forming a graphitic carbon layer on the electron transport layer;

forming an electrically insulating buffer layer on the graphitic carbon layer; and forming a metal layer on the buffer layer.

23) The process of claim 22, wherein the hole transport layer is composed of poly(bis(4- phenyl)(2,4,6-trimethylphenyl)amine) (PTAA) .

24)The process of claim 22 or 23, wherein the electron transport layer is composed of [6,6]- Phenyl C61 butyric acid methyl ester and C60.

25) The process of any one of claims 22 to 24, wherein the buffer layer is composed of bathocuproine.

26) A photo-rechargeable battery, including:

a photovoltaic component; and

a battery component;

wherein the battery component includes an metal battery having a metal anode, and the photovoltaic component includes a plurality of photovoltaic cells interconnected to provide a voltage for charging the metal battery; and

27) A photo-rechargeable battery production process, including:

forming a photovoltaic component and a battery component on a common substrate; wherein the battery component includes an metal battery having a metal anode, and the photovoltaic component includes a plurality of photovoltaic cells interconnected in series to provide a voltage for charging the metal battery; and

integrating the photovoltaic component and the battery component by forming a metal electrode to electrically interconnect the photovoltaic component and the battery component, wherein the metal electrode constitutes both an electrical contact of the photovoltaic component and the metal anode of the metal battery.

28) The battery or process of claim 26 or 27, wherein:

a) the metal battery is at least one of:

i) an aluminium battery;

ii) a lithium battery;

iii) a sodium battery;

iv) a magnesium battery;

v) a zinc battery; and,

vi) an iron battery; and,

b) the metal electrode is at least one of:

i) an aluminium electrode;

ii) a lithium electrode;

iii) a sodium electrode;

iv) a magnesium electrode;

v) a zinc electrode; and,

vi) an iron electrode. 29) The battery or process of claim 28, wherein the metal electrode and the metal battery include the same metal.

30)The battery or process of any one of the claims 26 to 29, wherein the metal battery is an aluminium-ion battery, and the metal electrode is an aluminium electrode.