WO2025060307A1 - Solid-state battery and electric apparatus - Google Patents

Abstract

Provided in the present application are a solid-state battery and an electric apparatus. The solid-state battery comprises an electrolyte and a composite negative electrode, wherein the composite negative electrode comprises a negative-electrode current collector, a metal electrode layer arranged on at least one surface of the negative-electrode current collector, and a solid-state electrolyte layer arranged on the surface of the metal electrode layer that is away from the negative-electrode current collector side, wherein the solid-state electrolyte layer is located between the metal electrode layer and the electrolyte. The cycling stability of the solid-state battery can be further improved.

Description

Solid-state batteries and electrical devices

Cross-references

This application refers to Chinese Patent Application No. 2023225524852, filed on September 19, 2023, entitled “Solid-State Battery and Electrical Device,” which is incorporated herein by reference in its entirety.

Technical Field

The present application relates to the technical field of secondary batteries, and in particular to a solid-state battery and an electrical device.

Background Art

Solid-state batteries are batteries that use solid electrodes and solid electrolytes. Compared with liquid batteries in the prior art, solid-state batteries use solid electrolytes to partially or completely replace electrolytes, making solid-state batteries have advantages over liquid batteries, such as higher safety, energy density, and long life. However, solid-state batteries still face many challenges, including battery life issues.

Summary of the invention

The present application is made in view of the above-mentioned problems, and its object is to provide a solid-state battery capable of improving cycle stability.

A first aspect of the present application provides a solid-state battery, which includes an electrolyte and a composite negative electrode, wherein the composite negative electrode includes a negative electrode current collector, a metal electrode layer disposed on at least one surface of the negative electrode current collector, and a solid electrolyte layer disposed on a surface of the metal electrode layer away from the current collector, and the solid electrolyte layer is located between the metal electrode layer and the electrolyte.

Placing the solid electrolyte layer on the surface of the metal electrode layer away from the current collector is beneficial to reducing the contact between the electrolyte and the metal electrode layer, reducing the probability of side reactions between the electrolyte and the metal electrode layer, thereby alleviating the temperature rise of the solid-state battery, reducing the consumption of the electrolyte, and improving the cycle stability of the solid-state battery. The surface on the fluid side also helps to reduce the probability of uneven deposition of active metal ions on the surface of the metal electrode layer to form dendrites and the possibility of a short circuit between the positive electrode plate and the composite negative electrode due to dendrite growth, further improving the cycle stability of the solid-state battery. The solid electrolyte layer is arranged on the surface of the metal electrode layer away from the negative electrode current collector side so that it is assembled into a composite negative electrode, which is also beneficial to improve the assembly efficiency of the solid-state battery and reduce the manufacturing cost. The second aspect of the present application provides an electrical device, which includes the solid-state battery described in the first aspect.

The electric device has excellent endurance performance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of a solid-state battery according to an embodiment of the present application;

FIG2 is a schematic diagram of a composite negative electrode of a solid-state battery according to an embodiment of the present application shown in FIG1 ;

FIG3 is a schematic diagram of a composite negative electrode of a solid-state battery according to an embodiment of the present application;

FIG4 is a schematic diagram of a composite negative electrode of a solid-state battery according to an embodiment of the present application;

FIG5 is a schematic diagram of a composite negative electrode of a solid-state battery according to an embodiment of the present application;

FIG6 is a schematic diagram of a composite negative electrode of a solid-state battery according to an embodiment of the present application;

FIG. 7 is a schematic diagram of a composite negative electrode of a solid-state battery according to an embodiment of the present application.

Description of reference numerals:
1 solid-state battery; 2 electrolyte; 3 composite negative electrode; 31 negative electrode current collector; 32 metal electrode layer; 33 solid electrolyte layer; 311 at least one end face of the negative electrode current collector; 312, 313 at least part of the surface of the negative electrode current collector adjacent to the metal electrode layer; 321 at least one end face of the metal electrode layer; 331 extension; 3311 first surface; 3312 second surface; 4 positive electrode sheet; H1 thickness of the solid electrolyte layer; H2 thickness of the metal electrode layer; L1 width of the metal electrode layer; L2 width of the negative electrode current collector; L3 width of at least part of the surface of the negative electrode current collector adjacent to the metal electrode layer.

DETAILED DESCRIPTION

In the following, only some exemplary embodiments are briefly described. As can be appreciated by those skilled in the art, without departing from the spirit or scope of the present application, The described embodiments may be modified in various different ways.Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive.

Solid-state batteries have higher safety, energy density and cycle stability, but at the same time, due to the solid-phase transmission of ions, solid-state batteries often have disadvantages such as large interface impedance and poor kinetic performance. In order to take into account the kinetic performance of solid-state batteries, some electrolytes are often retained in solid-state batteries. Metal electrodes are often used as negative electrodes of solid-state batteries due to their high specific capacity, low electrochemical potential and low density to further improve the energy density of batteries. However, during the charge and discharge process of metal solid-state batteries, the side reactions between the metal electrodes and the electrolyte will continue to produce insoluble side reaction products that accumulate on the surface of the metal electrodes, and the active metal ions are prone to uneven deposition and dendrite formation on the surface of the metal electrodes, resulting in continuous expansion of the battery and decreased cycle stability; at the same time, the side reactions between the metal and the electrolyte may also be accompanied by the phenomenon of exothermic reaction, resulting in continuous heating of the battery and further deterioration of the cycle stability.

Based on this, the present application provides a solid-state battery structure to effectively solve the above problems. A solid-state battery 1 according to an embodiment of the present application is described below with reference to FIGS. 1 to 4 .

As shown in Figures 1 and 2, the present application provides a solid-state battery 1, which includes an electrolyte 2 and a composite negative electrode 3. The composite negative electrode 3 includes a negative electrode collector 31, a metal electrode layer 32 arranged on at least one surface of the negative electrode collector 31, and a solid electrolyte layer 33 arranged on the surface of the metal electrode layer 32 away from the negative electrode collector 31, and the solid electrolyte layer 33 is located between the metal electrode layer 32 and the electrolyte 2.

In some embodiments, as shown in FIG3 , both surfaces of the negative electrode current collector 31 are provided with metal electrode layers 32 . The surfaces of the metal electrode layers 32 on both sides of the negative electrode current collector 31 away from the current collector side 31 are provided with solid electrolyte layers 33 .

Please continue to refer to FIG. 1 . In some embodiments, the solid-state battery includes a positive electrode plate 4 . The positive electrode plate 4 includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector. The positive electrode film layer includes a positive electrode active material.

In some embodiments, the positive electrode active material includes lithium-containing phosphates, lithium transition metal oxides and their respective modified compounds. Lithium transition metal oxides include but are not limited to lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, and lithium nickel cobalt manganese oxide. Lithium-containing phosphates include but are not limited to lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, and a composite material of lithium manganese phosphate and carbon. At least one of a composite material, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

Disposing the solid electrolyte layer 33 on the surface of the metal electrode layer 32 away from the current collector 31 is conducive to reducing the contact between the electrolyte 2 and the metal electrode layer 32, reducing the probability of the occurrence of side reactions between the electrolyte 2 and the metal electrode layer 32, thereby alleviating the temperature rise of the solid-state battery 1, reducing the consumption of the electrolyte 2, and improving the cycle stability of the solid-state battery 1. The solid electrolyte layer 33 can also reduce the probability of uneven deposition of active metal ions on the surface of the metal electrode layer 32 to form dendrites, reduce the probability of short circuit caused by the contact between the positive electrode plate 4 and the composite negative electrode 3 due to dendrite growth, and further improve the cycle stability of the solid-state battery 1. Disposing the solid electrolyte layer 33 on the surface of the metal electrode layer 32 away from the negative electrode current collector 31, so that it is assembled into a composite negative electrode 3, is also conducive to improving the assembly efficiency of the solid-state battery 1 and reducing the manufacturing cost.

In some embodiments, the surface of the solid electrolyte layer 33 close to the electrolyte 2 is a continuous morphology.

The surface morphology of the solid electrolyte layer 33 can be observed by a scanning electron microscope. If there are no obvious pores on the surface of the solid electrolyte layer 33 and the underlying metal electrode layer 32 is not exposed, it is considered that the surface of the solid electrolyte layer 33 presents a continuous morphology.

It can be understood that the surface of the solid electrolyte layer 33 close to the electrolyte 2 can be flat or undulating, which does not affect the continuous morphology of the surface of the solid electrolyte layer 33 close to the electrolyte 2.

The surface of the solid electrolyte layer 33 close to the electrolyte 2 has a continuous morphology, which can effectively reduce the probability of direct contact between the electrolyte and the metal electrode layer 32, and further improve the cycle stability of the solid-state battery 1.

Please continue to refer to FIG. 2 . In some embodiments, the thickness H1 of the solid electrolyte layer 33 is 2 um-50 um.

In some embodiments, the thickness H1 of the solid electrolyte layer 33 may be 2 um, 5 um, 10 um, 15 um, 20 um, 25 um, 30 um, 35 um, 40 um, 45 um, 50 um or any range therebetween.

Please continue to refer to FIG. 2 . In some embodiments, the thickness H2 of the metal electrode layer 32 does not exceed 50 μm.

In some embodiments, the thickness H2 of the metal electrode layer 32 may be 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm or any range therebetween.

In some embodiments, the solid electrolyte layer includes a solid electrolyte. Optionally, the solid electrolyte includes at least one of lithium lanthanum titanate (LLTO), lithium lanthanum zirconium oxide (LLZO), a LISICON-type electrolyte, a NASICON-type electrolyte, lithium sulfide, a doped material of lithium sulfide, and a composite material of lithium sulfide and other sulfides.

Solid electrolyte refers to solid ion conductor electrolyte. It has low flammability, non-volatility, high mechanical and thermal stability, easy processing, low self-discharge rate, and is conducive to achieving high power density of batteries.

As an example, lithium lanthanum titanate LLTO includes an electrolyte with a general formula of La _2/3-x1 Li _3x1 TiO ₃ , where 0<x1<2/3. As an example, lithium lanthanum zirconium oxide LLZO with a garnet structure includes Li ₇ La ₃ Zr ₂ O _12. As an example, a LISICON-type electrolyte includes an electrolyte with a general formula of Li _4-x2 M1 _{1- x2} M2 _x2 S ₄ , where M1 can be selected from one or more of Si, Sc, Ge, and Ti, and M2 can be selected from one or more of P, As, V, and Cr, where 0<x2<1. As an example, a NaSICON-type electrolyte includes Na _1+x3 Zr ₂ Si _x3 P _3-x3 O ₁₂ , where 0≤x3≤3.

In some embodiments, the doping material of lithium sulfide includes doping elements such as aluminum, phosphorus, silicon, titanium, tin, antimony, and lanthanum.

In some embodiments, the composite material of lithium sulfide and other sulfides further includes one or more of aluminum sulfide, phosphorus sulfide, silicon sulfide, titanium sulfide, tin sulfide, antimony sulfide, and lanthanum sulfide.

In some embodiments, the mass content of the solid electrolyte is not less than 90% based on the total mass of the solid electrolyte layer.

In some embodiments, based on the total mass of the solid electrolyte layer, the mass content of the solid electrolyte may be 90%, 92%, 94%, 96%, 98%, 100% or any range therebetween.

A solid electrolyte layer with a high mass content is beneficial to improving the ionic conductivity of the solid electrolyte layer and improving the electrochemical performance of the secondary battery.

In some embodiments, based on the total mass of the solid electrolyte layer, the mass content of the solid electrolyte is 100%, that is, the solid electrolyte layer does not require other additives and is formed by mechanical compounding.

In some embodiments, a binder and/or a dispersant is included in the solid electrolyte layer. In some embodiments, the binder comprises a polymer, including, by way of example, but not limited to, polyvinylidene fluoride (PVDF). In some embodiments, the dispersant comprises hydrogenated nitrile-butadiene rubber (HNBR).

The addition of a binder and/or a dispersant is beneficial to fixing the solid electrolyte into a film layer and arranging it on the surface of the metal electrode layer.

In some embodiments, the metal electrode layer includes at least one of lithium metal, lithium alloy, sodium metal, and sodium alloy.

In some embodiments, the metal electrode layer includes lithium metal.

Lithium metal is considered to be one of the most ideal materials for solid-state batteries due to its ultra-high theoretical specific capacity of 3860mAh/g, the lowest electrochemical potential (-3.04V vs standard hydrogen electrode) and extremely low density of 0.534g/ ^cm3 , which can effectively improve the energy density of solid-state batteries.

In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector, and the metal foil includes but is not limited to copper foil.

In some embodiments, as shown in FIG4 , the solid electrolyte layer 33 further includes an extension portion 331 disposed on at least one end face 321 of the metal electrode layer 32. The end face 321 of the metal electrode layer 32 is located in the thickness direction of the metal electrode layer 32, and its two end faces 321 connect its two surfaces to each other. The extension portion 331 of the solid electrolyte layer 33 disposed on at least one end face 321 of the metal electrode layer 32 can further isolate the direct contact between the electrolyte 2 and the metal electrode layer 32, thereby improving the cycle stability of the solid-state battery 3. In some embodiments, the extension portion 331 of the solid electrolyte layer 33 also covers at least one end face 311 of the negative electrode current collector 31.

In some embodiments, as shown in FIG5 , a metal electrode layer 32 is disposed on both surfaces of the negative electrode current collector 31. A solid electrolyte layer 33 is disposed on the surface of the metal electrode layer 32 on both sides of the negative electrode current collector 31 away from the current collector side 31, and the extensions 331 of the solid electrolyte layer 33 on both sides respectively cover at least one end surface 321 of the metal electrode layer 32 and converge on the end surface 311 of the current collector.

In some embodiments, as shown in FIG6 , at least some areas 312 and 313 on the surface of the negative electrode current collector 31 adjacent to the metal electrode layer 32 are in direct contact with the solid electrolyte layer 33. Please continue to refer to FIG6 , in some embodiments, in the x direction, that is, in the transverse direction (TD) parallel to the cold pressing roller for manufacturing the composite electrode sheet, the width L1 of the metal electrode layer 32 is smaller than the width L2 of the negative electrode current collector 31, so that the negative electrode current collector 31 and the metal electrode layer 32 are in direct contact with each other. At least some regions 312 and 313 on the adjacent surfaces are in direct contact with the solid electrolyte layer 33. In some embodiments, the first surface 3311 of the extension 331 of the solid electrolyte layer 33 covers at least one end surface 321 of the metal electrode layer 32; the second surface 3312 adjacent to the first surface 3311 of the extension 331 of the solid electrolyte layer 33 covers the surface of the negative electrode collector 31 that is not covered by the metal electrode layer 32. This further reduces the probability of contact between the electrolyte 2 and the metal electrode layer 32, which is conducive to further improving the cycle stability of the solid-state battery 3. In some embodiments, at least some regions 312 and 313 on the surface of the negative electrode collector 31 adjacent to the metal electrode layer 32 are in direct contact with the solid electrolyte layer 33, and its width L3 in the x direction is 0.5mm-2mm.

In some embodiments, as shown in FIG. 7 , the extension portion 331 of the solid electrolyte layer 33 is also disposed on at least one end surface of the negative electrode current collector 31 .

A second aspect of the present application provides an electrical device, which includes the solid-state battery of the first aspect.

The electric device has excellent endurance performance.

It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and the same effect as the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims (10)

A solid-state battery, characterized in that the solid-state battery comprises: An electrolyte and a composite negative electrode, wherein the composite negative electrode comprises a negative electrode collector, a metal electrode layer disposed on at least one surface of the negative electrode collector, and a solid electrolyte layer disposed on a surface of the metal electrode layer away from the negative electrode collector, and the solid electrolyte layer is located between the metal electrode layer and the electrolyte. The solid-state battery according to claim 1, characterized in that The surface of the solid electrolyte layer close to the electrolyte is a continuous morphology. The solid-state battery according to claim 1, characterized in that The solid electrolyte layer further includes an extension portion disposed on at least one end surface of the metal electrode layer. The solid-state battery according to claim 1, characterized in that At least a portion of the surface of the negative electrode current collector adjacent to the metal electrode layer is in direct contact with the solid electrolyte layer. The solid-state battery according to any one of claims 1 to 4, characterized in that The thickness of the solid electrolyte layer is 2um-50um. The solid-state battery according to any one of claims 1 to 4, characterized in that The solid electrolyte layer includes a solid electrolyte, and the solid electrolyte includes at least one of lithium lanthanum titanate (LLTO), lithium lanthanum zirconium oxide (LLZO), LISICON type electrolyte, NASICON type electrolyte, lithium sulfide, lithium sulfide doping material, lithium sulfide and other sulfide composite materials. The solid-state battery according to any one of claims 1 to 4, characterized in that Based on the total mass of the solid electrolyte layer, the mass percentage of the solid electrolyte is not less than 90%. The solid-state battery according to any one of claims 1 to 4, characterized in that The metal electrode layer includes at least one of lithium metal, lithium alloy, sodium metal, and sodium alloy. The solid-state battery according to any one of claims 1 to 4, characterized in that The thickness of the metal electrode layer does not exceed 50 um. An electrical device, characterized in that: The electrical device comprises the solid-state battery according to any one of claims 1 to 9.