Composite cathode material, all-solid-state battery, and charge-discharge method of all-solid-state battery

Abstract

The application provides a composite positive electrode material, a full-solid-state battery and a charging and discharging method of the full-solid-state battery, and relates to the technical field of batteries. The composite positive electrode material comprises a lithium-rich manganese-based positive electrode material, a halide solid-state electrolyte and a conductive agent, and the chemical general formula of the composite positive electrode material is Li 1.1+a Ni b Mn c M d O 2‑e F e , wherein M comprises at least one of Zr, Nb, Mg, Al and Ti, 0.04 <= a <= 0.08, 0.2

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of batteries, in particular to a composite positive electrode material, an all-solid-state battery and a charging and discharging method of the all-solid-state battery. BACKGROUND

[0002] With the rapid growth of demand for portable electronic devices, electric vehicles and renewable energy storage, there is an urgent need for advanced battery technology with high energy density and high safety. Although traditional lithium-ion batteries have made significant progress in energy density and cycle life, their theoretical energy density is close to the limit, and the safety hazards brought by liquid electrolyte have not been completely solved. These inherent defects seriously restrict the development of lithium-ion batteries in high-end application fields. In this context, lithium-rich manganese-based positive electrode materials have outstanding advantages in raw material cost and supply chain safety due to their ultra-high discharge specific capacity and energy density, and low cobalt (Co) and nickel (Ni) content, making them a new generation of positive electrode materials with great development potential. At the same time, all-solid-state lithium battery (All-Solid-State Lithium Batteries, abbreviated as ASSBs) technology completely replaces the traditional liquid electrolyte with non-flammable solid-state electrolyte, fundamentally solving the safety hazards of the battery, and showing a wider electrochemical window and better thermal stability. The combination of lithium-rich manganese-based positive electrode and all-solid-state battery technology can theoretically achieve the dual goals of high energy density and high safety, and this technical route has broad application prospects in electric vehicles and large-scale energy storage fields.

[0003] However, the practical application of lithium-rich manganese-based all-solid-state batteries still faces severe technical challenges. When the working voltage is raised to above 4.6V, lithium-rich manganese-based all-solid-state batteries will exhibit obvious performance degradation: on the one hand, lithium-rich manganese-based positive electrode materials will undergo a series of complex structural evolution processes such as lattice oxygen precipitation, phase structure transformation, transition metal ion migration, reduction and dissolution at high voltage; on the other hand, the interface between lithium-rich manganese-based positive electrode materials and solid-state electrolyte will undergo side reactions such as electrochemistry, chemistry, thermodynamics, and mechanical force, which will further exacerbate the performance degradation of the battery. These problems make it difficult for lithium-rich manganese-based all-solid-state batteries to meet the needs of large-scale applications in terms of cycle stability and capacity development.

[0004] In related technologies, component regulation, surface modification, element doping or structure optimization strategies are usually used to improve the performance of lithium-rich manganese-based all-solid-state batteries to improve the cycle life of lithium-rich manganese-based all-solid-state batteries. However, there is still a problem of low cycle life of lithium-rich manganese-based all-solid-state batteries. SUMMARY

[0005] The application provides a composite positive electrode material, a full solid-state battery and a charging and discharging method of the full solid-state battery, to improve the problem of low cycle life of a lithium-rich manganese-based full solid-state battery in the related art.

[0006] In a first aspect, the application provides a composite positive electrode material, comprising: a lithium-rich manganese-based positive electrode material, a halide solid-state electrolyte and a conductive agent, the chemical general formula of the composite positive electrode material is Li 1.1+a Ni b Mn c M d O 2-e F e , wherein M comprises at least one of Zr, Nb, Mg, Al and Ti, 0.04<=a<=0.08, 0.2

[0007] In a possible implementation, the chemical general formula of the halide solid-state electrolyte is Li 3-x In y Zr x Cl 6-z F z , wherein 0.1<=x<=0.3, 0.7<=y<=0.9, 0<=z<=0.6.

[0008] In a possible implementation, the median particle size of the halide solid-state electrolyte is 0.1-50 mu m, preferably 0.3-10 mu m.

[0009] In a possible implementation, the conductive agent is vapor-grown carbon fiber, the mass fraction of the lithium-rich manganese-based positive electrode material in the composite positive electrode material accounts for 57%-67%, the mass fraction of the halide solid-state electrolyte in the composite positive electrode material accounts for 30%-37%, and the mass fraction of the conductive agent in the composite positive electrode material accounts for 1%-5%.

[0010] In a second aspect, the application provides a full solid-state battery, comprising: a composite positive electrode, a double-layer electrolyte layer and a lithium-indium negative electrode, wherein the composite positive electrode is prepared from the composite positive electrode material of any one of the first aspect; the double-layer electrolyte layer comprises a positive electrode side electrolyte layer and a negative electrode side electrolyte layer, the positive electrode side electrolyte layer is prepared from the halide solid-state electrolyte, and the negative electrode side electrolyte layer is prepared from a sulfide solid-state electrolyte.

[0011] In a possible implementation, the chemical general formula of the halide solid-state electrolyte is Li 3-x In y Zr x Cl 6-z F zwherein 0.1≤x≤0.3, 0.7≤y≤0.9, 0≤z≤0.6; and / or, the chemical formula of the sulfide solid-state electrolyte is Li3P i S j Cl6, wherein 0.1≤i≤0.3, 0.7≤j≤0.9.

[0012] In a third aspect, the present application provides a charging and discharging method of a full solid-state battery, comprising:

[0013] (1) for the full solid-state battery as described in the second aspect, performing a first set number of charging and discharging cycles at a first rate in the voltage range of (2-2.2)-(2.6-2.8) V v.s. Li-In / In;

[0014] (2) performing a second set number of constant current and constant voltage charging and discharging cycles at a second rate in the voltage range of (2.4-3)-(3.8-3.9) V v.s. Li-In / In, wherein the constant voltage cutoff current density is set to the first rate, and the second rate is greater than the first rate;

[0015] (3) performing a cycle performance test at a third rate in the cycle voltage window of (2-2.4)-(4.1-4.2) V v.s. Li-In / In, wherein the third rate is greater than the second rate.

[0016] In a possible implementation, the first rate is 0.05C-0.15C rate, the second rate is 0.15C-0.3C rate, and the third rate is 0.5C-1C rate.

[0017] In a possible implementation, the cycle life of the full solid-state battery is greater than or equal to 700 times, and the average voltage decay rate of the full solid-state battery is less than or equal to 0.228 mV / cycle.

[0018] In a fourth aspect, the present application provides an energy storage device comprising a full solid-state battery adopting the charging and discharging method according to any one of the third aspect.

[0019] In a fifth aspect, the present application provides an electric equipment comprising a full solid-state battery adopting the charging and discharging method according to any one of the third aspect, or comprising an energy storage device according to the fourth aspect.

[0020] The implementation of the present application has at least the following beneficial effects:

[0021] (1) By mixing halide solid electrolyte with lithium-rich manganese-based positive electrode material, the electrochemical stability of the interface between lithium-rich positive electrode and halide solid electrolyte is significantly improved, the interface ion transmission capacity and mechanical stability are enhanced, and the structural degradation of lithium-rich positive electrode during charging and discharging process is effectively inhibited; at the same time, by limiting the specific elements and proportion range, the performance of the material is further optimized, and the cycle stability and overall performance of the all-solid-state battery are synergistically improved, which provides a key material basis for solving the capacity decay and voltage decay problems of lithium-rich manganese-based all-solid-state battery, thereby effectively improving the cycle life of all-solid-state battery.

[0022] (2) By adopting a unique three-stage charging and discharging strategy, first, small-range charging and discharging cycle in low voltage interval can effectively stabilize the interface between negative electrode and electrolyte, reduce the occurrence of interface side reactions, and lay a foundation for stable operation of all-solid-state battery; then gradually carry out high-voltage charging and discharging, and specifically inhibit a series of irreversible structural degradation problems such as lattice oxygen precipitation and phase structure transformation of lithium-rich positive electrode material during high-voltage charging; finally, cycle performance test is carried out in the optimized cycle voltage window, and the performance improvement effect of all-solid-state battery is further verified by reasonably setting the rate relationship. Through this charging and discharging improvement strategy, the cycle life and voltage stability of all-solid-state battery are further improved, which has a positive significance for promoting the large-scale application of all-solid-state battery. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present application and, together with the specification, serve to explain the principles of the application.

[0024] Figure 1 A schematic diagram of discharge specific capacity cycle data of all-solid-state battery provided for exemplary embodiments of the present application;

[0025] Figure 2 A schematic diagram of cycle average discharge voltage of all-solid-state battery provided for exemplary embodiments of the present application;

[0026] Figure 3 Another schematic diagram of discharge specific capacity cycle data of all-solid-state battery provided for exemplary embodiments of the present application;

[0027] Figure 4 Another schematic diagram of cycle average discharge voltage of all-solid-state battery provided for exemplary embodiments of the present application;

[0028] Figure 5 Still another schematic diagram of discharge specific capacity cycle data of all-solid-state battery provided for exemplary embodiments of the present application;

[0029] Figure 6Another diagram of the average discharge voltage of the full solid-state battery of the exemplary embodiments of the present application.

[0030] The specific embodiments of the present application have been shown by the above-described drawings, and will be described in more detail hereinafter. The drawings and the written description are not intended to restrict the scope of the present application by any means, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0031] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are some embodiments but not all embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of the present application.

[0032] It should be noted that the terms "first", "second" are used only for descriptive purposes and should not be construed as indicating or implying relative importance or implying the number of the technical features indicated. Therefore, the features defined with "first", "second" can include at least one of the features, explicitly or implicitly. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly and specifically limited.

[0033] In the present application, unless otherwise explicitly specified and limited, the "on" or "under" of the first feature to the second feature can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the "over", "above" and "on" of the first feature to the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The "under", "below" and "under" of the first feature to the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0034] In the above description, the description referring to the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0035] In the related art, only one of component regulation, surface modification, element doping or structure optimization is usually used to improve the performance of the lithium-rich manganese-based full solid-state battery. However, the lithium-rich manganese-based full solid-state battery faces multiple intrinsic defects such as lattice oxygen precipitation, phase structure transformation, transition metal ion migration, and complex interface side reactions between the solid-state electrolyte and other problems during high-voltage charge-discharge cycling. A single strategy cannot simultaneously address these complex problems, cannot optimize battery performance from multiple angles, and has limited effect on improving the cycle life of the full solid-state battery.

[0036] Based on the technical problems in the related art, the present application provides a composite positive electrode material scheme. By combining a lithium-rich manganese-based positive electrode material, a halide solid-state electrolyte and a conductive agent, and by limiting specific elements and proportion ranges, the advantages of multiple strategies such as component regulation, surface modification, element doping or structure optimization are effectively integrated. Not only are intrinsic defects of the lithium-rich manganese-based positive electrode material improved, reducing the occurrence of problems such as lattice oxygen precipitation and phase structure transformation, but also the interface performance between the positive electrode material and the solid-state electrolyte is optimized, effectively reducing the probability of interface side reactions. Through these comprehensive effects, the performance of the material is further optimized, the cycle stability and overall performance of the full solid-state battery are synergistically improved, providing a key material basis for solving the capacity decay and voltage decay problems of the lithium-rich manganese-based full solid-state battery, thereby effectively improving the cycle life of the full solid-state battery.

[0037] The technical solutions of the present application and how the technical solutions of the present application solve the above technical problems will be described in detail below with specific examples. The following specific examples can be combined with each other, and the same or similar concepts or processes may not be described again in some examples. The embodiments of the present application will be described below with reference to the accompanying drawings.

[0038] The embodiments of the present application provide a composite positive electrode material, which includes a lithium-rich manganese-based positive electrode material, a halide solid-state electrolyte and a conductive agent. The chemical general formula of the composite positive electrode material is Li 1.1+a Ni b Mn c M d O 2-e F e , wherein M includes at least one of Zr, Nb, Mg, Al and Ti, 0.04≤a≤0.08, 0.2<b≤0.21, 0.52≤c≤0.56, 0<d≤0.04, 0<e≤0.01.

[0039] Exemplarily, in one implementation, M includes any one of Zr, Nb, Mg, Al, Ti and the like, for example, M is Zr; in another implementation, M includes any combination of Zr, Nb, Mg, Al, Ti and the like, for example, M is a combination of Zr and Nb.

[0040] wherein a can be 0.04, 0.05, 0.06, 0.07, 0.08, or a range formed by any two of them, b can be 0.2, 0.201, 0.202, 0.203, 0.204, 0.205, 0.206, 0.207, 0.208, 0.209, 0.21, or a range formed by any two of them, c can be 0.52, 0.525, 0.53, 0.535, 0.54, 0.545, 0.55, 0.555, 0.56, or a range formed by any two of them, d can be 0, 0.005, 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, or a range formed by any two of them, and e can be 0, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, or a range formed by any two of them.

[0041] In the embodiments of the present application, by mixing the halide solid-state electrolyte with the lithium-rich manganese-based positive electrode material, the electrochemical stability of the interface between the lithium-rich positive electrode and the halide solid-state electrolyte is significantly improved, the ion transmission capacity and mechanical stability of the interface are enhanced, and the structural degradation of the lithium-rich positive electrode during the charging and discharging process is effectively inhibited; at the same time, by limiting the specific elements and proportion range, the performance of the material is further optimized, and the cycle stability and overall performance of the all-solid-state battery are synergistically improved, thereby providing a key material basis for solving the capacity decay and voltage decay problems of the lithium-rich manganese-based all-solid-state battery, and effectively improving the cycle life of the all-solid-state battery.

[0042] In a specific embodiment, the chemical formula of the halide solid-state electrolyte is Li 3-x In y Zr x Cl 6-z F z , wherein 0.1≤x≤0.3, 0.7≤y≤0.9, and 0≤z≤0.6.

[0043] Exemplarily, x can be 0.1, 0.15, 0.2, 0.25, 0.3, or a range formed by any two of them; y can be 0.7, 0.75, 0.8, 0.85, 0.9, or a range formed by any two of them; z can be 0, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, or a range formed by any two of them.

[0044] In the embodiments of the present application, the value ranges of x, y and z are reasonably set to optimize the crystal structure, provide a more unobstructed migration channel for lithium ions, effectively improve the lithium ion conductivity and reduce the internal resistance of the full solid-state battery, so that the full solid-state battery has more excellent performance when subjected to large current charging and discharging; in addition, Li 3-x In y Zr x Cl 6-z F z The halide solid-state electrolyte under the general formula can maintain good structural stability under different temperatures and electrochemical environments, can effectively reduce the side reaction with the positive and negative electrode materials, thereby prolonging the cycle life of the full solid-state battery; and by adjusting the z value to introduce fluorine elements, the mechanical strength and thermal stability of the electrolyte can be enhanced, which is helpful to further improve the safety and reliability of the full solid-state battery.

[0045] In a specific embodiment, the median particle size of the halide solid-state electrolyte is 0.1-50 μm, preferably 0.3-10 μm.

[0046] Exemplarily, the median particle size of the halide solid-state electrolyte can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, or a range formed by any two of them.

[0047] Preferably, the median particle size of the halide solid-state electrolyte can be 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 5 μm, 10 μm, or a range formed by any two of them.

[0048] In the embodiments of the present application, the median particle size of the halide solid-state electrolyte is set to The interval enables the electrolyte particles to better fill the gap between the positive and negative electrode materials, form a continuous and dense ion conduction channel, effectively improve the migration efficiency of lithium ions in the electrolyte, and thus reduce the internal resistance of the full solid-state battery, so that the full solid-state battery exhibits better performance when subjected to large current charging and discharging. Meanwhile, the uniformly dispersed electrolyte with a suitable particle size can reduce the local stress concentration caused by particle agglomeration, effectively reduce the risk of structural damage of the full solid-state battery during the cyclic use process, and significantly enhance the cycle stability and service life of the full solid-state battery. In addition, the particle size range is also conducive to improving the interface compatibility of the electrolyte and the electrode material, promoting the rapid transport of lithium ions at the interface, and thus further improving the overall electrochemical performance of the full solid-state battery.

[0049] In a specific embodiment, the conductive agent is vapor-grown carbon fiber, the mass fraction of the lithium-rich manganese-based positive electrode material in the composite positive electrode material is 57%-67%, the mass fraction of the halide solid-state electrolyte in the composite positive electrode material is 30%-37%, and the mass fraction of the conductive agent in the composite positive electrode material is 1%-5%.

[0050] The vapor-grown carbon fiber (VGCF) is a carbon fiber material formed by chemical vapor deposition (CVD) technology, in which a carbon-hydrogen compound gas is decomposed and deposited on the surface of a catalyst particle at high temperature, and then grown.

[0051] For example, the mass fraction of the lithium-rich manganese-based positive electrode material in the composite positive electrode material can be 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, or a range formed by any two of them; the mass fraction of the halide solid-state electrolyte in the composite positive electrode material can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, or a range formed by any two of them; and the mass fraction of the conductive agent in the composite positive electrode material can be 1%, 2%, 3%, 4%, 5%, or a range formed by any two of them.

[0052] The embodiments of the present application adopt gas phase grown carbon fibers as the conductive agent, and strictly control the mass fraction range of each component, so that the composite positive electrode material maintains high capacity while obtaining excellent conductivity and interface stability. Among them, the main proportion of lithium-rich manganese-based positive electrode material ensures the high energy density characteristics of the electrode, the addition of a proper amount of halide solid electrolyte constructs an efficient ion transmission channel, and the low content of gas phase grown carbon fiber network not only provides sufficient electron conduction path, but also reduces the hindrance of excessive carbon material to ion transmission. This component ratio promotes the formation of an ideal "core-shell" structure inside the electrode, significantly improves the interface contact condition, effectively suppresses the interface side reaction in the cycle process, and thus simultaneously realizes the excellent comprehensive performance of high energy output and long cycle life.

[0053] The present application also provides a full solid-state battery, comprising: a composite positive electrode, a double-layer electrolyte layer and a lithium-indium negative electrode, wherein the composite positive electrode is prepared from the composite positive electrode material of any one of the first aspect; the double-layer electrolyte layer comprises a positive electrode side electrolyte layer and a negative electrode side electrolyte layer, the positive electrode side electrolyte layer is prepared from a halide solid electrolyte, and the negative electrode side electrolyte layer is prepared from a sulfide solid electrolyte.

[0054] The present application does not make special limitations on the preparation method of the full solid-state battery, which can be prepared by referring to the conventional method in the art.

[0055] For example, in a specific embodiment, the full solid-state battery can be prepared by the following steps:

[0056] 1) Use a precision balance to weigh, for example, 50-80 mg of sulfide solid electrolyte, place it on a flat operation table, and use light tabletting to form a sheet structure with a certain thickness and uniformity as a negative electrode side electrolyte layer for standby.

[0057] 2) Similarly, use a precision balance to weigh, for example, 20-40 mg of halide solid electrolyte, and perform light tabletting operation in the same way as preparing the negative electrode side electrolyte layer to obtain the positive electrode side electrolyte layer.

[0058] 3) Place the prepared positive electrode side electrolyte layer in the designated position of the mold battery; use a precision balance to weigh, for example, 10-15 mg of composite positive electrode material, and place it evenly on the positive electrode side electrolyte layer; use a press to apply, for example, 2.5-3 t of pressure to the above combination, and maintain the pressure for, for example, 3-5 min to ensure that the composite positive electrode material is tightly combined with the positive electrode side electrolyte layer; after the pressure maintaining is completed, add a piece of carbon-coated aluminum foil current collector with a mass range of, for example, 25-30 mg and a diameter of, for example, 10 mm on the surface of the composite positive electrode material as the current collection component of the composite positive electrode.

[0059] 4) Put the prepared negative electrolyte layer in the mold cell opposite to the composite positive electrode, and place an In sheet with a thickness of, for example, 100 ± 0 um, a Li foil with a thickness in the range of, for example, 20-50 um, and a copper foil current collector on the negative electrolyte layer in sequence to form a lithium-indium negative electrode structure.

[0060] 5) The assembled composite positive electrode, double-layer electrolyte layer, and lithium-indium negative electrode mold cell is subjected to a preliminary tightening operation; a clamp is put on, and a torque wrench or the like is used to tighten the fixing screws under a pressure of, for example, 1-1.2 t to ensure that the battery components are in close contact, good electrical connection and structural stability are formed, and thus a prepared lithium-rich manganese-based-halide all-solid-state battery (Lrs-HSEs-ASSBs), that is, an all-solid-state battery, is obtained.

[0061] In the embodiments of the present application, by mixing the lithium-rich positive electrode and the high-pressure-resistant halide electrolyte in the composite positive electrode, the electrochemical stability of the interface between the lithium-rich positive electrode and the halide solid-state electrolyte is significantly improved; at the same time, by using the sulfide solid-state electrolyte in the negative electrolyte layer, the risk of low-pressure reduction side reactions of the halide solid-state electrolyte can also be effectively reduced.

[0062] In a specific embodiment, the chemical formula of the halide solid-state electrolyte is Li 3-x In y Zr x Cl 6-z F z , wherein 0.1≤x≤0.3, 0.7≤y≤0.9, and 0≤z≤0.6.

[0063] For example, x can be 0.1, 0.15, 0.2, 0.25, 0.3, or a range formed by any two of them; y can be 0.7, 0.75, 0.8, 0.85, 0.9, or a range formed by any two of them; and z can be 0, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, or a range formed by any two of them.

[0064] In a specific embodiment, the chemical formula of the sulfide solid-state electrolyte is Li i S j Cl6, wherein 0.1≤i≤0.3, 0.7≤j≤0.9.

[0065] For example, i can be 0.1, 0.15, 0.2, 0.25, 0.3, or a range formed by any two of them; and j can be 0.7, 0.75, 0.8, 0.85, 0.9, or a range formed by any two of them.

[0066] The application also provides a charging and discharging method of the all-solid-state battery, comprising:

[0067] (1) For the all-solid-state battery as described in the above embodiment, the first set number of charging and discharging cycles is performed at a first rate in the (2-2.2)-(2.6-2.8) V v.s. Li-In / In voltage interval;

[0068] (2) The second set number of constant current and constant voltage charging and discharging cycles is performed at a second rate in the (2.4-3)-(3.8-3.9) V v.s. Li-In / In voltage interval, wherein the constant voltage cutoff current density is set to the first rate, and the second rate is greater than the first rate;

[0069] (3) The cycle performance test is performed at a third rate in the (2-2.4)-(4.1-4.2) V v.s. Li-In / In cycle voltage window, and the third rate is greater than the second rate.

[0070] In a specific embodiment, the first rate is 0.05C-0.15C rate, the second rate is 0.15C-0.3C rate, and the third rate is 0.5C-1C rate.

[0071] Exemplarily, the charging and discharging method of the all-solid-state battery mainly includes the following three parts:

[0072] (1) The first set number of charging and discharging cycles is performed on the all-solid-state battery at a 0.05C-0.15C rate in the (2-2.2)-(2.6-2.8) V v.s. Li-In / In low voltage interval, wherein the first set number is, for example, 1-50 times;

[0073] (2) The second set number of constant current and constant voltage charging and discharging cycles is performed at a 0.15C-0.3C rate in the (2.4-3)-(3.8-3.9) V v.s. Li-In / In voltage interval, wherein the constant voltage cutoff current density is set to the 0.05C-0.15C rate to inhibit the structural degradation of the lithium-rich manganese-based positive electrode material, and the second set number is, for example, 1-4 times;

[0074] (3) The cycle performance test is performed at a 0.5C-1C rate in the (2-2.4)-(4.1-4.2) V v.s. Li-In / In cycle voltage window.

[0075] It should be noted that the first set number of 1-50 times and the second set number of 1-4 times are only examples, and in actual application, the first set number and the second set number can be set according to actual application requirements, which are not limited herein.

[0076] In a specific embodiment, the cycle life of the all-solid-state battery is greater than or equal to 700 cycles, and the average voltage decay rate of the all-solid-state battery is less than or equal to 0.228 mV / cycle.

[0077] For example, the cycle life of the all-solid-state battery is 700 cycles, 702 cycles, 705 cycles, 707 cycles, 709 cycles, 710 cycles, or other values greater than 700 cycles, and so on, thereby achieving comprehensive improvement of the performance of the all-solid-state battery. Compared with the prior art, not only is the problem of rapid battery capacity decay and voltage decay effectively solved, but also the cycle life and voltage stability of the all-solid-state battery are significantly improved, thereby providing strong technical support for large-scale application of the lithium-rich manganese-based all-solid-state battery.

[0078] The application also provides an energy storage device comprising the all-solid-state battery using the charging and discharging method as described in the above embodiments.

[0079] The application also provides an electric device comprising the all-solid-state battery using the charging and discharging method as described in the above embodiments, or comprising the energy storage device as described in the above embodiments.

[0080] The electric device is not particularly limited in the application, and can be any electric device comprising the all-solid-state battery using the charging and discharging method as described in the above embodiments, or any electric device comprising the energy storage device as described in the above embodiments. The electric device includes, but is not limited to, a mobile phone, a portable device, a notebook computer, an electric bicycle, an electric vehicle, an electric toy, an energy storage device, and the like.

[0081] In the following, the all-solid-state battery and the charging and discharging method of the all-solid-state battery provided by the application will be further described in combination with specific embodiments.

[0082] Unless otherwise specified, the reagents, materials, and instruments used in the following embodiments are conventional reagents, conventional materials, and conventional instruments in the art, and can be obtained by commercial purchase. The reagents involved can also be synthesized by conventional methods in the art.

[0083] Embodiment 1

[0084] The embodiment provides an all-solid-state battery and a charging and discharging method of the all-solid-state battery, a preparation method, and charging and discharging tests thereof as follows:

[0085] 1) Cell preparation: 50-80 mg of sulfide solid electrolyte was slightly pressed to obtain the negative side electrolyte layer; 20-40 mg of halide solid electrolyte was slightly pressed to obtain the positive side electrolyte layer; 10-15 mg of composite positive electrode material was placed evenly on the halide electrolyte layer of the double-layer solid electrolyte, a pressure of 2.5-3 t was applied for 3-5 min, and then a piece of 25-30 mg carbon-coated aluminum foil current collector with a diameter of about 10 mm was added; a piece of 100±10 um In sheet, 20-50 um Li foil and copper foil current collector were added on the sulfide electrolyte layer of the double-layer solid electrolyte; the mold cell was tightened, the clamp was covered, and the fixing screw was tightened under a pressure of 1-1.2 t.

[0086] 2) Charge-discharge test: for the all-solid-state battery, 10-15 cycles of charge-discharge were carried out at a rate of 0.05C-0.15C in the voltage range of (2-2.2)-(2.6-2.8) V v.s. Li-In / In low voltage range; then stepwise high voltage charge-discharge was carried out, 1-4 cycles of constant current, constant voltage charge-discharge were carried out at a rate of 0.15C-0.3C in the voltage range of (2.4-3)-(3.8-3.9) V v.s. Li-In / In, the constant voltage cutoff current density was set to 0.05C-0.15C to inhibit the structural degradation of the lithium-rich manganese-based positive electrode material; finally, the cycle performance test was carried out at a rate of 0.5C-1C in the cycle voltage window of (2-2.4)-(4.1-4.2) V v.s. Li-In / In.

[0087] For example, Figure 1 A schematic diagram of the discharge specific capacity cycle data of the all-solid-state battery provided by the exemplary embodiments of the present application is shown. As shown in Figure 1 , the highest discharge specific capacity of the Lrs-HSE-ASSBs (i.e. all-solid-state battery) during the 0.5C-1C rate cycle process is 224.0 mAh / g, and the discharge specific capacity after 702 cycles is 179.1 mAh / g, at which time the capacity retention rate is 79.96%, which is lower than 80%, the service life ends, and the cycle life is 702 times. Correspondingly, Figure 2 A schematic diagram of the average discharge voltage of the all-solid-state battery provided by the exemplary embodiments of the present application is shown. As shown in Figure 2 , in the 0.5C-1C rate cycle process, the average discharge voltage of the first cycle is 3.5982 V, the average discharge voltage of the 702th cycle is 3.4381 V, and the average voltage decay rate during the service life is (3.5982-3.4381) / (702-1)=0.228 mV / cycle.

[0088] Comparative Example 1

[0089] The present embodiment provides a kind of all-solid-state battery and the charge-discharge method of all-solid-state battery, its preparation method is identical with embodiment 1, its charge-discharge test is different from embodiment 1, it is not used " according to 0.05C-0.15C rate in (2 ~ 2.2) - (2.6 ~ 2.8) V v.s.Li-In / In low voltage interval charge-discharge cycle", but directly to all-solid-state battery is gradually high voltage charge-discharge, according to 0.15C-0.3C rate in (2.4 ~ 3) - (3.8 ~ 3.9) V v.s.Li-In / In voltage interval constant current, constant voltage charge-discharge cycle 1 ~ 4 times, constant voltage cut-off current density is set to 0.05C-0.15C rate, to inhibit the structural degradation of lithium-rich manganese-based positive electrode material;Finally, 0.5C-1C rate is in (2 ~ 2.4) - (4.1 ~ 4.2) V v.s.Li-In / In cycle voltage window is carried out cycle performance test.

[0090] Exemplarily, Figure 3 Another schematic diagram of the discharge specific capacity cycle data of the all-solid-state battery provided by the exemplary embodiments of the present application is shown. Figure 3 As shown, the highest discharge specific capacity of the all-solid-state battery during 0.5C-1C rate cycle is 223.1 mAh / g, and the discharge specific capacity is 178.4 mAh / g after 456 cycles, at which time the capacity retention rate is 79.96%, which is lower than 80%, the service life ends, and the cycle life is 456 times. Accordingly, Figure 4 Another schematic diagram of the average discharge voltage of the all-solid-state battery provided by the exemplary embodiments of the present application is shown. Figure 4 As shown, during 0.5C-1C rate cycle, the average discharge voltage of the first discharge is 3.6410V, and the average discharge voltage of the 456th cycle is 3.5327V, and the average voltage decay rate during the service life is (3.6410-3.5327) / (456-1)=0.238mV / cycle.

[0091] Comparative Example 2

[0092] The embodiment provides a full solid-state battery and a charge-discharge method of the full solid-state battery, and the preparation method is the same as that of embodiment 1. The difference between the charge-discharge test and that of embodiment 1 is that the charge-discharge test does not adopt "0.05C-0.15C rate in (2-2.2)-(2.6-2.8) V vs. Li-In / In low voltage interval charge-discharge cycle", and does not adopt "0.15C-0.3C rate in (2.4-3)-(3.8-3.9) V vs. Li-In / In voltage interval constant current, constant voltage charge-discharge cycle", but first adopts 0.15C-0.3C rate in (2-2.2)-(2.6-2.8) V vs. Li-In / In low voltage interval small range charge-discharge cycle 1-4 times; and then adopts 0.5C-1C rate in (2-2.4)-(4.1-4.2) V vs. Li-In / In cycle voltage window for cycle performance test.

[0093] Exemplarily, Figure 5 Another schematic diagram of the discharge specific capacity cycle data of the full solid-state battery provided by the exemplary embodiment of the application is shown. Figure 5 As shown in the figure, the highest discharge specific capacity of the full solid-state battery in the 0.5C-1C rate cycle process is 225.5 mAh / g, the discharge specific capacity is 180.1 mAh / g after 375 cycles, at this time, the capacity retention rate is 79.87%, which is lower than 80%, the service life ends, and the cycle life is 375 times. Correspondingly, Figure 6 Another schematic diagram of the cycle average discharge voltage of the full solid-state battery provided by the exemplary embodiment of the application is shown. Figure 6 As shown in the figure, in the 0.5C-1C rate cycle process, in the cycle life range, the first discharge average voltage is 3.6762 V, the discharge average voltage of the 375th cycle is 3.4917 V, and the average voltage decay rate during the service life is (3.6762-3.4917) / (375-1)=0.493 mV / cycle.

[0094] Exemplarily, Table 1 is an example of the charge-discharge test results corresponding to embodiment 1, comparative example 1 and comparative example 2.

[0095] Table 1

[0096]

[0097] Accordingly, as shown in Table 1, by Comparative Example 2, the all-solid-state battery provided by the present application, i.e., the lithium-rich manganese-based-halide all-solid-state battery (Lrs-HSEs-ASSBs), can achieve a high cycle performance of more than 350 times by improving the composition and structure of the composite cathode. On this basis, further taking the charge and discharge improvement strategy, according to Comparative Example 2 and Comparative Example 1, by using the improved charge and discharge strategy, the voltage and specific capacity cycle stability can be significantly improved, and the cycle life can reach 456 times. Further, by using the "composite cathode + three-stage charge and discharge" synergistic optimization, the cycle life of Example 1 reaches 702 times, which is 54% higher than that of Comparative Example 1 and 87.2% higher than that of Comparative Example 2; and the voltage decay rate (0.228 mV / cycle) of Example 1 is 4.2% lower than that of Comparative Example 1 (0.238 mV / cycle) and is significantly reduced by 53.8% compared with Comparative Example 2 (0.493 mV / cycle) without optimized charge and discharge strategy. It can be seen that Example 1 significantly improves the cycle life of the all-solid-state battery.

[0098] In summary, on the basis of the improvement of the composite cathode, specific elements and proportion range of the all-solid-state battery, by using the unique three-stage charge and discharge strategy, first, small-range charge and discharge cycling in the low-voltage interval can effectively stabilize the interface between the negative electrode and the electrolyte, reduce the occurrence of interface side reactions, and lay the foundation for stable operation of the all-solid-state battery; then by gradually performing high-voltage charge and discharge, a series of irreversible structural degradation problems such as lattice oxygen precipitation and phase structure transformation of the lithium-rich cathode material during high-voltage charging are targetedly inhibited; finally, the cycle performance test is performed in the optimized cycle voltage window. By using this charge and discharge improvement strategy, the cycle life and voltage stability of the all-solid-state battery are further improved, which has a positive significance for promoting the large-scale application of the all-solid-state battery.

[0099] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for part or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for charging and discharging an all-solid-state battery, characterized in that, include: (1) For the all-solid-state battery, a first set number of charge-discharge cycles are performed at a first rate in the voltage range of (2~2.2)-(2.6~2.8)V vs Li-In / In; (2) A second set number of constant current and constant voltage charge-discharge cycles are performed in the voltage range of (2.4~3)-(3.8~3.9)V vs Li-In / In at a second multiplier, wherein the constant voltage cutoff current density is set to the first multiplier, and the second multiplier is greater than the first multiplier; (3) Cyclic performance testing was performed at a third rate within a cyclic voltage window of (2~2.4) - (4.1~4.2) V vs Li-In / In, wherein the third rate is greater than the second rate; The all-solid-state battery comprises a composite positive electrode, a double electrolyte layer, and a lithium-indium negative electrode, wherein: The composite positive electrode is made of a composite positive electrode material, the composite positive electrode material includes a lithium-rich manganese-based positive electrode material, a halide solid electrolyte, and a conductive agent, and the chemical general formula of the composite positive electrode material is Li 1.1+a Ni b Mn c M d O 2-e F e , M includes at least one of Zr, Nb, Mg, Al, and Ti, 0.04 ≤ a ≤ 0.08, 0.2 < b ≤ 0.21, 0.52 ≤ c ≤ 0.56, 0 < d ≤ 0.04, 0 < e ≤ 0.01; the chemical general formula of the halide solid electrolyte is Li 3-x In y Zr x Cl 6-z F z , 0.1 ≤ x ≤ 0.3, 0.7 ≤ y ≤ 0.9, 0 ≤ z ≤ 0.6; The bilayer electrolyte layer includes a positive electrode side electrolyte layer and a negative electrode side electrolyte layer. The positive electrode side electrolyte layer is made of a halide solid electrolyte, and the negative electrode side electrolyte layer is made of a sulfide solid electrolyte.

2. The charging and discharging method for an all-solid-state battery according to claim 1, characterized in that, The median particle size of the halide solid electrolyte is 0.1-50 μm.

3. The charging and discharging method for an all-solid-state battery according to claim 2, characterized in that, The median particle size of the halide solid electrolyte is 0.3-10 μm.

4. The charging and discharging method for an all-solid-state battery according to claim 1, characterized in that, The conductive agent is vapor-grown carbon fiber, the lithium-rich manganese-based cathode material accounts for 57%-67% of the mass fraction of the composite cathode material, the halide solid electrolyte accounts for 30%-37% of the mass fraction of the composite cathode material, and the conductive agent accounts for 1%-5% of the mass fraction of the composite cathode material.

5. The charging and discharging method for an all-solid-state battery according to claim 1, characterized in that, The general chemical formula of the halide solid electrolyte is Li 3-x In y Zr x Cl 6-z F z Where 0.1≤x≤0.3, 0.7≤y≤0.9, and 0≤z≤0.6; And / or, the general chemical formula of the sulfide solid electrolyte is Li3P. i S j Cl6, where 0.1≤i≤0.3, 0.7≤j≤0.

9.

6. The charging and discharging method for an all-solid-state battery according to any one of claims 1 to 5, characterized in that, The first multiplier is 0.05C-0.15C, the second multiplier is 0.15C-0.3C, and the third multiplier is 0.5C-1C.

7. The charging and discharging method for an all-solid-state battery according to any one of claims 1 to 5, characterized in that, The all-solid-state battery has a cycle life of 700 cycles or more, and the average voltage decay rate of the all-solid-state battery is less than or equal to 0.228 mV / cycle.

8. An energy storage device, characterized in that, This includes all-solid-state batteries employing the charge-discharge method as described in any one of claims 1 to 7.

9. An electrical appliance, characterized in that, Includes all-solid-state batteries employing the charge-discharge method as described in any one of claims 1 to 7, or includes energy storage devices as described in claim 8.

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