An activation method for a lithium-rich manganese-based electrode material of an all-solid-state battery

Abstract

The application belongs to the technical field of all-solid-state lithium batteries, and discloses an activation method for a lithium-rich manganese-based electrode material of an all-solid-state battery.The application comprises the following steps: (1) preparation of a lithium-rich manganese-based electrode: uniformly mixing a lithium-rich manganese-based material and a solid-state electrolyte, and compression molding; (2) assembly of an all-solid-state lithium battery: taking the lithium-rich manganese-based electrode as a positive electrode, taking a lithium-indium metal sheet as a negative electrode, and taking a solid-state electrolyte as an ion-conducting medium; (3) large-current density activation treatment: charging and discharging in a voltage range of 1.38-4.18 V under a current density of 1C; and (4) small-current density cycle test: keeping the charging and discharging voltage range unchanged, switching the current density to 0.2C, and continuously performing charging and discharging cycles.The application significantly improves the specific capacity and cycle stability of the material through a two-step strategy of "large-current density activation-small-current density cycle".

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of all-solid-state lithium batteries, and more particularly to an activation method and application of a lithium-rich manganese-based electrode material for all-solid-state lithium batteries. BACKGROUND

[0002] All-solid-state lithium batteries have become the core development direction of the next generation of energy storage devices due to their high energy density, good safety, and no risk of electrolyte leakage. Lithium-rich manganese-based materials (such as xLi2MnO3 (1-x) LiMO2, M=Ni, Co, Mn, etc.) are considered one of the most promising positive electrode materials for all-solid-state lithium batteries due to their ultra-high theoretical specific capacity (>250 mAh g -1 ). However, lithium-rich manganese-based materials face the key problem of insufficient capacity when applied in all-solid-state lithium battery systems. This is mainly due to the unique interface and kinetic limitations of all-solid-state batteries: on the one hand, there is an interface gap and "point contact" phenomenon between the lithium-rich manganese-based material and the solid-state electrolyte, resulting in discontinuous ion conduction paths and high interface impedance; on the other hand, the activation of the bulk active phase (such as the Li2MnO3 phase) of the lithium-rich manganese-based material requires sufficient ion migration, while the ion diffusion rate is slow in the solid-state system, and the volume change during the charging and discharging process of the material is easily constrained by the rigidity of the solid-state electrolyte, making it difficult for active sites to fully participate in the reaction; in addition, the lithium-rich manganese-based material and the solid-state electrolyte may have an interface side reaction to generate a high impedance barrier layer, further inhibiting capacity.

[0003] In the prior art, the above problems are usually improved by optimizing the electrode preparation process, modifying the solid-state electrolyte, or constructing an interface buffer layer, but these methods often have defects such as complex process, high cost, or insufficient stability. Therefore, it is of great practical significance and application value to develop a simple and efficient, low-cost activation method for lithium-rich manganese-based materials to break through the capacity bottleneck of all-solid-state lithium batteries. SUMMARY

[0004] Therefore, the present application provides an activation method for lithium-rich manganese-based electrode materials for all-solid-state batteries. Through the two-step strategy of "high current density activation-low current density cycling", the specific capacity and cycle stability of the material are significantly improved.

[0005] To achieve the above purpose, the present application provides an activation method for lithium-rich manganese-based electrode materials for all-solid-state batteries, comprising the following steps:

[0006] (1) Preparation of lithium-rich manganese-based electrodes: mix lithium-rich manganese-based materials and solid-state electrolytes uniformly, and press form under a pressure of 10 MPa to obtain lithium-rich manganese-based electrodes;

[0007] (2) Assembling of the all-solid-state lithium battery: the lithium-rich manganese-based electrode is used as the positive electrode, the lithium-indium metal sheet is used as the negative electrode, and the solid-state electrolyte is used as the ion conduction medium, and the all-solid-state lithium battery is assembled in an argon-protected glove box;

[0008] (3) Large current density activation treatment: the all-solid-state lithium battery is charged and discharged in the voltage range of 1.38-4.18 V at a current density of 1C to complete the activation process.

[0009] The activation cycle number is 3 cycles, so as to optimize the interface and structure while avoiding excessive material loss.

[0010] (4) Small current density cycle test: after the activation is completed, the charge and discharge voltage range is kept unchanged, the current density is switched to 0.2C, and the charge and discharge cycle is continuously carried out to realize the full release and stable maintenance of the capacity.

[0011] Preferably, the mass ratio of the lithium-rich manganese-based material and the solid-state electrolyte is 60-80:20-40.

[0012] Preferably, the lithium-rich manganese-based material is Li 1.3 Ni 0.35 Mn 0.65 O2, Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O2 or Li 1.4 Ni 0.35 Mn 0.65 O2.

[0013] Preferably, the solid-state electrolyte is a halide electrolyte.

[0014] Preferably, the halide electrolyte is Li3InCl6, Li3YCl6 or Li2ZrCl6.

[0015] By means of the two-step strategy of “large current density activation-small current density cycle”, the capacity of the lithium-rich manganese-based material of the all-solid-state lithium battery is significantly improved, and the beneficial effects obtained are as follows:

[0016] 1. In the large current density activation process, the volume expansion and shrinkage of the lithium-rich manganese-based material caused by the rapid embedding and stripping of lithium ions can extrude the interface between the electrode and the solid-state electrolyte, reduce the interface gap, form a more compact physical contact, reconstruct a continuous ion conduction network, and reduce the interface impedance;

[0017] 2. The strong polarization effect under the large current can drive the structural transformation of the interface side reaction products or inhibit the excessive growth of the barrier layer, form a low impedance interface layer, and break the material bulk phase kinetic limitation, promote the full activation of the Li2MnO3 active phase, and awaken the inert part not involved in the reaction;

[0018] 3. The small current density cycle after activation can avoid the damage of large current to the material structure, so that the optimized interface and activated active phase can fully play a role, realizing efficient release and long-term stable maintenance of capacity;

[0019] 4. The method is simple to operate, does not need complex equipment or expensive modification reagents, is low in cost, can be directly applied to the existing full solid-state lithium battery production process, and has good compatibility and large-scale application potential. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of the provided drawings.

[0021] Figure 1 is the charge-discharge curve of Li 1.3 Ni 0.35 Mn 0.65 O2 in Example 1 at 1C after 3 cycles of activation.

[0022] Figure 2 is the first cycle charge-discharge curve of Li 1.3 Ni 0.35 Mn 0.65 O2 in Example 1 at 0.2C.

[0023] Figure 3 is the SEM image of Li 1.3 Ni 0.35 Mn 0.65 O2 in Example 1 at 1C after 3 cycles of activation.

[0024] Figure 4 is the charge-discharge cycle diagram of Li 1.3 Ni 0.35 Mn 0.65 O2 in Example 1 at 0.2C.

[0025] Figure 5 is the charge-discharge curve of Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O2 in Example 2 at 1C after 3 cycles of activation.

[0026] Figure 6 is the first cycle charge-discharge curve of Li 1.2 Mn 0.54 Ni 0.13 Co0.13 O2 at 0.2C.

[0027] Figure 7 is Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O2 at 0.2C.

[0028] Figure 8 is Li 1.4 Ni 0.35 Mn 0.65 O2 at 1C for 3 cycles.

[0029] Figure 9 is Li 1.4 Ni 0.35 Mn 0.65 O2 at 0.2C.

[0030] Figure 10 is Li 1.4 Ni 0.35 Mn 0.65 O2 at 0.2C.

[0031] Figure 11 is Li 1.3 Ni 0.35 Mn 0.65 O2 at 0.2C for 3 cycles.

[0032] Figure 12 is Li 1.3 Ni 0.35 Mn 0.65 O2 at 0.2C.

[0033] Figure 13 is Li 1.3 Ni 0.35 Mn 0.65 O2 at 0.2C for 3 cycles.

[0034] Figure 14 is Li 1.3 Ni 0.35 Mn 0.65 O2 at 0.2C.

[0035] Figure 15 is Li 1.3 Ni 0.35 Mn 0.65Charge-discharge curve of O2 at 0.05C for 3 cycles.

[0036] Figure 16 Li in Example 1 1.3 Ni 0.35 Mn 0.65 Charge-discharge curve of O2 at 0.2C for the first cycle.

[0037] Figure 17 Li in Example 1 1.3 Ni 0.35 Mn 0.65 SEM image of O2 at 0.05C for 3 cycles.

[0038] Figure 18 Li in Example 1 1.3 Ni 0.35 Mn 0.65 Charge-discharge cycle curve of O2 at 0.2C. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0040] Example 1

[0041] Preparation of lithium-rich manganese-based electrode: the lithium-rich manganese-based material (Li 1.3 Ni 0.35 Mn 0.65 O2) and halide electrolyte (Li3InCl6) were mixed uniformly at a mass ratio of 70:30, poured into the electrolyte side of the mold, and pressed under a pressure of 10 MPa to obtain a lithium-rich manganese-based electrode.

[0042] Assembly of all-solid-state lithium battery: the prepared lithium-rich manganese-based electrode was used as the positive electrode, a lithium-indium metal sheet was used as the negative electrode, and Li3InCl6 was used as the solid-state electrolyte sheet to assemble an all-solid-state lithium battery in an argon glove box.

[0043] High-current density activation treatment: the assembled all-solid-state lithium battery was placed on a blue light test system, and 3 cycles of charge-discharge cycles were performed at a current density of 1C (1C = 200 mAh / g) in a voltage range of 1.38-4.18 V (Li vs Li-In) to complete the activation.

[0044] Small current density cycling test: switch the current density to 0.2C, and perform cycling test in the same voltage range. The results show that the initial specific capacity of the material reaches 224.4 mAh g -1 The capacity retention rate is 115.2% after 100 cycles.

[0045] Example 2

[0046] Preparation of lithium-rich manganese-based electrode: the lithium-rich manganese-based material (Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O2) and halide electrolyte (Li3YCl6) are mixed uniformly at a mass ratio of 60:40, poured into the electrolyte side of the mold, and pressed under a pressure of 10 MPa to obtain a lithium-rich manganese-based electrode.

[0047] Assembly of all-solid-state lithium battery: the prepared lithium-rich manganese-based electrode is used as the positive electrode, the lithium-indium metal sheet is used as the negative electrode, and Li3YCl6 is used as the solid electrolyte sheet to assemble an all-solid-state lithium battery in an argon glove box.

[0048] Large current density activation treatment: the assembled all-solid-state lithium battery is placed on a blue light test system, and 3 cycles of charge and discharge are performed at a current density of 1C (1C=200 mAh / g) in a voltage range of 1.38-4.18 V (Li vs Li-In) to complete activation.

[0049] Small current density cycling test: switch the current density to 0.2C, and perform cycling test in the same voltage range. The results show that the initial specific capacity of the material reaches 245.4 mAh g -1 The capacity retention rate is 101.5% after 50 cycles.

[0050] Example 3

[0051] Preparation of lithium-rich manganese-based electrode: the lithium-rich manganese-based material (Li 1.4 Ni 0.35 Mn 0.65 O2) and halide electrolyte (Li2ZrCl6) are mixed uniformly at a mass ratio of 80:20, poured into the electrolyte side of the mold, and pressed under a pressure of 10 MPa to obtain a lithium-rich manganese-based electrode.

[0052] Assembly of all-solid-state lithium battery: the prepared lithium-rich manganese-based electrode is used as the positive electrode, the lithium-indium metal sheet is used as the negative electrode, and Li2ZrCl6 is used as the solid electrolyte sheet to assemble an all-solid-state lithium battery in an argon glove box.

[0053] High current density activation treatment: the assembled all-solid-state lithium battery was placed on a blue test system, and 3 cycles of charge-discharge were carried out at a current density of 1C (1C = 200 mAh / g) in the voltage range of 1.38-4.18 V (Li vs Li-In), and the activation was completed.

[0054] Small current density cycle test: the current density was switched to 0.2C, and the cycle test was carried out in the same voltage range. The results showed that the initial specific capacity of the material reached 233.6 mAh g -1 , and the capacity retention rate was 109.4% after 50 cycles.

[0055] Comparative Example 1

[0056] No high current density activation treatment was carried out, and the rest of the operations were exactly the same as Example 1. The cycle test was directly carried out at a current density of 0.2C. The initial specific capacity of the material was only 194.5 mAh g -1 , and the capacity retention rate was 100.2% after 100 cycles.

[0057] Comparative Example 2

[0058] 0.05C small current density activation treatment was carried out, and the rest of the operations were exactly the same as Example 1. Then the cycle test was carried out at a current density of 0.2C. The initial specific capacity of the material was only 193.3 mAh g -1 , and the capacity retention rate was 95.3% after 100 cycles.

[0059] The above description of the disclosed embodiments enables one skilled in the art to make or use the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An activation method for lithium-rich manganese-based electrode materials used in all-solid-state batteries, characterized in that, Includes the following steps: (1) Preparation of lithium-rich manganese-based electrode: The lithium-rich manganese-based material and solid electrolyte are mixed evenly and pressed into shape to obtain the lithium-rich manganese-based electrode; (2) Assembly of all-solid-state lithium battery: Using lithium-rich manganese-based electrode as positive electrode, lithium indium metal sheet as negative electrode, and solid electrolyte as ion conduction medium, an all-solid-state lithium battery is assembled. (3) High current density activation treatment: The all-solid-state lithium battery is charged and discharged at a current density of 1C within a voltage range of 1.38-4.18 V; (4) Low current density cycle test: Keep the charge and discharge voltage range unchanged, switch the current density to 0.2C, and continue to perform charge and discharge cycles to complete the cycle test; The lithium-rich manganese-based material is Li 1.3 Ni 0.35 Mn 0.65 O2, Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O2 or Li 1.4 Ni 0.35 Mn 0.65 O2; In step (3), the charge-discharge cycle is performed 3 times, and 1C = 200mAh / g.

2. The activation method for lithium-rich manganese-based electrode materials in all-solid-state batteries according to claim 1, characterized in that, The mass ratio of the lithium-rich manganese-based material to the solid electrolyte is 60-80:20-40.

3. The activation method for lithium-rich manganese-based electrode materials in all-solid-state batteries according to claim 2, characterized in that, The solid electrolyte is a halide electrolyte.

4. The activation method for lithium-rich manganese-based electrode materials in all-solid-state batteries according to claim 3, characterized in that, The halide electrolyte is Li3InCl6, Li3YCl6, or Li2ZrCl6.

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