Lithium metal negative electrode based on non-host precision configuration and preparation method and application thereof

Abstract

The application relates to a lithium metal negative electrode based on a non-host precise configuration in the technical field of lithium battery negative electrode materials and a preparation method and application thereof, and comprises a lithium metal negative electrode body, a plurality of regular hexagonal holes are constructed in the lithium metal negative electrode body, the plurality of regular hexagonal holes are uniformly arranged, the side length of the holes is 40-100 mu m, the center distance between two adjacent holes is 80-140 mu m, and the hole depth is 20-30 mu m. The scheme solves the problems of high mortality and low energy density of the existing lithium metal negative electrode host modification technology.

Description

Technical Field

[0001] This invention relates to the field of lithium battery anode material technology, specifically to lithium metal anodes based on non-host precision configurations, their preparation methods, and applications. Background Technology

[0002] Lithium metal, with its extremely high theoretical specific capacity and extremely low electrode potential, is considered an ideal anode material for next-generation high-energy-density lithium batteries. It can effectively overcome the energy density bottleneck of traditional graphite anode batteries and has broad application prospects in new energy power batteries, energy storage batteries, and other fields. However, lithium metal anodes exhibit a severe volume expansion effect during charge-discharge cycles and are highly susceptible to inducing disordered lithium dendrite growth. This not only significantly reduces battery cycle life and capacity but may also puncture the separator, causing short circuits, thermal runaway, and other safety hazards, severely restricting the industrial application of lithium metal batteries.

[0003] Currently, mainstream research on improving the cycle stability and structural stability of lithium metal anodes follows the host strategy paradigm. The core idea is to pre-construct a three-dimensional porous conductive framework as a functional host, and then incorporate lithium metal into the framework through methods such as melt implantation and electrochemical deposition to prepare a lithium metal composite anode. Commonly used host materials include copper foam, nickel foam, and graphene aerogel, and they are generally combined with lithiophilic coating surface modification processes to optimize electrode interface performance.

[0004] This traditional host strategy can, to some extent, utilize the porous framework's void space to accommodate volumetric deformation during lithium metal deposition / stripping, and rely on the uniform ion flow field within the electrode via a three-dimensional conductive network to effectively suppress disordered lithium dendrite growth and alleviate the overall battery volume expansion problem. However, this technical solution has fundamental drawbacks: First, the introduced three-dimensional host framework and modifying coating are both inert materials that do not contribute to battery capacity, resulting in a large amount of "dead weight" and significantly reducing the overall energy density of the battery; second, a large number of complex heterogeneous interfaces are formed between the exogenous host material and lithium metal, increasing interfacial impedance and affecting the battery's electrochemical kinetic performance; third, the composite modification process is cumbersome, has high preparation costs, and poor compatibility with existing large-scale battery production processes.

[0005] Therefore, existing host modification technologies have always relied on the traditional approach of "introducing foreign substances and performing composite modification", which cannot meet the dual core requirements of lithium metal batteries for low volume expansion and high energy density. Summary of the Invention

[0006] The present invention aims to provide a lithium metal anode based on a non-host precision configuration, its preparation method and application, in order to solve the problems of large "dead weight" and low energy density in existing lithium metal anode host modification technologies.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a lithium metal anode based on a non-host precision configuration, comprising: The lithium metal anode body has several hexagonal pores inside, which are evenly spaced and arranged at equal intervals. The side length of the pores is 40~100μm, the center distance between two adjacent pores is 80~140μm, the pore depth is 20~30μm, and the thickness of the lithium metal anode body is 50~70μm.

[0008] Preferably, as an improvement, the side length of the hole is 60 μm, the center distance between two adjacent holes is 100 μm, the hole depth is 25 μm, and the thickness of the lithium metal anode body is 60 μm.

[0009] The preparation method of lithium metal anode based on non-host precision configuration includes the following steps: S1, Based on the target hole structure and layout of the lithium metal anode body, an imprinting mold with regular hexagonal protrusions is designed and processed. S2, In an environment with humidity ≤2%, lay the lithium metal negative electrode flat on the temperature control base. The temperature control base temperature is 25℃±2℃. Place the imprinting mold on the surface of the lithium metal negative electrode and apply a vertical constant pressure of 40~80MPa to the imprinting mold for 20~60s. S3. After the pressure holding is completed, keep the pressure applied to the printing mold unchanged, heat the temperature control base to 55℃±2℃ and hold for 10 seconds, then unload the pressure and vertically lift the printing mold to obtain a three-dimensional porous lithium metal anode with holes arranged in a regular hexagonal shape.

[0010] Preferably, as an improvement, the embossing mold in step S1 is made of polytetrafluoroethylene.

[0011] Preferably, as an improvement, in step S2, a vertical constant pressure of 60 MPa is applied to the embossing mold and held for 30 seconds.

[0012] The lithium metal anode with a non-host precision configuration is combined with high-nickel ternary cathode material for use in pouch cell assembly.

[0013] The advantages of this solution compared to existing technologies are: 1. This invention constructs a regular hexagonal array of pores inside lithium metal through the synergistic optimization of embossing mold design and embossing process, thus abandoning the application of host materials such as foamed copper, foamed nickel, and graphene aerogel in traditional technologies, thereby avoiding a series of problems directly caused by these materials.

[0014] This invention is based on the assembly of a non-host precision-configured lithium metal anode and a high-nickel ternary cathode into a pouch cell, which gives the battery the dual advantages of high energy density and low cycle expansion force, effectively suppressing heterogeneous interface problems and solving the problem of energy density reduction caused by "dead weight".

[0015] 2. The preparation process of the non-host precision-configured lithium metal anode of the present invention is simple. In this scheme, the shape and arrangement of the holes form a honeycomb structure, which has the highest packing density and the smallest structural anisotropy in a two-dimensional plane. When the hole array is subjected to the internal stress generated by lithium deposition, the stress is evenly distributed along the three principal axes of the hexagon, avoiding the stress concentration problem at the corners (90° right angles) of existing square holes, and fundamentally improving the anti-collapse ability of the hole structure in the long cycle process.

[0016] 3. The soft-pack battery prepared using the lithium metal anode in this scheme effectively slows down the growth rate of battery expansion force during cycling, thereby optimizing the battery volume expansion problem.

[0017] 4. The embossing mold in this solution is made of polytetrafluoroethylene (PTFE). PTFE has extremely low surface energy (~18.6 mN / m) and naturally possesses anti-adhesion properties to lithium metal. After embossing, the embossing mold and lithium metal can be directly separated without any auxiliary demolding methods, effectively avoiding tearing defects at the edges of the holes. At the same time, PTFE material has a certain degree of toughness and mechanical strength, which is sufficient to withstand the mechanical load during repeated embossing without bulging deformation.

[0018] 5. In this design, the thermal expansion coefficients of the PTFE imprinting mold and lithium metal differ significantly. Upon heating to 55°C, the expansion of the PTFE protrusions exceeds that of the lithium metal cavity wall, creating a micron-level gap between the previously tightly packed protrusions and the cavity wall. Combined with PTFE's low surface energy, this significantly reduces the adhesion between the imprinting mold and the lithium metal, enabling non-destructive demolding with no tearing or stringing at the cavity edges and excellent structural integrity. Furthermore, the heating process allows for the release of residual stress generated during imprinting, improving the dimensional stability of the cavity during subsequent cyclic service. Attached Figure Description

[0019] Figure 1 This is a comparison diagram of the lithium metal anode prepared in Example 1 of the present invention and the lithium metal anode without polypore treatment.

[0020] Figure 2 The graphs show the charge-discharge specific capacity of the lithium metal anode prepared in Example 1 of this invention when applied to a pouch cell and a pouch cell with an anode that has not been porous.

[0021] Figure 3The graph shows the cyclic expansion force curves of the lithium metal anode prepared in Example 1 of this invention applied to a pouch cell and a pouch cell with an anode that has not been porous.

[0022] Figure 4 The graphs show the cycle capacity curves of the lithium metal anode prepared in Example 1 of this invention applied to a pouch cell and a pouch cell with an anode that has not been porous. Detailed Implementation

[0023] The following detailed description illustrates the specific implementation methods: Example 1: Lithium metal anodes based on non-host precision configurations include: The lithium metal anode body has several hexagonal pores inside, which are evenly arranged in a hexagonal pattern. The side length of each pore is 60 μm, the center distance between two adjacent pores is 100 μm, the pore depth is 25 μm, and the thickness of the lithium metal anode body is 60 μm.

[0024] Example 2 Lithium metal anodes based on non-host precision configurations include: The lithium metal anode body has several hexagonal pores inside, which are evenly arranged in a hexagonal pattern. The side length of the pores is 40 μm, the center distance between two adjacent pores is 80 μm, the pore depth is 20 μm, and the thickness of the lithium metal anode body is 50 μm.

[0025] Example 3 Lithium metal anodes based on non-host precision configurations include: The lithium metal anode body has several hexagonal pores inside, which are evenly arranged in a hexagonal pattern. The side length of each pore is 100 μm, the center distance between two adjacent pores is 140 μm, the pore depth is 30 μm, and the thickness of the lithium metal anode body is 70 μm.

[0026] The method for preparing a lithium metal anode based on a non-host precision configuration, taking Example 1 as an example, includes the following steps: S1 is made of polytetrafluoroethylene (PTFE) material. Based on the target hole structure of the lithium metal anode body, an imprinting mold with regular hexagonal protrusions is designed and processed. The side length of the regular hexagonal protrusion is 60μm, the protrusion height of the regular hexagonal protrusion is 25μm, and the center distance between two adjacent regular hexagonal protrusions is 100μm. S2, In an environment with humidity ≤2%, lay a 60μm thick lithium metal anode flat on a temperature control base. The temperature control base is 25℃±2℃. Place the imprinting mold on the surface of the lithium metal anode and apply a vertical constant pressure of 60MPa to the imprinting mold for 30s. S3. After the pressure holding is completed, keep the pressure applied to the printing mold unchanged, heat the temperature control base to 55℃±2℃ and hold for 10 seconds, then unload the pressure and vertically lift the printing mold to obtain a three-dimensional porous lithium metal anode with holes arranged in a regular hexagonal shape.

[0027] Figure 1 The image shown is a comparison of the initial state of the lithium metal anode and its state after pressing and forming.

[0028] A soft-pack battery using a lithium metal anode prepared in Example 1 combined with a high-nickel ternary cathode material, such as... Figure 2 As shown, using porous lithium metal in pouch batteries can enable the batteries to achieve higher specific capacity, thereby effectively improving the battery energy density.

[0029] Figure 3 As shown, the soft-pack battery based on the lithium metal anode prepared in Example 1 and the high-nickel ternary cathode material effectively slows down the growth rate of battery expansion force during cycling, thereby optimizing the battery volume expansion problem.

[0030] Figure 4 As shown, the soft-pack battery with porous treatment based on the lithium metal anode prepared in Example 1 and the high-nickel ternary cathode material maintained a stable specific capacity of about 230 mAh / g throughout the entire process, while the untreated battery only maintained a stable specific capacity of about 190 mAh / g. This clearly demonstrates that the present invention can increase the electrochemical active area, reduce the local current density, remove the host "dead weight" and improve the battery energy density by preparing a honeycomb porous structure in lithium metal, and can continuously output a higher and more stable reversible specific capacity under multiple cycles.

[0031] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A lithium metal anode based on a non-host precision configuration, characterized in that, include: The lithium metal anode body has several hexagonal pores inside, which are evenly spaced and arranged at equal intervals. The side length of the pores is 40~100μm, the center distance between two adjacent pores is 80~140μm, the pore depth is 20~30μm, and the thickness of the lithium metal anode body is 50~70μm.

2. The lithium metal anode based on a non-host precision configuration according to claim 1, characterized in that: The side length of the hole is 60μm, the center distance between two adjacent holes is 100μm, the hole depth is 25μm, and the thickness of the lithium metal anode body is 60μm.

3. The method for preparing a lithium metal anode based on a non-host precision configuration according to claim 1 or 2, characterized in that: Includes the following steps: S1, Based on the target hole structure and layout of the lithium metal anode body, an imprinting mold with regular hexagonal protrusions is designed and processed. S2, In an environment with humidity ≤2%, lay the lithium metal negative electrode flat on the temperature control base. The temperature control base temperature is 25℃±2℃. Place the imprinting mold on the surface of the lithium metal negative electrode and apply a vertical constant pressure of 40~80MPa to the imprinting mold for 20~60s. S3. After the pressure holding is completed, keep the pressure applied to the printing mold unchanged, heat the temperature control base to 55℃±2℃ and hold for 10 seconds, then unload the pressure and vertically lift the printing mold to obtain a three-dimensional porous lithium metal anode with holes arranged in a regular hexagonal shape.

4. The method for preparing a lithium metal anode based on a non-host precision configuration according to claim 3, characterized in that: The embossing mold in step S1 is made of polytetrafluoroethylene.

5. The method for preparing a lithium metal anode based on a non-host precision configuration according to claim 4, characterized in that: In step S2, a vertical constant pressure of 60 MPa is applied to the embossing mold and held for 30 seconds.

6. The lithium metal anode based on a non-host precision configuration, as described in claim 1 or 2, is combined with a high-nickel ternary cathode material and applied to the assembly of pouch cells.

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