Lithium ion battery silicon-carbon negative pole piece

Abstract

The utility model discloses a lithium ion battery silicon carbon negative pole piece, which comprises a current collector and active layers arranged on two sides of the current collector, each active layer is a composite structure of silicon particles and silicon-metal alloy, the silicon-metal alloy is filled and arranged in gaps among the silicon particles, and the silicon-metal alloy is arranged in the gaps among the silicon particles. The side, away from the current collector, of each active layer is coated with three graphene layers, and graphene pores of the three graphene layers are sequentially increased from inside to outside. Silicon and a silicon-metal alloy composite material are mainly used as active materials, metal is used as a buffer medium, the conductivity and mechanical strength of the materials are improved, the graphene layer with different pores can prevent silicon particles from being exposed when the volume changes and from being in direct contact with electrolyte, active sites are provided, and the conductivity and mechanical strength of the materials are improved. The migration and diffusion of ions / electrons are promoted, and a good conductive network is formed in the battery, so that the high-rate charge-discharge capacity and the cycling stability of the lithium battery are improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of lithium ion batteries, in particular to a silicon-carbon negative electrode piece for a lithium ion battery. Background Art

[0002] Silicon materials offer advantages such as high theoretical capacity, low operating voltage, and low cost, but they suffer from a significant volume effect. The internal stress generated by this volume effect can cause silicon particles to break and pulverize, leading to loss of electrical contact and increased polarization, resulting in rapid capacity decay. Furthermore, in lithium-ion batteries, a solid electrolyte interface (SEI) film forms at the interface between the anode material and the electrolyte. Silicon's volume effect causes this SEI film to be continuously destroyed and re-formed, consuming significant amounts of lithium and electrolyte. The resulting SEI film becomes increasingly thicker, increasing internal resistance. Furthermore, silicon itself has poor electrical conductivity. Combining silicon with a highly conductive metal without lithium intercalation activity to form an alloy improves both its conductivity and its volume effect. Coating the silicon surface with a carbon material helps isolate it from the electrolyte, forming a relatively stable SEI film. Among the various carbon materials, graphene, due to its large surface area, chemical stability, and excellent electrical conductivity, holds great potential as a material for lithium-ion batteries. Therefore, it is very important to develop a new type of lithium-ion battery silicon-carbon negative electrode to improve the performance of the silicon-carbon negative electrode. Utility Model Content

[0003] The utility model aims to provide a lithium-ion battery silicon-carbon negative electrode plate to solve the problems of silicon volume expansion, poor conductivity and direct contact with electrolyte.

[0004] In order to achieve the above-mentioned purpose of the utility model, the utility model adopts the following technical solutions:

[0005] A lithium-ion battery silicon-carbon negative electrode plate includes a current collector and an active layer arranged on both sides of the current collector. The active layer is a composite structure of silicon particles and a silicon-metal alloy. The silicon particles are evenly arranged on both sides of the current collector, and the silicon-metal alloy is filled in the gaps between the silicon particles. The side of the active layer away from the current collector is coated with three layers of graphene, and the graphene pores of the three layers of graphene increase sequentially from the inside to the outside.

[0006] Further technology of this utility model:

[0007] Preferably, the current collector is one of copper foil, nickel foil, foam copper, foam nickel, and carbon-coated copper foil.

[0008] Preferably, the silicon particles include one of elemental silicon, silicon carbon, silicon oxygen, and silicon oxygen carbon.

[0009] Preferably, the metal in the silicon-metal alloy is one of iron, copper, nickel, titanium and cobalt.

[0010] Preferably, the thickness of the current collector is 1-100 μm, the thickness of the active layer is 10-200 μm, the thickness of the single-layer graphene is 10-1000 μm, and the overall thickness of the pole piece is 71-6300 μm.

[0011] Preferably, the pore size of the graphene layer is 0.0001-100 μm, the particle size of the silicon particles is 0.01-50 μm, and the particle size of the silicon-metal alloy is 1-10000 nm.

[0012] The beneficial effects of the utility model are:

[0013] The silicon-carbon negative electrode plate for a lithium-ion battery described in this utility model utilizes a silicon-silicon alloy composite material as the active layer. The inert metal effectively mitigates silicon volume expansion and exhibits excellent electrical conductivity. Three graphene layers are coated on the active layer, with the graphene pores increasing in size from the inside out. This structure effectively prevents silicon from expanding and becoming exposed to the electrolyte, providing active sites. Its unique three-dimensional porous structure provides an excellent transport channel for electrons and ions, while forming a conductive network within the battery, resulting in excellent cycle and rate performance at high current densities. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 It is a structural diagram of the utility model;

[0016] Explanation of the accompanying symbols: 1. active layer; 2. graphene layer; 3. current collector; 4. silicon particles; 5. silicon-metal alloy. DETAILED DESCRIPTION

[0017] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0018] like Figure 1 As shown, the utility model provides a lithium-ion battery silicon-carbon negative electrode plate, including a current collector 3 and an active layer 1 arranged on both sides of the current collector 3, the active layer 1 is a composite structure of silicon particles 4 and a silicon-metal alloy 5, the silicon particles 4 are evenly arranged on both sides of the current collector 3, the silicon-metal alloy 5 is filled in the gaps between the silicon particles 4, and the side of the active layer 1 away from the current collector 3 is coated with three graphene layers 2, and the graphene pores of the three graphene layers increase successively from the inside to the outside.

[0019] Example 1. The current collector 3 in this example is a copper foil with a thickness of 5 μm. The active layer 1 is composed of a composite of 1 μm of elemental silicon and 3 nm of silicon-copper alloy. The thickness of the active layer 1 is 10 μm. The pore sizes of the graphene layer 2 from the inside to the outside are 10 nm, 20 nm, and 40 nm, respectively, and the thickness is 11 μm. The overall thickness of the electrode is 91 μm.

[0020] Example 2. The current collector 3 in this example is a copper foil with a thickness of 50 μm. The active layer 1 is composed of 30 μm of elemental silicon and 300 nm of silicon-copper alloy. The thickness of the active layer 1 is 100 μm. The pore sizes of the graphene layer 2 from the inside to the outside are 10 μm, 20 μm, and 40 μm, respectively, and the thickness is 300 μm. The overall thickness of the electrode is 2050 μm.

[0021] The above content is merely an example and explanation of the structure of the present utility model. Technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the utility model or exceed the scope defined by the claims, they should all fall within the scope of protection of the present utility model.

Claims

1. A lithium-ion battery silicon-carbon negative electrode plate, characterized in that: It includes a current collector and an active layer arranged on both sides of the current collector. The active layer is a composite structure of silicon particles and a silicon-metal alloy. The silicon particles are evenly arranged on both sides of the current collector, and the silicon-metal alloy is filled in the gaps between the silicon particles. The side of the active layer away from the current collector is coated with three layers of graphene, and the graphene pores of the three layers of graphene increase successively from the inside to the outside.

2. The lithium-ion battery silicon-carbon negative electrode according to claim 1, characterized in that: The current collector is one of copper foil, nickel foil, foam copper, foam nickel, and carbon-coated copper foil.

3. The lithium-ion battery silicon-carbon negative electrode according to claim 1, characterized in that: The silicon particles include one of elemental silicon, silicon carbon, silicon oxygen, and silicon oxygen carbon.

4. The lithium-ion battery silicon-carbon negative electrode according to claim 1, characterized in that: The metal in the silicon-metal alloy is one of iron, copper, nickel, titanium and cobalt.

5. The lithium-ion battery silicon-carbon negative electrode according to claim 1, characterized in that: The thickness of the current collector is 1-100 μm, the thickness of the active layer is 10-200 μm, the thickness of the single-layer graphene is 10-1000 μm, and the overall thickness of the pole piece is 71-6300 μm.

6. The lithium-ion battery silicon-carbon negative electrode according to claim 1, characterized in that: The pore size of the graphene layer is 0.0001-100 μm, the particle size of the silicon particles is 0.01-50 μm, and the particle size of the silicon-metal alloy is 1-10000 nm.

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