Multilayer Silicon Anode Structure for Volume Change Mitigation
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Solution Overview
Problem
Silicon-based anodes for secondary batteries face issues with volumetric expansion/contraction during charging/discharging, leading to cracks and reduced lifespan and rapid charging performance, especially in high-temperature environments.
Innovation Solution
A multilayer anode structure with a carbon-coated silicon-based active material in the first layer and metal-doped silicon-based active material in the second layer, along with specific conductive materials and carbon nanotubes, is used to alleviate volume changes and enhance conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based active material is used to increase capacity, then energy density is improved, but volumetric expansion/contraction occurs during charging/discharging
Solution Approach 1:
A carbon coating layer is formed on the surface of the silicon-based active material particles. This carbon shell acts as a flexible protective layer that can accommodate the volumetric expansion and contraction of the silicon core during lithium insertion and extraction, preventing structural degradation while maintaining the high capacity benefits of silicon.
Solution Approach 2:
The anode is constructed as a composite structure with silicon-based active material particles coated with carbon, mixed with conductive materials and binders. This composite approach combines the high capacity of silicon with the structural stability and conductivity of carbon-based materials, resolving the contradiction between capacity and volume stability.
2Quantity of substance
If silicon-based active material is used to increase capacity, then energy density is improved, but cracks occur in the active material
Solution Approach 1:
The carbon coating layer serves as a protective shell that prevents crack propagation in the silicon particles during repeated expansion and contraction cycles. This shell maintains particle integrity and prevents the formation of microcracks that would lead to material degradation and capacity loss.
Solution Approach 2:
The carbon coating is applied beforehand to the silicon particles before electrode fabrication. This pre-formed protective layer cushions the silicon core against mechanical stresses during subsequent charging/discharging cycles, preventing crack initiation and propagation before they can occur.
3Ease of manufacture
If conventional anode structure is used, then manufacturing is simple, but lifespan characteristics deteriorate in high temperature environment
Solution Approach 1:
The invention modifies the surface properties of silicon particles by coating them with carbon and controlling the composition of the anode mixture layer. These parameter changes (surface coating, compositional control) enhance thermal stability and lifespan characteristics in high-temperature environments while maintaining compatibility with conventional manufacturing processes.
4Ease of manufacture
If conventional anode structure is used, then manufacturing is simple, but rapid charging characteristics deteriorate in high temperature environment
Solution Approach 1:
The anode uses a composite mixture layer containing carbon-coated silicon particles, conductive materials (such as carbon black or graphene), and binders. This composite structure provides both structural integrity and enhanced electrical conductivity, enabling rapid charging in high-temperature environments while remaining compatible with standard manufacturing techniques.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a high-capacity anode with improved lifespan and rapid charging characteristics in both room and high-temperature environments, reducing electrolyte consumption and preventing anode peeling and short circuits.
Implementation Method 1
a first silicon-based active material including a carbon coating layer formed on a surface thereof
Implementation Method 2
a first conductive material... a second conductive material... having excellent rapid charging characteristics
Implementation Method 3
a second silicon-based active material doped with a metal... a second conductive material
Data Source
Figure 1
AI summary
An anode for a secondary battery is disclosed. In some implementations, the anode includes an anode current collector, a first anode mixture layer on at least one surface of the anode current collector, and a second anode mixture layer on the first anode mixture layer. The first anode mixture layer includes a first silicon-based active material including a carbon coating layer formed on a surface thereof, and a first conductive material. The second anode mixture layer includes a second silicon-based active material doped with a metal, and a second conductive material. The first conductive material has a Raman R value, greater than or equal to a Raman R value of the second conductive material. According to some implementations, volume expansion/contraction of a silicon-based active material may be alleviated during battery charging/discharging.