Porous Silicon Anode Skeleton for Lithium Ion Battery
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Solution Overview
Problem
Silicon anode materials in lithium-ion batteries face significant challenges due to large volumetric expansion during lithium intercalation and de-intercalation, leading to pulverization, loss of electrical contact, and decreased cycle stability, hindering their commercial application.
Innovation Solution
A composite anode material with a unique skeleton structure and porosity is developed, featuring primary particles with a main skeleton and branches, along with a coating layer or nano-particle layer, which enhances electronic conduction, ion diffusion, and stress relief, reducing expansion and improving cycle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon anode material is used to improve energy density, then capacity is improved, but volumetric expansion occurs during lithium intercalation and de-intercalation
Solution Approach 1:
The patent employs a porous silicon anode material with controlled pore structure. The pores provide internal void space that accommodates the volumetric expansion of silicon during lithium intercalation, preventing structural collapse and pulverization while maintaining high capacity. The porous structure allows lithium ions to diffuse throughout the material volume, achieving both high capacity and low expansion.
2Quantity of substance
If silicon anode material undergoes lithiation, then capacity is improved, but stress concentration at grain boundaries causes pulverization
Solution Approach 1:
The patent segments the silicon anode material into a hierarchical porous structure with interconnected pores and struts. This segmentation distributes the mechanical stress of lithiation throughout the network, preventing stress concentration at grain boundaries. The segmented structure allows controlled deformation while maintaining overall structural integrity, thereby preventing pulverization.
3Ease of manufacture
If traditional porous material agglomerates are used, then manufacturing is simplified, but grain boundaries cause stress concentration and structure destruction
Solution Approach 1:
The patent merges the pore-forming agent and silicon precursor into a single composite material system that undergoes controlled decomposition. Instead of aggregating separate porous particles, the method combines silicon-containing compounds with pore-forming agents, then thermally processes them to create an integrated porous silicon structure. This merging eliminates grain boundaries between aggregated particles while maintaining manufacturing simplicity.
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 composite anode material exhibits improved cycle performance, high capacity, long cycle service life, and low expansion, effectively addressing the issues of pulverization and stability in silicon anode materials.
Implementation Method 1
The entire skeleton structure enhances the electronic conduction and ion diffusion of the material
Implementation Method 2
The entire skeleton structure enhances the electronic conduction and ion diffusion of the material
Implementation Method 3
The stress after lithiation can be effectively released, thereby preventing from crack and pulverization of the material due to the stress concentrated at the boundary of the grain
Data Source
AI summary
The present disclosure relates to an anode material, a preparation method thereof, and a lithium ion battery. The anode material is primary particles. The primary particle includes a skeleton. The skeleton includes a main skeleton located inside the primary particle and multiple branches extending to the surface of the primary particle. The primary particles have a macroporous structure, and pores are formed inside the primary particles, and extend to the surface of the primary particles. Compared with the secondary porous structure formed by accumulating nano-particles, the anode material of the present disclosure has a more stable structure and low volume expansion while having a smaller specific surface area and a higher porosity.