Composite Anode Active Material for Lithium Battery Volumetric Stability
Solution Overview
Problem
Lithium batteries face challenges in achieving high-discharge capacity and extended lifespan due to volumetric changes in metal alloy anodes, which lead to deterioration and reduced battery life.
Innovation Solution
A composite anode active material with a multi-phase microstructure containing an amorphous Si phase and a nano-crystalline metal silicide phase, dispersed in a porous structure, is developed, which accommodates volumetric changes during charging and discharging, thereby enhancing battery lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metal alloyable with lithium (Si, Sn, Al) is used as anode active material to achieve high discharge capacity, then the discharge capacity is improved, but volumetric change during charging and discharging causes deterioration and poor lifespan characteristics
Solution Approach 1:
The patent employs a porous carbon matrix structure with controlled porosity to accommodate the volumetric changes of metal alloy particles during lithium insertion and extraction. The porous structure provides expansion space that prevents particle fracture and maintains electrode integrity over multiple cycles, thereby improving lifespan characteristics while preserving high discharge capacity.
Solution Approach 2:
The invention creates a composite anode material consisting of metal alloy particles (Si, Sn, or Al) dispersed within a carbon matrix. This composite structure combines the high capacity benefits of metal alloys with the structural stability and volumetric tolerance of carbon, resolving the contradiction between achieving high discharge capacity and maintaining reliable lifespan characteristics.
2Stability of the object's composition
If metal alloyable with lithium is dispersed in a matrix of metal oxide or alloy to reduce volumetric change, then volumetric stability is improved, but the metal alloy still experiences volumetric change leading to composite deterioration
Solution Approach 1:
The patent utilizes a porous carbon matrix instead of dense metal oxide or alloy matrices. The porous structure provides controlled void spaces that accommodate the volumetric expansion and contraction of metal alloy particles during cycling, reducing mechanical stress on the composite structure and preventing deterioration, thereby extending composite lifespan.
3Stability of the object's composition
If carbonaceous materials are used as anode active material to achieve volumetric stability, then volumetric change is reduced, but battery capacity decreases due to porous structure
Solution Approach 1:
The invention creates a composite anode material consisting of metal alloy particles (Si, Sn, or Al) dispersed within a carbon matrix. This composite anode material combines the high capacity benefits of metal alloys with the structural stability and volumetric tolerance of carbon, resolving the contradiction between achieving high discharge capacity and maintaining reliable lifespan characteristics.
Data Source
AI summary
Provided is a composite anode active material with pores having a composition represented by Formula 1, and, the composite anode active material contains an amorphous phase including Si and a nano-crystalline phase including a metal silicide:SixMyCz <Formula 1>wherein, in Formula 1,x, y, and z each represent an atomic percentage;x+y+z=100;x>y+z;x>0, y>0, and z≥0; andM is at least one metal selected from Mn, Mo, Nb, W, Ta, Fe, Cu, Ni, Co, Zr, Y, and a combination thereof.