Composite Particle for Lithium-Ion Battery Negative Electrode
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Solution Overview
Problem
Graphite-based negative electrode active materials in lithium-ion batteries face challenges with capacity deterioration due to significant volume expansion and contraction during charging and discharging, leading to reduced electron conductivity and short battery life.
Innovation Solution
A composite particle comprising specific alloy phases that undergo thermoelastic diffusionless transformation when releasing or occluding metal ions, bound with a non-graphite carbon or carbon precursor binding material, which mitigates strain and improves charge-discharge cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If alloy-based negative electrode active materials (Si or Sn) are used to increase capacity, then the capacity per volume is improved, but the charge-discharge cycle characteristics deteriorate due to large volume expansion/contraction
Solution Approach 1:
The alloy-based negative electrode active material is divided into fine particles (average diameter 0.1-10 μm) to segment the overall volume change. This segmentation reduces the stress concentration and prevents cracking of the coating film, thereby maintaining charge-discharge cycle characteristics while preserving high capacity per volume
Solution Approach 2:
Alloy particles are embedded within a composite structure that includes conductive carbon material and binder material. This nested configuration provides mechanical support and maintains electron conductivity pathways even when the alloy particles expand or contract during charging/discharging cycles
2Quantity of substance
If Si or Sn single substance is used as negative electrode material, then the capacity is improved, but the negative electrode plate cracks due to significant expansion and contraction
Solution Approach 1:
A composite negative electrode plate is constructed with alloy particles, conductive carbon material, and binder material. This composite structure provides mechanical strength to prevent cracking while maintaining the high capacity benefits of alloy materials. The conductive carbon network ensures electron conductivity is preserved despite volume changes
3Quantity of substance
If alloy-based negative electrode active material is used, then the capacity is improved, but electron conductivity is lost due to active substance detachment
Solution Approach 1:
Conductive carbon material serves as an intermediary that maintains electron conductivity pathways. Even when alloy particles expand, contract, or detach during charging/discharging cycles, the conductive carbon network provides continuous pathways for electron transport, preventing loss of electron conductivity while preserving high capacity
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 particle enhances volumetric discharge capacity and capacity retention ratio, effectively relaxing strain and suppressing electrolyte solvent decomposition, resulting in improved charge-discharge cycle performance.
Implementation Method 1
The alloy phase undergoes thermoelastic diffusionless transformation when releasing or occluding metal ions
Implementation Method 2
The plurality of specific particles are bound with each other via the binding material
Data Source
AI summary
Provided is a composite particle which can improve the capacity per volume and charge-discharge cycle characteristics. The composite particle includes a plurality of specific particles and a binding material. The specific particle contains an alloy phase. The alloy phase undergoes thermoelastic diffusionless transformation when releasing metal ions or occluding metal ions. The binding material contains at least one of non-graphite carbon and a carbon precursor. The plurality of specific particles bind with each other via the binding material.