Negative Electrode Active Material for Low-Swelling Battery Cycling
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Solution Overview
Problem
The cycle performance of lithium-ion batteries, particularly in medium- and large-sized batteries used in electric vehicles and energy storage systems, is a key technical issue that needs to be addressed due to issues with the negative electrode active material.
Innovation Solution
A negative electrode active material with specific particle size and surface area characteristics, enhanced by a high-viscosity additive, is used to form secondary particles with increased strength and reduced particle crushing, thereby improving cycle performance and reducing thickness swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the negative electrode active material uses conventional graphite particles, then the manufacturing cost is low and ease of manufacture is good, but the cycle performance deteriorates and thickness swelling increases
Solution Approach 1:
The patent applies composite materials by combining graphite particles with a specific viscosity additive to form a composite negative electrode active material. This composite structure improves cycle performance and reduces thickness swelling while maintaining manufacturing feasibility through controlled particle size distribution (Dv10=3-10μm, Dv50=15-25μm, Dv90=30-50μm) and additive content (1-20 wt%).
Solution Approach 2:
The patent employs parameter changes by optimizing the particle size distribution parameters (Dv10, Dv50, Dv90) and the viscosity additive content to achieve balanced performance. The specific ranges of particle sizes and additive concentrations are tuned to improve reliability while controlling manufacturing complexity.
2Volume of stationary object
If the negative electrode active material is compressed to increase density, then the volume energy density improves, but particle crushing increases and cycle performance deteriorates
Solution Approach 1:
The composite structure of graphite particles with viscosity additive provides enhanced mechanical strength and particle integrity during compression. The additive forms a protective matrix that prevents particle crushing while allowing sufficient compression to achieve desired volume energy density.
Solution Approach 2:
The viscosity additive is distributed locally around graphite particles to provide targeted reinforcement where needed during compression. This local quality enhancement protects particles from crushing while maintaining overall electrode density.
3Quantity of substance
If the specific surface area of the negative electrode active material is increased to improve capacity, then the initial coulomb efficiency improves, but the thickness swelling increases and cycle performance deteriorates
Solution Approach 1:
The patent optimizes the particle size distribution parameters (Dv10, Dv50, Dv90) to achieve an optimal balance between specific surface area and structural stability. The controlled size ranges ensure sufficient surface area for high capacity while maintaining particle integrity to minimize thickness swelling.
Solution Approach 2:
The viscosity additive forms a stabilizing matrix that prevents excessive thickness swelling even when specific surface area is increased. This composite structure allows the electrode to achieve high capacity through increased surface area while the additive constrains dimensional changes during cycling.
Data Source
AI summary
A negative electrode active material having a median particle size D1v50, the negative electrode active material has a median particle size D2v50 after being compressed under a pressure of 1 t, and D2v50/D1v50 is not less than 0.8. The negative electrode active material achieves a balance between high capacity and high cycle expansion performance of an electrochemical device.