Graphite Negative Active Material for Battery Cycle Retention
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Solution Overview
Problem
Existing batteries experience a significant decrease in cycle capacity retention rate at later cycle stages, leading to reduced cycling service life due to deteriorating cycling performance.
Innovation Solution
A negative active material with specific surface area and orientation index parameters is developed, where the specific surface area increases from X1 to X2 after compaction, and the orientation index OIa is controlled within a certain range, ensuring 0.05 < (X2 - X1) / OIa < 0.5, to enhance dynamic and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the negative active material undergoes compaction process to increase density, then the energy density improves, but the specific surface area decreases and cycling performance deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the specific surface area (X1, X2) and orientation index (OIa, OIb) of the negative active material to resolve the contradiction between energy density and cycling performance. By optimizing these parameters within specific ranges, the patent achieves both high energy density and excellent cycling stability, directly addressing the technical contradiction through quantitative parameter optimization.
2Productivity
If the specific surface area of negative active material is increased to improve reaction activity, then the capacity increases, but the material structure becomes less stable and cycle life decreases
Solution Approach 1:
The patent resolves this contradiction by establishing specific parameter ranges for specific surface area (X1, X2) and their relationship with orientation index ((X2-X1)/OIa). This parameter optimization ensures the material maintains sufficient surface area for high capacity while preserving structural stability through controlled orientation, achieving both high productivity and composition stability.
3Speed
If the orientation index of negative active material is optimized to improve ion diffusion, then the dynamic performance improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent addresses this contradiction by defining specific ranges for orientation index (OIa, OIb) and their relationship with specific surface area changes. These parameter specifications provide clear manufacturing targets that balance the need for optimized ion diffusion with achievable manufacturing precision, transforming the abstract requirement into quantifiable control parameters.
Data Source
AI summary
Provided are a negative active material, a negative electrode plate, and a battery. The negative active material includes graphite. A specific surface area of the negative active material before a compaction process on the negative active material is X1. A specific surface area of the negative active material after the compaction process is X2. An orientation index of the negative active material before the compaction process is OIa. The negative active material satisfies 0.05<(X2−X1)/OIa<0.5, where X1 and X2 are in units of m2/g.