1. Low specific surface area: As you said, waste graphite usually has a lower specific surface area, which reduces the contact area between the electrolyte and the graphite, affects the ion insertion and extraction during the initial charge and discharge, and thus reduces the initial Coulombic efficiency. Compaction and coating can increase the specific surface area, but the effect may be limited. A more fundamental solution is to choose a more suitable graphite source or improve the pretreatment method.
2. More impurities and defects: Waste graphite may contain some impurities and structural defects, which adversely affect carrier migration and charge transfer, reducing battery performance. Purifying graphite and optimizing modification methods can improve this.
3. Uneven graphite particle size distribution: Graphite with different particle sizes has different specific surface areas and structures, which causes the electrolyte to contact different graphite particles to different degrees, affecting the overall battery performance. Optimizing the powder forming process or subsequent processing to improve particle size uniformity.
4. Severe dust pollution: Dust pollution of graphite during production will affect its electrochemical performance and must be strictly controlled.
5. Formulation and process need to be optimized: The formula you provided is a typical reference formula. In actual applications, it should be optimized according to the specific performance and requirements of graphite. The key points are to control the amount and ratio of conductive agents and binders. Process control is also very important.
In summary, the most critical thing to improve the initial Coulombic efficiency is to solve the problems of graphite quality and performance from the source. My suggestion is to choose a high-quality source of waste graphite, and then improve its specific surface area, reduce impurities and optimize its structure through strict pretreatment, purification and modification methods. Produce products with stable and consistent performance through scientific formulation and process design.