Study on the cycling performance of silicon-based cylindrical batteries via process-structure optimization strategy

High-energy-density lithium-ion batteries (LIBs) were widely utilized as energy storage devices, but the electrodes undergo significant volume changes and the expansion of cells during operation, leading to irreversible stress accumulation within the batteries. In this study, process-structure optimization strategies were proposed to alleviate stress accumulation and electrode collapse in LiNi0.8Co0.15Al0.05O2/Si-graphite type 21,700 cylindrical batteries (with an energy density of 230 Wh/kg), caused by silicon anode expansion during cycling. By creating a quantitative model linking winding tension to electrode stress distribution, the study reveals radial stress at different winding diameters. Cells with optimized winding tension exhibited approximately 30% improvement in capacity retention after C-rate cycles. The introduction of polytetrafluoroethylene rods maintains cell integrity through dynamic stress buffering. This combined strategy boosts performance by 29.07% after C-rate cycles. The study elucidates the relationship between process parameters and mechanical failure, and offers new ideas for engineering research on high-energy-density LIBs.