Performance Analysis and Application Prospects of New Silicon-Carbon Anode Materials in Rail Transit Vehicle Soft-pack Batteries

Abstract

［Objective］ The large-scale application of silicon-containing anode materials in soft-pack battery for urban rail transit vehicles faces many challenges, primarily the failure of electrical performance due to the volume expansion of silicon. To address this issue, a more in-depth studies on the perfor-mance of new silicon-carbon anode materials in soft-pack battery is necessary. ［Method］ A comparative analysis is conducted between Ah-level soft-pack batteries containing standard silicon-carbon materials (′N1 batteries′) and those using silicon-carbon materials with an embedded structure (′N2 batteries′) regarding their cycle decay characteristics. Cycle performance tests are carried out on these two types of batteries, and post-cycle analysis is conducted on the disassembled batteries. The anode materials are tested and the results are analyzed to verify the optimization effects of the silicon anode structure at the full battery level. ［Result & Conclusion］ The main cause of failure in N1 batteries is excessive volume expansion of silicon in the anode, leading to the detachment of active materials and electrode breakage, ultimately resulting in the loss of electrical contact. In N2 batteries, the nanoscale silicon is uniformly dispersed within the carbon-based materials and encapsulated by carbon, effectively limiting the volume expansion of silicon during the battery cycle and maintaining structural integrity of the anode throughout the entire cycle process. The cycle performance of N2 batteries is superior to that of N1 batteries. Embedded structure silicon-carbon materials in lithium-rich silicon-carbon system batteries show promising application prospects.

Keywords

• rail transit vehicle
• soft-pack battery
• silicon-carbon composite material
• electrical performance failure