Evaluation of Scalable Porous Si-Rich Si/C Composites with Low Volume Expansion in Coin Cells to Prismatic Cell Formats

Li-ion battery cells on the basis of Si-containing anodes suffer from their large volume expansion of up to 300%, impeding their extensive application in the automotive field. Herein, the synthesis of a Si-rich Si/C composite is introduced. The implemented porosity of the composite has a buffering effect on the Si volume changes during cycling. The scalability of the material from lab-scale to industrial-scale batch sizes as well as from coin cell (<5 mAh), to pouch cell (approximate to 0.75 Ah), and to prismatic (PHEV) cells (approximate to 26 Ah) is demonstrated. The performance of the pouch cells and PHEV cells is further improved by cycling under an external mechanical pressure. The irreversible swelling of the pouch and the PHEV cells stays below 6% during cycling. Reproducible aging and swelling behavior of different cell types is observed and investigated in detail. The low irreversible volume increase is confirmed by X-ray computer tomography (CT) measurements of the PHEV cells before and after cycling.