Innovative lithium-ion pouch cell operating at low temperature (−40°C): comparison of different cell designs

Two different pouch cell designs (design A and B) of high energy density Li-ion batteries composed of novel Si anode material were studied under at low temperature. The pouch cells demonstrated different behavior in terms of initial capacity, cycle life stability and capacity retention in comparison with their respective behavior at room temperatures. In particular, design A cells exhibited a capacity retention of more than 65% when cycled at −40 °C (compared to 20°C) and it was able to deliver stable cycle life up to 40 cycles. On the other hand, design B cells showed lower discharge capacity retention of 44% (with respect to 20°C) and they lost only 20% of initial capacity retention of −40°C after 80 cycles. Though design A cell was able to deliver higher capacities at low temperature, the stability of cycle life is short. From transport properties investigation, with the aid of Continuous Voltage (CV) mode and Depth of Discharge (DoD) analysis at various cycles, cell design A exhibited better transport properties than design B. It is also revealed that, higher internal resistance of design B cell was responsible for the lower capacity at −40°C. Finally, extracted parameters from charging potential and current curves over time allowed us to further investigate the performance of the cells as a function of the number of cycles.