On the stress characteristics of graphite anode in commercial pouch lithium-ion battery

The stress of graphite anode in commercial pouch lithium-ion battery is characterized ex-situ by using micro-Raman mapping technique at 2 μm lateral resolution. The results show that the stress in graphite anode is always compressive and its distribution is inhomogeneous both in the manufacturing process and in cycling process. The stress mainly generates and accumulates in the early stage of cycling process, which causes not only big anode thickness swelling but also graphite particles cracking or even degrading. The deterioration of electrical contact of graphite particles from current collector caused by anode volume expansion and formation of solid electrolyte interface (SEI) in fresh surface of cracked graphite particle is responsible for the faster capacity fading of pouch battery in this early stage.