Comparative study of electrochemical performance of commercial solid-state thin film Li microbatteries

This work evaluates the behavior of three 4 V commercial all-solid-state lithium microbatteries, 80, 170 and 200 μm thick with the same announced capacity of 700 μA h. The electrochemical tests are based on galvanostatic experiments between 4.2 V and 3.6 V enabling to determine the real specific capacity achieved as a function of the C rate at room temperature and 60 °C. The results make differences visible between the three commercial thin film microbatteries. The thinnest battery exhibits the best properties with a high energy density of 42 mWh cm−3, i.e. two fold the value offered by the other cells ≈ 200 μm thick, and an excellent cycle life at C rate over 1000 cycles with 100% of capacity retention and 100% of depth of discharge. This shows the maturity of the thin film battery technology now commercially available. The present contribution provides a punctual picture of the outstanding characteristics already offered by all solid-state Li microbatteries.