Electrochemical measurements (CV, GCD and EIS) on the composite coin cells were carried out using an Ivium CompactStat. CV scans were carried out at a scan rate ranging from 5 to 1000 mV s -1 . GCD was conducted using at current density ranging from 0.5 to 10 A g -1 . EIS was carried out at frequencies range from 0.01 Hz to 100 kHz with an amplitude of 5 mV.