Electrochemical characterization and post-mortem analysis of aged LiMn2O4-NMC/graphite lithium ion batteries part II: Calendar aging

Electrochemical impedance measurements including symmetric laboratory test cells gained from new and aged cells revealed valuable information about changing charge-transfer processes. The 4.2 V-cathode and both aged anodes surprisingly exhibited a decreased charge-transfer resistance, while the 4.0 V-cathode's charge-transfer resistance increased.