Fig. 4. Long-term cycling performance of cells with coated and uncoated cathodes.

A Long-term cycling stability and (B) associated Coulombic efficiencies of LTO|SE|NMC cells with uncoated and Nb₂O₅-coated SC-NMC cathodes at 1C rate (3 mA·cm⁻²) cycled to 4.5 V and 4.7 V (vs Li/Li⁺) voltage limits using a CC charge/discharge protocol. Insets in (B) show Coulombic efficiency during the first 20 cycles and for cycles 250 to 300. C Comparison of long-term cycling stability of Nb₂O₅-coated cathodes at 1C rate cycled to 4.7 V limit using CC (where a current equivalent to 1C is applied until the cell reaches the voltage limit) and CCCV (where a current equivalent to 1C is applied until the cell reaches the voltage limit followed by a voltage hold at the limit such that entire half cycle takes 1 h time) charge/discharge protocols. The temperature during testing was 60 °C and stack pressure was 7 MPa.