Li₄Ti₅O₁₂−TiO₂ Composite Coated on Carbon Foam as Anode Material for Lithium Ion Capacitors: Evaluation of Rate Performance and Self‐Discharge

Abstract Li₄Ti₅O₁₂‐TiO₂ (LTO‐TO) composite is coated on carbon foam (CF) for anode of lithium ion capacitors (LICs). The resulting CF@LTO‐TO electrodes with varied mass loadings of LTO‐TO exhibit much improved rate performance compared to pristine LTO electrode. Specifically, asymmetric LICs based on activated carbon cathode and CF@LTO‐TO anode (AC//CF@LTO‐TO) with 25 wt% of LTO‐TO delivers a specific capacity of 65 mAh g⁻¹ at 300 C. In addition, the self‐discharge rates of the LICs are evaluated. It is found that AC//CF@LTO‐TO LIC with 45 wt% of LTO‐TO shows much reduced self‐discharge rate (open circuit voltage drops from 2.5 to 1.1 V in 144 hours) relative to AC//CF@LTO‐TO with different LTO‐TO mass loadings. The results of this study suggest that the introduction of TO in LTO anode can affect both the rate performance and the self‐discharge behavior, which may be due to the fast faradaic reaction kinetic of TO and the rich LTO‐TO grain boundary interfaces.