High mass loading, binder free MXene anodes for high areal capacity Li ion batteries
Though anodes with high Li gravimetric capacities, beyond commercial graphite, have been intensively studied, gravimetric capacity does not precisely reflect the performance of a packed cell. Li anodes with high mass loadings, which can achieve high areal capacities, are required for many commercial applications. Herein, anodes with high mass loadings were fabricated using two dimensional transition metal carbides (MXenes) Powders of the latter were cold pressed, without binders, at a pressure of 1 GPa, to create ~300 mm thick, free standing discs. When Ti3C2 was used as the anode for lithium, the initial reversible areal capacity was ~15 mAh/cm2, which decreased to 5.9 mAh/cm2 after 50 cycles, but the decrease after the first ~20 cycles was very gradual. The latter is one of the highest values ever reported to date. When Nb2C was used as the anode instead, the initial reversible capacity was ~16 mAh/cm2; this value decreased to 6.7 mAh/cm2 after 50 cycles, which is about a 14% increase compared to Ti3C2. As the research on MXenes for lithium ion batteries has just begun, there is certainly room for further improving their electrochemical performance.