Battery Cycle Stability in Additive-free MAX(Ti3AlC2) Li-ion Battery Anode

Abstract

We fabricated an additive-free MAX(Ti3AlC2) phase Li-ion battery (LIB) electrode using the electrophoretic deposition (EPD) method. In this study, MAX, a precursor of MXene, which has recently been receiving great attention as a negative electrode material for LIBs, was manufactured as a coin cell through EPD rather than the conventional slurry system. We excluded the effect of additives on the electrochemical performance, enabling evaluation of the intrinsic electrochemical properties related to battery charging and discharging. As a result, the battery using MAX as an anode material showed a large specific capacity of 148.2 mAh/g in the first discharge and superior cycle stability. Enhanced cycle stability and reversible electrochemical reactions were attributed to activation of faradaic and non-faradaic behavior, i.e., pseudocapacitive behavior, caused by delamination of the MAX(Ti3AlC2) into MXene (Ti3C2). This was confirmed by the decrease in the charge transfer resistance and the increase in total capacitance at the interface, using electrochemical impedance spectroscopy and cyclic voltammetry measurements. In addition, the activation of pseudocapacitive behavior was confirmed by the change in kinetic mechanism, as evidenced from a significant increase in the Li ion diffusivity with cycles. These results demonstrate that MAX(Ti3AlC2) is promising as an anode material for LIBs and at the same time shows potential for tuning electrochemical properties through the electrochemical delamination process.