Pseudocapacitance of Cl-Terminated MXene Nanosheets for Efficient Chloride-Ion Hybrid Capacitors
Linzhou Zhu, Jiapeng Ji, Huajie Yin, Huijun Zhao
Abstract
Chloride-ion batteries (CIBs) have the advantages of being widely sourced, environmentally friendly, and having high theoretical volumetric energy density (2500 Wh·L –1 ). However, the electrochemical reaction kinetics and cycle performance of CIBs suffer from poor structural reversibility and insufficient electrical conductivity of chlorine storage materials. Herein, we report the synthesis of a Cl-terminated MXene (Ti 3 C 2 Cl 2 ) with high Cl – capacity and low Cl – diffusion barrier as a cathode material for chloride-ion hybrid capacitors (CHCs). The constructed Ti 3 C 2 Cl 2 electrode delivers a gravimetric capacity of 536 mAh·g –1 and a Coulombic efficiency of >99.5% after 1000 cycles of charge and discharge at a current density of 0.2 A·g –1 . It also exhibits superior rate capability of 153.1 mAh·g –1 at 1 A·g –1 and 121.2 mAh·g –1 at 2 A·g –1, respectively.