Porous Ti₃C₂T_<i>x</i> MXene for Ultrahigh-Rate Sodium-Ion Storage with Long Cycle Life

The development of anode materials remains a challenge to satisfy the requirements of sodium-ion storage for large-scale energy-storage applications, which is ascribed to the low kinetics of ionic/electron transfer of electrode materials. Here we show that the controlled anisotropic assembly of highly conductive Ti3C2Tx MXene nanosheets to form a porous structure can enhance the sodium-ion storage kinetics. At high current densities of 1 and 10 A g–1, the porous Ti3C2Tx electrode delivered capacities of 166 and 124 mA h g–1, respectively. Even at an extremely high current density of 100 A g–1, a capacity of 24 mA h g–1 could be achieved. The porous Ti3C2Tx electrode also exhibited a long cycle life that can be extended to 1000 cycles with no capacity decay at a current density of 1 A g–1. This work demonstrates successful control of the Ti3C2Tx architecture to push electrochemical sodium-ion storage closer to large-scale applications and is expected to shed light on the rational utilization of the outstanding properties of MXenes by controlling their microscopic assembly.