Self‐Templating Synthesis of Mesoporous Carbon Cathode Materials for High‐Performance Lithium‐Ion Capacitors

Lithium-ion capacitors (LICs) have attracted considerable interest because of their excellent power and energy densities. However, the development of LICs is limited by the low capacity of the cathode and the kinetics mismatch between the cathode and anode. In this work, mesoporous carbon materials (MCs) with uniform pore sizes were prepared using magnesium citrate as the raw material through a self-templating method. During the carbonization process, MgO nanoparticles generated from magnesium citrate act as a template, resulting in a more orderly pore structure. The resultant MCs demonstrate a high specific surface area of 1673 m² g^-1 and an abundance of small mesopores, which significantly accelerated ion migration within the electrolyte and expedited the formation of electric double layers. Benefiting from these advantages, the MCs cathode demonstrates a high reversible specific capacity, excellent cycling stability, and rate performance. The assembled MCs-based LIC provides a high energy density of 152.2 Wh kg^-1 and a high power density of 14.3 kW kg^-1. After 5000 cycles, a capacity retention rate of 80 % at the current density of 1 A g^-1 is obtained. These results highlight the excellent potential of MCs as a cathode material for LICs.