Recent progress in the realization of metal-ion capacitors with alloying anodic hosts: A mini review

Abstract

Metal-ion capacitors (MICs) based on a battery-type anode and a capacitive positive electrode in an organic electrolyte, have come to the foreground in recent years, owing to their higher output energy than electrical double-layer capacitors (EDLCs). However, the MIC's technology, especially the fabrication of stable anodic materials combining a high reversible capacity, a low irreversible capacity and a good rate capability, still needs to be optimized. Herein, the advantages, limitations and recent progresses in implementing alloying anodic hosts in MICs are critically discussed. The manuscript highlights the possible benefits from in-situ pre-metalation of the host and provides guidelines for optimizing the output energy and life span of metal-ion capacitors with alloy-based anodes.