Nanomaterials and Technologies for Lithium-Ion Hybrid Supercapacitors

For developing energy storage devices with both high energy and power density, lithium-ion hybrid supercapacitors (LIHSs) are the optimal candidate to bridge the gap between lithium-ion batteries (LIBs) and conventional supercapacitors. A LIHS consists of a capacitor-type cathode and a LIB-type anode. However, the particle size of LIB-type anode materials should be within approximate to 10 nm to overcome the sluggish ion diffusion in the bulk. In addition, capacitor-type cathode materials are required to possess high capacitance to match with LIB-type anodes. Meanwhile, pre-lithiation proves an effective strategy to achieve high cell voltages and high energy density accordingly. In this review we first summarize the requirement on electrode materials for LIHSs, and then propose two levels of LIHSs with the clarification of true LIHSs according to the energy and power density. Finally, we give an outlook for future LIHSs.