Toward high energy-density and long cycling-lifespan lithium ion capacitors: A 3D carbon modified low-potential Li₂TiSiO₅ anode coupled with a lignin-derived activated carbon cathode

Lithium ion capacitors (LIC), which can bridge the gap between lithium ion batteries and supercapacitors by combining the merits of the two systems, are thus considered as some of the most promising energy storage devices. However, the imbalances in specific capacity, high-rate behavior, and cycling lifespan between the two electrodes make it a challenge to develop LICs with high energy density at high power density output along with long cycle life. Herein, a LIC consisting of a three-dimensional carbon modified LTSO (3DC@LTSO) anode and a lignin-derived activated carbon (LDAC) cathode is designed and fabricated. These two electrode materials with desirable electrochemical properties will much favorably offset the imbalances between the two electrodes. Moreover, a novel electrode-matching strategic approach, which will further offset the imbalance between the two electrodes, is developed. Thereby, the assembled LDAC//3DC@LTSO LIC cell shows a high energy density of 115.3 W h kg^-1 at 163.5 W kg^-1 and a high power density of 6560 W kg^-1 at 60 W h kg^-1, coupled with an excellent cycling lifespan of 90% capacity retention after 6000 cycles at a current density of 2.0 A g^-1. These combined results are impressive in terms of obtaining high energy density and long cycling lifespan LICs.