Nitrogen-doped carbon nanoboxes as high rate capability and long-life anode materials for high-performance Li-ion capacitors

Lithium ion capacitors (LICs), lately evolved energy storage devices which integrate the merits of both lithium ion batteries (LIBs) and supercapacitors (SCs) for high energy and power densities, have attracted substantial research attention in recent years. Here, a Prussian blue analogue nanocube templating process was developed to produce N-doped carbon nanoboxes (N-CNB) as high performance anode materials for lithium ion based energy storage. The N-CNB exhibited high specific capacities and excellent rate capability and cycling performances as an anode. If paired with glucose derived carbon nanospheres (GCNS) cathodes, the N-CNB//GCNS LIC delivered a high energy density of 77.5 Wh kg(-1) at the power density of 311.3 W kg(-1) and maintained a decent energy density of 40.4 Wh kg(-1) at a high power density of 112 kW kg(-1). Its cycling performances were outstanding, reaching an ultrahigh, over 100%, capacity retention of 138% after a 40,000 cycle operation at 10 A g(-1), attributable to the continuous electrochemical activation of the electrode materials. The success of the present LIC can be attributed to the advantageous nanobox structure in serving as nano-reservoirs for Li-ion to enable local, fast lithiation/delithiation and in buffering the volume expansion/shrinkage during lithiation/delithiation cycles.