Li, YangWang, YanCai, RuiYu, CuipingZhang, JianfangWu, JingjieZhang, YongTan, Hark HoeJagadish, ChennupatiWu, Yucheng2023-07-132168-0485http://hdl.handle.net/1885/294220Lithium-ion hybrid capacitors (LIHCs), as a novel energy storage device combining the mechanism of lithium-ion batteries and supercapacitors, can achieve high energy and power density simultaneously. Pseudocapacitive materials with rapid lithium-ion storage characteristics have great potential for improving the kinetic mismatch between cathodes and anodes in LIHCs. Herein, we successfully synthesized niobium oxynitride (NbOxNy) nanosheets with a three-dimensional (3D) architecture and tunable nitrogen and oxygen contents through solvothermal treatment followed by a controllable solid-state nitridation process. Benefiting from the resulting short transport path, 3D morphology, optimized N/O atom ratio, and the enhanced electrical conductivity, the NbOxNy electrode with pseudocapacitive lithium-ion storage characteristics exhibits excellent rate capability and cycling stability. By matching with an activated carbon (AC) cathode, a novel NbOxNy//AC LIHC device was fabricated, which delivers an ultrahigh energy density of 158.3 W h kg-1 at 200 W kg-1. A convincing energy density of 45 W h kg-1 could also be achieved at 20 kW kg-1. Furthermore, the NbOxNy//AC LIHC demonstrates superior cycling performance after 10,000 cycles at 1 A g-1.This work was financially supported by the National Natural Science Foundation of China (51772072, 52172293, and 52072106), the Key R&D Projects of Anhui Province (202104b11020016), the Natural Science Foundation of Anhui Province (2108085QB66), the China Postdoctoral Science Foundation (2019M662139), and the Fundamental Research Funds for the Central Universities (PA2021GDSK0088, PA2021GDSK0094, and JZ2021HGQA0188). We also would like to thank the financial support from the 111 Project (B18018).application/pdfen-AU© 2021 American Chemical Societyniobium oxynitride nanosheetssolid-state nitridationlithium-ion hybrid capacitorsrate performancehigh energy/power density202110.1021/acssuschemeng.1c053862022-05-08