A high-energy, long cycle life aqueous hybrid supercapacitor enabled by efficient battery electrode and widened potential window

For the development of high-performance aqueous hybrid supercapacitor, the exploration of high-rate battery electrode and breakthrough of potential window are urgently needed. In this work, N-doped carbon coated LiMn2O4 nanoparticles (LMO@C) have been designed and successfully fabricated, and "water-in-salt" electrolyte is applied. The as-prepared LMO@C delivers a high specific capacitance of 688 F g(-1) at the scan rate of 0.5 mV s(-1) and retains 258 F g(-1) at 50 mV s(-1) as cathode in 5 M LiTFSI aqueous electrolyte. With an enlarged working potential of 2.5 V, LMO@C//AC hybrid supercapacitor shows a high energy density of 95.3 W kg(-1), and 95% of initial capacitance retention after 15,000 cycles. The excellent electrochemical performance suggests that the carbon coated lithium manganate nanocomposite and high-concentration electrolyte could be potential candidates for practical aqueous hybrid energy storage devices. (C) 2021 Published by Elsevier B.V.