One dimensional graphene nanoscroll-wrapped MnO nanoparticles for high-performance lithium ion hybrid capacitors

Abstract

Lithium ion hybrid capacitors (LIHCs) have high power density and high energy density. One of the biggest problems in LIHCs is the kinetics mismatch of a battery-type anode and capacitive cathode due to relatively slow Li⁺ reaction kinetics compared to fast ion adsorption/desorption behavior. Here, to address this challenge, an efficient strategy was proposed to prepare a one dimensional (1D) graphene nanoscroll wrapped MnO nanoparticle (GNS@MnO) material by a simple freeze-drying process followed by annealing treatment. The topological end-opening architecture of the GNS and the wrapping of graphene layers facilitate fast Li⁺ diffusion and electron transfer. As an anode material of lithium ion batteries (LIBs), the optimized GNS@MnO-600 electrode exhibits outstanding performance for Li⁺ ion storage with a high specific capacity of 437 mA h g⁻¹ even at 5.0 A g⁻¹. The constructed LIHC based on the GNS@MnO-600 anode and 3D framework activated carbon (3DFAC) with a high specific surface area delivered a high energy density of 197 W h kg⁻¹ at 235 W kg⁻¹. Even at a high power density of 23.5 kW kg⁻¹, a high energy density of 114 W h kg⁻¹ is still maintained, as well as a long cycling life (84.8% capacity retention after 3000 cycles). We believe that this highly efficient 1D GNS wrapping strategy provides a novel design concept for the construction of fast kinetics anode materials for LIBs and LIHCs.