Tunable surface pseudocapacitance assisted fast and flexible lithium storage of graphene wrapped NiO nano-arrays on nitrogen-doped carbon foams

Abstract

Advanced materials incorporating battery-like high capacity and capacitor-like high rate capability hold promise for achieving both high energy and power density lithium ion batteries (LIBs). However, capacitive behavior for high capacity NiO anode has seldom been reported because the surface or near-surface fast faradic surface redox reactions highly depends on specific structure design. Herein, a flexible electrode that graphene wrapped NiO nanosheet arrays anchor on three-dimensional porous nitrogen-doped carbon foam (rGO@NiONCF) is fabricated. The rGO@NiONCF composite possesses a unique sandwich structure with 3D porous NCF as the inner conductive scaffold, ultrathin NiO nanosheet arrays as a middle layer, and rGO as the outer conductive buffer layer. The elaborated structure design endows rGO@NiONCF with enhanced electronic conductivity, sufficient electrolyte infiltration and restricted volume variation. As a result, the rGO@NiONCF electrode delivers high reversible capacity (1583 mAh g−1 at 0.1 A g−1) and superior cycling stability (maintains 607 mA h g−1 at 1 A g−1 after 500 cycles). Moreover, the enhanced surface capacitance adroitly facilitates an impressive fast charge and slow discharge performance. These results reveal that rational material design to encourage pseudocapacitance effect is a valuable roadmap for NiO-based battery towards more practical applications.