All‐Solid‐State Flexible Symmetric Supercapacitor Based on Morphology Oriented Amorphous Cu−Co−B Alloy Nanosheets for Energy Storage

Abstract

AbstractMetastable amorphous alloys having 2‐dimensional morphology are expected to be an excellent electrode materials for supercapacitors because of their defect rich nature, high degree of compositional as well as topological disorder and internal stresses. Herein, we investigated and demonstrated a new series of Cu−Co−B amorphous alloy nanosheets for energy storage. A clear and significant energy storage improvement by this Cu−Co−B nanosheets over the state‐of‐the‐art materials and flexible devices are manifested. Among the as‐synthesized materials, CuCo2B nanosheets exhibits an excellent specific capacity of 3503.6 F g−1 (389.2 mAh g−1) and a 99 % (at 50 A g−1) retention rate after 3000 cycles. An all‐solid state flexible symmetric Cu−Co−B|[EMIM][BF4] supercapacitor device (0–180° bending, 2.5 V) demonstrates a high energy density of 90.2 Wh kg−1, specific capacity (289.2 mAh g−1), power density (4623.6 W kg−1) and prolonged cycling stability (89 %) and Coulombic efficiency (104 %) over 10000 charge‐discharge cycles.