Ferroconcrete-inspired design of nonwoven graphene fiber fabrics enforced electrode toward flexible fast-charging sodium ion storage device
Flexible fast-charging sodium ion storage devices are poised to flourish the future wearable electronics, if the materials that build such devices can present a versatile integration. Herein, inspired by the ferroconcrete, nonwoven graphene fiber (GF) fabrics enforced electrodes are successfully demonstrated in flexible sodium ion capacitors (SICs). For the fabrics, functionalities of a fast electron transport and ion permeation network, a high compatible electrode materials host, an efficient capacity contributor, and a robust flexible framework are synergistically integrated. These are contributed from high conductivity of graphene sheets, tunable porosity of GFs, and interlocked structure, compatibility with materials, surface capacitive contribution of fabrics. Nonwoven fabrics hosted multi-dimensional active materials as the ferroconcrete electrode exhibit exceptional electrochemical and mechanical properties individually. The SICs can complete an entire charge-discharge process within 15 s. A digital LED and watch powered by the flexible SICs with superior volumetric performances (12 mWh cm-3@37 mW cm-3, and 6 mWh email@example.com W cm-3) prove the practical capability of our design. We believe that the proposed nonwoven GF fabrics and such ferroconcrete electrode structure will be a universal design, and shed new light on flexible fast-charging sodium ion storage devices.