Kinetically boosted potassium ion storage capability of 1D K2Ti6O13 nanobelts by 3D porous carbon framework for fiber-shaped potassium ion capacitors

Abstract

One dimensional (1D) fiber-shaped energy storage device demonstrates a great potential for the future power source textiles. However, delivering high energy/power densities and long cycle life is still the crucially electrochemical themes to meet the ever-stringent demands. Herein, we report a novel non-aqueous fiber-shaped potassium ion capacitors (PICs), in which 1D K2Ti6O13 nanobelts (KTO) interweaved with three-dimensional (3D) porous carbon framework was synthesized as anode materials. The low specific capacity and sluggish reaction kinetics of the bare KTO is boosted by the 3D porous carbon framework. Its hierarchical porosity and 3D structure impede the aggregation of the KTO, and favor the permeation of potassium ions in electrolyte. Its graphitic carbon improves the electrical conductivity of the KTO. Meanwhile, it also offers a suitable potassium ion storage capacity. These features enable KTO@3D-C with high specific capacity and rate performance. A single non-aqueous fiber-shaped PICs with a high working voltage up to 3.5 V can lead to maximum areal and volumetric energy densities of 12.1 μWh cm−2 and 1.9 m Wh cm−3, indicating apparent energy advantages over the ones with aqueous electrolyte and symmetric configuration. Our integratable and robust fiber-shaped PICs prototype demonstrates a great potential for future power source textiles.