Aligned Ti₃C₂T_X Aerogel with High Rate Performance, Power Density and Sub-Zero-Temperature Stability

Abstract

Ti3C2Tx-based aerogels have attracted widespread attention for three-dimensional porous structures, which are promising to realize high-rate energy storage. However, disordered Ti3C2Tx aerogels with highly tortuous porosity fabricated by conventional unidirectional freeze-casting substantially increase ion diffusion lengths and hinder electrolyte ions transport. Herein we demonstrate a new bidirectional ice-templated approach to synthesize porous ordered Ti3C2Tx aerogel with straight and aligned channels, straight and short ion diffusion pathways, leading to better ion accessibility. The aligned Ti3C2Tx aerogel exhibits the high specific capacitance of 345 F g−1 at 20 mV s−1 and rate capability of 52.2% from 10 to 5000 mV s−1. The specific capacitance is insensitive of mass loadings even at 10 mg cm−2 and an excellent power density of 137.3 mW cm–2 is obtained in symmetric supercapacitors. The electrochemical properties of Ti3C2Tx aerogel supercapacitors at sub-zero (to −30 °C) temperatures are reported for the first time. The aligned Ti3C2Tx aerogel delivers temperature-independent rate performance and high capacitance retention (73% at 50 mV s−1 from 25 to −30 °C) due to the unique structure with metallic conductivity.

Keywords

• supercapacitor
• aligned Ti₃C₂T_x aerogel
• rate performance
• power density
• sub-zero-temperature stability