| Summary: | Ti<sub>3</sub>C<sub>2</sub>T<sub>x</sub>-based aerogels have attracted widespread attention for three-dimensional porous structures, which are promising to realize high-rate energy storage. However, disordered Ti<sub>3</sub>C<sub>2</sub>T<sub>x</sub> 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 Ti<sub>3</sub>C<sub>2</sub>T<sub>x</sub> aerogel with straight and aligned channels, straight and short ion diffusion pathways, leading to better ion accessibility. The aligned Ti<sub>3</sub>C<sub>2</sub>T<sub>x</sub> aerogel exhibits the high specific capacitance of 345 F g<sup>−1</sup> at 20 mV s<sup>−1</sup> and rate capability of 52.2% from 10 to 5000 mV s<sup>−1</sup>. The specific capacitance is insensitive of mass loadings even at 10 mg cm<sup>−2</sup> and an excellent power density of 137.3 mW cm<sup>–2</sup> is obtained in symmetric supercapacitors. The electrochemical properties of Ti<sub>3</sub>C<sub>2</sub>T<sub>x</sub> aerogel supercapacitors at sub-zero (to −30 °C) temperatures are reported for the first time. The aligned Ti<sub>3</sub>C<sub>2</sub>T<sub>x</sub> aerogel delivers temperature-independent rate performance and high capacitance retention (73% at 50 mV s<sup>−1</sup> from 25 to −30 °C) due to the unique structure with metallic conductivity.
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