Ice-Templated, Sustainable Carbon Aerogels with Hierarchically Tailored Channels for Sodium- and Potassium-Ion Batteries

Abstract

Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) are prospective candidates for large-scale energy storage systems cause of their abundant resources. However, unsatisfactory rate and cycling performance of carbon-based anodes present a bottleneck for the applications of SIBs/PIBs due to the large sizes of sodium/potassium ions. Herein, oxygen-doped vertically aligned carbon aerogels (VCAs) with hierarchically tailored channels are synthesized as anodes in SIBs/PIBs via a controllable unidirectional ice-templating technique. VCA-3 (cooling rate of 3 K min−1) delivers the highest reversible capacity of ≈298 mAh g−1 at 0.1 C with an excellent cycling performance over 2000 cycles at 0.5 C for SIBs, while VCA-5 manifests a superior capacity of ≈258 mAh g−1 at 0.1 C with an 82.7% retention over 1000 cycles at 0.5 C for PIBs. Moreover, their full cells demonstrate the promising potential of VCAs in applications. This novel controllable ice-templating strategy opens unique avenues to tune the construction of hollow aligned channels for shortening ion-transport pathways and ensuring structural integrity. New insights into structure-performance correlations regulated by the cooling rates of an ice-templating strategy and design guidelines for electrodes applicable in multiple energy storage technologies are reported.