Jackfruit-like electrode design for advanced Na-Se batteries

Sodium-selenium (Na–Se) batteries are attracting much attention because of their high energy density. However, their practical application is still restricted by rapid capacity fading resulting from the inferior electrode kinetics, low utilization of Se and enormous volumetric expansion. Herein, a jackfruit-like electrode is designed for advanced Na–Se batteries to solve these problems. The carbon nanorods are well-aligned to form a jackfruit-like design as the Se host. Thanks to the unique structure, many hollow nanochannels between nanorods are able to provide multifold pathways for Na-ions diffusion and electrolyte penetration. Moreover, the nanopores in carbon nanorods can provide adequate space to store Se and to buffer volumetric expansion during cycling. More importantly, the well-aligned carbon nanorods can enable a fast electron transfer to improve the utilization of Se. As a result, the jackfruit-like Se-carbon electrodes exhibit a high capacity of 616 mAh g−1 at 0.2 C, outstanding rate capability and long cycling life up to 600 cycles at 2 C with a very low capacity decay of 0.066% per cycle.