LAUSR

Abstract Electrochemical conversion reaction provides options for high-capacity Na-storage, but the poor cycleability is hindering the application. Herein, a hydroxyl hyperbranched polyamide (HHP) is used as an electrode additive for CuS. The HHP regulates formation of hierarchical microspheres composed of CuS nanoneedles. More importantly, HHP acts as an additive uniformly distributed in CuS, offering an elastic framework to enhance the cycleability. This CuS shows a high capacity of 415 mAh g 1 and a superior cycleability over 1000 cycles. Further kinetic study demonstrates fast solid-state Na+ diffusion in such CuS, which leads to an outstanding rate capability of 180 mAh g−1 at 20 A g−1. The present research provides a novel approach to enhance the Na-storage performance of CuS by using an organic polymer additive.