High capacity and long service in sodium-ion batteries achieved by the refinement of BiOCl from lamellar to flower-like in ether electrolyte

Abstract

Sodium-ion batteries (SIBs) have emerged as a promising contender in power systems owing to their cost-effectiveness and safety advantages. However, alloy-type anode materials, crucial for SIB performance, often face challenges such as significant volume expansion and rapid capacity decay at high current densities. In this study, an ion-exchange strategy is used to fabricate ultra-thin and porous BiOCl nanosheets (UTP BiOCl NS) as an anode material for SIB. Remarkably, lamellar UTP BiOCl NSs can transform a flower-like shape in ether electrolytes. This structural change is beneficial in shortening the Na+ transport path, which facilitates rapid electrolyte entry and enhances the dynamic behavior of SIBs. Electrochemically, UTP BiOCl NS demonstrates an exceptional capacity of 212.4 mAh/g and high service stability of up to 3000 cycles at a high current density of 5 A/g, showcasing exceptional durability and promising application potential. Furthermore, the SIB full-cell, coupled with a Na3V2(PO4)3 cathode and UTP BiOCl NS anode, enables an outstanding sodium storage capacity of 140.5 mAh/g and powers a 3 W bulb. This research provides a strategic approach for identifying suitable SIB anodes and aims to inspire researchers to focus on advancing anode materials in SIBs.