Optimizing sodium storage and durability in metal sulfide anodes with a 3D graphene architecture†

Abstract

Transition metal chalcogenides (TMCs) with a high theoretical capacity are regarded as promising anodes for sodium-ion batteries (SIBs) but encounter several challenges because of the complex conversion process, which leads to numerous side reactions and the inevitable disintegration of active materials, thereby impeding their practical application. In this work, inspired by a three-dimensional (3D) structure design, stable 3D reduced graphene oxide with heteroatom-site coordinated carbon centers (3DNSrGO) is fabricated, which features uniform and abundant nickel sulfide (NiS) particles within the empty spaces, along with sufficient access to the liquid electrolyte, thereby enabling more efficient transfer of sodium ions. Nevertheless, the NiS/3DNSrGO electrode still suffers from unexpected cycling instability and failure issues because of the short-circuiting, resulting from sodium (Na) metal corrosion and the deterioration of the glass fiber (GF) separator. The issue of short cycle life is significantly mitigated at the cell configuration level (inclusion of the polypropylene membrane) by lowering the risks of Na–metal corrosion and protecting the GF membrane. This study holds considerable potential for addressing (1) the growing requirement for efficient and sustainable Na⁺ host materials and (2) a newfangled approach that optimizes the long-term cycling stability of SIBs via a better cell configuration.