Boosting the lithium storage performance by synergistically coupling ultrafine heazlewoodite nanoparticle with N, S co-doped carbon

Abstract

Transition metal sulfides, as an important class of inorganics, have been shown to be potential high-performance electrode candidates for lithium-ion batteries (LIBs) in account of their high activity towards lithium storage, rich types and diverse structures. Despite these advantages, structure degradation related with volume variations upon electrochemical cycling restricts their further development. In this present study, a unique hybrid structure with ultrafine heazlewoodite nanoparticles (less than 10 nm) in-situ confined in nitrogen and sulfur dual-doped carbon (Ni3S2@NSC) was constructed though a facile pyrolysis process, using a novel Ni-based metal chelates as the precursor. Specifically, enhanced structure stability, shortened Li+ migration distance and improved reaction dynamics can be obtained simultaneously in the designed structure, thereby allowing to realize high lithium storage performance. Consequently, a remarkable reversible capacity of 955.9 mAh g−1 (0.1 A g−1 after 100 cycles) and a superior long-term cycling stability up to 1200 cycles (863.7 mAh g−1 at 1.0 A g−1) are obtained. Importantly, the fundamental understanding on the improved lithium storage of Ni3S2@NSC based on the synergistic coupling reveals that the combination between Ni3S2 and NSC at the hetero-interface through the doped sulfur atoms contributes to the integrity of electrode and improved kinetics.