Hollow heterostructure design enables self-cleaning surface for enhanced polysulfides conversion in advanced lithium-sulfur batteries

Constructing interpenetrating heterointerface with reasonable interface energy barriers to improve electron/ion transport and accelerate the deposition/decomposition of lithium sulfide (Li2S) is an effective method to improve the electrochemical performance of lithium-sulfur (Li-S) batteries. Herein, NiCoO2/NiCoP heterostructures with hollow nanocage morphology are prepared for efficient multifunctional Li-S batteries. The hollow nanocage structure exposes abundant active sites, traps lithium polysulfides and inhibits the shuttle effect. The NiCoO2/NiCoP heterostructure, combing strong adsorption capacity of NiCoO2 and excellent catalytic ability of NiCoP, facilitates the process of anchoring-diffusion-transformation of polysulfides. The successful construction of heterostructures reduces the reaction barrier, accelerating the lithium ion (Li+) diffusion rate and thus effectively enhancing the redox reaction kinetics. More importantly, NiCoO2/NiCoP heterostructure plays a role in self-cleaning that minimizes solid sulfur species accumulation to maintain surface clean during long cycling for a continuously catalysis of the polysulfides conversion reactions. With the merit of these features, the NiCoO2/NiCoP modified separator exhibits excellent cycling stability with a low capacity decay of 0.043% per cycle up to 1000 cycles at 2 C. The design of NiCoO2/NiCoP hollow nanocage heterostructures offers a new option for high-performance electrochemical energy storage devices.