A hollow Co_0.12Ni_1.88S₂/NiO heterostructure that synergistically facilitates lithium polysulfide adsorption and conversion for lithium-sulfur batteries

The significant capacity deterioration and inadequate cycling lifespan that are mainly caused by the undesirable “shuttle effect” and torpid redox kinetics have encumbered the development of practically applicable lithium-sulfur (Li-S) battery technology. Modifying sulfur cathodes with lithium polysulfide (LiPS) adsorptive and electrocatalytic host materials is a promising approach to resolving these issues. Herein, a Co_0.12Ni_1.88S₂/NiO heterostructure, which has multiple merits, is designed and serves as a sulfur host to improve the electrochemical performance of Li-S batteries. Possessing strong LiPS adsorbability and excellent electrocatalytic activity, the heterostructural Co_0.12Ni_1.88S₂/NiO exhibits favorable synergistic effects, which effectively facilitate the anchoring and converting of diffused LiPSs. As a result, the corresponding cell delivers rapid redox kinetics and higher sulfur utilization. An impressive initial discharge capacity of 1424.8 mAh g⁻¹ and a reversible capacity near 1056.7 mAh g⁻¹ at 1 C over 1000 cycles are achieved with an average Coulombic efficiency of 98.8%. Benefiting from the unique nanoarchitecture and superior catalytic efficiency, only a very small amount of Co_0.12Ni_1.88S₂/NiO (∼7 wt% in the cathode) is used as the sulfur host. The rational design of Co_0.12Ni_1.88S₂/NiO in this work will hopefully offer inspiration for exploring advanced heterostructure materials for Li-S batteries and other electrochemical devices.