Lithium-sulfur batteries are considered as one of the potential solutions as integrating renewable energy systems for large-scale energy storage because of their high theoretical energy density (2600 Wh·kg^-1) and specific capacity (1675 mAh·g^-1). Currently, various strategies have been proposed to overcome the technical barriers, e.g., “shuttle effect”, capacity decay and volumetric change, which impede the successful commercialization of lithium-sulfur batteries. This paper reviews the applications of metal nitrides as the cathode hosts for high-performance lithium-sulfur batteries, summarizes the design strategies of different host materials, and discusses the relationship between the properties of metal nitrides and their electrochemical performances. Finally, reasonable suggestions for the design and development of metal nitrides, along with ideas to promote future breakthroughs, are proposed. We hope that this review could attract more attention to metal nitrides and their derivatives, and further promote the electrochemical performance of lithium-sulfur batteries.

Lithium nickel oxide (Li₂NiO₂), as a sacrificial cathode prelithiation additive, has been used to compensate for the lithium loss for improving the lifespan of lithium-ion batteries (LIBs). However, high-cost Li₂NiO₂ suffers from inferior delithiation kinetics during the first cycle. Herein, we investigated the effects of the cost-effective copper substituted Li₂Ni_1-xCu_xO₂ (x = 0, 0.2, 0.3, 0.5, 0.7) synthesized by a high-temperature solid-phase method on the structure, morphology, electrochemical performance of graphite‖LiFePO₄ battery. The X-ray diffraction (XRD) refinement result demonstrated that Cu substitution strategy could be favorable for eliminating the NiO_x impurity phase and weakening Li-O bond. Analysis on density of states (DOS) indicates that Cu substitution is good for enhancing the electronic conductivity, as well as reducing the delithiation voltage polarization confirmed by electrochemical characterizations. Therefore, the optimal Li₂Ni_0.7Cu_0.3O₂ delivered a high delithiation capacity of 437 mAh·g^-1, around 8% above that of the pristine Li₂NiO₂. Furthermore, a graphite‖LiFePO₄ pouch cell with a nominal capacity of 3000 mAh demonstrated a notably improved reversible capacity, energy density and cycle life through introducing 2 wt% Li₂Ni_0.7Cu_0.3O₂ additive, delivering a 6.2 mAh·g^-1 higher initial discharge capacity and achieving around 5% improvement in capacity retentnion at 0.5P over 1000 cycles. Additionally, the post-mortem analyses testified that the Li₂Ni_0.7Cu_0.3O₂ additive could suppress solid electrolyte interphase (SEI) decomposition and homogenize the Li distribution, which benefits to stabilizing interface between graphite and electrolyte, and alleviating dendritic Li plating. In conclusion, the Li₂Ni_0.7Cu_0.3O₂ additive may offer advantages such as lower cost, lower delithiation voltage and higher prelithiation capacity compared with Li₂NiO₂, making it a promising candidate of cathode prelithiation additive for next-generation LIBs.

Due to the high capacity and moderate volume expansion of silicon protoxide SiO_x (160%) compared with that of Si (300%), reducing silicon dioxide SiO₂ into SiO_x while maintaining its special nano-morphology makes it attractive as an anode of Li-ion batteries. Herein, through a one-pot facile high-temperature annealing route, using SBA15 as the silicon source, and embedding tin dioxide SnO₂ particles into carbon coated SiO_x, the mesoporous SiO_x-SnO₂@C rod composite was prepared and tested as the anode material. The results revealed that the SnO₂ particles were distributed uniformly in the wall, which could further improve their volume energy densities. The coated carbon plays a role in maintaining structural integrality during lithiation, and the rich mesopores structure can release the expanded volume and enhance Li-ion transfer. At 0.1 A·g^-1, the gravimetric and volumetric capacities of the composite were as high as 1271 mAh·g^-1and 1573 mAh·cm^-3, respectively. After 200 cycles, the 95% capacity could be retained compared with that upon the 2nd cycle at 0.5 A·g^-1. And the rod morphology was well kept, except that the diameter of the rod was 3 times larger than its original size after the cell was discharged into 0.01 V.