Rechargeable Mg²⁺/Li⁺, Mg²⁺/Na⁺, and Mg²⁺/K⁺ Hybrid Batteries Based on Layered VS₂

Abstract

Rechargeable Mg batteries have great potential in next-generation scalable energy-storage applications, but the electrochemical performance is limited by the Mg-intercalation cathodes. Hybrid batteries based on dual-cation (Mg2+ and alkali metal cations) electrolytes would not only improve the electrochemical performance but also induce the co-intercalation of Mg2+ with alkali metal cations. As previous reports overwhelmingly focus on Mg2+/Li+ hybrid batteries, in this work, Mg2+/Na+ and Mg2+/K+ hybrid batteries are constructed using a typical layered VS2 cathode and studied in comparison with Mg2+/Li+ batteries. It is observed that Mg2+ could co-intercalate into VS2 with Li+, Na+, or K+. However, Mg-intercalation is irreversible in the Mg2+/Li+ system, and co-intercalation of Mg2+ and K+ would cause a collapse of VS2. Comparatively, the co-intercalation of Mg2+ and Na+ into VS2 exhibits the highest reversibility, and the Mg2+/Na+ hybrid battery shows the best cycling stability without capacity fading within 1000 cycles. Our work highlights the co-intercalation reversibility of a non-pre-expanded layered disulfide cathode and delivers insights for the development of high-performance rechargeable Mg metal batteries.

Thermodynamics and kinetics of Mg2+/Li+ and Mg2+/Na+ co-intercalation into layered titanium disulfide

“…26,27,29 The layer spacings of the Na-intercalation (d = 6.9 Å) and the Mg-Na mixed intercalation (d = 8.7 Å) were larger than those of the Liintercalation (d = 6.1 Å) and Mg-Li mixed intercalation (d = 8.5 Å), respectively, due to the larger size of the Na + . 30 The layer spacings of the interlaced intercalations were slightly smaller than twice that of the Li + or Na + intercalations, which was due to the smaller spacing of the Mg-intercalation layer. A peak split is observed for the Mg-Na mixed intercalation (10.21), which might be because of the large ion potential difference between Mg 2+ and Na + and the complicated location of the Mg 2+ and Na + in the same layer.…”

Morphology Engineering of VS4 Microspheres as High-Performance Cathodes for Hybrid Mg2+/Li+ Batteries

“…When the current density returns to 50 mA g –1 , the discharge capacity is 272.3 mAh g –1 , which is only marginally lower than the values before the current density increases. Therefore, compared with VS 4 @NC-2, VS 4 @NC-8, or other previously reported cathodes for MLIBs, such as VS 2 , CuS, Nb 2 O 5 , LiTi 2 (PO 4 ) 3 , MoSSe/G, V 2 C, etc., the obtained VS 4 @NC-5 cathode exhibits the best rate capability (Figure f). For comparison, the rate capability of the VS 4 -5 cathode was investigated and is shown in Figure S3d.…”

Advanced V-based materials for multivalent-ion storage applications

“…Meanwhile, in the charge process, the situation is just the opposite. A hybrid Mg-Li-ion battery combines the advantages of a Mg anode without dendrite deposition and a fast lithium insertion cathode, making it a better alternative to LIBs for power storage [104] .…”