Many problems associated with Li-S and Na-S batteries essentially root in the generation of their soluble polysulfide intermediates. While conventional wisdom mainly focuses on trapping polysulfides at the cathode using various functional materials, few strategies are available at present to fully resolve or circumvent this long-standing issue. In this study, we propose the concept of sulfur-equivalent cathode materials, and demonstrate the great potential of amorphous MoS as such a material for room-temperature Li-S and Na-S batteries. In Li-S batteries, MoS exhibits sulfur-like behavior with large reversible specific capacity, excellent cycle life, and the possibility to achieve high areal capacity. Most remarkably, it is also fully cyclable in the carbonate electrolyte under a relatively high temperature of 55 °C. MoS can also be used as the cathode material of even more challenging Na-S batteries to enable decent capacity and good cycle life. X-ray absorption spectroscopy (XAS) experiments are carried out to track the structural evolution of MoS It largely preserves its chain-like structure during repetitive battery cycling without generating any free polysulfide intermediates.

A novel aqueous rechargeable dual-ion battery system is demonstrated in this study, which consists of BiF3 as a fluoride ion electrochemical anode, NMO as a sodium ion electrochemical cathode, and aqueous NaF as the electrolyte.

Both freshwater shortage and energy crisis are global issues. Herein, we present a double-function system of faradaic desalination and a redox flow battery consisting of VCl3|NaI redox flow electrodes and a feed stream. The system has a nominal cell potential (E0 = +0.79 V). During the discharge process, the salt ions in the feed are extracted by the redox reaction of the flow electrodes, which is indicated by salt removal. Stable and reversible salt removal capacity and electricity can be achieved up to 30 cycles. The energy consumption is as low as 10.27 kJ mol-1 salt. The energy efficiency is as high as 50% in the current aqueous redox flow battery. With energy recovery, the desalination energy consumption decreases greatly to 5.38 kJ mol-1; this is the lowest reported value to date. This "redox flow battery desalination generator" can be operated in a voltage range of 0.3-1.1 V. Our research provides a novel method for obtaining energy-saving desalination and redox flow batteries.

Symmetric sodium-ion batteries possess promising features such as low cost, easy manufacturing process, and facile recycling post-process, which are suitable for the application of large-scale stationary energy storage. Herein, we proposed a symmetric sodium-ion battery based on dual-electron reactions of a NASICON-structured Na3MnTi­(PO4)3 material. The Na3MnTi­(PO4)3 electrode can deliver a stable capacity of up to 160 mAh g–1 with a Coulombic efficiency of 97% at 0.1 C by utilizing the redox reactions of Ti3+/4+, Mn2+/3+, and Mn3+/4+. This is the first time to investigate the symmetric sodium-ion full cell using Na3MnTi­(PO4)3 as both cathode and anode in the organic electrolyte, demonstrating excellent reversibility and cycling performance with voltage plateaus of about 1.4 and 1.9 V. The full cell exhibits a reversible capacity of 75 mAh g–1 at 0.1 C and an energy density of 52 Wh kg–1. In addition, both ex situ X-ray diffraction (XRD) analysis and first-principles calculations are employed to investigate the sodiation mechanism and structural evolution. The current research provides a feasible strategy for the symmetric sodium-ion batteries to achieve high energy density.

The sodium super ionic conductor (NASICON) materials are considered as the attractive cathode in sodium-ion batteries. Although the three-electron reactions in Na3MnTi(PO4)3 have greatly enhanced the capacity of NASICON-structure materials,...

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