No abstract

In the applications of large-scale energy storage, aqueous batteries are considered as rivals for organic batteries due to their environmentally friendly and low-cost nature. However, carrier ions always exhibit huge hydrated radius in aqueous electrolyte, which brings difficulty to find suitable host materials that can achieve highly reversible insertion and extraction of cations. Owing to open three-dimensional rigid framework and facile synthesis, Prussian blue analogues (PBAs) receive the most extensive attention among various host candidates in aqueous system. Herein, a comprehensive review on recent progresses of PBAs in aqueous batteries is presented. Based on the application in different aqueous systems, the relationship between electrochemical behaviors (redox potential, capacity, cycling stability and rate performance) and structural characteristics (preparation method, structure type, particle size, morphology, crystallinity, defect, metal atom in high-spin state and chemical composition) is analyzed and summarized thoroughly. It can be concluded that the required type of PBAs is different for various carrier ions. In particular, the desalination batteries worked with the same mechanism as aqueous batteries are also discussed in detail to introduce the application of PBAs in aqueous systems comprehensively. This report can help the readers to understand the relationship between physical/chemical characteristics and electrochemical properties for PBAs and find a way to fabricate high-performance PBAs in aqueous batteries and desalination batteries.

No abstract

In aqueous/nonaqueous metal-sulfur batteries, sulfur-based redox couple exhibits significant challenges mainly due to its low electrochemical kinetics, potential shuttle effect, and large volume change. Although massive researches have been conducted to optimize or replace metal anode and cathode composite, major challenges caused by the dependency on sulfurbased redox couple still remain. In this study, a novel redox couple of CuS/ Cu 2 S, which provides the same theoretical capacity (based on conventional S/S 2− redox couple) by changing the valence of ion charge carrier, is proposed. For achieving high reversibility, commercially viable laser-induced graphene (LIG) is fabricated and used for the first time in aqueous metalsulfur batteries. By virtue of the synergism between novel redox couple and LIG, aqueous CuS/Cu 2 S battery delivers a highly reversible capacity of 1654.9 mAh g −1 in the initial cycle and retains 91.2% with 1509.5 mAh g −1 after 328 cycles. When being cycled at 2.8 A g −1 , its reversible capacity still retains 92.1% after 410 cycles. This study provides a new choice by using a sulfur-free redox couple from screening thermodynamic parameters and analyzes the functional mechanism of LIG by density functional theory, aiming to innovate the energy storage mechanism of aqueous metal-sulfur batteries.

Significance Based on the analysis of three thermodynamic parameters of various M-S systems (solubility of metal sulfides [M x S y ] in aqueous solution, volume change of the metal-sulfur [M-S] battery system, and the potential of S/M x S y cathode redox couple), an aqueous Pb-S battery operated by synergistic dual conversion reactions (cathode: S⇄PbS, anode: Pb 2+ ⇄PbO 2 ) has been officially reported. Benefitting from the inherent insolubility of PbS and a conversion-type counter electrode, the aqueous Pb-S battery exhibited two advantages: it is shuttle effect free and has a dendrite-free nature. Moreover, the practical value of the Pb-S battery was further certified by the prototype S|Pb(NO 3 ) 2 ǁZn(NO 3 ) 2 |Zn hybrid cell, which afforded an energy density of 930.9 Wh kg −1 sulfur .