Electrolyte Concentration Regulation Boosting Zinc Storage Stability of High-Capacity K0.486V2O5 Cathode for Bendable Quasi-Solid-State Zinc Ion Batteries

Vanadium-based cathodes have attracted great interest in aqueous zinc ion batteries(AZIBs)due to their large capacities,good rate performance and facile synthesis in large scale.However,their practical application is greatly hampered by vanadium dissolution issue in conventional dilute electrolytes.Herein,taking a new potassium vanadate K0.486V2O5(KVO)cathode with large interlayer spacing(~0.95 nm)and high capacity as an example,we propose that the cycle life of vanadates can be greatly upgraded in AZIBs by regulating the concentration of ZnCl2 electrolyte,but with no need to approach“water-in-salt”threshold.With the optimized moderate concentration of 15 m ZnCl2 electrolyte,the KVO exhibits the best cycling stability with ~95.02% capacity retention after 1400 cycles.We further design a novel sodium carboxymethyl cellulose(CMC)-moderate concentration ZnCl2 gel electrolyte with high ionic conductivity of 10.08 mS cm^-1 for the first time and assemble a quasi-solid-state AZIB.This device is bendable with remarkable energy density(268.2 Wh kg^−1),excellent stability(97.35% after 2800 cycles),low self-discharge rate,and good environmental(temperature,pressure)suitability,and is capable of powering small electronics.The device also exhibits good electrochemical performance with high KVO mass loading(5 and 10 mg cm^-2).Our work sheds light on the feasibility of using moderately concentrated electrolyte to address the stability issue of aqueous soluble electrode materials.

Binder-free electrodes for advanced potassium-ion batteries:A review

Potassium-ion batteries(PIBs)have attracted enormous attention due to the abundance of potassium resources,low cost,fast ionic conductivity of electrolyte and relatively high operating voltage.Despite great effo rts and progress,researches on PIBs are still at the initial stage,especially in the emerging field of flexible and wearable PIBs.The inevitable challenges for PIBs include low reversible capacity,unsatisfactory cycling stability and insufficient energy density,the solution to which mostly relies on designing adva nced electrodes.Binder-free electrodes have emerged as promising electrode architecture for PIBs.Such electrodes avoid the use of insulating binders,which can be designed with various synergistic functional materials to address the aforementioned PIB issues and be endowed with flexibility/wearability.In this review,we mainly summarize the recent progress on binde r-free electrodes for PIBs,with the focus on the methodologies,detailed strategies and functional materials for electrode construction.One strategy for binder-free electrodes is to assemble free-standing architecture with the help of carbon nanotubes(CNTs),graphitic fibers,and other carbon or mechanically robust materials,either alone or in combination.The other effective strategy is current collector substrate-assisted direct growth,including the use of carbon cloth,metal.MXenes and other conductive substrates.Additionally,challenges and research opportunities are put forward at the end as the guidance for future development of binder-free PIB devices.

水系混合超级电容器先进电极材料与器件研究进展

使用有毒、易燃有机电解液的传统电化学储能器件存在较大的安全隐患.相比之下,新型水系混合超级电容器(AHSCs)具有更高的安全性和环境友好性.AHSCs作为水系电池和水系超级电容器之间的桥梁,能够结合电池电极高的比容量和电容电极大功率和长寿命的优点,有望与电池系统结合使用或者完全替代电池系统.在过去的几十年中,研究者致力于开发先进的电极材料和设计结构新颖的水系混合电容器.然而,全电池搭配时电池型电极和电容型电极存在容量和动力学不匹配的问题.本文从电池电极、电容电极和新型电解质的概念设计三个方面综述了AHSCs的研究进展,讨论了具有“双离子”储能机制和非极性特性的多功能AHSCs,并进一步阐述了多价AHSCs(特别是锌离子AHSCs)的最新进展及有待解决的关键问题.最后,本文总结了AHSCs面临的挑战,并对未来构筑更高功率密度和多功能AHSCs器件的发展方向作出了展望.

直接生长纳米结构电极构建高功率和高稳定性的碱性镍/铋电池（英文）

氧化铋(Bi_2O_3)作为碱性镍/铋电池的负极材料,因其理论容量高、易制备而受到广泛关注.然而,金属氧化物普遍较差的导电性以及氧化铋的循环不稳定性严重限制了器件的性能.本文用直接生长的具有动力学优势的氧化铋纳米片薄膜作为镍/铋电池的负极;同时将葡萄糖衍生的碳包覆在纳米片的表面,不仅促进了电子传递,还缓冲了氧化铋转换反应过程中的体积膨胀,有助于维持电极的循环稳定性.该Bi_2O_3@C电极表现出高比容量,优异的倍率性能(在6.7 s内充满电)以及良好的循环稳定性(约1200次;每圈仅衰减0.011%).与氧化镍(NiO)纳米片阵列正极搭配,组装的完全无粘结剂的碱性镍/铋电池展现出34.29 W h kg^(-1)的最大能量密度和12159.8 W kg^(-1)的最大功率密度以及良好的循环性能;其功率密度甚至远远优于许多混合/非对称型超级电容器.本研究展现了新一代薄膜镍/铋电池在高功率电子器件应用上的巨大潜力.