Synergistically constructed lamination-like network of redox-active polyimide and MXene via π-π interactions for aqueous NH_(4)^(+) storage

As a nonmetallic charge carrier,ammonium ion(NH_(4)^(+))has garnered significant attention in the construction of aqueous batteries due to its advantages of low molar mass,small hydration size and rapid diffusion in aqueous solutions.Polymers are a kind of potential electro-active materials for aqueous NH_(4)^(+)storage.However,traditional polymer electrodes are typically created by covering the bulky collectors with excessive additives,which could lead to low volume capacity and unsatisfactory stability.Herein,a nanoparticle-like polyimide(PI)was synthesized and then combined with MXene nanosheets to synergistically construct an additive-free and self-standing PI@MXene composite electrode.Significantly,the redox-active PI nanoparticles are enclosed between conductive MXene flakes to create a 3D lamination-like network that promotes electron transmission,while theπ-πinteractions existing between PI and MXene contribute to the enhanced structural integrity and stability within the composite electrode.As such,it delivers superior aqueous NH_(4)^(+)storage behaviors in terms of a notable specific capacity of 110.7 mA·h·cm^(–3) and a long lifespan with only 0.0064%drop each cycle.Furthermore,in-situ Raman and UV–Vis examinations provide evidence of reversible and stable redox mechanism of the PI@MXene composite electrode during NH_(4)^(+)uptake/removal,highlighting its significance in the area of electrochemical energy storage.

A biomimetic-structured wood-derived carbon sponge with highly compressible and biocompatible properties for human-motion detection

Piezoresistive sensors,as an indispensable part of electronic and intelligent wearable devices,are often hindered by nonrenewable resources(graphene,conventional metal,or silicon).Biomass-derived carbonaceous materials boast many advantages such as their light weight,renewability,and excellent chemical stabilization.However,a major challenge is that the strength and resilience of carbon-based piezoresistive materials still falls short of requirements due to their random microarchitectures which cannot provide sufficiently good stress distribution.Encouraged by the excellent compressible properties and extraordinary strength of the Thalia dealbata stem,we propose a wood biomassderived carbon piezoresistive sensor with an artificial interconnected lamellar structure like the stem itself.By introducing a freezing-induced assembly process,a wood-based,completely delignified,nano-lignocellulose material can be built into a“bridges supported lamellar”type architecture,where subsequent freeze-drying and pyrolysis results in carbon aerogel monoliths.The resultant bioinspired carbon sponge has high compressibility and strength,of the order of two to five times higher than that of conventional metal,carbon,and organic materials.Combined with excellent biocompatible properties and chemical durability,these are useful properties for intelligent wearable devices and human-motion detection.

自发短路反应原位构筑锌离子传导界面层稳定锌负极

水系锌离子电池具有高安全性、大容量、低成本、环境友好等优点,在大型储能系统中显示出巨大的潜力.然而,金属锌负极上枝晶的生长、析氢腐蚀、钝化等问题严重阻碍了锌离子电池的应用.在锌负极表面构筑一层界面层被证明是一种简单有效的方法.目前已经报道的无机界面涂层材料如纳米Ca CO_(3)、无定形Ti O_(2)等,主要通过物理作用机械阻隔枝晶,但这些材料本身不具有锌离子的导电性,无法化学调控锌离子的传输.本文采用ZnxV_(2)O_(5)·n H_(2)O(Zn VO)作为界面改性材料,将锌离子电池常用的正极材料层状钒氧化物应用于锌负极的界面保护,通过V_(2)O_(5)·n H_(2)O与金属锌之间的自发短路反应,在锌负极表面上原位构建了Zn VO材料的锌离子导电界面层.与无修饰的锌负极相比,Zn VO涂覆后的锌负极,在减少电解液与锌负极直接接触的同时引导锌离子的传输,表现出更好的电化学性能.其中,锌对称电池的循环寿命提高了10倍以上.