Wu Zhitan, Deng Yaqian, Yu Jinyang, Han Junwei, Shang Tongxin, Chen Derong, Wang Ning, Gu Sichen, Lv Wei, Kang Feiyu, Tao Ying, Yang Quan-Hong
Nanoyang Group, Tianjin Key Laboratory of Advanced Carbon and Electrochemical Energy Storage, School of Chemical Engineering and Technology, National Industry-Education Integration Platform of Energy Storage, and Collaborative Innovation Center of Chemical Science and Engineering, Tianjin, 300072, China.
Shenzhen Key Laboratory for Graphene-based Materials, Engineering Laboratory for Functionalized Carbon Materials, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China.
Adv Mater. 2023 Jul;35(29):e2300580. doi: 10.1002/adma.202300580. Epub 2023 Jun 4.
The assembly of 3D structured materials from 2D units paves a royal road for building thick and dense electrodes, which are long sought after for practical energy-storage devices. 2D transitional metal carbides (MXene) are promising for this due to their capabilities of solution-based assembly and intrinsic high density, yet face huge challenges in yielding high areal capacitance electrodes owing to the absence of porous ion-transport paths. Here, a gelation-densification process initiated by hydroiodide acids (HI) is proposed, where the protons break the electrostatic balance of MXene nanosheets to trigger gelation, while HI serves as a spacer to prevent nanosheets from restacking during capillary shrinkage. More promising, the controlled evaporation of reductive HI leaves superiorly shrinking yet porous network for ion transport, and the produced monoliths exhibit a high density of 2.74 g cm and an unprecedented areal capacitance of 18.6 F cm .
从二维单元组装三维结构材料为构建厚且致密的电极铺平了道路，这种电极是实际储能装置长期以来所追求的。二维过渡金属碳化物（MXene）因其基于溶液的组装能力和固有的高密度而有望用于此，但由于缺乏多孔离子传输路径，在制备高面积电容电极方面面临巨大挑战。在此，提出了一种由氢碘酸（HI）引发的凝胶化致密化过程，其中质子打破MXene纳米片的静电平衡以触发凝胶化，而HI作为间隔物防止纳米片在毛细管收缩过程中重新堆叠。更有前景的是，还原性HI的可控蒸发留下了用于离子传输的高度收缩但多孔的网络，所制备的整体材料表现出2.74 g/cm³的高密度和18.6 F/cm²的前所未有的面积电容。
