Ren Zhou-Hong, Zhang Zhi-Ruo, Ma Li-Jun, Luo Chen-Yue, Dai Jie, Zhu Qin-Yu
College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P. R. China.
ACS Appl Mater Interfaces. 2023 Feb 8;15(5):6621-6630. doi: 10.1021/acsami.2c17523. Epub 2023 Jan 25.
Poor electrical conductivity and instability of metal-organic frameworks (MOFs) have limited their energy storage and conversion efficiency. In this work, we report the application of oxidatively doped tetrathiafulvalene (TTF)-based MOFs for high-performance electrodes in supercapatteries. Two isostructural MOFs, formulated as [M(py-TTF-py)(BPDC)]·2HO (M = Ni (), Zn (); py-TTF-py = 2,6-bis(4'-pyridyl)TTF; HBPDC = biphenyl-4,4'-dicarboxylic acid), are crystallographically characterized. The structural analyses show that the two MOFs possess a three-dimensional 8-fold interpenetrating diamond-like topology, which is the first example for TTF-based dual-ligand MOFs. Upon iodine treatment, MOFs and are converted into oxidatively doped and with high crystallinity. The electrical conductivity of and is significantly increased by six∼seven orders of magnitude. Benefiting from the unique structure and the pronounced development of electrical conductivity, the specific capacities reach 833.2 and 828.3 C g at a specific current of 1 A g for and , respectively. When used as a battery-type positrode to assemble a supercapattery, the AC∥ and AC∥ (AC = activated carbon) present an energy density of 90.3 and 83.0 Wh kg at a power density of 1.18 kW kg and great cycling stability with 82% of original capacity and 92% columbic efficiency retention after 10,000 cycles. Ex situ characterization illustrates the ligand-dominated mechanism in the charge/discharge processes. The excellent electrochemical performances of and are rarely reported for supercapatteries, illustrating that the construction of unique highly dense and robust structures of MOFs followed by postsynthetic oxidative doping is an effective approach to fabricate MOF-based electrode materials.
金属有机框架材料（MOFs）较差的导电性和不稳定性限制了它们的能量存储和转换效率。在这项工作中，我们报道了基于氧化掺杂四硫富瓦烯（TTF）的MOFs在超级电容器高性能电极中的应用。对两种同构的MOFs进行了晶体学表征，其化学式为[M(py-TTF-py)(BPDC)]·2H₂O（M = Ni (1)，Zn (2)；py-TTF-py = 2,6-双(4'-吡啶基)TTF；H₂BPDC = 联苯-4,4'-二羧酸）。结构分析表明，这两种MOFs具有三维八重互穿的类金刚石拓扑结构，这是基于TTF的双配体MOFs的首个实例。经过碘处理后，MOFs 1和2转变为具有高结晶度的氧化掺杂产物1'和2'。1'和2'的电导率显著提高了六个至七个数量级。得益于独特的结构和显著提高的电导率，在1 A g的比电流下，1'和2'的比电容分别达到833.2和828.3 C g⁻¹。当用作电池型正极来组装超级电容器时，AC∥1'和AC∥2'（AC = 活性炭）在1.18 kW kg⁻¹的功率密度下能量密度分别为90.3和83.0 Wh kg⁻¹，并且具有出色的循环稳定性，在10000次循环后分别保留了82%的初始容量和92%的库仑效率。非原位表征揭示了电荷/放电过程中以配体为主导的机制。1'和2'优异的电化学性能在超级电容器中鲜有报道，这表明构建独特的高密度且坚固的MOF结构，随后进行后合成氧化掺杂，是制备基于MOF的电极材料的有效方法。
