Water Evaporation Triggered Self‐Assembly of MXene on Non‐Carbonized Wood with Well‐Aligned Channels as Size‐Customizable Free‐Standing Electrode for Supercapacitors

• Published in: Energy & environmental materials (Hoboken, N.J.) Vol. 6; no. 5
• Main Authors: Chen, Weimin, Li, Zhao, Jiang, Feng, Luo, Min, Yang, Kai, Zhang, Daotong, Xu, Wangwang, Liu, Chaozheng, Zhou, Xiaoyan
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.09.2023
• Subjects: Capacitance; Channels; Current carriers; Electrical conductivity; Electrical resistivity; Electrochemistry; Electrodes; Evaporation; Mechanical properties; Microspheres; MXenes; Nanostructure; Self-assembly; Separators; Supercapacitors; Wood; Wood composites
• ISSN: 2575-0356; 2575-0356
• DOI: 10.1002/eem2.12406

Herein, non‐carbonized wood‐based electrodes and separators with well‐aligned channels and excellent mechanical properties are developed for supercapacitors. To enhance the conductivity and boost the capacitance, Ti 3 C 2 (MXene) nanosheets with high electrical conductivity and excellent electrochemical activity are loaded into the wood cells via self‐assembly triggered by fast evaporating water in Ti 3 C 2 suspension. By the assistance of positive charged polydopamine microspheres with large surface area, the self‐restacking of Ti 3 C 2 nanosheets can be avoided and the high mass loading (50 wt%) can be achieved due to the extra driving force for Ti 3 C 2 absorption. Benefiting from the conductive Ti 3 C 2 nanosheets with massive active sites and the multiple well‐aligned channels in wood with efficient transportation pathways for charge carriers, the as‐designed free‐standing electrode shows a large areal capacitance of 1060 mF cm −2 at 0.5 mA cm −2 and high capacitance retention of 67% at 10 mA cm −2 . Also, this electrode is highly size‐customizable, showing a good ability to be industrially processed into various shapes and dimensions. Furthermore, an all‐wood based supercapacitor with Ti 3 C 2 /wood composites as two layers of electrodes and a wood slice as the separator is fabricated, presenting a high energy density of 10.5 μW h cm −2 at 389.9 μW cm −2 .