Flexible Nitrogen‐Doped 2D Titanium Carbides (MXene) Films Constructed by an Ex Situ Solvothermal Method with Extraordinary Volumetric Capacitance

• Published in: Advanced energy materials 2018-11, Vol.8 (31), p.n/a
• Main Authors: Yang, Chenhui, Tang, Yi, Tian, Yapeng, Luo, Yangyang, Faraz Ud Din, Muhammad, Yin, Xingtian, Que, Wenxiu
• Format: Article
• Language: English
• Subjects: Capacitance; Capacitors; Doping; Electrochemical analysis; electrochemical capacitors; ex situ solvothermal method; Flux density; Monoethanolamine (MEA); MXene; MXenes; Nitrogen; nitrogen doping; Solid solutions; Sulfuric acid; Titanium carbide; Ureas; volumetric performance
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.201802087

A facile and controllable strategy, which combines solvothermal treatment with ex situ nitrogen doping by using urea saturated alcohol solution or monoethanolamine as nitrogen source, is used to prepare flexible, freestanding, and compact nitrogen‐doped delaminated Ti3C2 (abbreviated N‐Ti3C2) film electrodes for symmetric electrochemical capacitors (ECs). Compared with the N sites from in situ N solid solution doping, those of ex situ N solvothermal doping enable larger contributions to the capacitance through regulating nitrogen species and content. As a result, the urea‐assisted N‐Ti3C2 (UN‐Ti3C2) film exhibits an ultrahigh volumetric capacitance of 2836 F cm−3 (927 F g−1) at 5 mV s−1 in 3 m H2SO4 solution. This value surpasses the all previously reported volumetric performance of MXenes. A large capacitance of 2643 F cm−3 (786 F g−1) is also obtained for the monoethanolamine‐assisted N‐Ti3C2 film. In addition, the symmetric electrochemical capacitor fabricated from the binder‐free UN‐Ti3C2 film exhibits a high volumetric energy density of 76 Wh L−1, which is the highest value achieved compared to those of MXenes so far. This work presents the effects of nitrogen species and solvothermal treatment on the electrochemical performance of MXene, and opens up an exciting opportunity for fabricating highly flexible and integrated ECs. Nitrogen‐doped delaminated Ti3C2 films are fabricated by an ex situ solvothermal method and shows flexible, freestanding, and ultrahigh‐performance characteristics. This work exhibits the effects of nitrogen species and solvothermal treatment on electrochemical performance of 2D MXene materials and opens up a new opportunity for next‐generation flexible and highly integrated electrochemical capacitors.