Yuan Chengzhi, Chen Chaofan, Yang Zhiwei, Cheng Jiaji, Weng Ji, Tan Shuhui, Hou Renzhong, Cao Tao, Tang Zeguo, Chen Wei, Xu Baomin, Wang Xuehang, Tang Jun
College of New Materials and New Energy, Shenzhen Technology University, Shenzhen, Guangdong 518118, China.
School of Materials Science Engineering, Hubei University, Wuhan, Hubei 430062, China.
ACS Appl Mater Interfaces. 2024 Oct 6. doi: 10.1021/acsami.4c08094.
Titanium carbide MXene, TiCT, exhibits ultrahigh capacitance in acidic electrolytes at negative potentials yet poor stability at positive potentials, resulting in low-energy densities for TiCT-based symmetric supercapacitors. Utilizing "water-in-salt" electrolytes has successfully expanded the stable operation potential window of MXenes. However, this advancement comes at the cost of sacrificing their high capacitance in acidic electrolytes. In this work, we report an acidic "water-in-salt" (AWIS) electrolyte composed of sulfuric acid and saturated lithium halide, which effectively doubled the energy density of the TiCT-based symmetric supercapacitor compared to those with bare acidic electrolytes. Specifically, the AWIS electrolyte successfully expanded the voltage window of the symmetric device to 1.1 V. A high specific capacitance of 112.34 F g (at 10 mV s) was obtained due to the presence of proton redox. As a result, the symmetric device achieved a high-energy density of 19.1 Wh kg and a high capacitance retention of 96.3% after 10,000 cycles. This work demonstrates the importance of designing stable and redox-active electrolytes for high-energy MXene-based symmetric supercapacitors.
碳化钛MXene（TiCT）在酸性电解质中于负电位下表现出超高电容，但在正电位下稳定性较差，这导致基于TiCT的对称超级电容器能量密度较低。使用“盐包水”电解质成功地扩大了MXene的稳定工作电位窗口。然而，这一进展是以牺牲其在酸性电解质中的高电容为代价的。在这项工作中，我们报道了一种由硫酸和饱和卤化锂组成的酸性“盐包水”（AWIS）电解质，与使用纯酸性电解质的相比，它有效地使基于TiCT的对称超级电容器的能量密度提高了一倍。具体而言，AWIS电解质成功地将对称器件的电压窗口扩大到1.1 V。由于质子氧化还原的存在，获得了112.34 F g（在10 mV s下）的高比电容。结果，该对称器件实现了19.1 Wh kg的高能量密度，并且在10000次循环后具有96.3%的高电容保持率。这项工作证明了为基于MXene的高能量对称超级电容器设计稳定且具有氧化还原活性的电解质的重要性。
