Journal of Power Sources ( IF 9.2 ) Pub Date : 2021-02-24 , DOI: 10.1016/j.jpowsour.2021.229639 Zheng Bo , Kexin Yi , Huachao Yang , Xinzheng Guo , Zhesong Huang , Zhouwei Zheng , Jianhua Yan , Kefa Cen , Kostya (Ken) Ostrikov
Ever-increasing mass loading of transition metal oxides (TMOs) yields high pseudocapacitance in laboratory electrochemical capacitors. However, their performance based on whole electrode mass is still far from industry standards. Highly-promising solution based on loading TMOs into 3D porous electrodes causes a yet unresolved challenge to find ways to achieve ultimate energy storage by atomically precisely loading less active material. Inspired by single-atom catalysis, we propose a new “more from less but precise” concept of homogeneously dispersing a common MnO2 TMO via atomic sites to maximize atom redox reaction efficiency for industry-relevant pseudocapacitance. The concept is materialized by multifunctional MXene aerogel with super-hydrophilicity and surface functional groups, which provides 3D atomic nucleation sites to homogeneously load in-situ-formed, covalently-bonded MnO2 nanosheets. The gravimetric capacitance of MnO2 is largely enhanced, yielding superior pseudocapacitance of >400 F/g at > 5 mg/cm2 that is typically achieved at 10 times lower loadings. Outstanding electrode areal capacitance is achieved using 2–3 times less MnO2 mass, demonstrating industry-relevant pseudocapacitance almost twice higher than in state-of-the-art devices. MnO2/MXene//MXene asymmetric supercapacitor shows practically-high energy (~50.1 Wh/kg) and power (~10.0 kW/kg) densities, among the best MnO2 pseudocapacitors. Capacitive-mechanism-controlled redox reactions, rarely achievable in diffusion-controlled porous pseudocapacitive electrodes, are revealed.
中文翻译:
更多,更少但更精确:多功能MXene气凝胶中原子精确负载的MnO 2的与行业相关的伪电容
过渡金属氧化物(TMO)的质量负载不断增加,在实验室电化学电容器中会产生很高的伪电容。然而,它们基于整个电极质量的性能仍远未达到行业标准。基于将TMO加载到3D多孔电极中的极有前途的解决方案带来了一个尚未解决的挑战,即寻找通过原子精确地加载较少的活性材料来实现最终能量存储的方法。受单原子催化的启发,我们提出了一种新的“从少而精”的概念,将普通的MnO 2均匀分散。通过原子位点进行TMO,以最大限度地提高原子氧化还原反应的效率,以实现与行业相关的伪电容。该概念通过具有超亲水性和表面官能团的多功能MXene气凝胶得以实现,该气凝胶提供3D原子成核位点,以均匀加载原位形成的共价键合的MnO 2纳米片。MnO 2的重量电容大大提高,在> 5 mg / cm 2的情况下产生的伪电容> 400 F / g,这通常是在较低负载下获得的10倍。使用MnO 2的质量要少2-3倍即可获得出色的电极面电容,这表明与行业相关的伪电容几乎是最新设备的两倍。二氧化锰2 / MXene // MXene不对称超级电容器在最佳MnO 2伪电容器中表现出实际上高的能量(〜50.1 Wh / kg)和功率(〜10.0 kW / kg)密度。揭示了电容机制控制的氧化还原反应,这在扩散控制的多孔伪电容电极中很少实现。