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Freestanding MXene–MnO2 Films for Li–CO2 Cathodes with Low Overpotential and Long-Term Cycling
ACS Applied Energy Materials ( IF 5.4 ) Pub Date : 2021-08-27 , DOI: 10.1021/acsaem.1c01921
Yangyang Wang 1 , Xue Wang 1 , Bingcheng Ge 1 , Jianxin Guo 2 , Carlos Fernandez 3 , Qiuming Peng 1
Affiliation  

The Li–CO2 battery is a potential energy storage device that not only possesses a theoretical energy density as high as 1876 W h kg–1 but also alleviates the consumption of fossil resources by converting the greenhouse gas CO2 into electric energy. However, some technique bottlenecks, such as high overpotential, low recyclability, and low energy density, severely prohibit its application rhythm. Here, we prepare a binder-free MXene–MnO2 composite film using vacuum-assisted filtration and in situ reduction, which can be used as a freestanding cathode for Li–CO2 batteries. This MXene–MnO2 film electrode bestows good cycle stability (∼220 cycles), high specific capacity, and lower overpotential (∼0.89 V) in Li–CO2 batteries. Both experimental tests and first-principles calculations reveal that the enhanced electrochemical properties are associated with three aspects. First, the MXene–MnO2 film offers a high electrical conductivity and porous structure, which provide fast transport channels for electrons and ions. Then, the replacement of Mn by Ti increases the adsorption of Li ions, which facilitates the rapid decomposition of Li2CO3. Finally, the synergistic effect of MXene and MnO2 exposes a large number of active sites, which increases the capacity of Li–CO2 batteries. Therefore, this self-supporting strategy on the MXene composite paves a way to develop high-performance Li–CO2 batteries.

中文翻译:

用于具有低过电位和长期循环的 Li-CO2 阴极的独立式 MXene-MnO2 薄膜

Li-CO 2电池是一种潜在的储能装置,不仅具有高达1876 W h kg –1的理论能量密度,而且通过将温室气体CO 2转化为电能来减少化石资源的消耗。然而,一些技术瓶颈,如高过电位、低可回收性和低能量密度,严重阻碍了其应用节奏。在这里,我们使用真空辅助过滤和原位还原制备了一种不含粘合剂的 MXene-MnO 2复合膜,可用作 Li-CO 2电池的独立阴极。这种 MXene-MnO 2薄膜电极赋予 Li-CO 2电池良好的循环稳定性(~220 次循环)、高比容量和较低的过电位(~0.89 V)。实验测试和第一性原理计算都表明,增强的电化学性能与三个方面有关。首先,MXene-MnO 2薄膜具有高导电性和多孔结构,为电子和离子提供快速传输通道。然后,Ti 取代Mn 增加了Li 离子的吸附,促进了Li 2 CO 3的快速分解。最后,MXene 和 MnO 2的协同作用暴露了大量的活性位点,从而增加了 Li-CO 2的容量电池。因此,MXene 复合材料上的这种自支撑策略为开发高性能 Li-CO 2电池铺平了道路。
更新日期:2021-09-27
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