Freestanding MXene–MnO2 films for Li–CO2 cathodes with low overpotential and long-term cycling.

Wang, Yangyang; Wang, Xue; Ge, Bingcheng; Guo, Jianxin; Fernandez, Carlos; Peng, Qiuming

Abstract

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.

Citation

WANG, Y., WANG, X., GE, B., GUO, J., FERNANDEZ, C. and PENG, Q. 2021. Freestanding MXene-MnO2 films for Li-CO2 cathodes with low overpotential and long-term cycling. ACS applied energy materials [online], 4(9), 9961–9968. Available from: https://doi.org/10.1021/acsaem.1c01921

• Journal Article Type: Article
• Acceptance Date: Aug 20, 2021
• Online Publication Date: Aug 27, 2021
• Publication Date: Sep 27, 2021
• Deposit Date: Oct 12, 2021
• Publicly Available Date: Aug 28, 2022
• Journal: ACS Applied Energy Materials
• Electronic ISSN: 2574-0962
• Publisher: ACS Publications
• Peer Reviewed: Peer Reviewed
• Volume: 4
• Issue: 9
• Pages: 9961–9968
• DOI: https://doi.org/10.1021/acsaem.1c01921
• Keywords: Li−CO2 batteries; Catalyst; Cycle stability; MXene−MnO2 film; Freestanding cathode
• Public URL: https://rgu-repository.worktribe.com/output/1457278
• Additional Information: The accompanying file for this output contains supplementary figures at the end of the full text article.