Highly Efficient Nb2C MXene Cathode Catalyst with Uniform O‐Terminated Surface for Lithium–Oxygen Batteries. Issue 1 (11th November 2020)

• Record Type: Journal Article
• Authors: Li, Gaoyang; Li, Na; Peng, Shuting; He, Biao; Wang, Jun; Du, Yong; Zhang, Weibin; Han, Kai; Dang, Feng
• Is Part Of: Advanced energy materials. Volume 11:Issue 1(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-11-11
• Subjects: cathode materials -- DFT calculations -- lithium–oxygen batteries -- Nb2C MXene -- uniform O‐terminated surfaces; Energy harvesting -- Materials -- Periodicals; Energy conversion -- Materials -- Periodicals; Energy storage -- Materials -- Periodicals; Photovoltaics -- Periodicals; Fuel cells -- Periodicals; Thermoelectric materials -- Periodicals; 621.31
• DOI: 10.1002/aenm.202002721
• Languages: English
• ISSNs: 1614-6832

Abstract

Abstract: Highly‐efficient cathode catalysts are the key to improve high rate cycle stability, avoid side reactions, and lower the overpotential of lithium–oxygen batteries (LOBs). MXenes are predicted to be one of the most impressive materials for energy applications. In this work, the catalytic capability of Nb2 C MXene is demonstrated with a uniform O‐terminated surface as a cathode material for LOBs. The easily fabricated uniform O‐terminated surface, high catalytic activity of Nb2 CO2 sites, and unique reaction kinetics contribute to the excellent electrocatalytic performance of Nb2 C MXene. The uniform O‐terminated surface on Nb2 C MXene is obtained after heat treatment. Density functional theory calculations reveal the superior catalytic activity of Nb2 CO2 compared to other anchor groups and bare surfaces. The calculations also reveal the multinucleation and growth/decomposition mechanism for discharge products on the Nb2 CO2 surface. This mechanism is believed to account for the results characterized by ex situ and in situ measurements. The spatial‐direction accumulated porous discharge products at high current density contribute to the excellent high‐rate cycle stability. For example, the cathodes exhibit cycle stability for 130 cycles at an ultrahigh current density of 3 A g −1 . The present work provides insights into the modulation of catalytic capabilities, and the rational design of high‐performance MXenes based electrocatalysts. Abstract : Nb2 C MXene with a uniform O‐terminated surface is fabricated as a cathode for lithium–oxygen batteries (LOBs). Density functional theory calculations and experimental analysis reveal that the high catalytic activity of Nb2 CO2 sites, easy fabrication of the uniform O‐terminated surface, and unique reaction kinetics contribute to an excellent electrocatalytic performance for LOBs.