Promising anode materials for alkali metal ion batteries: A case study on cobalt anti-MXenes

30 March 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


There is a continuous demand for energy storage devices with high energy density in consumer electronics, electric vehicles, and the grid energy market. Although commercial lithium-ion batteries (LIBs) satisfy the current needs, the limited availability of raw materials and moderate specific charge capacities (SCC) of LIBS, motivated scientists to search for alternate anode materials for LIBs and also to find technologies beyond LIBs. In this work, we studied the potential of six Cobalt anti-MXenes (CoAs, CoB, CoP, CoS, CoSe, and CoSi), a class of newly discovered 2D materials, as anode materials for lithium, sodium, and potassium ion batteries (LIBs, NIBs, and KIBs). We found that these materials are good electrical conductors and have high adsorption stability for the alkali metal ions, which helps to prevent the formation of dendrites and increase the cycle life of the battery. They also show moderate to low migration energy barriers (MEBs), indicating the potential for faster charge-discharge kinetics. We also explained the slightly counter-intuitive result of observing low MEBs along with high adsorption stability. Furthermore, Co-anti-MXenes can adsorb multiple alkali atoms per formula unit, resulting in high specific charge capacities and low average anodic voltages. For example, as anode materials for lithium-ion batteries, CoP and CoSi have SCC values of 1075.4 mAh g-1 and 934 mAh g-1, and anodic voltages as low as 0.28 V and 0.43 V, respectively. Moreover, even the maximally metallated Co-anti-MXenes did not show agglomeration tendency at room temperature. Also, the volume expansion of these materials is minimum for both Li and Na adsorption. As a whole, we find that Co-anti-MXenes can act as promising anode materials for alkali metal ion batteries.


cobalt anti-MXenes
2D materials
Energy storage
High specific capacity
Migration energy barrier
adsorption energy

Supplementary materials

Supporting information for Promising anode materials for alkali metal-ion batteries: A case study on cobalt anti-MXenes
This file contains the following supporting information to our manuscript. Phonon spectra of cobalt anti-MXenes 2 Band structures and projected density of states of Co-anti-MXenes 3 Co-PDOS in pristine Co-anti-MXenes 4 CDD plots for the adsorption of Li/Na/K on various Co-anti-MXenes 6 Optimized structures of maximally lithiated Co-anti-MXenes 7 Optimized structures of maximally sodiated Co-anti-MXenes 8 Optimized structures of maximally potassiated Co-anti-MXenes 8 Thermal stability of maximally sodiated structures 9 ELF plots of maximally lithiated Co-anti-MXenes 10 ELF plots of maximally potassiated Co-anti-MXenes 10 ELF plots of Co-anti-MXenes with two layers of K atoms 10 Expansion of the CoP bilayer after the intercalation of Li 11 Expansion of the CoS bilayer after the intercalation of Na 12 Variation in the bandstructure of the CoS with Hubbard U 13 Validation for the kinetic energy cutoff and the k-mesh 14


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