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Stable and metallic two-dimensional TaC2 as an anode material for lithium-Ion battery

Abstract

Relative to advanced cathode materials, the anode materials become one of the key factors to hamper the performance improvement of lithium-ion batteries (LIBs). Recently, two-dimensional (2D) transition metal carbides (e.g. MXenes) have drawn great attentions due to their high Li storage ability. However, metal-rich 2D transition metal carbides as anodes usually need surface functionalization, leading to decrease of rate performances. Here, we propose that increasing carbon composition in 2D TaxCy is beneficial for not only eliminating surface functionalization but also greatly improving battery performance. First-principles swarm structural searches were used to explore structures and stabilities of 2D TaxCy (x = 1 and y = 1 - 4, or x = 2 and y = 1). Besides reproducing the reported 2D TaC, TaC2 and Ta2C are found to be stable, and have high thermal stabilities. Metallic TaC2 and Ta2C provide good electronic conductivity. Intriguingly, carbon-rich TaC2 contains carbon dimers exposing on surface, enabling it directly adsorb Li atoms. After adsorption of two-layer Li atoms, its structural integrity is well preserved. The resultant specific capacity, diffusion energy barrier, and open-circuit-voltage (OCV) of TaC2 are much better than those of commercial graphite, f-Ti3C2 or Ti2C monolayer. Compared with TaC2, TaC, and Ta2C as anode materials, the overall performance of carbon-rich TaxCy is better. Our work provides a useful strategy for designing new-type 2D transition metal materials for LIBs.

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Publication details

The article was received on 19 May 2017, accepted on 09 Aug 2017 and first published on 09 Aug 2017


Article type: Paper
DOI: 10.1039/C7TA04390B
Citation: J. Mater. Chem. A, 2017, Accepted Manuscript
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    Stable and metallic two-dimensional TaC2 as an anode material for lithium-Ion battery

    T. Yu, S. Zhang, F. Li, Z. Zhao, L. Liu, H. Xu and G. Yang, J. Mater. Chem. A, 2017, Accepted Manuscript , DOI: 10.1039/C7TA04390B

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