Sodium Adsorption and Intercalation in Bilayer Graphene Doped with B, N, Si and P: A First-Principles Study
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https://doi.org/10.1007/s11664-020-08371-9 2020 The Minerals, Metals & Materials Society
Sodium Adsorption and Intercalation in Bilayer Graphene Doped with B, N, Si and P: A First-Principles Study SINAN LI
,1,3 JINGMING ZHAO,1 LINGLING LI,1 and WEI DONG2
1.—School of Metallurgy Engineering, Liaoning Institute of Science and Technology, Benxi 117004, People’s Republic of China. 2.—College of Materials Science and Engineering, Liaoning Technical University, Fuxin 123000, People’s Republic of China. 3.—e-mail: [email protected]
Heteroatom-doped graphene is a potential anode material in sodium-ion batteries (SIBs). However, understanding the mechanisms of Na adsorption on the surface and intercalation in the interlayer remains a critical challenge to develop a suitable heteroatom-doped graphene anode. In this work, the structural and electronic influences in B-, N-, Si- and P-doped bilayer graphene (BLG) have been investigated by first-principles calculations. Pyridinic N, graphitic B and Si-doped BLG have preferential adsorption for Na with stronger surface binding than intercalation. The undoped carbon layer of Bdoped BLG can be converted into n-type doping state by inserting Na, and the doped layer remains p-type mainly caused by the different electrons transfer to carbon layers from Na. Additionally, the electronic conductivity and Na diffusions on surfaces and in interlayers during sodiation are improved by doping heteroatoms. However, pyridinic N, graphitic Si and P doping promote the Na storage on surfaces and in interlayers of BLG due to the structural influence of carbon vacancy, which leads to high activation barriers during desodiation. The graphitic N-doped BLG is unsuitable and reduces the numbers of storage sites for Na in/on it. Therefore, B-doped and pyridinic N-doped BLG are promising anodes for SIBs because of stronger attraction and better kinetics of the electronic and cationic transport. Key words: Sodium-ion batteries, heteroatom doped, bilayer graphene, adsorption, intercalation
INTRODUCTION Sodium-ion batteries (SIBs), one of the most promising alternatives to Li-ion batteries (LIBs), have aroused increasing attention for large-scale and stationary energy storage, due to higher sodium resource abundance, smaller desolvation energy and their similar electrochemical performance to lithium.1 Graphite, widely used as a commercialized anode for LIBs, delivers a lower specific capacity (less 35 mAhg1) for SIBs.2 The large radius of the Na ion compared to the Li ion, which leads to the large activation energy to open the interlayer
(Received April 26, 2020; accepted July 29, 2020)
spacing, and the weak interaction between Na and pristine graphene layers hamper Na storage in the interlayers of graphite. Therefore, developing suitable carbon electrode materials with high capacity and stable cycling performance is extremely urgent for SIBs.3 Disordered carbon materials exhibit high Na intercalation capacity due to large interlayer distance and strong binding between carbon-vacancy defects and N
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