Ab Initio Study of Phosphorus Anodes for Lithium- and Sodium-Ion Batteries

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• 作者：Martin Mayo ; Kent J. Griffith ; Chris J. Pickard ; Andrew J. Morris
• 刊名：Chemistry of Materials
• 出版年：2016
• 出版时间：April 12, 2016
• 年：2016
• 卷：28
• 期：7
• 页码：2011-2021
• 全文大小：765K
• 年卷期：0
• ISSN：1520-5002

文摘

Phosphorus has received recent attention in the context of high-capacity and high-rate anodes for lithium- and sodium-ion batteries. Here, we present a first-principles structure prediction study combined with NMR calculations, which gives us insights into its lithiation/sodiation process. We report a variety of new phases found by the ab initio random structure searching (AIRSS) and the atomic species swapping methods. Of particular interest, a stable Na₅P₄–C2/m structure and locally stable structures found less than 10 meV/f.u. from the convex hull such as Li₄P₃–P2₁2₁2₁, NaP₅–Pnma, and Na₄P₃–Cmcm. The mechanical stability of Na₅P₄–C2/m and Li₄P₃–P2₁2₁2₁ has been studied by first-principles phonon calculations. We have calculated average voltages, which suggest that black phosphorus (BP) can be considered as a safe anode in lithium-ion batteries due to its high lithium insertion voltage, 1.5 V; moreover, BP exhibits a relatively low theoretical volume expansion compared with other intercalation anodes, 216% (ΔV/V). We identify that specific ranges in the calculated shielding can be associated with specific ionic arrangements, results that play an important role in the interpretation of NMR spectroscopy experiments. Since the lithium-phosphides are found to be insulating even at high lithium concentrations, we show that Li–P-doped phases with aluminum have electronic states at the Fermi level suggesting that using aluminum as a dopant can improve the electrochemical performance of P anodes.