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0D‐in‐1D Peapod‐like CoP@C boosts high-performance lithium-ion battery

2018-06-26 来源:亚科官网
26 June 2018
  Recently, Prof. Li Xingguo and Zheng Jie from Peking University published a paper entitled “Peapod-like CoP@C nanostructure from phosphorization in low-temperature molten salt for high-performance lithium ion batteries”[1] in the international journal Angew. Chem. Int. Ed. The article [1] uses a low-toxic, stoichiometric ratio of PCl3 as a phosphorus source. a low-temperature molten salt phosphating method for the first time to synthesize pod-like carbon-coated CoP nanomaterials (CoP@C), which shows great advantages used as lithium-ion battery material.
  Transition metal phosphides have been widely studied due to their excellent physicochemical properties, low price, and chemical stability. Since the 1960s, more and more researchers have begun to study transition metal phosphides as electrode materials for energy storage and conversion. At present, most of the preparation methods of transition metal phosphides are as follows:
  • P steam: due to chemical inertness, its phosphating usually requires above 500°C;
  • PH3: low temperature, but it is highly toxic and spontaneous combustion;
  • NaH2PO2 as an alternative phosphorus source precursor, can be decomposed to PH3 when heated to 350°C.
  The above-mentioned phosphating method has a complicated process, large energy consumption and serious pollution, and is not suitable for large-scale production and utilization. Therefore, the research and development of efficient preparation of transition metal phosphides is an important research direction in the field of energy storage and energy conversion.
  In this study, the researchers used PCl3 as a phosphorus source, ultra-low melting point (90°C) NaCl-KCl-AlCl3 molten salt as a reaction medium, Mg as a reducing agent, reacted at 250 °C for 24h to obtain a pod-like CoP@C product. Because PCl3 is only used to complete the reaction, it is more efficient to use; The molten NaCl‐KCl‐AlCl3 not only provide a liquid environment but also participate in the electron transport by the reversible conversion of Al3+/Al redox couple, which is conducive to more safe and efficient inorganic synthesis. The obtained CoP nanoparticles have a diameter of less than 50 nm and are evenly wrapped in one-dimensional carbon nanotubes (CoP@C). With periodic intervals, the CoP nanoparticles are a kind of 0D‐in‐1D peapod CoP@C structure.
  The structure and matter of CoP@C are highly reversible: CoP@C will gradually change to a 1D structure during the process of Li+ intercalation, and it will change back to a pod-like form after Li+ is removed. The phase transition is reversible when charging and discharging and there is a partially lithiated LixCoP transition phase. When used as a negative electrode material for lithium ion batteries, it exhibits good rate performance and outstanding cycle stability, and exhibits a high degree of competitiveness compared to other transition metal phosphides.
[1] Zhiliang Liu, Sungjin Yang, Bingxue Sun, et al. Peapod‐likeCoP@C nanostructure from phosphorization in low‐temperature molten salt forhigh‐performance lithium ion batteries, Angew. Chem. Int. Ed., 2018, DOI: 10.1002/anie.201805468.
Edited by Suzhou Yacoo Science Co., Ltd.