Zhang Cunliang, Liu Yanmei, Li Jian, Zhu Kai, Chen Zhe, Liao Shijun, Zhang Xinhe
Mcnair Technology Co., Ltd Dongguan 523800 China
School of Chemistry and Chemical Engineering, South China University of Technology Guangzhou 510641 China.
RSC Adv. 2018 May 25;8(34):19335-19340. doi: 10.1039/c8ra02490a. eCollection 2018 May 22.
Decreasing particle size is an efficient strategy for improving the lithium storage properties of LiV(PO) (LVP) due to a shorter transport distances of lithium ion and electrons. However, designing and synthesizing LVP nanocrystals (NCs) with sizes smaller than 30 nm remains a challenge. In this work, we developed a facile approach for the fabrication of the monodisperse LVP NCs through a robust high-temperature organic-phase method. The thermodynamics of the synthesis and the possible reaction mechanism were investigated. The results indicate that the organic-phase environment (at 320 °C) may not thermodynamically allow the crystallization of LVP. Nevertheless, oleic acid (OA) and oleylamine (OAm) are essential as capping agents to hinder the agglomeration and growth of the particles. Based on the thermodynamic need, calcination is essential to prepare LVP. The surface electronic conductivity of the LVP NCs was enhanced through a subsequent carbon-coating treatment. The optimum combination of reduction and carbon coating is very favorable for the kinetics of electron transfer and lithium ion diffusion. Therefore, the fabricated LVP@C NCs exhibit superior lithium storage properties with excellent rate capability (84 mA h g at a rate of 20C) and perfect cyclic stability (96.2% capacity retention after 200 cycles at 5C), demonstrating their potential application in high-performance lithium-ion batteries.
减小粒径是改善LiV(PO)（LVP）储锂性能的有效策略，因为锂离子和电子的传输距离更短。然而，设计和合成尺寸小于30nm的LVP纳米晶体（NCs）仍然是一个挑战。在这项工作中，我们通过一种稳健的高温有机相方法开发了一种简便的制备单分散LVP NCs的方法。研究了合成的热力学和可能的反应机理。结果表明，有机相环境（320℃）在热力学上可能不允许LVP结晶。然而，油酸（OA）和油胺（OAm）作为封端剂对于阻碍颗粒的团聚和生长至关重要。基于热力学需求，煅烧对于制备LVP是必不可少的。通过后续的碳包覆处理提高了LVP NCs的表面电子导电性。还原和碳包覆的最佳组合非常有利于电子转移和锂离子扩散的动力学。因此，制备的LVP@C NCs表现出优异的储锂性能，具有出色的倍率性能（在20C倍率下为84 mA h g）和完美的循环稳定性（在5C下200次循环后容量保持率为96.2%），证明了它们在高性能锂离子电池中的潜在应用。
