Liang Kang, Zhao Hongshun, Li Jianbin, Huang Xiaobing, Jia Shuyong, Chen Wenkai, Ren Yurong
School of Materials Science and Engineering, Jiangsu Province Engineering Research Center of Intelligent Manufacturing Technology for the New Energy Vehicle Power Battery, Changzhou Key Laboratory of Intelligent Manufacturing and Advanced Technology for Power Battery, Changzhou University, Changzhou, 213164, P. R. China.
College of Chemistry and Materials Engineering, Hunan University of Arts and Science, Hunan, 415000, P. R. China.
Small. 2023 May;19(19):e2207562. doi: 10.1002/smll.202207562. Epub 2023 Feb 17.
Na V (PO ) F (NVPF) is a suitable cathode for sodium-ion batteries owing to its stable structure. However, the large radius of Na restricts diffusion kinetics during charging and discharging. Thus, in this study, a phosphomolybdic acid (PMA)-assisted hydrothermal method is proposed. In the hydrothermal process, the NVPF morphologies vary from bulk to cuboid with varying PMA contents. The optimal channel for accelerated Na transmission is obtained by cuboid NVPF. With nitrogen-doping of carbon, the conductivity of NVPF is further enhanced. Combined with crystal growth engineering and surface modification, the optimal nitrogen-doped carbon-covered NVPF cuboid (c-NVPF@NC) exhibits a high initial discharge capacity of 121 mAh g at 0.2 C. Coupled with a commercial hard carbon (CHC) anode, the c-NVPF@NC||CHC full battery delivers 118 mAh g at 0.2 C, thereby achieving a high energy density of 450 Wh kg . Therefore, this work provides a novel strategy for boosting electrochemical performance by crystal growth engineering and surface modification.
NaV(PO₄)F（NVPF）因其稳定的结构而成为钠离子电池的合适正极材料。然而，钠离子半径较大限制了充放电过程中的扩散动力学。因此，在本研究中，提出了一种磷钼酸（PMA）辅助水热法。在水热过程中，随着PMA含量的变化，NVPF的形态从块状变为长方体状。长方体状的NVPF获得了加速钠离子传输的最佳通道。通过碳的氮掺杂，NVPF的电导率进一步提高。结合晶体生长工程和表面改性，最佳的氮掺杂碳包覆NVPF长方体（c-NVPF@NC）在0.2C下表现出121 mAh g的高初始放电容量。与商用硬碳（CHC）负极耦合，c-NVPF@NC||CHC全电池在0.2C下的放电容量为118 mAh g，从而实现了450 Wh kg的高能量密度。因此，这项工作提供了一种通过晶体生长工程和表面改性提高电化学性能的新策略。
