Followed by decades of successful efforts in developing cathode materials for high specific capacity lithium-ion batteries, currently the attention is on developing a high-voltage battery (>5 V vs Li/Li⁺) with an aim to increase the energy density for their many fold advantages over conventional <4 V batteries. Among the various cathode materials, phosphate polyanion materials (LiMPO₄, where M is a single metal or a combination of metals) showed promising candidacy given their high electrochemical potential (4.8–5 V vs Li/Li⁺), long cycle stability, low cost, and achieved specific capacity (∼165 mAh·g^–1) near to its theoretical limit (170 mAh·g^–1). In this review, factors affecting the electrochemical potential of the cathode materials are reviewed and discussed. Techniques to improve the electrical and ionic conductivities of phosphate polyanion cathodes, namely, surface coating, particle size reduction, doping, and morphology engineering, are also discussed. A processing–property correlation in phosphate polyanion materials is also undertaken to understand relative merits and drawbacks of diverse processing techniques to deliver a material with targeted functionality. Strategies required for high-voltage phosphate polyanion cathode materials are envisioned, which are expected to deliver lithium-ion battery cathodes with higher working potential and gravimetric specific capacity.

中文翻译：

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磷酸盐聚阴离子材料作为高压锂离子电池正极：综述

在开发高比容量锂离子电池正极材料数十年的成功努力之后，目前的注意力集中在开发高电压电池（>5 V vs Li/Li ⁺），旨在提高其能量密度。与传统 <4 V 电池相比具有许多倍的优势。在各种正极材料中，磷酸盐聚阴离子材料（LiMPO ₄，其中 M 是单一金属或金属组合）因其高电化学势（4.8-5 V vs Li/Li ⁺）、长循环稳定性、低成本，并取得比容量（毫安~165·克^-1）接近其理论极限（170毫安·克^-1）。在这篇综述中，回顾和讨论了影响正极材料电化学电位的因素。还讨论了提高磷酸盐聚阴离子阴极的电导率和离子电导率的技术，即表面涂层、粒径减小、掺杂和形态工程。还进行了磷酸盐聚阴离子材料的加工性能相关性，以了解不同加工技术的相对优点和缺点，以提供具有目标功能的材料。设想了高压磷酸盐聚阴离子阴极材料所需的策略，有望提供具有更高工作电位和重量比容量的锂离子电池阴极。