Elevating the voltage of lithium‐ion batteries (currently 3.8 V) is a simple and pragmatic way to achieve high‐density energy storage. Many so‐called “5 V‐class” cathodes have been discovered over the past decade; however, they have been studied below 5 V (vs. Li/Li⁺) because of the severe oxidation of electrolytes and other cell components. Here, highly reversible charge‐discharge cycling of Li₂CoPO₄F/graphite full‐cells up to a cut‐off voltage of 5.2 V is demonstrated for the first time. This result is achieved with synergetic effects of an optimized cell design and a newly designed concentrated electrolyte based on LiBF₄, propylene carbonate (PC), and fluoroethylene carbonate (FEC). As an electrolyte design rationale, two important properties of high oxidation stability and anode‐passivation ability are clearly allocated for LiBF₄ and FEC, respectively. Besides, all other cell components (e. g., conductive carbon, separator, and binder) are reconsidered and customized for use at >5 V. The new concentrated electrolyte and optimized cell design presented here will pave the way for developing over‐5 V rechargeable batteries.

中文翻译：

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通过浓缩电解质和优化电池设计实现的4.8 V可逆Li2CoPO4F /石墨电池

升高锂离子电池的电压（当前为3.8 V）是实现高密度能量存储的一种简单而实用的方法。在过去十年中发现了许多所谓的“ 5 V级”阴极。然而，由于电解质和其他电池组件的严重氧化，已在低于5 V（相对于Li / Li ⁺）的条件下进行了研究。在此，首次展示了Li ₂ CoPO ₄ F /石墨全电池的高可逆充放电循环，其截止电压为5.2V。通过优化的电池设计和基于LiBF ₄的新设计的浓缩电解质的协同作用，可以实现此结果。，碳酸亚丙酯（PC）和氟代碳酸亚乙酯（FEC）。作为电解液的设计依据，分别为LiBF ₄和FEC明确分配了两个重要的高氧化稳定性和阳极钝化能力。此外，所有其他电池组件（例如，导电碳，隔膜和粘合剂）都经过重新考虑并定制用于大于5 V的电压。此处介绍的新型浓缩电解液和优化的电池设计将为开发5 V以上的可充电电池铺平道路。 。