Since the advent of the Li ion batteries (LIBs), the energy density has been tripled, mainly attributed to the increase of the electrode capacities. Now, the capacity of transition metal oxide cathodes is approaching the limit due to the stability limitation of the electrolytes. To further promote the energy density of LIBs, the most promising strategies are to enhance the cut-off voltage of the prevailing cathodes or explore novel high-capacity and high-voltage cathode materials, and also replacing the graphite anode with Si/Si–C or Li metal. However, the commercial ethylene carbonate (EC)-based electrolytes with relatively low anodic stability of ∼4.3 V vs. Li⁺/Li cannot sustain high-voltage cathodes. The bottleneck restricting the electrochemical performance in Li batteries has veered towards new electrolyte compositions catering for aggressive next-generation cathodes and Si/Si–C or Li metal anodes, since the oxidation-resistance of the electrolytes and the in situ formed cathode electrolyte interphase (CEI) layers at the high-voltage cathodes and solid electrolyte interphase (SEI) layers on anodes critically control the electrochemical performance of these high-voltage Li batteries. In this review, we present a comprehensive and in-depth overview on the recent advances, fundamental mechanisms, scientific challenges, and design strategies for the novel high-voltage electrolyte systems, especially focused on stability issues of the electrolytes, the compatibility and interactions between the electrolytes and the electrodes, and reaction mechanisms. Finally, novel insights, promising directions and potential solutions for high voltage electrolytes associated with effective SEI/CEI layers are proposed to motivate revolutionary next-generation high-voltage Li battery chemistries.

中文翻译：

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锂电池高压电解液：进展与展望

自锂离子电池（LIBs）问世以来，能量密度增加了两倍，这主要归功于电极容量的增加。现在，由于电解质的稳定性限制，过渡金属氧化物正极的容量正在接近极限。为了进一步提高LIBs的能量密度，最有前途的策略是提高主流正极的截止电压或探索新型高容量和高压正极材料，以及用Si/Si-C代替石墨负极或锂金属。然而，商业碳酸亚乙酯 (EC) 基电解质的阳极稳定性相对较低，约为 4.3 V vs. Li ⁺/Li 不能承受高压阴极。限制锂电池电化学性能的瓶颈已经转向适合下一代正极和 Si/Si-C 或 Li 金属负极的新型电解质组合物，因为电解质的抗氧化性和原位在高压正极上形成的正极电解质中间相（CEI）层和在负极上形成的固体电解质中间相（SEI）层严格控制了这些高压锂电池的电化学性能。在这篇综述中，我们对新型高压电解质系统的最新进展、基本机制、科学挑战和设计策略进行了全面而深入的概述，特别关注电解质的稳定性问题、电解质之间的相容性和相互作用。电解质和电极，以及反应机制。最后，提出了与有效 SEI/CEI 层相关的高压电解质的新见解、有前途的方向和潜在解决方案，以激发革命性的下一代高压锂电池化学。