Cheng Fangyuan, Zhang Wen, Li Qing, Fang Chun, Han Jiantao, Huang Yunhui
State Key Laboratory of Material Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China.
ACS Nano. 2023 Dec 12;17(23):24259-24267. doi: 10.1021/acsnano.3c09759. Epub 2023 Nov 27.
The optimal electrolyte for ultrahigh energy density (>400 Wh/kg) lithium-metal batteries with a LiNiCoMnO cathode is required to withstand high voltage (≥4.7 V) and be adaptable over a wide temperature range. However, the battery performance is degraded by aggressive electrode-electrolyte reactions at high temperature and high voltage, while excessive growth of lithium dendrites usually occurs due to poor kinetics at low temperature. Accordingly, the development of electrolytes has encountered challenges in that there is almost no electrolyte simultaneously meeting the above requirements. Herein, a high chaos electrolyte design strategy is proposed, which promotes the formation of weak solvation structures involving multiple anions. By tailoring a Li-EMC-DMC-DFOB-POF-PF multiple-anion-rich solvation sheath, a robust inorganic-rich interphase is obtained for the electrode-electrolyte interphase (EEI), which is resistant to the intense interfacial reactions at high voltage (4.7 V) and high temperature (45 °C). In addition, the Li solvation is weakened by the multiple-anion solvation structure, which is a benefit to Li desolventization at low temperature (-30 °C), greatly improving the charge transfer kinetics and inhibiting the lithium dendrite growth. This work provides an innovative strategy to manipulate the high chaos electrolyte to further optimize solvation chemistry for high voltage and wide temperature applications.
对于采用LiNiCoMnO阴极的超高能量密度(>400 Wh/kg)锂金属电池而言,其理想电解质需要承受高电压(≥4.7 V)并能在宽温度范围内适用。然而,在高温和高电压下,电极与电解质之间剧烈的反应会导致电池性能下降,而在低温下,由于动力学较差,通常会出现锂枝晶过度生长的情况。因此,电解质的开发面临挑战,因为几乎没有电解质能同时满足上述要求。在此,提出了一种高无序电解质设计策略,该策略促进了涉及多种阴离子的弱溶剂化结构的形成。通过定制富含Li-EMC-DMC-DFOB-POF-PF多种阴离子的溶剂化鞘层,在电极-电解质界面(EEI)处获得了坚固的富含无机物的界面层,该界面层能抵抗在高电压(4.7 V)和高温(45°C)下的剧烈界面反应。此外,多种阴离子溶剂化结构削弱了Li溶剂化,这有利于在低温(-30°C)下Li的去溶剂化,极大地改善了电荷转移动力学并抑制了锂枝晶生长。这项工作提供了一种创新策略来调控高无序电解质,以进一步优化溶剂化化学,用于高电压和宽温度应用。