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[交流] 减少电渗牵引的电解质可改善锂离子电池的快速充电性能

Electrolytes that reduce electro-osmotic drag improve fast charging of lithium-ion batteries

减少电渗牵引的电解质可改善锂离子电池的快速充电性能

▲ 作者:CHANG-XIN ZHAO4, ZEYI WANG, DAVID JACOBSON, YUE LI, BORIS KHAYKOVICH, SEAN FAYFAR, LEI ZHENG, JACOB LAMANNA, XILIN CHEN , AND CHUNSHENG WANG

▲链接:

https://www.science.org/doi/10.1126/science.adv1739

▲摘要:

快速充电(速率大于4C)对于电动汽车中的高能锂离子电池至关重要,但由于对快充障碍缺乏理解,这仍然是一个挑战。传统的优化策略侧重于通过电极结构修饰来缩短锂离子传输路径,但这常常会牺牲能量密度。

研究者证明了厚电极的快速充电能力受限于多孔电极内的溶剂抽离以及由此产生的电渗牵引极化,该效应由阳离子诱导的电渗牵引驱动。为降低电渗牵引极化,他们设计了具有弱阳离子溶剂化和强阴离子溶剂化特性的电解质。

其中一种二氟化溶剂能弱化锂阳离子的溶剂化作用,而其二氟甲基氢原子则通过氢键增强阴离子的溶剂化作用。这种电解质使得采用厚电极的高能量密度电池能够在13分钟内完成80%的充电。

▲ Abstract:

Fast charging (at rates greater than 4 C) is essential for high-energy lithium-ion batteries in electric vehicles yet remains challenging owing to a lack of understanding of fast-charging barriers. Conventional optimization strategies concentrate on shortening lithium-ion transport pathways through electrode structure modification, which often compromises energy densities. In this work, we demonstrate that thick-electrode fast charging is constrained by solvent withdrawal within porous electrodes and the resulting electro-osmotic drag polarization, which is driven by cation-induced electro-osmotic drag. To reduce electro-osmotic drag polarization, we designed electrolytes with weak cation solvation and strong anion solvation, where a difluorinated solvent weakens lithium-cation solvation and its difluoromethyl hydrogen atoms enhance anion solvation through hydrogen bonding. This electrolyte enables thick-electrode, energy-dense batteries to achieve 80% charge within 13 minutes.
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