Phan An L, Nan Bo, Le Phung M L, Miao Qiushi, Wu Zhaohui, Le Kha, Chen Fu, Engelhard Mark, Dan Nguyen Thien, Han Kee Sung, Heo Jiyun, Zhang Weiran, Baek Minsung, Xu Jijian, Zhang Xiyue, Liu Ping, Ma Lin, Wang Chunsheng
Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, 20742, USA.
Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, 20742, USA.
Adv Mater. 2024 Aug;36(35):e2406594. doi: 10.1002/adma.202406594. Epub 2024 Jul 4.
Sulfurized polyacrylonitrile (SPAN) recently emerges as a promising cathode for high-energy lithium (Li) metal batteries owing to its high capacity, extended cycle life, and liberty from costly transition metals. As the high capacities of both Li metal and SPAN lead to relatively small electrode weights, the weight and specific energy density of Li/SPAN batteries are particularly sensitive to electrolyte weight, highlighting the importance of minimizing electrolyte density. Besides, the large volume changes of Li metal anode and SPAN cathode require inorganic-rich interphases that can guarantee intactness and protectivity throughout long cycles. This work addresses these crucial aspects with an electrolyte design where lightweight dibutyl ether (DBE) is used as a diluent for concentrated lithium bis(fluorosulfonyl)imide (LiFSI)-triethyl phosphate (TEP) solution. The designed electrolyte (d = 1.04 g mL) is 40%-50% lighter than conventional localized high-concentration electrolytes (LHCEs), leading to 12%-20% extra energy density at the cell level. Besides, the use of DBE introduces substantial solvent-diluent affinity, resulting in a unique solvation structure with strengthened capability to form favorable anion-derived inorganic-rich interphases, minimize electrolyte consumption, and improve cell cyclability. The electrolyte also exhibits low volatility and offers good protection to both Li metal anode and SPAN cathode under thermal abuse.
硫化聚丙烯腈（SPAN）最近成为高能锂金属电池一种很有前景的正极材料，因为它具有高容量、长循环寿命且不含昂贵的过渡金属。由于锂金属和SPAN的高容量导致电极重量相对较小，锂/SPAN电池的重量和比能量密度对电解质重量特别敏感，这突出了最小化电解质密度的重要性。此外，锂金属负极和SPAN正极的大量体积变化需要富含无机物的界面相，以确保在长循环过程中的完整性和保护性。这项工作通过一种电解质设计解决了这些关键问题，其中轻质二丁醚（DBE）用作浓缩双（氟磺酰）亚胺锂（LiFSI）-磷酸三乙酯（TEP）溶液的稀释剂。所设计的电解质（d = 1.04 g/mL）比传统的局部高浓度电解质（LHCE）轻40%-50%，在电池层面可带来12%-20%的额外能量密度。此外，DBE的使用引入了显著的溶剂-稀释剂亲和力，形成了独特的溶剂化结构，增强了形成有利的阴离子衍生富含无机物界面相的能力，减少了电解质消耗，并提高了电池的循环性能。该电解质还具有低挥发性，在热滥用情况下对锂金属负极和SPAN正极都有良好的保护作用。
