Helmholtz Institute Ulm (HIU), Helmholtzstraße 11, D-89081, Ulm, Germany.
Karlsruhe Institute of Technology (KIT), P.O. Box 3640, D-76021, Karlsruhe, Germany.
Adv Mater. 2022 Dec;34(49):e2207155. doi: 10.1002/adma.202207155. Epub 2022 Oct 31.
The development of Li/sulfurized polyacrylonitrile (SPAN) batteries requires electrolytes that can form stable electrolyte/electrode interphases simultaneously on lithium-metal anodes (LMAs) and SPAN cathodes. Herein, a low-flammability locally concentrated ionic liquid electrolyte (LCILE) employing monofluorobenzene (mFBn) as the diluent is proposed for Li/SPAN cells. Unlike non-solvating diluents in other LCILEs, mFBn partially solvates Li , decreasing the coordination between Li and bis(fluorosulfonyl)imide (FSI ). In turn, this triggers a more substantial decomposition of FSI and consequently results in the formation of a solid electrolyte interphase (SEI) rich in inorganic compounds, which enables a remarkable Coulombic efficiency (99.72%) of LMAs. Meanwhile, a protective cathode electrolyte interphase (CEI), derived mainly from FSI and organic cations, is generated on the SPAN cathodes, preventing the dissolution of polysulfides. Benefiting from the robust interphases simultaneously formed on both the electrodes, a highly stable cycling of Li/SPAN cells for 250 cycles with a capacity retention of 71% is achieved employing the LCILE and only 80% lithium-metal excess.
锂/硫化聚丙烯腈（SPAN）电池的发展需要电解质，这种电解质能够在锂金属阳极（LMA）和SPAN 阴极上同时形成稳定的电解质/电极界面。本文提出了一种采用单氟苯（mFBn）作为稀释剂的低可燃性局部浓缩离子液体电解质（LCILE），用于 Li/SPAN 电池。与其他 LCILE 中的非溶剂化稀释剂不同，mFBn 部分溶解 Li ，减少了 Li 和双（氟磺酰基）亚胺（FSI）之间的配位。反过来，这会引发更大量的 FSI 分解，从而导致富含无机物的固体电解质界面（SEI）的形成，这使得 LMA 的库仑效率（99.72%）显著提高。同时，在 SPAN 阴极上形成了主要由 FSI 和有机阳离子组成的保护性阴极电解质界面（CEI），防止了多硫化物的溶解。得益于在两个电极上同时形成的坚固界面，采用 LCILE 和仅 80%的过量锂金属，Li/SPAN 电池在 250 次循环中具有高达 71%的容量保持率，实现了高度稳定的循环。
