Abstract
The safety problem caused by lithium dendrite of lithium metal anode and the rapid capacity decay problem caused by the shuttle effect of polysulfide and polyselenide during the charge and discharge of selenium disulfide cathode limit the application of lithium selenium disulfide batteries significantly. Here, a fibrous ATFG-COF, containing rich carbonyl and amino functional groups, was applied as the separator coating layer. Density Functional Theory (DFT) theoretical calculations and experimental results showed that the abundant carbonyl group in ATFG-COF had a positive effect on lithium ions, and the amino group formed hydrogen bonds with bis ((trifluoromethyl) sulfonyl) azanide anionics (TFSI−), which fixed TFSI− in the channel, so as to improve the transfer number of lithium ions and narrow the channels. Therefore, ATFG-COF fiber coating can not only form a rapid and uniform lithium-ion flow on the lithium anode to inhibit the growth of lithium dendrites, but also effectively screen polysulfide and polyselenide ions to suppress the shuttle effect. The Li-SeS2 cell with ATFG-COF/polypropylene (ATFG-COF/PP) separator exhibited good cycle stability at 0.5 C and maintained a specific capacity of 509 mAh/g after 200 cycles. Our work provides insights into the design of dual-function separators with high-performance batteries.
Highlights
The safety problem of lithium metal anode caused by the lithium dendrite and the rapid capacity decay problem caused by the shuttle effect of polysulfides and polyselenides during the charge and discharge of selenium disulfide cathode have severely limited the application of lithium selenium disulfide batteries
The Density Functional Theory (DFT) calculation showed that the carbonyl group of ATFGCOF can effectively adsorb lithium ions, and that TFSI− anions have good interactions with
The abundant carbonyl group in ATFG-Covalent organic framework (COF) had a positive effect on lithium ions, and the amino group formed hydrogen bonds with bis ((trifluoromethyl) sulfonyl) azanide anionics (TFSI− ), which fixed TFSI− in the channel, thereby improving the transfer number of lithium ions and narrowing the channels
Summary
With the rapid development of portable electronic devices and electric vehicles, it has been difficult to meet their needs with traditional lithium-ion batteries; developing a new-generation energy storage system with high energy density is crucial [1,2,3,4,5,6].Due to the high theoretical specific capacity and low electrode potential of lithium metal anode, lithium metal batteries are regarded as the generation of highly specific energy secondary batteries, such as lithium-air batteries, lithium-sulfur batteries, lithium-selenium disulfide (Li-SeS2 ) batteries, etc. [7,8,9,10,11,12,13]. Selenium disulfide has good electrical conductivity and high theoretical specific capacity, which has led lithium selenium disulfide batteries to attract significant attention from researchers [14,15,16,17]. The safety problem of lithium metal anode caused by the lithium dendrite and the rapid capacity decay problem caused by the shuttle effect of polysulfides and polyselenides during the charge and discharge of selenium disulfide cathode have severely limited the application of lithium selenium disulfide batteries. In order to reduce the uneven concentration of lithium ions in batteries and alleviate the problem of lithium dendrite, researchers have undertaken many attempts and put forward several effective strategies [18,19,20,21,22,23,24,25,26,27,28,29,30]. In order to suppress the shuttle effect in lithium–
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