Lithium Polystyrene Sulfonate Based Interfacial Protective Layer for Lithium Metal Anodes

摘要

Due to the ultrahigh theoretical specific capacity (3860 mA.h/g) and lowest negative electrochemical potential[ -3.04 V (vs. SIIE), iitlill on metal has long been considered as an ideal anode for inext-generation highenergy -density lithium batteries. However, several critical issues such as volume expansion, lithium dendrite, and side reaction have restricted its practical application. Here, lithium polystyrene sulfonic (PSSLi) was evenly coated on the surface of commercial lithium metal foil to form the PSSLi@Li composite electrode. Fourier transform infrared spectroscopy (FTIR), electrochemical impedance (EIS), battery performance test and finite -element-based solver simulation were used to analyze the physical and electrochemical properties of this composite anode. The results indicated the PSSLi layer can effectively avoid the side reaction bets-men electrolyte and Li metal, restricting the formation of "dead Li". In addition, PSSI,i with the neatly arranged sulfonic groups can homogenize the Li ions flux and distribution on the electrode surface, which ensures the uniform plating/stripping of Li metal. The ele(tro(4iernical test showed that die coulomliic efficiency of the PSSI:i@Cu composite electrode can remain above 99.5% after 350 cycles. And the symmetrical cell assembled with PSSLi@Li composite electrodes presents an excellent cycling life over 1200 h under the current density of 1 11'1A/ern' and area capacity of 1 nA"11/cm2. Moreover, the LiPePO, (LIT) coupled full cell can maintain at 115 rn A "h/g under the rate of 1C after 500 cycles and realize art ideal capacity retention (81%). The full cell also exhibits an excellent rate performance of 105 mA"h/g at the rate of 8C.

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