Slurry-Fabricable Li+-Conductive Polymeric Binders for Practical All-Solid-State Lithium-Ion Batteries Enabled by Solvate Ionic Liquids

Abstract

For mass production of all-solid-state lithium-ion batteries (ASLBs) employing highly Li+ conductive and mechanically sinterable sulfide solid electrolytes (SEs), the wet-slurry process is imperative. Unfortunately, the poor chemical stability of sulfide SEs severely restrict available candidates for solvents and in turn polymeric binders. Moreover, the binders interrupt Li+-ionic contacts at interfaces, resulting in the below par electrochemical performance. In this work, a new scalable slurry fabrication protocol for sheet-type ASLB electrodes made of Li+-conductive polymeric binders is reported. The use of intermediatepolarity solvent (e.g., dibromomethane) for the slurry allows for accommodating Li6PS5Cl and solvate-ionic-liquid-based polymeric binders (NBR-Li(G3) TFSI, NBR: nitrile-butadiene rubber, G3: triethylene glycol dimethyl ether, LiTFSI: lithium bis(trifluoromethanesulfonyl) imide) together without suffering from undesirable side reactions or phase separation. The LiNi0.6Co0.2Mn0.2O2 and Li4Ti5O12 electrodes employing NBR-Li(G3) TFSI show high capacities of 174 and 160 mA h g(-1) at 30 degrees C, respectively, which are far superior to those using conventional NBR (144 and 76 mA h g(-1)). Moreover, high areal capacity of 7.4 mA h cm(-2) is highlighted for the LiNi0.7Co0.15Mn0.15O2 electrodes with ultrahigh mass loading of 45 mg cm(-2). The facilitated Li+-ionic contacts at interfaces paved by NBR-Li(G3) TFSI are evidenced by the complementary analysis from electrochemical and 7Li nuclear magnetic resonance measurements.