An effective solid-electrolyte interphase for stable solid-state batteries

Interface chemistry inevitably manipulates Li-dendrite and interfacial resistance, which pose serious challenges in solid-state Li-metal batteries. In the November issue of Chem, Wang co-workers designed a thin, polymeric, fluoride-salt-concentrated interlayer as precursor template to form stable, LiF-rich solid-electrolyte interphase, thereby overcoming above-mentioned issues. Main textSolid-state batteries (SSLBs) with high-capacity (3,860 mAh g?1) Li metal nonflammable solid electrolytes are expected satisfy urgent need for next-generation energy upgrades by considerably improving density safety relative most-advanced commercial Li-ion available nowadays.1Zhao Q. Stalin S. Zhao C.-Z. Archer L.A. Designing safe, energy-dense batteries.Nat. Rev. Mater. 2020; 5: 229-252Google Scholar As an extremely important component SSLBs, have been extensively investigated enhance their conducting capability; examples include Li9.54Si1.74P1.44S11.7Cl0.3 sulfides dual-salt polymers high ion conductivity close that liquid electrolytes.2Kato Y. Hori Saito T. Suzuki K. Hirayama M. Mitsui A. Yonemura Iba H. Kanno R. High-power all-solid-state using sulfide superionic conductors.Nat. Energy. 2016; 1: 16030Google Scholar,3Li Chen Y.-M. Liang W. Shao Liu Nikolov Z. Zhu A Superionic Conductive, Electrochemically Stable Dual-Salt Polymer Electrolyte.Joule. 2018; 2: 1838-1856Google However, most chemically unstable when contact tend uncontrollable interphase (SEI) layer during charging/discharging process, triggers decrease increase resistance.4Chen X. Yao C. Xue Yu D. Kim S.Y. Yang F. et al.Li deposition stripping battery via Coble creep.Nature. 578: 251-255Google The inhomogeneous chemical composition along Li/SEI interface also restrains uniform flux amplifies local current density, ultimately inducing growth irregular dendrite eventually evolves into dead Li. These defects substantially restrict power cycle life SSLBs.Although composite polymer electrolyte (CPE) presents superiority terms flexibility, ionic conductivity, ease mass fabrication comparison fragile inorganic low conductive electrolytes, CPE can only be recycled at critical (CCD) 0.2?0.5 mA cm?2 due obstinate issues SSLBs. Several principles explored address these challenges, levels success achieved polymeric Using external pressure adjust is good option given its versatility convenience, but it lowers cell’s total additional devices.5Kasemchainan J. Zekoll Spencer Jolly Ning Hartley G.O. Marrow Bruce P.G. Critical leads formation on plating lithium anode cells.Nat. 2019; 18: 1105-1111Google Optimizing SEI, directly performs action metal, considered particularly promising.6Liang J.Y. Zhang X.D. Huang L.B. Yan Shen Z.Z. Wen Tang Shi J.L. al.Cooperative Shielding Bi-Electrodes Situ Amorphous Electrode-Electrolyte Interphases Practical High-Energy Lithium-Metal Batteries.J. Am. Chem. Soc. 2021; 143: 16768-16776Google By introducing Mg(ClO4)2 additive CPE, situ-formed Li2MgCl4/LiF successfully improves mobility promotes CCD up 2 cm?2. stability still not enough meet practical requirements such those from electric-powered road vehicles. Thus, effective strategies optimizing urgently needed achieve competitive SSLBs safety.With regard widely adopted studied liquid-electrolyte system, diverse SEI remedies proposed promote performance, highly concentrated (HCEs), catalysis, polymer-participated SEI.7Wan Song Qin Dai Hu P. al.Ultra-High Initial Coulombic Efficiency Induced Engineering Enables Rapid, Sodium Storage.Angew. Int. Ed. Engl. 60: 11481-11486Google Scholar, 8Chen L. Mi PAANa-induced ductile bare micro-sized FeS enables sodium-ion storage performance.Sci. China 64: 105-114Google 9Cheng X.B. C.Z. Toward Safe Lithium Metal Anode Rechargeable Batteries: Review.Chem. 2017; 117: 10403-10473Google applying approaches difficult. For example, challenge catalysis electrode slides bonding or specific further enhanced difficult-to-process surface. Moreover, viscosity, wettability, cost HCEs limit application SSLBs.Recently, rationally cross-linked interlayers formed situ obtain polymer-inorganic (LiF)-rich mechanical strength rapid transfer capability interface, greatly reduced resistance (4.5 cm?2).10Deng Cao He A.-M. Xu Bai Jin Ma al.In stable lithium-metal batteries.Chem. 7: 3052-3068Google (Figures 1A 1B ) This work enlightening shows careful design, excellent ideas effectively applied electrolytes.The authors skillfully fabricated polymerized HCE (PHCE) thin rigid flexible PVDF-based film through ultraviolet (UV) curing process. During cycling, PHCE functions customized fluoride salt features inherited inner salts outer layer. Such resolves continuous thus helping realize platting/stripping suppress dendrites Li.The CPE-PHCE (1.2 × 10?4 S cm?1), number (0.67), extended oxidation (relative Li/Li+) >5.0 V coating Reduced between high-energy Co-free LiNiO2 cathode (LNO) (Figure 1C). Consequently, assembled attain 81% capacity after 200 cycles (Coulombic efficiency >99.5%) more than Li|CPE|LNO cells Li|LiPF6-EC/DMC|LNO conventional elaborate design described follows: (1) simple UV polymerization strategy compactly bridge two layers CPE-PHCE; (2) crosslinked low-molecular-weight poly(ethylene glycol)methyl ether methacrylate (PEGMA) generally small crystal region accessible flexibility; (3) benefiting molarity, less S-F bond compared C-F bond, bis(fluorosulfonyl)imide (LiFSI) instead bis(trifluoromethanesulfonyl)imide (LiTFSI) selected (the former easily SEI); (4) confined fluoroethylene carbonate (FEC) contributes without spoiling layer.In summary, well-designed based UV-polymerized high-concentration developed metal/electrolyte stability. CPE-PHCE, helps plating/stripping. potentially applicable other types quasi-solid-state artificial engineering liquid-state Meanwhile, pertinent targeted experiment layouts characterizations reveal decomposition mechanism layer, could guide accurately decorated sophisticated prolong thousands SSLBs’ application. Solid-state Although safety. With Recently, electrolytes. supported National Nature Science Foundation ( U1804129 , 21771164 ), Zhongyuan Youth Talent Support Program Henan Province Project Zhengzhou University . batteriesDeng al.ChemJuly 12, 2021In BriefPolymeric (PHCE-CPEs) enable both >99%, representing new solution (SSBs). PHCE-CPEs surface penetration, while SSBs. findings should therefore general interest broad audience working batteries, material science engineering, electrochemistry. Full-Text PDF