Long‐Life Lithium‐Metal All‐Solid‐State Batteries and Stable Li Plating Enabled by In Situ Formation of Li₃PS₄ in the SEI Layer

Abstract

of serious interfacial reactions, Li dendrite growth, large interfacial resistance, etc. [2] To overcome these issues, a chemically/ electrochemically stable, mechanically compatible, Li + -conductive and electronically insulating solid electrolyte interphase (SEI) layer needs to be formed on electrolyte/Li interface.Here in this work, a sulfide and polymer composite solid electrolyte (CSE) is developed to overcome these issues. More specifically, lithium polysulfidophosphate (LPS) is introduced as an additive for poly(ethylene oxide) (PEO)-based CSEs to synergistically react with lithium metal for in situ formation of an ideal SEI layer in Li-metal-anode ASSB. PEO itself has various drawbacks, including low Li + conductivity (10 −6 S cm −1 at room temperature), [3] narrow electrochemical window, [4] and intrinsic soft mechanical properties causing small critical current densities (CCDs). [5] Multiple approaches have been employed to solve these problems, including co-polymerization, [6] polymer blend, [7] introduction of secondary phases as inert fillers (e.g., BaTiO 3 /Al 2 O 3 /TiO 2 /SiO 2 / CeO 2 ), [8] Li + conducting active fillers (e.g., NASICON, garnet, perovskite, and sulfides), [9] and plasticizers (e.g., propylene carbonate, ethylene carbonate, and succinonitrile). [10] For the PEO-lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) system, the interfacial stability issue between polymer-salt and lithium metal cannot be ignored because of the unstable SEI at the interface. [11] During cycling, SEI grows continuously An ultrastable and kinetically favorable interface is constructed between sulfide-poly(ethylene oxide) (PEO) composite solid electrolytes (CSEs) and lithium metal, via in situ formation of a solid electrolyte interphase (SEI) layer containing Li 3 PS 4 . A specially designed sulfide, lithium polysulfidophosphate (LPS), can distribute uniformly in the PEO matrix via a simple stirring process because of its complete solubility in acetonitrile solvent, which is advantageous for creating a homogeneous SEI layer. The CSE/Li interface with high Li + transportation capability is stabilized quickly through in situ formation of a Li 3 PS 4 /Li 2 S/LiF layer via the reaction between LPS and lithium metal to inhibit lithium dendrite growth. A Li/Li symmetric cell with the LPS-integrated CSE exhibits constant and small CSE/Li resistance of 10 Ω cm 2 during cycling, delivering stable cycling for 3475 h at a current density of 0.2 mA cm −2 and a high critical current density of 0.9 mA cm −2 at 60 °C. Impressive electrochemical performance is also demonstrated for LiFePO 4 /CSE/Li all-solid-state batteries with capacity of 127.6 mAh g −1 after 1000 cycles at 1 C.

High-capacity sulfide all-solid-state lithium battery with a conversion-type iron fluoride cathode

“…In contrast, soft sulfide SEs 30,31 with high ionic conductivities can provide intimate contact between cathodes and SEs, which is crucial for constructing ASSLBs with high energy density and high safety. 32–46…”

Long‐Cycling All‐Solid‐State Batteries Achieved by 2D Interface between Prelithiated Aluminum Foil Anode and Sulfide Electrolyte

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To date, various SSEs have been developed, including inorganic-type, organic-type, and composite-type. [9][10][11][12] After improving the air stability, interface stability, and processing problems, sulfide electrolytes possessing high ionic conductivity are considered to be one of the most promising SSEs. [13][14][15][16][17][18] Unfortunately, the application of Li anode in all-solid-state batteries (ASSBs) is further limited by the low critical current densities at room temperature, which stems from the chemical and electrochemical instability between Li and most SSEs.

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Polypropylene separator-reinforced polymer-in-salt solid composite electrolytes for high-performance lithium ion batteries at room temperature

“…1b and e). Based on a similar principle, 41,42 this evolution becomes much more obvious with the further addition of LLZTO nanollers (Fig. S1 †); specically, the PVDF-Li-LZ SCEs exhibit a tightly connected spherical structure with the smallest size of only 1-2 mm (Fig.…”