Lithium Dendrite Suppression with UV-Curable Polysilsesquioxane Separator Binders

Abstract

For the first time, an inorganic-organic hybrid polymer binder was used for the coating of hybrid composites on separators to enhance thermal stability and to prevent formation of lithium dendrite in lithium metal batteries. The fabricated hybrid-composite-coated separators exhibited minimal thermal shrinkage compared with the previous composite separators (<5% change in dimension), maintenance of porosity (Gurley number ∼400 s/100 cm(3)), and high ionic conductivity (0.82 mS/cm). Lithium metal battery cell examinations with our hybrid-composite-coated separators revealed excellent C-rate and cyclability performance due to the prevention of lithium dendrite growth on the lithium anode even after 200 cycles under 0.2-5C (charge-discharge) conditions. The mechanism for lithium dendrite prevention was attributed to exceptional nanoscale surface mechanical properties of the hybrid composite coating layer compared with the lithium metal anode, as the elastic modulus of the hybrid-composite-coated separator far exceeded those of both the lithium metal anode and the required threshold for lithium metal dendrite prevention.

Reviving Lithium‐Metal Anodes for Next‐Generation High‐Energy Batteries

“…Coating is one of the most useful techniques to modulate the properties of commercial separators. Relevant materials, such as mussel‐inspired polydopamine, boron‐nitride (BN) nanosheets, ultrathin nitrogen/sulfur co‐doped graphene nanosheets (NSG), ZrO 2 /POSS multilayer, Al 2 O 3 /poly(phenyl‐ co ‐methacryloxypropyl)silsesquioxane composites, etc., have been adopted with different functions. Specifically, the polydopamine coating increases the wettability between the PE separators and electrolytes, and thus enables a well‐distributed lithium‐ion flux over the whole lithium surface.…”

Mechanism of Lithium Metal Penetration through Inorganic Solid Electrolytes

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vast improvements in energy density may be achieved with lithium metal anodes owing to their high gravimetric capacity (3869 mA h g −1 ) and low density (0.534 g cm −3 ). [11][12][13][14][15] As reviewed by Takada, [12] inorganic solid electrolytes have now been widely studied, [16][17][18][19][20] but are not yet commercialized. [4][5][6] Although several approaches have reduced dendrite formation, [7][8][9][10] to date the phenomenon has not been avoided under all relevant conditions.

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Dendrite‐Free, High‐Rate, Long‐Life Lithium Metal Batteries with a 3D Cross‐Linked Network Polymer Electrolyte

“…Thus, the formation of a uniform and stable SEI layer is critical for ensuring a homogeneous current distribution and suppressing Li dendrite growth, which is intimately related to a high Coulombic efficiency and long cycle life . Over the years, extensive efforts have been made to address the inherent problems of Li metal anodes, and there have been good advances in stabilizing the SEI layer with functional solvents, lithium salts and electrolyte additives, modifying the surface of the Li metal and producing dendrite‐free current collectors, novel separators, and solid electrolytes . Replacing the liquid electrolyte, which is very reactive with Li metal, a gel polymer electrolyte (GPE) or solid polymer electrolyte has been shown to effectively suppress the lithium dendrite growth because both are usually less reactive with Li metal and exhibit significantly stronger adhesion to Li surfaces.…”