Interface Modification Of Lithium Metal Batteries Based On Liquid Ester And Ether Electrolyte And Solid Garnet Electrolyte

Lithium metal is considered as the most promising anode material to promote the development of the next generation of energy storage devices because of its unparalleled theoretical specific capacity and extremely low redox electrochemical potential.However,due to the uncontrolled growth of lithium dendrites in the continuous electroplating process,the safety and capacity retention of lithium metal batteries（LMBs）are poor,which limits their wide application.Solid state battery based on garnet electrolyte has excellent comprehensive performances.However,the poor interfacial wettability due to the formed Li₂CO₃ passivation usually leads to unstable contact and dendritic growth at the Li/garnet interface.In this paper,the composition of solid electrolyte interphase（SEI）and the electroplating behavior of lithium can be effectively changed by introducing functional additives into the liquid electrolyte,and the special deposition behavior of lithium is realized by the alloy layer strategy.In addition,through the interface modification of garnet based solid electrolyte,the stable cycle of solid-state battery has been realized.The details are as follows:（1）Liquid polydimethylsiloxane（PDMS）terminated by-OCH₃ group is proposed as a graftable additive in ester-based electrolyte to reinforce the anode dendrite suppression for LMBs.Such a grafting triggers the formation of a hybrid SEI with increased fractions of Li F and Li-Si-O based moieties,which can serve as rigid barrier and ionic conductors for uniform Li-ion flux and Li-mass deposition.The residual PDMS organic moieties can mitigate the fragility of SEI.Grafting protected anode endows LMBS with ultra-long cycle life,low interfacial resistance,high coulombic efficiency and high reversible capacity.The liquid PDMS additive shows advantage over other solid siloxane additives with poor grafting ability in terms of Li surface compaction,SEI stabilization and therefore prolonged cycling life.（2）Complexes derived from the interaction of anionic Keggin-type polyoxometalates（POMs）clusters with polymeric cations of ionic liquid（IL）are proposed as a novel-class of additives for LMBs.The suspended complexes in ether-based electrolytes are absorbed around the protuberances of anodes by electrostatic forces due to their cationic surfaces,which triggers a lithiophobic repulsion mechanism for the Li⁺ion flow redistribution.The gradually released anionic oxygen-rich POM clusters with unlocalized charge distribution and distinct absorption feature would collect and enrich Li⁺ions at the interface,which would deposit via a co-assembly way after capturing electrons at the anode.The well-defined inorganic polyanions would further guide uniform Li deposition.This work proposes a Li⁺repulsion-enrichment synergism mechanism inspired by POM@IL complexes to dominate Li nucleation and regulate electrode/electrolyte interphase components.（3）A mode of selective wrapping deposition of Li mediated by in-situ planted Cu Ga₂ seeds on liquid metal painted Cu collector is proposed.The lithiophilic Cu Ga₂layer significantly reduces the nucleation barrier during Li plating and acts as a uniform conductive host to confine Li mass within its grain boundaries.The alloying of rich Ga with Cu collector is responsible for the low nucleation barrier and the tight bonding of Cu Ga₂ seeds with substrate enables the high endurance of repeat Li deposition.（4）A Li₂CO₃-affiliative mechanism for air-accessible interface engineering of garnet electrolyte via facile liquid metal（LM）painting is proposed.The natural LM oxide skin enables a superior wettability of LM interlayer towards ceramic electrolyte and high lithiophility towards Li anode.Therein the removal of Li₂CO₃ passivation network is not necessary,in view of its delamination and fragmentation by LM penetration.This dissipation effect allows the lithiated LM nanodomains to serve as alternative Li-ion flux carriers at Li-garnet interface.This work provides a new and scalable way to significantly improve the interface performance of garnet electrolyte without the requirement of air isolation.This concept of building Li₂CO₃-affiliative interlayer with the dilution and embrittlement of Li₂CO₃ nanodomains is worthy to focus for further development of garnet based solid state batteries.