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Deep eutectic electrolytes (DEEs) are regarded as one of the next‐generation electrolytes to promote the development of lithium metal batteries (LMBs) due to their unparalleled advantages compared to both liquid electrolytes and solid electrolytes. However, its application in LMBs is limited by electrode interface compatibility. Here, we introduce a novel solid dimethylmalononitrile (DMMN)‐based DEE induced by N coordination to dissociate LiTFSI. We confirmed that the DMMN molecule can promote the dissociation of LiTFSI by the interaction between the N atom and Li+, and form the hydrogen bond with TFSI− anion, which can promote the dissociation of LiTFSI to form DEE. More importantly, due to the absence of active α‐hydrogen, DMMN exhibits greatly enhanced reduction stability with Li metal, resulting in favorable electrode/electrolyte interface compatibility. Polymer electrolytes based on this DEE exhibit high ionic conductivity (0.67 mS cm−1 at 25 °C), high oxidation voltage (5.0 V vs. Li+/Li), favorable interfacial stability, and nonflammability. Li‖LFP and Li‖NCM811 full batteries utilizing this DEE polymer electrolyte exhibit excellent long‐term cycling stability and excellent rate performance at high rates. Therefore, the new DMMN‐based DEE overcomes the limitations of traditional electrolytes in electrode interface compatibility and opens new possibilities for improving the performance of LMBs. [ABSTRACT FROM AUTHOR]

Solid‐state lithium metal batteries (SSLMBs) with polymer electrolytes (SPEs) have attracted tremendous attention owing to their superior safety and high energy density. However, the unstable solid electrolyte interphase (SEI) between Lithium (Li) and SPEs hinders their practical application. Herein, an innovative interfacial catalysis strategy is applied to the in situ construction of a multifunctional inorganic‐rich SEI. The transfer of unpaired electrons adjacent to calcium vacancies (VCa) to the TFSI− anion promotes the breaking of S─N and C─F bonds during the electrochemical decomposition of TFSI−, thus enhancing its decomposition kinetics. The inorganic‐rich SEI derived from TFSI− is super‐stable and kinetically favorable for fast and homogeneous transport of Li ions, thereby hindering the growth of lithium dendrites. Consequently, the interfacial catalysis strategy endows Li||Li symmetric cells, LFP||Li and NCM811||Li full batteries with enhanced cyclability. Thus, this work expands the interfacial catalysis strategy to a platform for designing multifunctional SEI in long‐life SSLMB. [ABSTRACT FROM AUTHOR]

Gel-state polymer electrolytes with superior mechanical properties, self-healing abilities and high Li + transference numbers can be obtained by in situ polymerization of monomers with hydrogen-bonding moieties. However, it is overlooked that the active hydrogen atoms in hydrogen-bond donors experience displacement reactions with lithium metal in lithium metal batteries (LMBs), leading to corrosion of the lithium metal. Herein, it is discovered that the addition of hydrogen-bond acceptors to hydrogen-bond-rich gel-state electrolytes modulates the chemical activity of the active hydrogen atoms via the formation of hydrogen-bonded intermolecular interactions. The characterizations reveal that the added hydrogen-bond acceptors encapsulate the active hydrogen atoms to suppress the interfacial chemical corrosions of lithium metals, thereby enhancing the chemical stability of the polymer structure and interphase. With the employment of this strategy, a 1.1 Ah LiNi 0.8 Co 0.1 Mn 0.1 O 2 /Li metal pouch cell achieves stable cycling with 96.3 % capacity retention at 100 cycles. This new approach indicates a feasible path for achieving in situ polymerization of highly stable gel-state-based LMBs., (© 2024 Wiley-VCH GmbH.)