Composite solid electrolytes (CSEs) combine the flexibility of polymers with the stability of inorganic electrolytes, making them promising candidates for next-generation solid-state lithium-metal batteries (LMBs). However, their practical application is limited by low room-temperature ionic conductivity, primarily due to poor polymer-inorganic interfacial compatibility that hinders Li+ transport. In this work, we introduce a polymer-compatible ionic liquid (IL) to mediate the interphase between the polymer and ceramic components, simultaneously preventing ceramic particle aggregation for uniform dispersion and activating ceramic-polymer interfaces to construct continuous Li+ transport pathways across ceramic domains and interfacial boundaries. The interfacial engineered CSEs exhibit a substantial enhancement in room-temperature ionic conductivity to 1.64 × 10−3 S cm−1. At the ambient temperature, the Li||Li symmetric cells demonstrate stable and reversible lithium plating/stripping for 4000 h, and the Li||LiFePO4 cell delivers an initial specific capacity of 172.1 mAh g−1 at 0.5C with 90.4% capacity retention after 300 cycles. Furthermore, the Li||LiNi0.8Co0.1Mn0.1O2 cells demonstrate stable performance even under high-voltage operation (4.5 V). This work provides a practical interfacial design strategy for developing high-performance CSEs in the next-generation solid-state LMBs.

Aqueous zinc-bromine flow batteries (ZBFBs) are one of the most attractive candidates for large-scale stationary energy storage due to their high energy density, intrinsic safety, and low cost. However, the low efficiency and restricted lifespan caused by the bromine shuttling and slow reaction kinetics severely limit their future development. Herein, the zeolitic imidazolate framework (ZIF) is proposed to be used with a novel strategy to improve the Br2 complexing ability of the mature complexing agent (i.e., N-methyl-N-ethyl pyrrolidinium bromide (MEP) ionic liquid). The organic ligands (imidazole and benzimidazole) from the decomposed zinc ZIF-62 facilitate the complexation of MEP. Both advanced experimental characterizations and theoretical calculations confirm that the optimal mass ratio of MEP/ZIF-62 is 5%, the synergistic effect between imidazole/benzimidazole of the decomposed ZIF-62 toward bromine species and MEP toward bromine species, effectively inhibits the bromine shuttle effect and improves the transformation kinetics of bromine species. Notably, the assembled in situ optical characterization directly confirmed that ZIF-62/5% MEP enhances the complex ability toward bromine species, promotes the formation of more oily phase products, and makes the electrolyte more uniform to form well-distributed floating droplets. The obtained ZBFBs deliver superior long-cycle performance up to 1500 cycles without obvious performance decay, and, notably, even at a high areal capacity of 80 mAh cm−2, they also stably operate for 50 cycles. The auxiliary complexation strategy based on metal-organic frameworks is beneficial in improving the comprehensive performance of ZBFBs.

Quasi-solid-state composite electrolytes (QSCEs) show promise for high-performance solid-state batteries, while they still struggle with interfacial stability and cycling performance. Herein, a F-grafted QSCE (F-QSCE) was developed via copolymerizing the F monomers and ionic liquid monomers. The F-QSCE demonstrates better overall performance, such as high ionic conductivity of 1.21 mS cm–1 at 25 °C, wide electrochemical windows of 5.20 V, and stable cycling stability for Li//Li symmetric cells over 4000 h. This is attributed to the significant electronegativity difference between C and F in the fluorinated chain (‒CF2‒CF‒CF3), which causes the electron cloud to shift toward the F atom, surrounding it with a negative charge and producing the inductive effect. Furthermore, the interactions between Li+ and F, TFSI‒, and C are enhanced, reducing ion pair aggregation (Li+‒TFSI‒‒Li+) and promoting Li+ transport. Besides, ‒CF2‒CF‒CF3 decomposes to form LiF preferentially over TFSI–, resulting in better interfacial stability for F-QSCE. This work provides a pathway to enable the development of high-performance Li metal batteries.

Quasi-solid polymer electrolytes (QSPEs) are promising electrolytes for next-generation high-energy-density lithium metal batteries, benefiting from their flexibility and intimate interfacial contact with electrodes. However, conventional QSPEs encounter challenges such as limited Li+ mobility and poor mechanical properties. Herein, we design a multiple-crosslinked ionogel electrolyte, featuring a high Li+ transference number of 0.74, superior stability against oxidation up to 4.8 V, and high mechanical strength (0.8 MPa) simultaneously. The ionogel electrolyte constructs rapid Li+ conductive pathways and promotes the formation of lithium fluoride (LiF), lithium nitride (Li3N), and lithium sulfide (Li2S)-enriched passivation layers during Li deposition, greatly enhancing the reversibility of lithium metal deposition. Consequently, the Li‖Li cell demonstrates superior lithium plating/stripping stability for 5000 h, and the Li‖LiFePO4 cell shows stable cycling performance with 80% capacity retention after 1000 cycles at a rate of 0.5C. Remarkably, the high-voltage Li‖NCM532 cell maintains about 76% of its capacity over 200 cycles at 4.2 V.