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The electrolyte stability under high‐voltage conditions considerably limits the upper cut‐off potential of solid‐state electrolytes (SSEs) and therefore the energy density of all‐solid‐state batteries (ASSBs). In this work, metal‐organic frameworks (MOFs) were fluorinated to lower the energy level of HOMO orbital and allow access to a 4F‐MOF that exhibit enhanced anodic stability. The composited 4F‐MOF/PEO electrolyte could not only transport Li+ ions in the ordered framework channels, but also provide a remarkable high‐voltage stability up to 5.0 V, shielding oxidative decomposition that would otherwise occur at around 3.9 V for conventional PEO electrolytes. In addition, stable lithium deposition was demonstrated for more than 1,300 hours at 0.1 mA ⋅ cm−2, while reversible charge‐discharge cycling performance was delivered in assembled Li||LiNi0.5Mn1.5O4 (LNMO) ASSBs up to 5.0 V. Post‐mortem X‐ray photoelectron spectroscopy (XPS) investigation on cathodes revealed presence of a LiF‐rich cathode electrolyte interface (CEI), supporting promoted stability towards high‐voltage ASSBs. [ABSTRACT FROM AUTHOR]

A nanoporous all-solid-state MOF-laden polymer electrolyte that is simply mediated by an electronic effect shows remarkably high lithium electrodeposition stability of hundreds of charge–discharge cycles and over 1500 operating hours, while maintaining a very small voltage polarization. This result is a significant improvement relative to conventional PEO and, when used in an all-solid-state battery (ASSB), this electrolyte enabled enhanced cycle life. This new all-solid-state electrolyte shows a promising rational design for the emerging microporous polymeric materials as novel SPEs in ASSBs. [ABSTRACT FROM AUTHOR]

Given the increased use of room temperature ionic liquid electrolytes in Li-ion batteries, due to their non-flammability and negligible volatility, this study evaluates the lithiation kinetics to understand and improve the rate performance of Li-ion batteries. Lithium titanate spinel is used as a model electrode and the electrolyte is composed of LiTFSI and TFSI-coordinated alkoxy-modified phosphonium ionic liquid. Based on the analysis of activation energies for each process, we report that the charge-transfer reaction at the electrode/electrolyte interface is the rate-limiting step for cell operation. This finding is further supported by the observation that a 50-fold decrease in charge-transfer resistance at higher temperatures leads to a significant performance improvement over that of a traditional organic electrolyte at room temperature. Charge-transfer resistance and electrolyte wetting on the electrode surface are critical processes for optimal battery performance, and such processes need to be included when designing new ionic liquids in order to exceed the power density obtained with the use of current carbonate-based electrolytes. [ABSTRACT FROM AUTHOR]

High‐voltage lithium‐metal batteries (LMBs) are promising for energy storage applications but suffer from poor electrochemical window of solid polymer electrolytes (SPEs), which are difficult to achieve via a single polymeric functionality. Herein, a hybrid Si/F‐based polymeric 3D network is reported bearing polysiloxane backbone with fluorinated pendants to tune the highest occupied molecular orbital (HOMO)/the lowest unoccupied molecular orbital LUMO energies, thermodynamically expanding intrinsic electrochemical window of solid polymer electrolyte (SPE). Meanwhile, the hybrid Si/F functionalities with high fluorine abundance is identified to furnish dual interfacial kinetic stability at both anode and cathode interfaces with stabilized solid electrolyte interface (SEI) and cathode electrolyte interface (CEI), respectively. As a result, stable cycling in solid‐state high‐voltage LMBs is achieved up to an ultrahigh operating voltage of 4.9 V. Furthermore, it shows that in situ blending the Si/F SPE with eutectic electrolytes (EE) to form a non‐flammable gel polymer electrolyte can mitigate parasitic reactions of EE against metallic Li anode and achieve highly reversible charge–discharge cycling from 4.2 to 4.8 V at 25 °C. [ABSTRACT FROM AUTHOR]