Thermoresponsive Electrolytes for Safe Lithium‐Metal Batteries

Abstract

Exploring advanced strategies in alleviating the thermal runaway of lithium‐metal batteries (LMBs) is critically essential. Herein, a novel electrolyte system with thermoresponsive characteristics is designed to largely enhance the thermal safety of 1.0 Ah LMBs. Specifically, vinyl carbonate (VC) with azodiisobutyronitrile is introduced as a thermoresponsive solvent to boost the thermal stability of both the solid electrolyte interphase (SEI) and electrolyte. First, abundant poly(VC) is formed in SEI with thermoresponsive electrolyte, which is more thermally stable against lithium hexafluorophosphate compared to the inorganic components widely acquired in routine electrolyte. This increases the critical temperature for thermal safety (the beginning temperature of obvious self‐heating) from 71.5 to 137.4 °C. The remained VC solvents can be polymerized into poly(VC) as the battery temperature abnormally increases. The poly(VC) can not only afford as a barrier to prevent the direct contact between electrodes, but also immobilize the free liquid solvents, thereby reducing the exothermic reactions between electrodes and electrolytes. Consequently, the internal‐short‐circuit temperature and “ignition point” temperature (the starting temperature of thermal runaway) of LMBs are largely increased from 126.3 and 100.3 °C to 176.5 and 203.6 °C. This work provides novel insights for pursuing thermally stable LMBs with the addition of various thermoresponsive solvents in commercial electrolytes.

Monodispersed MOF-Modified Nanofibers as Versatile Building Blocks for the Ion Regulations in Safe Lithium–Sulfur Batteries

“…Typical XRD patterns of CPE and BCSZ-CPE are shown in Figure S16. The characteristic peaks are detected around 18, 20, and 40°, which indicates α-phase PVDF-HFP in the matrix . After mixing with the filler of the BCSZ nanofiber, the diffraction peak intensity decreased, which demonstrated the increase of the amorphous region, thereby improving the ionic conductivity.…”

Selection of Polymer Segment Species Matters for Electrolyte Properties and Performance in Lithium Metal Batteries

“…In summary, this experimental approach successfully demonstrates that the homogeneity of electrolyte properties affects relevant electrochemical features including cycling performance, e.g., due to nonuniformity of charge carrier transport, thereby introducing an important parameter and strategy toward the targeted design of advanced copolymer electrolytes. Note that in a future work, a reduction of the cell operation temperatures might be achieved upon combination of segment-tailored polymers with recently introduced thermally responsive electrolytes, , creating synergies based on robust and homogeneous SEI formation as well as enhanced thermal stability, thereby potentially bestowing the ability to delay the thermal runaway of the cycled cells, also enabling cell operation at ambient temperatures.…”

Engineering the Li-ion flux and interfacial chemistry toward a stable Li metal anodeviaa simple separator coating strategy

“…2d), 34 which can improve the wettability of the composite separator with an organic electrolyte, so as to increase the lithium-ion transport channels and realize the uniform deposition of lithium. [35][36][37][38] Designing a good solid electrolyte can avoid the thermal safety risks of cells. Considering the poor thermal stability of routine PP separators, this paper improves the separators' thermal stability by introducing an organic-inorganic composite cladding layer, a polymer PVDF as a binder to wrap ceramic particles LATP and semiconductor ITO powder, PVDF can wrap around the outer surface of LATP-ITO and PP to form a whole cover of the self-supporting film, thus affecting the filmforming properties of the composite separator; in particular, under high temperatures conditions, this composite separator still shows no thermal shrinkage.…”