As the core of modern energy technology, lithium-ion batteries (LIBs) have been widely integrated into many key areas, especially in the automotive industry, particularly represented by electric vehicles (EVs). The spread of LIBs has contributed to the sustainable development of societies, especially in the promotion of green transportation. However, the high demand for battery performance and safety in these fields has made the high viscosity, volatility, and potential leakage inherent in traditional organic liquid electrolytes a constraint on their further expansion. Especially at low temperature, the increased viscosity of the electrolyte, reduced solubility of lithium salts, crystallization or solidification of the electrolyte, increased resistance to charge transfer due to interfacial by-products, and short-circuiting due to the growth of anode lithium dendrites all affect the performance and safety of LIBs. Therefore, improving the safety performance of LIBs under low-temperature environments has become a focus of current research. This paper primarily reviews the progress made in utilizing different types of electrolytes in LIBs to enhance safety and optimize low temperature performance and discusses the current research progress as well as the future development direction of the field.

Solid-state electrolytes are widely anticipated to revitalize high-energy-density and high-safety lithium-ion batteries. However, low ionic conductivity and high interfacial resistance at room temperature pose challenges for their practical application. In this work, the dual-matrix concept is applied to the design of a bilayer heterogeneous structure. The electrolyte in contact with the cathode blends PVDF-HFP and oxidation-resistant PAN. In contrast, the electrolyte in contact with the anode blends PVDF-HFP and reduction-resistant PEO. A UV-curing process was used to fabricate the bilayer heterostructure electrolyte. The heterostructure electrolyte exhibits an ionic conductivity of 4.27 × 10⁻⁴ S/cm and a Li⁺ transference number of 0.68 at room temperature. Additionally, when assembled into LiFePO₄/CPEs/Li batteries, it shows a high initial discharge capacity at room temperature (168 mAh g⁻¹ at 0.1 C and 60 mAh g⁻¹ at 2 C), with a capacity retention of 93.3% after 100 cycles at a current density of 0.2 C. Notably, at 60 °C, the battery maintains a discharge capacity of 90 mAh g⁻¹ at 2 C, with a capacity retention of 97.4% after 100 cycles at 0.2 C. Therefore, solid-state batteries using this bilayer heterogeneous structure electrolyte demonstrate promising performance, including effective capacity output and cycling stability.

Solid-state electrolytes are widely anticipated to revitalize lithium-ion batteries with high energy density and safety. However, low ionic conductivity and high interfacial resistance at room temperature pose challenges for practical applications. This study combines the rigid oxide electrolyte LLZTO with the flexible polymer electrolyte poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) to achieve effective coupling of rigidity and flexibility. The semi-interpenetrating network structure endows the PEL composite solid electrolyte with excellent lithium-ion transport capabilities, resulting in an ionic conductivity of up to 5.1 × 10⁻⁴ S cm⁻¹ and lithium-ion transference number of 0.41. The assembled LiFePO₄/PEL/Li solid-state battery demonstrates an initial discharge capacity of 132 mAh g⁻¹ at a rate of 0.1 C. After 100 charge–discharge cycles, the capacity retention is 81%. This research provides a promising strategy for preparing composite solid electrolytes in solid-state lithium-ion batteries.

The Ni6035WC/WC-10Co-4Cr wear- and scour-resistant composite coating was fabricated using supersonic flame spraying technology. To further enhance the wear and scour resistance of the HVAF-sprayed Ni6035WC/WC-10Co-4Cr composite coatings, a post-treatment was conducted via vacuum remelting. This involved placing the coatings in a vacuum sintering process at 1120 °C for 10 min. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and hardness testing were employed to characterize the structure and morphology of the Ni6035WC/WC-10Co-4Cr coating, as well as to assess its wear and scour resistance. The results indicate that vacuum sintering significantly enhances the wear and scour resistance of the coating, while also improving its hardness, density, and bonding strength. The hardness of each coating after vacuum sintering, 1019 HV, 920 HV, and 897 HV, was improved by 6% compared to 966 HV, 906 HV, and 845 HV before sintering. The average wear rate of each coating after sintering was 13% lower than before vacuum sintering. Furthermore, the impact of varying WC-10Co-4Cr content on the coating’s properties was examined under identical test conditions. It was found that the optimal overall performance was achieved with a WC-10Co-4Cr content of 20%, resulting in an average wear rate that was 19% lower than that of other coatings.