Yujiang Wang

High safety gel polymer electrolyte (GPE) is used in lithium metal solid state batteries, which has the advantages of high energy density, wide temperature range, high safety, and is considered as a subversive new generation battery technology. However, solid-state lithium batteries with multiple layers and large capacity currently have poor cycle life and a large gap between the actual output cycle capacity retention rate and the theoretical level. In this paper, polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP)/polyacrylonitrile (PAN)—lithium perchlorate (LiClO₄)—lithium lanthanum zirconium tantalate (LLZTO) gel polymer electrolytes was prepared by UV curing process using a UV curing machine at a speed of 0.01 m/min for 10 s, with the temperature controlled at 30 °C and wavelength 365 nm. In order to study the performance and failure mechanism of multilayer solid state batteries, single and three layers of solid state batteries with ceramic/polymer composite gel electrolyte were assembled. The results show that the rate and cycle performance of single-layer solid state battery with gel electrolyte are better than those of three-layer solid state battery. As the number of cycles increases, the interface impedance of both single-layer and three-layer electrolyte membrane solid-state batteries shows an increasing trend. Specifically, the three-layer battery impedance increased from 17 Ω to 42 Ω after 100 cycles, while the single-layer battery showed a smaller increase, from 2.2 Ω to 4.8 Ω, indicating better interfacial stability. After 100 cycles, the interface impedance of multi-layer solid-state batteries increases by 9.61 times that of single-layer batteries. After 100 cycles, the corresponding capacity retention rates were 48.9% and 15.6%, respectively. This work provides a new strategy for large capacity solid state batteries with gel electrolyte design.

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.

Gel electrolytes for lithium-ion batteries continue to replace the organic liquid electrolytes in conventional batteries due to their advantages of being less prone to leakage and non-explosive and possessing a high modulus of elasticity. However, the development of gel electrolytes has been hindered by their generally low ionic conductivity at room temperature and high interfacial impedance with electrodes. In this paper, a poly (vinylidene fluoride)-hexafluoropropylene copolymer (PVdF-HFP) with a flexible structure, Li₆PS₅Cl (LPSCl) powder of the sulfur–silver–germanium ore type, and lithium perchlorate salt (LiClO₄) were prepared into sulfide gel composite electrolyte films (GCEs) via a thermosetting process. The experimental results showed that the gel composite electrolyte with 1% LPSCl in the PVdF-HFP matrix exhibited an ionic conductivity as high as 1.27 × 10⁻³ S·cm⁻¹ at 25 °C and a lithium ion transference number of 0.63. The assembled LiFePO₄||GCEs||Li batteries have excellent rate (130 mAh·g⁻¹ at 1 C and 54 mAh·g⁻¹ at 5 C) and cycling (capacity retention was 93% after 100 cycles at 0.1 C and 80% after 150 cycles at 0.2 C) performance. This work provides new methods and strategies for the design and fabrication of solid-state batteries with high ionic conductivity and high specific energy.

Gel polymer electrolytes (GPEs) have high safety and excellent electrochemical performance, so applying GPEs in lithium batteries has received much attention. However, their poor lithium ion transfer number, cycling stability, and low room temperature ionic conductivity seriously affect the utilization of gel polymer electrolytes. This paper successfully synthesized flexible poly (vinylidene fluoride-hexafluoropropylene)–lithium titanium aluminum phosphate (PVDF-HFP-LATP) gel polymer electrolytes using the immersion precipitation method. The resulting GPE has a porous honeycomb structure, which ensures that the GPE has sufficient space to store the liquid electrolyte. The GPE has a high ionic conductivity of 1.03 ×10⁻³ S cm⁻¹ at room temperature (25 °C). The GPE was applied to LiFePO₄/GPE/Li batteries with good rate performance at room temperature. The discharge specific capacity of 1C was as high as 121.5 mAh/g, and the capacity retention rate was 94.0% after 300 cycles. These results indicate that PVDF-HFP-LATP-based GPEs have the advantage of simplifying the production process and can improve the utility of gel polymer lithium metal batteries.

Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)-based gel polymer electrolytes (GPEs) are considered a promising electrolyte candidate for polymer lithium-ion batteries (LIBs) because of their free-standing shape, versatility, security, flexibility, lightweight, reliability, and so on. However, due to problems such as low ionic conductivity, PVDF-HFP can only be used on a small scale when used as a substrate alone. To overcome the above shortcomings, GPEs were designed and synthesized by a UV curing process by adding NASICON-type Li_1.5Al_0.5Ge_1.5(PO₄)₃ (LAGP) and garnet-type Li_6.46La₃Zr_1.46Ta_0.54O₁₂ (LLZTO) to PVDF-HFP. Experimentally, GPEs with 10% weight LLZTO in a PVDF-HFP matrix had an ionic conductivity of up to 3 × 10⁻⁴ S cm⁻¹ at 25 °C. When assembled into LiFePO₄/GPEs/Li batteries, a discharge-specific capacity of 81.5 mAh g⁻¹ at a current density of 1 C and a capacity retention rate of 98.1% after 100 cycles at a current density of 0.2 C occurred. Therefore, GPEs added to LLZTO have a broad application prospect regarding rechargeable lithium-ion batteries.

Lithium-ion solid-state batteries with spinel Li₄Ti₅O₁₂ (LTO) electrodes have significant advantages, such as stability, long life, and good multiplication performance. In this work, the LTO electrode was obtained by the atmospheric plasma spraying method, and a composite solid electrolyte was prepared by in situ ultraviolet (UV) curing on the LTO electrode. The composite solid electrolyte was designed using a soft–hard combination strategy, and the electrolyte was prepared into a composite of a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) flexible structure and high-conductivity Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) hard particles. The composite electrolyte exhibited a good ionic conductivity up to 0.35 mS cm⁻¹ at 30 °C and an electrochemical window above 4.0 V. In situ and ex situ electrolytes were assembled into LTO//electrolyte//Li solid-state batteries to investigate their impact on the electrochemical performance of the batteries. As a result, the assembled Li₄Ti₅O₁₂//in situ electrolytes//Li batteries exhibited excellent rate of performance, and their capacity retention rate was 90% at 0.2 mA/cm² after 300 cycles. This work provides a new method for the fabrication of novel advanced solid-state electrolytes and electrodes for applications in solid-state batteries.