The stability and wide temperature performance range of solid electrolytes are the keys to the development of high-energy density all-solid-state lithium-ion batteries. In this work, a PVDF-HFP-LiClO₄-Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) composite solid electrolyte was prepared using the solution pouring method. The PVDF-HFP-LiClO₄-LLZTO composite solid electrolyte shows excellent electrochemical performance in the temperature range of 30 to 60 °C. By assembling this electrolyte into the battery, the LiFePO₄/PVDF-HFP-LiClO₄-LLZTO/Li battery shows outstanding electrochemical performance in the temperature range of 30 to 60 °C. The ionic conductivity of the composite electrolyte membrane at 30 °C and 60 °C is 5.5 × 10⁻⁵ S cm⁻¹ and 1.0 × 10⁻⁵ S cm⁻¹, respectively. At a current density of 0.2 C, the LiFePO₄/PVDF-HFP-LiClO₄-LLZTO/Li battery shows a high initial specific discharge capacity of 133.3 and 167.2 mAh g⁻¹ at 30 °C and 60 °C, respectively. After 50 cycles, the reversible electrochemical capacity of the battery is 121.5 and 154.6 mAh g⁻¹ at 30 °C and 60 °C; the corresponding capacity retention rates are 91.2% and 92.5%, respectively. Therefore, this work provides an effective strategy for the design and preparation of solid-state lithium-ion batteries.

With high safety and good flexibility, polymer-based composite solid electrolytes are considered to be promising electrolytes and are widely investigated in solid lithium batteries. However, the low conductivity and high interfacial impedance of polymer-based solid electrolytes hinder their industrial applications. Herein, a composite solid-state electrolyte containing graphene (PVDF-LATP-LiClO4-Graphene) with structurally stable and good electrochemical performance is explored and enables excellent electrochemical properties for lithium-ion batteries. The ionic conductivity of the composite electrolyte membrane containing 5 wt% graphene reaches 2.00 × 10⁻³ S cm⁻¹ at 25 °C, which is higher than that of the composite electrolyte membrane without graphene (2.67 × 10⁻⁴ S cm⁻¹). The electrochemical window of the composite electrolyte membrane containing 5 wt% graphene reaches 4.6 V, and its Li⁺ transference numbers reach 0.84. Assembling this electrolyte into the battery, the LFP/PVDF-LATP-LiClO4-Graphene /Li battery has a specific discharge capacity of 107 mAh g⁻¹ at 0.2 C, and the capacity retention rate was 91.58% after 100 cycles, higher than that of the LiFePO₄/PVDF-LATP-LiClO₄/Li (LFP/PLL/Li) battery, being 94 mAh g⁻¹ and 89.36%, respectively. This work provides a feasible solution for the potential application of composite solid electrolytes.

As a potential anode material for lithium-ion batteries (LIBs), metal tin shows a high specific capacity. However, its inherent “volume effect” may easily turn tin-based electrode materials into powder and make them fall off in the cycle process, eventually leading to the reduction of the specific capacity, rate and cycle performance of the batteries. Considering the “volume effect” of tin, this study proposes to construct a carbon coating and three-dimensional graphene network to obtain a “double confinement” of metal tin, so as to improve the cycle and rate performance of the composite. This excellent construction can stabilize the tin and prevent its agglomeration during heat treatment and its pulverization during cycling, improving the electrochemical properties of tin-based composites. When the optimized composite material of C@Sn/NSGr-7.5 was used as an anode material in LIB, it maintained a specific capacity of about 667 mAh g⁻¹ after 150 cycles at the current density of 0.1 A g⁻¹ and exhibited a good cycle performance. It also displayed a good rate performance with a capability of 663 mAh g⁻¹, 516 mAh g⁻¹, 389 mAh g⁻¹, 290 mAh g⁻¹, 209 mAh g⁻¹ and 141 mAh g⁻¹ at 0.1 A g⁻¹, 0.2 A g⁻¹, 0.5 A g⁻¹, 1 A g⁻¹, 2 A g⁻¹ and 5 A g⁻¹, respectively. Furthermore, it delivered certain capacitance characteristics, which could improve the specific capacity of the battery. The above results showed that this is an effective method to obtain high-performance tin-based anode materials, which is of great significance for the development of new anode materials for LIBs.