## 2 Results and Discussion
As the temperature increases, the PVDF-HFP polymer backbone undergoes substantial breakdown, with its typical degradation process accompanied by the release of gases such as HF, leading to a sharp mass loss. Simultaneously, the organic ligands in ZIF-8 also enter their decomposition phase, further accelerating the overall weight reduction. The addition of lithium salt causes the decomposition temperature of ZIF-8 to shift earlier [34]. After decomposition, ZIF-8 may form inorganic products such as ZnO, which are relatively stable [35]. DSC testing also showed that PHZ material exhibited significant decomposition reactions at 300 \({}^{\circ}\)C, accompanied by endothermic peaks, corresponding to the weight loss changes in PHZ at different ratios in TG testing. A clear endothermic peak also appeared at around 500 \({}^{\circ}\)C, corresponding to the change in TG weight loss of ZIF-8 in PHZmaterial. Polymer gel electrolyte membranes with different proportions of ZIF-8 were systematically tested using coin-type symmetric cells and an electrochemical workstation. As shown in Figure 3c, the results indicate that when 4% ZIF-8 is added to the electrolyte membrane, its ionic conductivity reaches the highest value of 1.17 \(\times\) 10\({}^{-3}\) S/cm. However, with a further increase in ZIF-8 content, the ionic conductivity gradually decreases. This phenomenon can be attributed to the intensified trends of particle agglomeration and interfacial blocking effects when the ZIF-8 loading surpasses 4%, resulting in the obstruction of ion transport pathways and subsequent impairment of ionic transport kinetics. Compared to pure PVDF-HFP electrolyte membranes (1 \(\times\) 10\({}^{-4}\) S/cm), the conductivity of PHZ increases by an order of magnitude. Additionally, Figure 3b shows the linear sweep voltammetry (LSV) curves of PHZ electrolyte membranes with different ZIF-8 addition ratios. When the amount of ZIF added is 4%, the electrochemical window of the electrolyte membrane expands to 4.7 V, which is significantly better than that of PHZ membranes with other addition ratios. In PVDF-HFP-based electrolyte membranes, excessive addition of MOF may lead to insufficient binder and affect the mechanical strength of the membrane. If it is too low, it cannot effectively regulate the pore structure. Therefore, an appropriate ratio of MOF to PVDF HFP can expand the range of battery LSV [36]. The porous network structure of ZIF-8 forms additional ion-conduction pathways within the polymer matrix, thereby accelerating ion migration. Given that the PHZ electrolyte membrane achieved the highest conductivity when 4% of zif-8 was added, we conducted lithium migration tests on this specific proportion of PHZ, as illustrated in Figure 3d. The synergistic effect between ZIF-8 and the local segmental motion of the amorphous region in PVDF-HFP enhances lithium-ion transference [37; 38], achieving a lithium-ion transference number (TLi\({}^{+}\)) of 0.7. To further evaluate the electrochemical performance of the PHZ solid-state battery, rate performance and cycling tests were conducted at room temperature (25 \({}^{\circ}\)C) by an electrochemical workstation (Figure 4a, b). The initial discharge capacity is 168 mAh g\({}^{-1}\). At a discharge rate of 0.2 C, the discharge capacity was 141 mAh g\({}^{-1}\), while at 0.5 C, it was 105 mAh g\({}^{-1}\). At 1 C, the discharge capacity was 88 mAh g\({}^{-1}\), and it was 68 mAh g\({}^{-1}\) at 2 C. When the discharge rate returned to 0.1 C, the battery still maintained a discharge capacity of 168 mAh g\({}^{-1}\). In contrast, the solid-state battery with the PVDF-HFP electrolyte membrane (without ZIF-8) exhibited an initial discharge capacity of only 149 mAh g\({}^{-1}\) at 0.1 C. At 0.2 C, the discharge capacity was 133 mAh g\({}^{-1}\); at 0.5 C, it was 77 mAh g\({}^{-1}\); at 1 C, it was 48 mAh g\({}^{-1}\); and at 2 C, it was 28 mAh g\({}^{-1}\).