PVDF-based polymers have garnered significant attention in the field of high-power density electrostatic capacitors due to their exceptional dielectric strength . However, their practical applications are constrained by low charge-discharge efficiency ( η ) and energy storage density ( U e ), which stem from high ferroelectric relaxation and low breakdown strength ( E b ). Here, a hydrogenated glassy polymer poly(styrene-methyl methacrylate-methylallyl alcohol) (PSMA) is designed and synthesized to be homogeneously distributed in PVDF through voltage-assisted 3D printing-hot pressing, resulting in a flexible composite film . The findings demonstrate that PSMA, rich in hydrogen bonds and high modulus strength, effectively mitigates the ferroelectric phase transition of PVDF to enhance η . Additionally, the voltage-assisted 3D printing process induces an entropy gain mechanism, facilitating the uniform distribution of the two phases and enhancing the interfacial properties for enhancing E b . Remarkably, the study achieves prominent growth in energy storage performance, with U e and η reaching 18.1 J/cm 3 and 80 % at 525 MV/m, respectively. These remarkable results highlight the potential of 3D printing technology in enhancing the energy storage performance of PVDF-based dielectrics.
Shi Zhou,Min Liu,Bangfu Yin,Xiaoyi Chen,Lingguang Yi,Linqing Wang,Jiali Liu,Huahui Zhao,Jun Li,Li Yang,Hong Liu,Xianyou Wang
PVDF-based polymer electrolytes are particularly interesting due to their high ionic conductivity. However, the residual solvent N , N -dimethylformamide (DMF) in the electrolyte tends to decompose on the surface of lithium metal anodes, leading to numerous organic small molecules that deteriorate the solid electrolyte interface (SEI) and limit their application in lithium metal batteries. In this work, a composite solid electrolyte (CSE) is fabricated by chitosan (CHI@Mg), which adsorbs Mg 2+ , as a filler into a PVDF-HFP electrolyte. It has been found that the abundance of -OH, O , and -NH₂ groups in chitosan can facilitate the dissociation of LiTFSI. Additionally, -OH and -NH₂ groups can also anchor residual DMF in the electrolyte to weaken the solvation coordination between Li + and DMF, this effectively inhibits the decomposition of DMF on lithium metal, resulting in improved interfacial stability. Moreover, the Mg 2+ absorbed by chitosan can be conveyed to the lithium anode, participate in the formation of the SEI layer and construct MgF₂-SEI, which facilitate uniform lithium deposition and restrict lithium dendrite growth. Due to the CHI@Mg anchored DMF and construction of the MgF 2 -SEI, the Li||LiFePO₄ battery demonstrates an impressive capacity retention rate of 86.6 % after 1000 cycles at a 2C rate. Additionally, the Li||LiNi 0.7 Co₀.₁Mn₀.₂O₂ cells maintain a capacity retention of 89.2 % after 100 cycles at a cutoff voltage of 4.4 V. This work provides a valuable exploration for improving the interfacial stability between PVDF-HFP-based electrolytes and lithium-metal anodes and promoting the development of solid-state lithium metal batteries.
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