Fabrication of High-Stability PVDF Solid-State Electrolytes via Molecular Weight Tailoring and Zinc Complex Modification

As promising next-generation energy storage candidates with high safety and energy density, solid-state lithium metal batteries are constrained by the twin critical issues of low ionic conductivity and poor interfacial contact. Herein, a composite polymer electrolyte (PPM) is fabricated via polymer molecular chain modulation coupled with zinc complex modification, where a mixed polymer chain (M-PVDF) is derived from two molecular-weight-distinct PVDF grades (Kynar 761/Solvay 5130, 1:1 mass ratio), and an oxygen-rich amorphous zinc complex (MO) acts as a multifunctional filler. Specifically, the M-PVDF matrix constructs a continuous electrolyte surface that enables unobstructed ion transport and reinforces electrolyte-electrode interfacial contact, thereby enhancing long-term cycling stability. Meanwhile, the MO filler exerts synergistic effects through three key functions: its abundant carbonyl groups accelerate Li-salt dissociation to boost ionic conductivity; its NMP ligands act as “solvent immobilizers” to create extra ion migration sites; and its metal active centers modulate charge distribution for uniform Li deposition and dendrite suppression. Benefiting from this rational structural design, the PPM electrolyte delivers exceptional electrochemical properties, including a 5.2 V voltage window, an ionic conductivity of 4.29 × 10–4 S cm–1 and a high lithium-ion transference number of 0.65. Assembled into an LFP battery, it retains 93% of the initial capacity after 360 cycles at 0.2 C, demonstrating superior cycling stability. Moreover, the pouch cell exhibits excellent bending resistance and damage tolerance, highlighting great potential for flexible and wearable battery applications.