Formatted PVDF in lamellar composite solid electrolyte for solid-state lithium metal battery

Solid polymer electrolytes (SPEs) hold great application potential for solid-state lithium metal battery because of the excellent interfacial contact and processibility, but being hampered by the poor room-temperature conductivity (∼ 10−⁷ S·cm⁻¹) and low lithium-ion transference number \(({t_{{\rm{L}}{{\rm{i}}^ + }}})\) $$(t_{{\text{Li}}^{+}})$$ . Here, a lamellar composite solid electrolyte (Vr-NH₂@polyvinylidene fluoride (PVDF) LCSE) with β-conformation PVDF is fabricated by confining PVDF in the interlayer channel of -NH₂ modified vermiculite lamellar framework. We demonstrate that the conformation of PVDF can be manipulated by the nanoconfinement effect and the interaction from channel wall. The presence of -NH₂ groups could induce the formation of β-conformation PVDF through electrostatic interaction, which serves as continuous and rapid lithium-ion transfer pathway. As a result, a high room-temperature ionic conductivity of 1.77 × 10⁻⁴ S·cm⁻¹ is achieved, 1–2 orders of magnitude higher than most SPEs. Furthermore, Vr-NH₂@PVDF LCSE shows a high \({t_{{\rm{L}}{{\rm{i}}^ + }}}\) $$t_{{\text{Li}}^{+}}$$ of 0.68 because of the high dielectric constant, ∼ 3 times of that of PVDF SPE, and surpassing most of reported SPEs. The LiNi_0.8Co_0.1Mn_0.1O₂∥Li cell assembled by Vr-NH₂@PVDF LCSE obtains a discharge specific capacity of 137.1 mA·hg⁻¹ after 150 cycles with a capacity retention rate of 93% at 1 C and 25 °C. This study may pave a new avenue for high-performance SPEs.