In Situ Generated Fireproof Gel Polymer Electrolyte with Li_6.4Ga_0.2La₃Zr₂O₁₂ As Initiator and Ion‐Conductive Filler

Abstract

Poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP) based gel polymer electrolyte is regarded as a promising candidate to settle the safety issues of liquid electrolytes. However, the currently reported gel polymer electrolytes are still not safe enough owing to high amount of flammable liquid solvents contained in them. Herein, a fireproof PVDF‐HFP based gel polymer electrolyte is designed and synthesized through an in situ crosslinking method, with Li6.4Ga0.2La3Zr2O12 as initiator and ion‐conductive filler. The obtained gel polymer electrolyte demonstrates superior fire resisting properties. The optimized gel polymer electrolyte exhibits an ionic conductivity as high as 1.84 × 10−3 S cm−1 at 20 °C with an electrochemical window up to 4.75 V at room temperature. Moreover, the obtained gel polymer electrolyte shows excellent compatibility with lithium anodes. Therefore, the lithium anode is well protected. Lithium batteries assembled with the gel polymer electrolyte possess superb safety properties in cutting and burning tests. Furthermore, the batteries also show a discharge retention rate as high as 94.08% (in comparison with the initial discharge capacity) after cycling at 0.5 C for 360 cycles with an average columbic efficiency higher than 98%. The purpose of this report is to show the great potential of applying fire‐retardant gel polymer electrolyte to achieve high safety lithium batteries.

A Flexible Ceramic/Polymer Hybrid Solid Electrolyte for Solid‐State Lithium Metal Batteries

“…[ 24–26 ] Nan's group utilized the catalysis of La in dehydrofluorination and prepared poly(vinylidenefluoride) (PVDF)–Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 (LLZTO) HSE whose ionic conductivity is as high as 5 × 10 −4 S cm −1 at 25 °C. [ 26 ] But this strategy can only be applied to those polymers consisting of H and F in neighbor carbon atoms such as PVDF or poly(vinylidene fluoride‐ co ‐hexafluoropropylene) (PVDF‐HFP) [ 24 ] which cannot contribute to ionic transport. Archer's group proposed a more universal method by preparing a kind of soft colloidal glasses HSE that PEO chains were covalently grafted onto silica nanoparticles.…”

“…The HSE works stable in high‐voltage nickel cobalt manganese oxide (NCM) LMB whose operate voltage is as high as 4.3 V. Therefore, making chemical binding interaction is an effective way to resolve the issue of interphase and facilitate the uniform dispersion of inorganic fillers into polymer matrix thus contributes to flexible HSE with both high conductivity and electrochemical stability. [ 24–26 ]…”

Nonflammable quasi-solid-state electrolyte for stable lithium-metal batteries

“…By adding Ga/Ta-doped LLZO nanoscale llers, poly(vinylidene uoride) (PVDF)-based electrolytes show superior ionic conductivity and thermal stability, probably due to the interaction between ceramics and dehy-drouorinated PVDF. 31 Compared to homogenous structure, sandwich-type SCE can suppress dendrite as well as form a good interface contact with the electrodes, via regulating the ratio of PEO and Ta-doping LLZO. 32 Furthermore, gelling SCEs by plasticizers, namely forming quasi-solid composite electrolytes (QCEs), together with in situ polymerization, 33,34 has proved to be a feasible way to improve rate and cycle performance of the batteries.…”

Rechargeable Battery Electrolytes Capable of Operating over Wide Temperature Windows and Delivering High Safety

“…If fast ionic conductors are added into a composite solid electrolyte, the composite can also benefit from the ionic conductivity of the SIEs. Various groups have shown that the electrochemical performance of CPEs can be significantly promoted by including Li + -stuffed ionic-conducting fillers in PEO, [229,[231][232][233][234] PPC, [235] polyacrylonitrile (PAN), [236] PVDF, [237][238][239] and PVDF-HFP [37,240] polymer matrices.…”