Enhanced Electrochemical Performance of a Silica Bead-Embedded Porous Fluoropolymer Composite Matrix for Li-Ion Batteries

Abstract

Potential composite polymer electrolyte (CPE) membranes, comprising a poly(vinylidene difluoride) (PVdF) and poly(vinylidene fluoride-hexafluoropropylene) (P(VdF-HFP)) blend with embedded silica spheres are fabricated through a spinning cum immersion precipitation technique. Especially, when the weight percentage of PVdF/ P(VdF-HFP)/SiO 2 is 55/40/05, the membrane exhibits low electrolyte leakage and low thermal shrinkage. The fabricated membranes and the corresponding polymer electrolytes are utilized as CPEs for Li + batteries, and their electrochemical performances are evaluated. Among the membranes studied in this work, the ionic conductivity of S5-CPE is measured to be the highest value of 9.9 mS cm −1 at room temperature, which is favorable for displaying good electrochemical performances. A LiFePO 4 |Li cell with the as-prepared S5based CPE exhibits a higher initial discharge capacity of 157 mAh g −1 and outstanding cyclic stability with 92% capacity retention at 0.2C rate after 500 cycles. The lithium transference number (t + ) of the system is found to be 0.28. This can be attributed to the excellent compatibility of the synthesized CPE membrane possessing high cyclic stability and capacity retention for Li + -ion batteries.

Ionic guest in ionic host: ionosilica ionogel composites via ionic liquid confinement in ionosilica supports

“…46,47 We then compared the ionic conductivity of ionosilica ionogels to that of conventional silica based ionogels, synthesized by an analogous non-hydrolytic sol-gel method using TMOS instead of the tris-trialcoxysilylated amine precursor. 48 Interestingly, the ionic conductivities of all the ionosilica-based ionogels remain lower than those measured with ionogels based on conventional silica, even when the silica matrix is made with the smallest amount of IL, i.e. TMOS 1 IL (0.37 S m À1 , Fig.…”

Perspectives on Improving the Safety and Sustainability of High Voltage Lithium‐Ion Batteries Through the Electrolyte and Separator Region

“…[191] For practical applications in LIBs, GPEs must also have good mechanical and chemical stability, high ionic conductivity, high Li + transference numbers, and promote good interfacial contact with the electrode surfaces. [192] In recent years, there has been a great deal of research into the topic of GPEs, with studies demonstrating the application of GPEs in HV batteries with more common polymers (such as PEO, [193][194][195][196][197] PVDF, [198][199][200][201][202] and acrylate-based polymers such as polyacrylonitrile, PAN, [203][204][205][206][207] or poly(methyl methacrylate), PMMA), [208,209] as well as with more sustainable, biodegradable polymers such as cellulose [185,[210][211][212][213][214][215][216][217] or starch. [218,219] Some of these GPEs have even been capable of ionic conductivities comparable to commercial LEs (≈11.07 mS cm −1 for a 1 m LiPF 6 electrolyte in EC:DMC (1:1, v/v)).…”

Understanding the Electrochemical Performance of Spongy C–F Derivative Chains as an Effective Anion Trapping Composite Matrix for Li-Ion Batteries

“…Particularly, boron atoms can effectively trap anions in the liquid electrolyte via Lewis acid–base interaction between the BN particles and anions in the liquid electrolyte. − Furthermore, the uniform thickness of the membrane plays an essential role in the long cycle life of the batteries . As an alternative to the traditional doctor blade technique, the thickness of the membrane can be controlled using spinning …”

“…In this context, many endeavors have been employed to improve the vital characteristics of separators via blending, inclusion of inorganic fillers, copolymerization, and cross-linking with polymers. Blending two polymers is one of the widely adopted remedies to overcome the difficulties. − Blending is a facile and low-cost technique to develop novel polymeric materials with a splendid performance. , Several polymer matrices with polar groups such as −O–, O, −N–, CO, CN, and C–F have been extensively investigated as separators and CPEs (composite polymer electrolytes) for LIB applications. ,− Among various candidates, C–F functional group derivatives have received an upsurge of consideration owing to their high dielectric constant, high stability at positive potentials, and insoluble nature in many organic solvents. Inspired by a recent assessment of the prior investigations, poly­(vinylidene fluoride cohexafluoropropylene) (PVDF-HFP) polymer skeletons have gained foremost concern owing to their semicrystalline nature, electron-withdrawing fluorine atoms, good mechanical stability, and better electrochemical performance. − Nevertheless, they have some serious obstacles, such as low ionic conductivity and safety issues that do not satisfy LIB applications’ necessities .…”