Preparation Of Multi-shell Hollow Microspheres And Its Application In Gel Composite Electrolytes

Multi-shell hollow microspheres have many advantages such as large specific surface area and large internal storage space.It's important for many fields,such as catalysis,energy storage,and biomedicine.Silica double shell hollow microspheres?DSHMs?are valued for potential applications.One-step template method with the polymer-silica core-shell hollow microspheres?SHHM@SiO₂?as the templates are successful.The shape,internal structure and components of the DSHMs were determined.DSHMs are used as a filler for gel polymer electrolytes?GPEs?in lithium ion batteries to form gel composite electrolytes?GCEs?.GCEs shows better cycle performance,higher ionic conductivity and better rate performance than GPEs at high current densities.This paper designs a series of polymer microspheres and applies DSHMs in lithium-ion batteries.The main research contents are as follows:?1?Polystyrene microspheres?PSt?were first prepared by dispersion polymerization,and their size and PDI were 1.04?m and 0.05.Then they were used as seed microspheres to prepare single-hole hollow microspheres?SHHMs?.The seed microspheres,swelling agents,emulsifiers,and initiators were mixed to form a stable seed emulsion.After the seed microspheres fully swell,the seed shell cross-linking reaction was initiated.Hydrophilic acrylamide was added to the system.After the reaction was completed,SHHMs were obtained after removing the swelling agent,and the particle size and PDI were 1.65?m and 0.316.Through the study of the preparation mechanism of SHHMs,we found that the key to the successful preparation of SHHMs was the efficient and rapid phase separation of cross-linked shells and swelling cores.?2?The SHHMs obtained by the seed emulsion polymerization method were mixed with the organic solvent ethanol to form a stable emulsion,and then polymer-silica core-shell hollow microspheres?SHHM@SiO₂?were obtained by the sol-gel method.The product SHHM@SiO₂ obtained by the above method was placed in a crucible and placed in an open vacuum atmosphere tube furnace for calcining at a heating rate of 1.0°C min^-1,a calcination temperature of 600°C,and a calcination time of 2 h.Finally,white powdery product silica double shell hollow microspheres?DSHMs?obtained by a one-step template process.?4?DSHMs were added to P?VDF-HFP?to obtain GCEs.Compared with GPEs,the ionic conductivity was higher(1.09×10-3 S cm^-1),which improved the rate performance of the battery.At low current density?0.2 C,0.5 C?,the battery using GPEs was almost the same discharge capacity as the battery using GCEs.But at high current density?1 C,2 C,5 C?.The battery using GCEs was a higher specific discharge capacity(129 mAh g^-1).This advantage of the battery with GCEs was higher discharge specific capacity at high current density.It was possible to use in high-power lithium ion batteries.