Nanoparticle-coated Separators for Lithium-ion Batteries with Advanced Electrochemical Performance

摘要

We report a simple, scalable approach to improve the interfacialcharacteristics and, thereby, the performance of commonly usedpolyolefin based battery separators. The nanoparticle-coatedseparators are synthesized by first plasma treating the membranein oxygen to create surface anchoring groups followed by immersioninto a dispersion of positively charged SiO2 nanoparticles.The process leads to nanoparticles electrostatically adsorbed notonly onto the exterior of the surface but also inside the pores ofthe membrane. The thickness and depth of the coatings can befine-tuned by controlling the f-potential of the nanoparticles.The membranes show improved wetting to common batteryelectrolytes such as propylenecarbonate. Cells based on thenanoparticle-coated membranes are operable even in a simplemixture of EC/PC. In contrast, an identical cell based on thepristine, untreated membrane fails to be charged even afteraddition of a surfactant to improve electrolyte wetting. Whenevaluated in a Li-ion cell using an EC/PC/DEC/VC electrolytemixture, the nanoparticle-coated separator retains 92% of itscharge capacity after 100 cycles compared to 80 and 77% for theplasma only treated and pristine membrane, respectively.