Application of Low Cost Non-Woven Fabric in 4.4 V LiCoO2 Based Lithium Ion Battery by Simple Coating Blended Polymer

Abstract

Low cost non-woven fabric cannot be used as separator in lithium ion battery due to its asymmetrically large pores that easily lead to short circuit of a battery. We introduce a convenient method by coating blended copolymer onto both sides of non-woven fabric to make it possibly use in high voltage lithium ion battery in this paper. Cellulose acetate phthalate (CAP) copolymer is used as secondary copolymer to blend with poly(vinylidene fluoride-hexafluoropropylene) (P(VdF-HFP)) copolymer to offset the disadvantage of P(VdF-HFP) with low ionic conductivity and poor interfacial compatibility. It is found that the PC2 blended GPE shows better electrolyte uptake and higher ionic conductivity. When cycled at the voltage range of 3.0 V and 4.4 V, CR2025 coin cell with the structure of Li/GPE/LiCoO2 exhibits acceptable cyclic stability and rate performance. After 100 cycles, the blended GPE based coin cell keeps 79% of original discharge capacity compared with that traditional Celgard Polyethylene membrane (saturated with liquid electrolyte) remains 77% of capacity, although non-woven fabric membrane falls down to no capacity after 7 cycles. Additionally, LiCoO2 cathode combined with blended GPE still shows a high discharge capacity of 158 mAh g−1 at 2C, remaining 91.3% capacity of 0.1C rate.