Preparation of porous fluorinated polyimide separator for lithium-ion batteries by non-solvent induced phase separation process. (September 2021)

• Record Type: Journal Article
• Authors: Shi, Yake; Yuan, Biao; He, Yanzhen; Duan, Cuijia; Yan, Shuo; Lin, Quanfan; Yu, Haibin; Chen, Zan; Han, Enshan
• Is Part Of: High performance polymers. Volume 33:Number 7(2021)
• Page Start: 774
• Page End: 784
• Publication Date: 2021-09
• Subjects: Fluorinated polyimide -- porous separator -- non-solvent induced phase separation process -- lithium-ion batteries; Polymerization -- Periodicals; Polymers -- Periodicals; 547.7
• DOI: 10.1177/0954008320988156
• Languages: English
• ISSNs: 0954-0083

Abstract

A series of novel porous fluorinated polyimide (FPI) separators containing trifluoromethyl group (–CF3 ) were prepared by the non-solvent induced phase separation (NIPS) strategy. The prepared FPI separator with 60% molar content (fluorinated dianhydride: non-fluorinated dianhydride: diamine = 60: 40: 100) of fluorinated groups (FPI-60%) could stably exist in the electrolyte as a LIBs separator. The resultant FPI-60% separator possesses high thermal stability with the Tg of 289.4°C and exhibits no shrinkage even at 200°C. The morphologies of the FPI-60% separators were adjusted by introducing small molecular non-solvent additives-ethanol, and the FPI-60% separators present the spongy-like and interconnected structure with different porosity as the amount of ethanol changed from 1 wt% to 10 wt%. The FPI-60% separators display excellent electrolyte uptake with 170%–200% and the ionic conductive could reach 1.17 mS/cm which is four times approximately than that of the PP separator. The lithium-ion batteries (LIBs) using FPI-60% separators with 10 wt% ethanol added show better rate capacities (102.8 mAh/g, 70.8 mAh/g of PI-10 and PP separator at 2 C, respectively) and the capacity retention rate is 93.2% after 50 cycles. The results prove that the porous FPI separator is a promising candidate for high-performance LIBs.