高导三元共聚物P(VDF-TrFE-CFE)隔膜的制备与性能研究

Preparation and Properties of Highly Conductive Ternary Copolymer P(VDF-TrFE-CFE) Separators

关键词:  PVDF三元共聚物  P(VDF-TrFE-CFE)  锂离子电池隔膜

Key Words:PVDF ternary copolymer  P(VDF-TrFE-CFE)  lithium-ion battery separators

摘要:本研究以三元共聚物聚(偏氟乙烯-三氟乙烯-氯氟乙烯)（P(VDF-TrFE-CFE)）为基体，采用非溶剂诱导相分离、热诱导相分离、盐浸出法及静电纺丝等多种工艺，制备了新型锂离子电池隔膜，系统研究了不同制备工艺对隔膜孔隙结构、电化学性能及电池循环稳定性的调控作用。结果表明，制备工艺是影响隔膜微观结构与力学性能的关键因素。其中，盐浸出法与热诱导相分离法可有效调控隔膜孔隙率，使其能在23%~66%的范围内变化。在电化学性能方面，所有隔膜均表现出较高的离子电导率，静电纺丝隔膜电导率最高可达1.8 mS/cm，热诱导相分离膜则为0.20 mS/cm。此外，所有样品的锂离子迁移数均超过0.20，其中盐浸出膜与热诱导相分离膜锂离子迁移数最高可达0.55。倍率性能测试显示，采用这些隔膜组装的电池均能提供稳定的放电容量和优良的可逆性能。盐浸出法制备的隔膜在2 C倍率下循环10次后，放电容量仍能保持在41.9 mAh/g左右。

Abstract:This study investigated the ternary copolymer poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (P(VDF-TrFE-CFE)) as a matrix material for advanced lithium-ion battery separators. Novel separators were fabricated using non-solvent-induced phase separation (NIPS)， thermally induced phase separation (TIPS)， salt leaching (SL)， and electrospinning (ES). A systematic investigation was carried out to elucidate the influence of these processing routes on the separator microstructure， pore architecture， electrochemical properties， and battery cycling performance. The results showed that the preparation method was a key factor governing the membrane microstructure and mechanical behavior. In particular， salt leaching and TIPS enabled effective tuning of separator porosity within the range of 23%~66%. All P(VDF-TrFE-CFE) separators exhibited relatively high ionic conductivity： the ES separators achieved a conductivity of up to 1.8 mS/cm， while the TIPS-derived separators showed a value of approximately 0.20 mS/cm. The lithium-ion transference numbers of all samples exceed 0.20， with maximum values of 0.55 obtained for the salt-leached and TIPS separators， indicating favorable ion-transport selectivity. Rate-capability tests revealed that batteries assembled with these separators deliver stable discharge capacities and excellent reversibility. Notably， the separators prepared by SL maintained a discharge capacity of around 41.9 mAh/g after 10 cycles at a 2 C rate.