Achieving superiorly highheat‐dimensionalstability, high strength, and good electrochemical performance for electrospun separators in powerlithium‐ionbattery through building unique condensed structure based on polyimide and poly (m‐phenylene isophthalamide)

Abstract

It is still a challenge for simultaneously achieving high heat resistance, high strength and outstanding electrochemical performance for separators in power lithium-ion battery (PLB). Herein, new high performance electrospun separators are developed through building unique structure based on polyimide (PI) and poly (m-phenylene isophthalamide) (PMIA). Orthogonal tests (4 4 ) show that the magnitude order of electrospinning factors on the morphology of membrane is concentration>injection rate>receiving distance>voltage. With the optimum factors, the electrospun membrane (PI/PMIA) was prepared, which was further pressed at 100 C for 10 min to get treated membrane (H-PI/ PMIA). Interestingly, the comprehensive performance of PI/PMIA is not a simple combination of those of PI and PMIA; instead, PI/PMIA has much better thermal and mechanical properties than both PI and PMIA, proving that PI/PMIA has a synergistic effect. PI/PMIA and H-PI/PMIA not only have good ionic conductivity and electrochemical stability, but also have superiorly high properties including dimensional stability (thermal shrinkage temperature>300 C), tensile strengths (24.1 MPa for PI/PMIA, 34.3 MPa for H-PI/PMIA) and capacity retentions (97.9%, 99.2%) compared with electrospun membranes for PLBs reported in the literature so far (SCI database). The mechanism behind these attractive performances is discussed from condensed structure of membranes. K E Y W O R D Sbatteries and fuel cells, membranes, structure-property relationships | INTRODUCTIONBesides the wide applications in electronic and electrical fields, lithium-ion battery is becoming one main power source and expected to replace petroleum. 1 Separator is not only the key component, which is also key factor of determining the heat resistance, safety, efficiency, and cycling performance of power lithium-ion battery (PLB). 2

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“…11a). 112 PI/PMIA and H-PI/PMIA have the best thermal stability (300 °C), tensile strength (24.1 MPa PI/PMIA and 34.3 MPa H-PI/PMIA) and electrochemical capacity retention (97.9% and 99.2%), as shown in Fig. 11b.…”