Ion Transport Regulated Lithium Metal Batteries Achieved by Electrospun ZIF/PAN Composite Separator with Suitable Electrolyte Wettability

Abstract

Lithium metal battery (LMB) is a topic receiving growing attention due to the high theoretical capacity, while its practical application is seriously hindered by the lithium dendrites issue. As the physical barrier between two electrodes, the separator can achieve dendrite suppression by means of providing higher mechanical strength, regulating ion transport and facilitating homogeneous lithium deposition. Based on this, a composite separator is fabricated with zeolitic imidazolate framework (ZIF-8) and polyacrylonitrile (PAN) via electrospinning techniques, and its physical properties and electrochemical performances, together with its dendrite suppression mechanism, are investigated. The ZIF8-PAN separator possesses a unique 3D interconnected porous skeleton, displaying higher electrolyte uptake, preferable electrolyte wettability, and lower thermal shrinkage compared with the commercial polypropylene separator. In addition, a battery assembled with the ZIF8-PAN separator can effectively regulate ion transport and suppress dendrites growth, which exhibits an enhanced ionic conductivity (1.176 mS/cm), an increased lithium-ion transference number (0.306), a wider electrochemical stability window (5.04 V), and superior cycling stability (over 600 h with voltage hysteresis of 30 mV). This work offers a promising strategy to realize safe separator for dendrite suppression in LMB.

Keywords

• composite separator
• electrospinning techniques
• electrolyte wettability
• ion-transport regulation
• lithium dendrites suppression