A core@sheath nanofiber separator with combined hardness and softness for lithium-metal batteries

Lithium metal shows great promise to be the anode material of next-generation electrical energy storage, but the uncontrollable growth of dendritic and mossy lithium greatly restricts the practical application of lithium-metal batteries. Herein, we demonstrate a sustainable strategy for creating a core-shell structured [email protected] poly-m-phenyleneisophthalamide ([email protected]) nanofiber separator coupled hardness with softness via coaxial electrospinning technique. The PI core with good heat-resistance and breaking tenacity acts as a steady and powerful skeleton support to guarantee the structural stability of the [email protected] separator, even in the wet environment of the working battery. Meanwhile, the gel F-PMIA shell can endow the [email protected] membrane with a more intimate electrolyte contact to further enhance the electrolyte affinity so as to improve the ion transport capacity. Therefore, the as-prepared [email protected] nanofiber membrane delivers the synchronous characteristics of the favorable wetting mechanical flexibility, laudable thermal stability, excellent electrolyte uptake as well as distinct gelation phase, which has the capability to overcome the obstacle of lithium dendrites growth and enable a homogeneous stable electrolyte interface. As a result, the good ionic conductivity and interfacial compatibility can be obtained by using the functionalized [email protected] separator, and the voltage of the relevant lithium symmetrical battery delivers the relatively minor change during 350 h at 2.0 mA·cm−2. More importantly, the as-assembled [email protected] lithium-metal cells present superior cycling stability with the capacity retention of 83.1% and Coulombic efficiency of 99.7% after 200 cycles at 0.5 C rate, accompanied by an excellent rate recovery capability. It follows that the newfangled [email protected] nanofiber membrane with softness and strength can be perceived to be a highly qualified separator for high-safety and dendrite-proof lithium-metal batteries.