Six-armed and dicationic polymeric ionic liquid for highly stretchable, nonflammable and notch-insensitive intrinsic self-healing solid-state polymer electrolyte for flexible and safe lithium batteries

Solid-state polymer electrolytes (SPEs) with outstanding flexibility and self-healing capacity are appealing for utilization in reliable and wearable electronic devices. Herein, a highly stretchable (extensibility 2 h, 25 celcius). Moreover, DPIL-6-SPE presents a superior adhesion strength (weight loading 200 g) towards lithium electrode, signifying excellent interfacial compatibility. Compared with the counterpart of monocationic polymeric ionic liquid derived SPE (MPIL-6-SPE), the multiple cationic center in DPIL-6-SPE facilitates the dissociation of lithium salt and liberates more Li+ from trapping with TFSI-, thereby resulting in a superior ionic conductivity (over 10(-5) S cm(-1) at room temperature) and lithium ion transference number (0.46). The as-assembled LiFePOoPIL-6-SPE/Li battery can deliver a high discharge capacity of 152.6 mAh g(-1) at 0.1C, and its capacity retention rate reaches 94% after 50 cycles with a coulombic efficiency of 96%. In particular, the mechanical properties and conductivity of DPIL-6-SPE can fully recover after repeated damage, conferring the derived soft-pack battery stable powering capacity upon multi-angle bending and folding. The design of multi-armed and multiple charged PILs provides new avenues for developing flexible electronic devices with self-healing capacity.

Automated summary

DPIL-6-SPE shows excellent stretchability and adhesion strength towards lithium electrode, resulting in high ionic conductivity and lithium ion transference number. The battery assembled with DPIL-6-SPE exhibits high discharge capacity, good capacity retention rate and stable powering capacity even after repeated damage.