An ultra-durable gel electrolyte stabilizing ion deposition and trapping polysulfides for lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries with high energy density are promising next-generation battery systems, but the limited power density, short cycle life and safety concerns caused by uncontrollable loss of active sulfur and severe growth of lithium dendrites impede their further development and broad applications. Herein, to address these issues, we report an ultra-durable composite gel electrolyte (u-CGE) that is capable of simultaneously stabilizing lithium metal anode and sulfur cathode. The u-CGE matrix is achieved via integrating zein protein nanofibers on super flexible nitrogen-doped carbon nanofabric leading to super mechanical durability and excellent electrolyte wettability/uptake. The resulting u-CGEs show high ionic conductivity (2.1 x 10(-3) S/cm), Li-ion transfer number (0.68), and excellent interfacial compatibility. Furthermore, benefiting from pyrrolic/pyridinic nitrogen (e.g. 15 wt%) on carbon structure and polar groups of zein protein nanofibers, the u-CGE effectively suppresses the growth of lithium dendrite and loss of active sulfur. As a result, long-lived (600 h) symmetric Li/Li cells with the u-CGEs display stable performance even at high current rates. More significantly, armed with the resulting u-CGE, the Li-S battery exhibits excellent rate stability (953 mAh/g at 2 A/g), in addition to the dramatically enhanced capacity and cycling stability.