(475g) Dendrite Suppressing Solid Ion Conductor From Aramid Nanofibers

Piercing of porous polymer membranes by lithium dendrites is one of the failure mechanisms in lithium batteries. This can often lead to short circuit and fire. In this presentation, we demonstrated the combination of ionic conducting polymer poly(ethylene oxide) (PEO) and the ultrastrong aramid nanofibers (ANF) by layer-by-layer assembly (LBL) to create robust solid ion-conducting, dendrite suppressing membranes for lithium batteries. The nanocomposite membranes exhibited high mechanical strength of 169 MPa with 4.95 GPa of elastic modulus. With high ionic conductivity measured to be at the range of 5.5x10^-5 S/cm, the high flexibility of these nanocomposite membranes make them more versatile in applications in comparison to ceramic and solid electrolytes. The exceptional high thermal stability easily out-performs common polymer (PE/PP-based) separators to substantially improve lithium battery thermal safety. Experiment results, using stronger copper dendrites as a experimental model, showed very successful dendrite suppression by PEO-ANF membranes. Superb mechanical properties of PEO-ANF membranes coupled with ionic conductivity represent a big step toward safer and durable lithium batteries.