Incorporating Ionic Paths into 3D Conducting Scaffolds for High Volumetric and Areal Capacity, High Rate Lithium-Metal Anodes.

Lithium-metal batteries can fulfill the ever-growing demand of the high-energy-density requirement of electronics and electric vehicles. However, lithium-metal anodes have many challenges, especially their inhomogeneous dendritic formation and infinite dimensional change during cycling. 3D scaffold design can mitigate electrode thickness fluctuation and regulate the deposition morphology. However, in an insulating or ion-conducting matrix, Li as the exclusive electron conductor can become disconnected, whereas in an electron-conducting matrix, the rate performance is restrained by the sluggish Li+ diffusion. Herein, the advantages of both ion- and electron-conducting paths are integrated into a mixed scaffold. In the mixed ion- and electron-conducting network, the charge diffusion and distribution are facilitated leading to significantly improved electrochemical performance. By incorporating Li6.4 La3 Zr2 Al0.2 O12 nanoparticles into 3D carbon nanofibers scaffold, the Li metal anodes can deliver areal capacity of 16 mAh cm-2 , volumetric capacity of 1600 mAh cm-3 , and remain stable over 1000 h under current density of 5 mA cm-2 . The volumetric and areal capacities as well as the rate capability are among the highest values reported. It is anticipated that the 3D mixed scaffold could be combined with further electrolytes and cathodes to develop high-performance energy systems.