A solid 3D Li-S battery design via stacking 2D conductive microporous coordination polymers and amorphous Li-S layers

In order to make a Li-S battery practical, not only high gravimetric energy capacity is important, high volumetric energy capacity will also be required. The currently explored Li-S cathode designs often deploy systems with liquid electrolyte infiltration, hence with relatively low volumetric capacity. In the current study, we theoretically test a compact solid 3D design (more like a Li-ion battery cathode than a conventional Li-S cathode) consisted of a sandwich structure alternating between the 2D Mn-HAB layer and amorphous Li-S layer. We study the theoretical limits for both its gravimetric and volumetric energy capacity, as well as its structural stability and Li diffusion within the cathode system. In order to study the Li diffusion within an amorphous system, we also develop a pull-atom molecular dynamics (PA-MD) to calculate the barrier heights of such disordered systems. We reveal the mechanism which determines the Li diffusion in the amorphous layer of the system. Overall, we find such 3D solid Li-S cathode can be practical, with sufficient large gravimetric and volumetric energy capacity, as well as the Li diffusion constant. It also solves many other common Li-S cathode problems, from Li polysulfide dissolution, to electrical insulating, and structure instabilities.