Topometric Design of Reticulated Nanofiber Composites for Lithium-Sulfur Batteries

Abstract

Abstract Large local stresses, heterogeneous deformation states, low cathode conductivity, and rapid polysulfide diffusion create multiple fundamental barriers for lithium-sulfur batteries1 to attain Coulombic efficiency, discharge rate, and cyclability performance comparable to Li ion cells 2–4. Here we show that sulfur cathodes structured as reticulated nanofiber composites (RNCs) address these problems and provide a general pathway to design materials for different battery chemistries using topometric descriptors that combine parameters from topological and Euclidian spaces. Specifically, high nodal degree and volumetric nodal density combined with low Ohm centrality and high Freundlich nodal density of networks from carbon nanotubes grown on top of carbonized aramid nanofibers5 engender composites with failure-resilient deformations, stress-adaptable charge transport, minimal dead volume, and high affinity to lithium polysulfides. The lithium-sulfur batteries with obtained cathodes exhibit charge-discharge rates as high as 10C, specific/areal capacity as high as 17.0 mAh/cm2, and cycle life > 2500 cycles. The electrochemical parameters exceed leading batteries with metal oxide cathodes by 300-500% and DOE targets for electric vehicle batteries by 300% 6. Topometric design can be extended to other materials with complex architectures needed to satisfy mutually restrictive stress, mass, and charge transport requirements for energy, biomedical and water technologies.