3D Composite Anode Enables the Long Cycle Life of Li-S Batteries

Li metal is believed as the most promising anode candidate in pursuing the higher-energy Li-based batteries (Li-ion, Li-S, Li-O2, etc.)1-3 because of its high theoretical capacity (3860 mAh/g) and low redox potential (-3.04 V vs SHE). However, the Li metal anodes suffer instability with cycling due to the huge volume change (~2.4 mm/Ah in height), side reactions with electrolytes, Li dendrite formation, etc.4 With 3D structure, Li can be stabilized with minimized volume change, stable interface with electrolyte, and uniform Li plating/stripping morphology. However, making 3D Li electrode has lots of technical challenges due to the wettability and high reactivity of Li. Besides, the controllable Li plating/stripping from the 3D structure is also a big challenge. The most common 3D anodes are the composites of Li metal and conductive networks (Cu foam, Ni foam, carbon nanotube, carbon fiber, reduced graphene, graphene, etc.).5 However, due to the Li-ion diffusion path limitation, Li is more likely plated on top of the conductive 3D network rather than in its pores. Eventually, the 3D Li electrode will evolute to a bi-layer structure: electrochemical reactive Li on the top (facing the separator) and 3D conductive network on the bottom (facing the current collector). Here we report 3D Li composites with the continuous Li-ion conductive networks. Different from the traditional electrical conductivity 3D Li host, Li-ion conductive network could guarantee homogenous Li-ion diffusion through electrolyte or the 3D Li-ion conductive materials. Additionally, the insulating material could minimize the side reactions with electrolytes. Due to the high surface area, our 3D Li anode enables the high-rate capability. Therefore, our 3D Li composite electrodes could provide much better cycling performance than traditional 3D network as we discussed in the above section. Except for the fundamental understanding, Lyten is focused on scaling up this type of advanced Li anode to supply MWh-scale Li-S battery application. Reference Xue, W., Huang, M., Li, Y., et al. (2021). Ultra-high-voltage Ni-rich layered cathodes in practical Li metal batteries enabled by a sulfonamide-based electrolyte. Nature Energy, 6(5), 495-505. Pang, Q., Shyamsunder, A., Narayanan, B., et al. (2018). Tuning the electrolyte network structure to invoke quasi-solid state sulfur conversion and suppress lithium dendrite formation in Li–S batteries. Nature Energy, 3(9), 783-791. Zhu, Y. G., Leverick, G., Giordano, L., et al. (2022). Nitrate-mediated four-electron oxygen reduction on metal oxides for lithium-oxygen batteries. Joule, 6(8), 1887-1903. He, X., Bresser, D., Passerini, S., et al. (2021). The passivity of lithium electrodes in liquid electrolytes for secondary batteries. Nature Reviews Materials, 6(11), 1036-1052. Park, S., Jin, H. J., & Yun, Y. S. (2020). Advances in the design of 3D‐structured electrode materials for lithium‐metal anodes.Advanced Materials, 32(51), 2002193.