A facile process for preparing highly stable LiSi alloy anodes for rechargeable Li ion batteries

Lithium-Sulfur (Li-S) batteries have been attracted tremendous attention as a next generation energy storage devices for high energy density batteries. This can be ideal for propelling drones. They are especially attractive for electro-mobility due to their high theoretical energy density (2600Wh kg⁻¹), low cost and being environmentally friendly. Li-S batteries are generally constructed using sulphur as the cathode active material and lithium-metal as an anode material. However, Li-S batteries are still struggling for commercialization due to the poor cycling performance and safety risks which is mainly caused by the Li metal anodes. We propose to replace Li metal by LiSi alloy as the anode material in sulphur based cathodes.

Generally, lithiation (alloying) process of Si is done electrochemically in half cells with Li metal as the counter electrode. With these, successive disassembly and reassembly steps are required for a final elaboration of Li/Si-S batteries. This disadvantage of a complex procedure makes commercialization of such systems difficult in the view of too high process costs. Presently, we develop a facile process for LiSi alloy formation for the fabrication of full Li/Si-S batteries. A polymer based material and LiPF₆ in organic solvents are used as binder and electrolyte, respectively. In our study, we demonstrate that LiSi alloy electrodes show very good performance as anodes for secondary batteries. Our study suggests that the pre-lithiation process that we have developed is an effective method for improving cycling stability of Li batteries based on Li/Si alloys and is also suitable for industrial use.