An interface-modified solid-state electrochemical device for lithium extraction from seawater

Electrolysis-based technology is a potential low-cost method for Li extraction from seawater that can bridge the gap between the supply and demand. An all-solid-state electrochemical device can effectively prevent the side reactions of metallic lithium and liquid organic electrolyte. However, its Li-ion conductivity is at least three orders of magnitude lower than expected due to extremely poor wetting between the metallic Li and the solid-state electrolyte (SSE). To overcome this problem, an artificial interface-modified solid-state sandwich device with a TiO2 layer (Li/TiO2/SSE) is developed. The lithiated LixTiO2 film improves physical contact between Li and the SSE, and the interfacial resistance is reduced by 2–3 orders of magnitude. The average Li extraction efficiency of the solid-state device reaches 110 μg-Li/cm2 over 1 h in natural seawater via a flow-through column system. Charging voltage fluctuations of ±0.05V reveal the stability and reliability of the artificially modified device over 40 cycles. These superior properties demonstrate the potential of this system as a next-generation electrolysis-based device for Li extraction from natural seawater.