Lithium Intercalation from Aqueous Solutions

Abstract

Lithium can be intercalated into a variety of materials using aqueous electrochemical methods, provided that certain criteria are met. The materials must be stable in concentrated Li+ aqueous solution and Li intercalation must take priority over hydrogen intercalation. We use X-ray and neutron diffraction, as well as electrochemical methods to investigate if lithium or hydrogen is intercalated into certain hosts. For example, spinel Li²Mn²O⁴ can be made from spinel LiMn²0⁴ by intercalating one Li per mole in an electrochemical cell with 1 M LiOH electrolyte. If the electrochemical reduction is carried out further, beyond one electron per mole, Mn(OH)² is then formed, as we prove using neutron diffraction. By carefully selecting electrode materials and electrolyte composition it is possible to make rechargeable lithium-ion cells with aqueous electrolytes. For example, LiMn²0⁴/γ-Li^0.36MnO² can be selected as an electrode couple, and5 M LiNO³ in water as an electrolyte to make lithium-ion cells with aqueous electrolytes.