Hydrothermal control of the lithium-rich Li$_2$MnO$_3$ phase in lithium manganese oxide nanocomposites and their application as precursors for lithium adsorbents

Abstract

Lithium manganese oxides (LMO) are key materials due to their role in Li-ion batteries and lithium recovery from aqueous lithium resources. In the present work, we investigated the effect of the crystallization temperature on the formation by hydrothermal synthesis of LMO nanocomposites with high Li/Mn ratios. It is demonstrated that LMO with a high Li/Mn ratio can be formed by systematically favoring the lithium-rich layered monoclinic phase (Li$_2$MnO$_3$) in a mixture of monoclinic and spinel crystalline phases. LMO nanocomposites have been characterized in terms of morphology, size, crystallinity, chemical composition and surface properties. Moreover, lithium adsorption experiments were conducted using acid-treated LMO (HMO) to evaluate the functionality of the nanocomposites as lithium adsorbent materials in LiCl buffer solution. This study spotlights in the structural, compositional, and functional properties of the different LMO nanocomposites obtained by the hydrothermal method using the same Li and Mn precursor compounds under slight variation crystallization temperatures. According to our knowledge, this is the first report of the successful application of lithium-rich Li$_2$MnO$_3$ phase in lithium manganese oxide nanocomposites as lithium adsorbent materials. With the recovered information, specific LMO nanocomposites with controlled amounts of the layered phase can be engineered to optimize lithium recovery from aqueous lithium resources.