Uzunok, Kim, Çolak, Kim, Kim, Kim, Yamauchi, Dag (2019) Lyotropic Liquid Crystalline Mesophases Made of Salt-Acid-Surfactant Systems for the Synthesis of Novel Mesoporous Lithium Metal Phosphates ChemPlusChem 84(10) 1544-1553
Mesoporous lithium metal phosphates are an important class of materials for the development of lithium ion batteries. However, there is a limited success in producing mesoporous lithium metal phosphates in the literature. Here, a lyotropic liquid crystalline (LLC) templating method was employed to synthesize the first examples of LiMPO4 (LMP) of Mn(II), Co(II), and Ni(II). A homogeneous aqueous solution of lithium and transition metal nitrate salts, phosphoric acid (PA), and surfactant (P123) can be spin coated or drop-cast coated over glass slides to form the LLC mesophases which can be calcined into mesoporous amorphous LMPs (MA-LMPs). The metal salts of Mn(II), Co(II) and Ni(II) produce MA-LMPs that crystallize into olivine structures by heat treatment of the LLC mesophase. The Fe(II) compound undergoes air oxidation. Therefore, both Fe(II) and Fe(III) precursors produce a crystalline Li3 Fe2 (PO4 )3 phase at over 400 °C. The MA-LMPs show no reactivity towards lithium, however the crystalline iron compound exhibits electrochemical reactivity with lithium and a good electrochemical energy storage ability using a lithium-ion battery test. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.