LiMBO3 (M = Mn, Fe, Co): synthesis, crystal structure and lithium deinsertion/insertion properties

The LiMBO3 (M = Mn, Fe, Co) compounds were synthesized by a solid state rea ction. LiFeBO3 and h-LiMnBO3 crystal structures were determined from single crystal data. LiFeBO, exhibits the same structure as that of other already described LiMBO3 compounds (M = Mg, Mn, Co, Zn). The structure of h-LiMnBO 3 is isotypic with the hexagonal form of LiCdBO3. The elecrrochemical study shows that a very small amount of lithium (less than 0.04 Li per formula u nit) can be deinserted reversibly from the three compounds. According to th e thermodynamic study performed in the case of LiFeBO3, the Fe3+/Fe2+ redox couple lies between 3.1 and 2.9 V/Li, demonstrating an important inductive effect of the BO3 group. (C) 2001 Elsevier Science B.V. All rights reserve d.