Structure and electrochemical performance of Li2MnSiO4 and Li2FeSiO4 as potential Li-battery cathode materials

Electrochemical characteristics of Li2−VTiO4 rock salt phase in Li-ion batteries

“…Among those, the most promising seem to be certain mixtures of simple oxides LiMO 2 (M= Co, Ni, Mn,…) which can give capacities higher than 200 mAh/g [1], the use of oxygen from air as a cathode in Li-air batteries [2] and selected new compounds that can reversibly exchange more than 1 lithium per formula unit. An example of the latter are silicate-based positive materials with two lithium atoms per formula unit [3,4]; however, it is still not completely clear if in practice a >1 electron reaction is possible [5]. Another family of positive materials which theoretically enable a reversible exploration of more than 1 mol of lithium per formula unit are lithium transition metal oxides stabilized with titanium (so-called "titanates").…”

Vanadium Substitution in Li2MnSiO4/C as Positive Electrode for Li Ion Batteries

“…Most syntheses include an annealing step at elevated temperatures between 600 and 800 °C and result in orthorhombic Pmn2 1 or a mixture of Pmn2 1 and Pmnb. 2,[6][7][8][9] A major drawback of Li 2 MnSiO 4 is the structural instability upon cycling which is believed to be caused by cooperative Jahn-Teller distortions during oxidation. Both, triand tetravalent Mn are highly destabilized in a tetrahedral crystal field by the partial occupation of the energetically unfavorable t 2 orbitals.…”

“…1 These polyanion compounds consist of abundant elements and allow in theory the reversible exchange of 2 Li ions per formula unit. [2][3][4] Li 2 MnSiO 4 is an interesting candidate, since Mn can exist in different oxidation states (II, III, IV) within the potential window of a commercial Li-ion battery, thus gives rise to a high theoretical capacity of 333 mAhg -1 for the exchange of 2 Li per formula unit. 5 Li 2 MnSiO 4 adopts β and γ Li 3 PO 4 structures where all cations are tetrahedrally coordinated.…”

“…This results in a loss of the lithiation paths and of long-range order and hence causes severe capacity decay. 10,11 Furthermore, the rather insulating character and the low ionic conductivity of Li 2 MnSiO 4 need to be addressed. Dominko et al reported a low electronic conductivity of 3·10 -14 Scm -1 at 60 °C.…”

“…Environmentally benign lithium transition metal orthosilicates of the general formula Li 2 Li-ion batteries. 1 These polyanion compounds consist of abundant elements and allow in theory the reversible exchange of 2 Li ions per formula unit.…”