Lithium insertion electrode materials based on orthosilicate derivatives

A lithium insertion-type electrode materials having an orthosilicate structure and having the formula:

• Li.sub.x M.sub.m-(d+t+q+r) D.sub.d T.sub.t Q.sub.q R.sub.r [SiO.sub.4 ].sub.l-(p+s+g+v+a+b) [SO.sub.4 ].sub.s [PO.sub.4 ].sub.p [GeO.sub.4 ].sub.g [VO.sub.4 ].sub.4 [AlO.sub.4 ].sub.a [BO.sub.4 ].sub.b
• wherein
• M represents Mn.sup.2+ or Fe.sup.2+ and mixtures thereof;
• D represents a metal in the +2 oxidation state selected from the group consisting of:
• Mg.sup.2+, Ni.sup.2+, Co.sup.2+, Zn.sup.2+, Cu.sup.2+, Ti.sup.2+, V.sup.2+ and Ca.sup.2+ ;
• T represents a metal in the +3 oxidation state selected from the group consisting of
• Al.sup.3+, Ti.sup.3+, Cr.sup.3+, Fe.sup.3+, Mn.sup.3+, Ga.sup.3+, Zn.sup.2+ and V.sup.3+ ;
• Q represents a metal in the +4 oxidation state selected from the group consisting of
• Ge.sup.4+, Sn.sup.4+ Ti.sup.4+ and V.sup.4+ ;
• R represents a metal in the +5 oxidation state selected from the group consisting of
• V.sup.5+, Nb.sup.5+ and Ta.sup.5+ ;
• M, D, T, Q, R, are elements residing in octahedral or tetrahedral sites;
• s, p, g, v, a, and b are the stoichiometric coefficient for S.sup.6+ (sulfate), P.sup.5+ (phosphate), Ge.sup.4+ (germanate), V.sup.5+ (vanadate), Al.sup.3+ (aluminate) and B.sup.3+ (borate) respectively residing in the silicon tetrahedral sites;
• the stoichiometric coefficients d, t, q, r, p, s, g, v, a, b are all positive and range from zero (inclusive) and 1 (inclusive);
• 0.ltoreq.x.ltoreq.2, 1.ltoreq.m.ltoreq.2, p+s+g+v+a+b<1 (exclusive) and x+2m+t+2q+3r=4-p-2s-v+a+b.