Lithium vanadium phosphates, their production and their use lithium-ion batteries

摘要

An electrode comprises: (i) an active material composed of a phosphorus compound. In a first condition, the compound has a nominal formula: Li(3-x)E'E''(PO4)3 where x = 0, where at least one of the elements E' and E'' is a metal, and where E' and E'' are the same or different. In a second condition, the compound has a nominal formula as above, where 0 x =3, and where at least one of the elements E' and E'' has an oxidation state higher than that in the phosphorus compound in its first condition. Also claimed is an electrochemical cell consisting of a first electrode and a second counter electrode, where the first electrode comprises a phosphorus compound of nominal formula: Li(3-x)M'M''(PO4)3 where M' and M'' are metallic or semi-metallic elements, and M' and M'' are the same or different. In the case when M' and M'' are the same, they are both transition metals. In the case when M' and M'' are different, at least one is a transition metal. An electrochemical cell consists of a first electrode and a second counter electrode, where the first electrode comprises a phosphorus compound of nominal formula: Li(3-x)E'E''(PO4)3 where E' and E'' are the same or different. In the case when E' and E'' are the same, the element has more than one oxidation state. In the case when E' and E'' are different, they are each independently selected from a group of elements, where at least one of E' and E'' has more than one oxidation state. Further claimed is a method for operating electrochemical cells, by: (a) providing a first electrode (12), comprising a Li-metal-phosphate compound, a second counter electrode (14) and an electrolyte (16) therebetween; (b) electrochemically de-intercalating Li ions from the Li-metal-phosphate compound and transferring the ions to the counter electrode to charge the cell; and (c) electrochemically removing at least a portion of the transferred Li ions from the counter electrode for re-intercalation into the Li-metal-phosphate compound, whereupon electrochemical energy is obtained from the cell during discharge. Another claim is a battery as above, where the Li-metal-phosphate compound is represented by Li(3-x)M'yM''(2-y)(PO4)3 and where, during charge and discharge, the value of x Li ions transferred between the electrode varies as 0+-x+-3.