Carbon Coated Electrochemically Active Powder

An electrochemically active powder comprising particles which contain a core which is provided with a coating layer, whereby the core contains a compound represented by formula LiaMm(XO4)n wherein M comprises at least one transition metal and optionally at least one non-transition metal;

• and X is selected from the group consisting of S, P and Si;
• wherein 0<a≦3.2;
• 1≦m≦2;
• and 1≦n≦3;
• wherein said particles are at least partially coated by said coating layer and whereby the coating layer comprises a carbonaceous material, said carbonaceous material comprising a highly ordered graphite, wherein said highly ordered graphite has a ratio (I1360/I1580) of a peak intensity (I1360) at 1360 cm−1 to a peak intensity (I1580) at 1580 cm−1, obtained by Raman spectrum analysis, of at least 1.5 and at most 3.05.

A method for making a carbon coated electrochemically active powder, said powder comprising particles containing a compound represented by formula LiaMm(XO4)n wherein 0<a≦3.2;

• 1≦m≦2;
• and 1≦n≦3;
• M comprises at least one transition metal and optionally at least one non-transition metal;
• and X is selected from the group consisting of S, P and Si;
• said method comprising:
• i. providing a mixture of the following precursors
• a. a source of Li;
• b. a source of an element M;
• c. a source of an element X;
• and
• d. a source of carbon;
• wherein the sources of elements A, M and X are introduced in whole or in part in the form of compounds having the at least one source element;
• ii. heating up said mixture in a sintering chamber to a sintering temperature of at least 500° C. and sintering said mixture at said sintering temperature for a first period of time, wherein a stream of inert gas is provided to said chamber;
• iii. continuously injecting steam in said sintering chamber before or during the heating up, and before or during the sintering the mixture, for an injection time;
• thereby producing particles containing said compound wherein the particles are at least partially coated with a carbonaceous material containing a highly graphitized carbon;
• and
• iv. cooling said powder.