Cathodes and electrolytes for rechargeable magnesium batteries and methods of manufacture
The invention relates to Chevrel-phase materials and methods of preparing these materials utilizing a precursor approach. The Chevrel-phase materials are useful in assembling electrodes, e.g., cathodes, for use in electrochemical cells, such as rechargeable batteries. The Chevrel-phase materials have a general formula of Mo 6 Z 8 and the precursors have a general formula of M x Mo 6 Z 8 . The cathode containing the Chevrel-phase material in accordance with the invention can be combined with a magnesium-containing anode and an electrolyte.
1. A method of synthesizing a Chevrel-phase cathode material, comprising:
combining stoichiometric amounts of MZ, MoZ 2 and Mo to form a chemically reactive mixture, wherein M is a metallic element and Z is a chalcogen with or without a presence of oxygen;
charging the mixture into a high energy mechanical milling apparatus;
forming a high energy mechanically milled precursor powder of a formula M x Mo 6 Z 8 , wherein x is a number from 1 to 4; and
removing the metallic element from the high energy mechanically milled precursor powder to form a Chevrel-phase cathode material of a formula Mo 6 Z 8 .
2. The method of claim 1 , wherein Z is selected from the group consisting of sulfur, selenium, tellurium and mixtures thereof.
3. The method of claim 1 , wherein the combining step comprises:
combining stoichiometric amounts of ammonium tetrathiomolybdate, anhydrous copper chloride and N,N dimethylformamide to form a mixture.
4. The method of claim 1 , further comprising:
heating the high energy mechanically milled precursor powder, prior to the removing step.
5. The method of claim 1 , further comprising:
heating the high energy mechanically milled precursor powder;
yielding a precursor material of a formula M 2 Mo 6 Z 8 ;
removing M 2 ions; and
obtaining the Chevrel-phase cathode material of a formula Mo 6 Z 8 .
6. The method of claim 2 , wherein the combining step comprises:
combining stoichiometric amounts of copper (II) selenide, molybdenum, and molybdenum diselenide to form a mixture.
7. The method of claim 1 , wherein the high energy mechanically milled precursor powder is a ball-milled powder.
8. The method of claim 1 , wherein the stoichiometric amounts of MZ, MoZ 2 and Mo are combined in a stainless steel vial having a powder:ball ratio of 1:10.