Methods of making electroactive composite materials for an electrochemical cell

A solvent-free method of making an electroactive composite material for an electrochemical cell, the method comprising:

• introducing a particle mixture into a dry-coating device comprising a rotatable vessel having a wall defining a cavity with an elliptical cross-sectional shape and an elliptical shaped rotor disposed within the cavity, wherein the particle mixture comprises a first particle comprising a first electroactive material that comprises graphite and a second particle comprising a second electroactive material that comprises silicon (Si), wherein the first particle has a first average diameter (R1) that is greater than or equal to about 1 μm to less than or equal to about 100 μm and the second particle has a second average diameter (R2) that is less than or equal to about 5 μm;
• rotating the rotatable vessel at a first speed in a first direction;
• and
• rotating the elliptical shaped rotor at a second speed greater than the first speed in a second direction opposing the first direction, wherein a minimum clearance (C) between the wall of the cavity and the rotor is greater than or equal to a sum of the first average diameter (R1) and two times the second average diameter (R2), so that C≥R1+2R2;
• wherein the particle mixture flows between the wall defining the cavity and the elliptical shaped rotor at the clearance that creates a substantially uniform coating comprising the second electroactive material on one or more exposed surfaces of the first particle.

A method of making an electroactive composite material for an electrochemical cell, the method comprising:

• introducing a particle mixture into a dry-coating device comprising a rotatable vessel having a wall defining a cavity and a rotor disposed within the cavity, wherein the particle mixture includes a first particle having a first average diameter (R1) that includes a first electroactive material comprising a positive electrode material selected from the group consisting of silicon (Si), lithium manganese nickel cobalt oxide (LiNiMnCoO2), and combinations thereof and a second particle having a second average diameter (R2) that includes a second electroactive material selected from the group consisting of graphite, graphene, graphene platelet, and combinations thereof, wherein the first average diameter (R1) is greater than the second average diameter (R2);
• rotating the rotatable vessel at a first speed in a first direction;
• and
• rotating the rotor at a second speed greater than the first speed in a second direction opposite to the first direction, wherein a minimum clearance (C) between the wall of the cavity and the rotor is greater than or equal to a sum of the first average diameter (R1) and two times the second average diameter (R2), so that C≥R1+2R2,
• wherein the particle mixture flows between the wall defining the cavity and the rotor at the clearance so that the rotor exfoliates the second electroactive material to create a substantially uniform coating comprising the second electroactive material on one or more exposed surfaces of the first particle.