Method of manufacturing composite electrodes

A method of manufacturing a composite positive electrode for an electrochemical cell that cycles lithium ions, the method comprising the following steps:

• (a) introducing a solvent mixture comprising a polar aprotic solvent and a binder into a screw extruder, wherein the polar aprotic solvent comprises γ-valerolactone, dihydrolevoglucosenone, or a combination thereof, and wherein the binder comprises polyvinylidene fluoride or a copolymer thereof;
• (b) introducing electroactive material particles and an electrically conductive agent into the solvent mixture in the screw extruder to form an electrode precursor mixture having a solids content of, by weight, greater than or equal to about 80%, the electroactive material particles comprising at least one transition metal oxide;
• (c) discharging the electrode precursor mixture from the screw extruder and depositing the electrode precursor mixture on a surface of a metal substrate to form an electrode precursor layer on the metal substrate, the electrode precursor layer having a facing surface that faces away from the metal substrate;
• (d) applying a release film to the facing surface of the electrode precursor layer to form a laminate structure including the metal substrate, the electrode precursor layer, and the release film;
• (e) calendaring the electrode precursor layer by passing the laminate structure between a first set of rollers to adhere the electrode precursor layer to and uniformly distribute the electrode precursor layer over the metal substrate;
• (f) removing the release film from the facing surface of the electrode precursor layer;
• (g) drying the electrode precursor layer to remove the solvent from the electrode precursor layer and form a solid electrode layer including the electroactive material particles, the electrically conductive agent, and the binder on the surface of the metal substrate;
• and
• (h) calendaring the solid electrode layer by passing the solid electrode layer and the metal substrate between a second set of rollers to consolidate the electroactive material particles, the electrically conductive agent, and the binder in the solid electrode layer and form the composite positive electrode.