| CPC H01M 4/0435 (2013.01) [H01M 4/666 (2013.01); H01M 4/667 (2013.01)] | 9 Claims |
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1. A method of producing an electrode sheet including a current collecting foil having a surface on which an electrode mixture layer is provided, the method comprising:
heating, before pressing, the electrode sheet including the current collecting foil and the electrode mixture layer formed of composite particles composed of active material particles and binder particles to soften or melt the binder particles contained in the electrode mixture layer, in which each of the binder particles has a smaller diameter than each of the active material particles so that a plurality of the binder particles bind to a surface of each of the active material particles; and
roll-pressing the heated electrode sheet in the heating between a first roll and a second roll to compress the electrode mixture layer in a thickness direction, so that the active material particles are bonded to each other and the electrode mixture layer is bonded to the surface of the current collecting foil through the softened or melted binder particles,
wherein
the roll-pressing includes pressing the electrode sheet by setting a temperature of an outer peripheral surface of the first roll with which an outer surface of the electrode mixture layer of the electrode sheet contacts lower than a softening temperature of the binder particles to reduce an adhesive strength of the binder particles in the electrode mixture layer to the first roll to be lower than an adhesive strength of the binder particles to the current collecting foil, and
the method further comprises, after the electrode sheet is roll-pressed in the roll-pressing, feeding the electrode sheet by a fixed distance along the outer peripheral surface of the first roll while maintaining the outer surface of the electrode mixture layer in contact with the outer peripheral surface of the first roll, and then separating the electrode sheet from the outer peripheral surface of the first roll, and
the fixed distance by which the electrode sheet is fed along the outer peripheral surface of the first roll is determined based on an acute angle at which the electrode sheet is wound around the outer peripheral surface of the first roll from a point where the electrode sheet contacts the outer peripheral surface of the first roll to a point where the electrode sheet separates from the outer peripheral surface of the first roll.
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