COMPOSITE LAYER OF BALLS MADE OF AN ACTIVE MATERIAL Russian patent published in 2021 - IPC B29C70/00 H01M4/02 

FIELD: composite materials.

SUBSTANCE: invention relates to a composite layer for an electrochemical apparatus, in particular, to a composite layer with balls made of an active material, formed from active materials with a large change in the volume during electrochemical reactions. The composite layer comprises multiple balls made of an active material, each of the balls made of an active material includes multiple particles of a first active material, a first electrically conductive material and an internal binder, wherein the particles of the first active material and the first electrically conductive material are adhered by an internal binder, wherein the change in the volume of particles of the first active material during charging and discharging processes is in the range from 15% to 400%; wherein the particles of the first active material are particles of an active material based on silicon or lithium-nickel-manganese cobalt (NMC), and the particles of an active material based on silicon include the entire active material containing silicon, such as elemental silicon or silicon oxide (SiOx); a second electrically conductive material located outside of the balls made of an active material; and an external binder adherein the balls made of an active material and the second electrically conductive material. The elasticity of the internal binder is therein less than the elasticity of the external binder, the internal binder includes a cross-linked polymer selected from polyimide (PI), acrylic resin, epoxy resin or combinations thereof, and the external binder includes a linear polymer selected from polyvinylidene fluoride (PVDF), polyvinylidene fluoride hexafluoropropylene (PVDF-HFP), styrene-butadiene (SBR), sodium- carboxymethylcellulose (CMC) or combinations thereof. The volume content of the first electrically conductive material in the balls made of an active material is therein greater than the volume content of the second electrically conductive material in the total volume of the composite layer, excluding the balls made of an active material.

EFFECT: provided that the ratio of the electrically conductive materials and the binder is maintained, the volume expansion of particles of the active material can be effectively controlled during charging and discharging processes, the problems of voids are solved, the flexibility of the composite layer is maintained and the specific capacitance, electrical conductivity and ion conductivity are improved.

12 cl, 4 dwg, 1 tbl