Search

EP-4738472-A1 - CARBON ADDITIVE WITH A MODIFICATION FOR OR IN A USE FOR A BATTERY'S ELECTRODE AND THE BATTERY

EP4738472A1EP 4738472 A1EP4738472 A1EP 4738472A1EP-4738472-A1

Abstract

Conductive carbon with a modification is used as a conductive additive of a composite electrode for an all-solid-state battery, wherein the modification is a fluorination providing inorganic particles on a carbon surface.

Inventors

  • CASTRO, Laurent
  • GUEGUEN, Aurelie
  • EL KAZZI, MARIO
  • SILLER, Valerie
  • VIGNESH, Ramasamy Hari

Assignees

  • TOYOTA JIDOSHA KABUSHIKI KAISHA

Dates

Publication Date
20260506
Application Date
20241105

Claims (15)

  1. A composite electrode for an all-solid-state battery, comprising an electrode active material, a solid electrolyte and an additive being conductive carbon with a modification, wherein the modification is the presence of inorganic particles on a surface of conductive carbon which comprise F.
  2. The composite electrode according to claim 1, wherein an amount of the additive is 10 weight-% or less of the total weight of the composite electrode.
  3. The composite electrode according to claim 1 or 2, wherein the modification is obtainable by treatment of the surface of conductive carbon with a gas flow of a dry and non-oxidizing gas composed of one or more fluorination compound(s) being a fluoroalkane or a nitrogen fluoride and optionally an inert gas.
  4. The composite electrode according to claim 3, wherein the dry and non-oxidizing gas is purified nitrogen trifluoride.
  5. A composite electrode according to any of claims 1, 2, 3, and 4, wherein the inorganic particles are composed of elements further comprising Si and/or O in addition to F.
  6. The composite electrode according to any of claims 1, 2, 3, 4 and 5, wherein the conductive carbon is selected from at least one of carbon black, carbon nanotubes, a graphene product, a vapor-grown carbon fiber, and a product obtained from ball milling a vapor-grown carbon fiber.
  7. The composite electrode according to any of claims 1, 2, 3, 4, 5 and 6, wherein an X-ray photoelectron spectroscopy of the carbon fiber shows peak intensities corresponding 3 at% or more at a binding energy peak corresponding to F 1s and corresponding 90 at% or more at a binding energy peak corresponding to C 1s.
  8. An all-solid-state battery comprising the composite electrode according to any of claims 1, 2, 3, 4, 5, 6 and 7.
  9. A conductive additive for a composite electrode for an all-solid-state battery, the conductive additive consisting of conductive carbon with a modification, wherein the modification is the presence of inorganic particles on a surface of conductive carbon which comprise F.
  10. The conductive additive according to claim 9, wherein the modification is obtainable by treatment of the surface of conductive carbon with a gas flow of a dry and non-oxidizing gas composed of one or more fluorination compound(s) being a fluoroalkane and/or a nitrogen fluoride and optionally an inert gas.
  11. The conductive additive according to claim 9 or 10, wherein the dry and non-oxidizing gas is purified nitrogen trifluoride.
  12. The conductive additive according to any of claims 9, 10, and 11, wherein inorganic particles are composed of elements further comprising Si and/or O in addition to F.
  13. The conductive additive according to any of claims 9, 10, 11 and 12, wherein the conductive carbon is selected from at least one of carbon black, carbon nanotubes, a graphene product, a vapor-grown carbon fiber, and a product obtained from ball milling a vapor-grown carbon fiber.
  14. The conductive additive according to any of claim 9, 10, 11, 12, and 13, wherein an X-ray photoelectron spectroscopy of the conductive carbon shows peak intensities corresponding 3 at% or more at a binding energy peak corresponding to F 1s and corresponding 70 at% or more at a binding energy peak corresponding to C 1s.
  15. A use of the conductive additive according to any of claims 9, 10, 11, 12, 13, and 14, as a component for a composite electrode for an all-solid-state battery.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention The present disclosure relates to a carbon additive with a modification, its use in an electrode and a related electrode and battery. 2. Description of Related Art All-solid-state batteries are known. Typically, a positive electrode in such a battery is a composite of an electrode active material, a solid electrolyte, and a conductive additive. A known conductive additive is a carbon fiber, e.g., a vapor-grown carbon fiber, in particular the product VGCF-H (Vapor Grown Carbon Fiber) offered at www.resonac.com. Literature 2 shows modifying a vapor-grown carbon fiber with an oxidative acid treatment. Literature 1 shows X-ray photoelectron spectroscopy (XPS) observations on battery components. WO 2022/033820 A1 teaches the fluorination of all-solid-state battery components with fluorocarbon compounds for improving battery performance and durability. The all-solid-state battery components addressed are cathode active, anode active, solid electrolyte materials, and a current collector material. Literature Literature 1: Wu, X.; Villevieille, C.; Novák, P.; El Kazzi, M., Monitoring the chemical and electronic properties of electrolyte-electrode interfaces in all-solid-state batteries using operando X-ray photoelectron spectroscopy. Physical Chemistry Chemical Physics 2018, 20 (16), 11123-11129.Literature 2: Figueiredo, J.L., Serp, P. (2001). Gasification and Surface Modification of Vapor-Grown Carbon Fibers. In: Biró, L.P., Bernardo, C.A., Tibbetts, G.G., Lambin, P. (eds) Carbon Filaments and Nanotubes: Common Origins, Differing Applications?. NATO Science Series, vol 372. In an all-solid-state battery, the solid electrolyte is oxidized during a first battery charging leading to partial degradation of ionic conductivity in the battery (linked with battery cell performances). There is a demand for improved battery cell performance. SUMMARY The object of the present invention is to allow an improvement in battery cell performance. The inventors found that mitigating the oxidation of the solid electrolyte in an all-solid-state battery is possible with a surface modification of a conductive carbon additive, e.g. a VGCF (vapor-grown carbon fiber), as a conductive additive in a composite electrode of the all-solid-state battery. Less oxidation of solid electrolytes in the all-solid-state battery's electrode and the possibility to incorporate more active material and use less solid electrolyte will lead to an increased energy density of the battery cell and are results of this finding. The invention is defined in the claims. The additive according to or used according to the invention or contained in the composite electrode according to the invention is obtainable from a method of modifying a conductive carbon (e.g. a carbon fiber) comprising, converting a pristine conductive carbon into a conductive carbon with a modification. A particular example of a conductive carbon is a pristine carbon fiber obtainable by vapor-growth of a carbon fiber, e.g., the above-mentioned fiber VGCF-H. The converting proceeds under a gas flow of a dry and non-oxidizing gas composed of one or more fluorination compound(s) being a fluoroalkane, in particular fluoroform or carbon tetrafluoride, or a nitrogen fluoride, in particular nitrogen trifluoride, and optionally an inert gas. A reactor and/or fluorination measures as shown in WO 2022/033820 A1, which is herewith incorporated by reference, may be used for the converting. Suitable conditions for the conversion comprise a temperature between 280°C and 480°C for 0.7 to 4.5 hours. The one or more fluorination compound(s) consist preferably of NF3 (nitrogen trifluoride, mp = -26.8°C). Particularly preferred for the converting is an atmosphere of nitrogen trifluoride (as flow gas) and a temperature between 250°C and 450°C, preferably between 350°C and 450°C, for 0.9 to 4.9 hours, preferably 0.9 to 1.5 hours and particularly preferably a non-pressurized gas flow. The conversion is one for obtaining a conductive additive (i.e. preserving at least a significant extent of conductivity of the conductive carbon subjected to the conversion) preferably such that a fluoride-based surface passivation is at least partially added to a conductive carbon without changing the composition of the conductive carbon providing the surface in the conversion. In particular, the modification may be one based on physisorption of a material providing the surface passivation. The aforementioned conversion features may be confirmed by essentially unaffected or poorly affected binding energy peaks corresponding to C 1s in X-ray photoelectron spectroscopy (XPS) and/or particles on the surface in a scanning electron microscope (SEM) observation. SEM may be performed as in Literature 1, incorporated herewith by reference, to confirm the presence of the particles on the surface. Furthermore SEM/EDX (energy dispersive X-ray spectroscopy) may be used to observe the surface, e