Composite positive electrode active material for all-solid-state secondary battery, method for manufacturing same, positive electrode, and all-solid-state secondary battery
AssigneeOsaka Prefecture University Public Corporation
InventorsSatoru WATANO, Hideya NAKAMURA
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Abstract
A composite positive electrode active material for an all-solid-state secondary battery containing particles of a positive electrode active material and a sulfide-based solid electrolyte layer coating surfaces of the particles, wherein the composite positive electrode active material has an average roundness that is 1.3 times or more of that of a positive electrode active material at an inner core of the composite positive electrode active material.
Claims13
A composite positive electrode active material for an all-solid-state secondary battery containing particles of a positive electrode active material and a sulfide-based solid electrolyte layer coating surfaces of the particles, wherein the composite positive electrode active material has an average roundness Rave that is 1.3 times or more of that of a positive electrode active material at an inner core of the composite positive electrode active material, wherein the average roundness Rave is defined by following formulae (1) and (2):
- [
- Expression
-
-
- 1
- ]
- Average
-
-
- roundness
-
-
- R
- ave
- =
- 1
- N
- p
-
- ∑
- j
- =
- 1
- N
- p
-
- R
- j
- (
- 1
- )
- R
- j
- =
- median
-
- (
- r
- 1
- r
- A
- ,
- r
- 2
- r
- A
-
-
- …
-
-
- r
- n
- r
- A
- )
- (
- 2
- )
- wherein Np is the number of measured particles;
- Rj is the roundness of individual particle;
- median( ) is the median of the numerical values in the brackets;
- r1, r2 . . . rn are respectively the curvature radius of each projection in a two-dimensional projected figure of a particle measured;
- n is the total number of the projections of which curvature radii are measured;
- and rA is the circle equivalent radius of a particle measured.
A positive electrode for an all-solid-state secondary battery, formed with a composite positive electrode active material containing particles of a positive electrode active material and a sulfide-based solid electrolyte layer coating surfaces of the particles, wherein a value obtained by multiplying a contact ratio calculated from a cross-sectional image of the positive electrode by an area occupancy ratio is 40% or more,
- wherein the contact ratio is a percentage of the length of an interface at which the positive electrode active material contacts the solid electrolyte layer relative to the length of an interface of the positive electrode active material;
- and the area occupancy ratio is an area occupancy ratio of the positive electrode active material.
Dependencies are inferred from the claim text.