CN-122000318-A - Positive electrode material, preparation method and application thereof, and all-solid-state battery

CN122000318ACN 122000318 ACN122000318 ACN 122000318ACN-122000318-A

Abstract

The invention relates to the technical field of batteries, in particular to a positive electrode material, a preparation method and application thereof and an all-solid-state battery. The positive electrode material comprises an inner core and an interface modification layer, wherein the inner core contains a nickel-rich ternary material, the interface modification layer is coated on at least part of the surface of the inner core, and the interface modification layer comprises lithium phosphorus oxide and metal sulfide. The positive electrode material can better reduce the interface impedance of the battery, improve the critical current density and prolong the cycle life.

Inventors

Request for anonymity
Request for anonymity
LI YANTAO
Request for anonymity
Request for anonymity

Assignees

晶核能源(嘉兴)有限公司

Dates

Publication Date: 20260508
Application Date: 20251219

Claims (10)

1. A positive electrode material, characterized by comprising: a core comprising a nickel-rich ternary material; The interface modification layer is coated on at least part of the surface of the inner core, and comprises lithium phosphorus oxide and metal sulfide.
2. The positive electrode material according to claim 1, wherein, The metal sulfide is embedded into the lithium phosphorus oxide in the form of nanometer islands, the grain diameter of the nanometer islands is not more than 5nm, and the mass content of the metal sulfide in the lithium phosphorus oxide is 8% -25%; and/or the inner core is connected with the interface modification layer through a P-S-Ni bond; and/or the thickness of the interface modification layer is 10nm-50nm; and/or the inner core is divided into a bulk region and a near-surface gradient region positioned outside the bulk region, wherein the near-surface gradient region is provided with oxygen vacancies, the concentration of the oxygen vacancies in the near-surface gradient region gradually decreases from the interface of the interface modification layer and the inner core to the bulk region, and the thickness of the near-surface gradient region is 2nm-5nm; And/or the Dv50 particle size of the nickel-rich ternary material is 3-8 mu m.
3. The positive electrode material according to claim 1 or 2, wherein, The chemical general formula of the lithium phosphorus oxide is Li 3 PO 4 ; And/or the chemical general formula of the metal sulfide is Ni a S b , wherein a and b are positive integers corresponding to valence states; And/or the chemical formula of the nickel-rich ternary material is LiNi x Co y Mn z O 2 , wherein x is more than or equal to 0.6, y is more than 0, z is more than 0, and x+y+z=1; and/or the nickel-rich ternary material is a single crystal material.
4. The preparation method of the positive electrode material is characterized by comprising the following steps: S1, constructing an oxygen vacancy site of a nickel-rich ternary material to obtain an oxygen vacancy activating material; s2, ball milling is carried out on the sulfide solid electrolyte and the oxygen vacancy activating material to obtain sulfide composite powder; s3, performing hot press vulcanization reaction on the sulfide composite powder to obtain a positive electrode material; wherein the sulfide solid state electrolyte contains Li, P, S.
5. The method for producing a positive electrode material according to claim 4, wherein, The oxygen vacancy-activating material has an oxygen vacancy concentration of 5% to 10%; And/or in the step S1, carrying out reduction treatment on the nickel-rich ternary material to construct the oxygen vacancy sites, wherein the reduction treatment condition comprises carrying out in a mixed gas containing hydrogen and inert gas, wherein the volume concentration of the hydrogen in the mixed gas is 3-8%, the temperature is 280-320 ℃, and the time is 60-180 min.
6. The method for producing a positive electrode material according to claim 4, wherein, In the step S2, the ball milling is carried out under inert atmosphere, the ball milling rotating speed is 100rpm-800rpm, the ball milling time is 10min-60min, the ball milling medium comprises one or more of zirconia beads, agate beads and steel balls, the diameter of the ball milling medium is 0.1mm-20mm, and the ball-to-material ratio is (1-100): 1; And/or in the step S3, the hot press vulcanization reaction conditions comprise that the hot press vulcanization reaction is carried out under inert atmosphere, the reaction temperature is 330-370 ℃, the mechanical pressure is 40-60 MPa, and the reaction time is 1-3 h; and/or, in the step S3, the reaction temperature in the hot press vulcanization reaction is recorded as a ℃ and the mechanical pressure is recorded as bMPa, and a and b meet the requirement that b is more than or equal to 0.2a-60; And/or the preparation method further comprises cooling after the hot press vulcanization reaction, wherein the cooling method comprises the steps of firstly cooling to 150-250 ℃ at 0.2-0.6 ℃ per minute, then cooling to 60-100 ℃ at 0.8-1.5 ℃ per minute, and finally naturally cooling to room temperature.
7. The method for producing a positive electrode material according to any one of claims 4 to 6, wherein, The chemical formula of the nickel-rich ternary material is LiNi x Co y Mn z O 2 , wherein x is more than or equal to 0.6, y is more than 0, z is more than 0, and x+y+z=1; And/or the Dv50 particle size of the nickel-rich ternary material is 3-8 mu m; and/or the sulfide solid state electrolyte has a chemical formula of Li 6 PS 5 X, wherein X is halogen; and/or the mass ratio of the sulfide solid state electrolyte to the oxygen vacancy-activating material is (5-20): 1.
8. Use of the positive electrode material according to any one of claims 1 to 3, or the positive electrode material prepared by the method for preparing the positive electrode material according to any one of claims 4 to 7, in an all-solid-state battery.
9. An all-solid battery comprising the positive electrode material according to any one of claims 1 to 3, or the positive electrode material produced by the method for producing the positive electrode material according to any one of claims 4 to 7.
10. The all-solid battery according to claim 9, wherein, The all-solid battery further includes a sulfide solid electrolyte.

Description

Positive electrode material, preparation method and application thereof, and all-solid-state battery Technical Field The invention relates to the technical field of batteries, in particular to a positive electrode material, a preparation method and application thereof and an all-solid-state battery. Background All-solid-state batteries employ non-combustible solid-state electrolytes (such as sulfide Li6 PS5 Cl), theoretical energy densities >500Wh/kg, and are expected to fundamentally eliminate the risk of thermal runaway. However, the practical performance is severely limited by the positive electrode/electrolyte interface problem, namely 1. Physical contact degradation is that the solid-solid contact area is limited due to the high rigidity of the material, the void ratio of the contact interface between the positive electrode and the electrolyte is more than 30%, so that the interface impedance is seriously degraded, 2. Process mixing is difficult, and ideally, active substances (such as NCM) are obtained in the positive electrode sheet and fully contacted with the solid electrolyte, and the solid electrolyte can form a continuous ion conducting channel, but in the practical process, various defects are often difficult to avoid, and the structural integrity and the electrochemical performance are influenced. The current method for improving the interface problem of the positive electrode/electrolyte comprises coating, a core-shell structure, compounding, doping and the like, wherein the current main stream solution has serious defects that 1, the wet LiNbO 3 coating technology is used for improving the solid-solid interface contact by means of material flexibility, but the oxidation potential is generally lower than 4.2V, so that cracking occurs after circulation, 2, the positive electrode core-shell structure adopts the combined design of a high-nickel core (such as Ni 83) and a shell LiAlO 2, the interface is directly contacted through structural encapsulation, the core side reaction is caused by shell cracking, and the degradation of the volume expansion rate is seriously caused under the condition of high active material loading, and 3, the compound method which uses polymers such as PEO, PVDF and the like as a buffer layer can be used for improving the solid-solid interface contact by means of material flexibility, but the oxidation potential is generally lower than 4.2V, so that the application of the positive electrode material (such as Li +/Li) which is commonly used at present is difficult to be matched with the high-voltage positive electrode material (such as more than or equal to 4.5V vs), and the application in a high-voltage system is severely restricted. In summary, although various technical paths such as cladding, core-shell, and composite have been widely explored, the existing solutions still have significant drawbacks in terms of coverage, structural integrity, and voltage compatibility. Disclosure of Invention The invention aims to overcome the problems in the prior art and provide a positive electrode material, a preparation method and application thereof and an all-solid-state battery. The positive electrode material can better reduce the interface impedance of the battery, improve the critical current density and prolong the cycle life. In order to achieve the above object, a first aspect of the present invention provides a positive electrode material comprising: a core comprising a nickel-rich ternary material; The interface modification layer is coated on at least part of the surface of the inner core, and comprises lithium phosphorus oxide and metal sulfide. The second aspect of the present invention provides a method for preparing a positive electrode material, the method comprising: S1, constructing an oxygen vacancy site of a nickel-rich ternary material to obtain an oxygen vacancy activating material; s2, ball milling is carried out on the sulfide solid electrolyte and the oxygen vacancy activating material to obtain sulfide composite powder; s3, performing hot press vulcanization reaction on the sulfide composite powder to obtain a positive electrode material; wherein the sulfide solid state electrolyte contains Li, P, S. The third aspect of the invention provides an application of the positive electrode material of the first aspect of the invention or the positive electrode material prepared by the preparation method of the positive electrode material of the second aspect of the invention in an all-solid-state battery. According to a fourth aspect of the present invention, there is provided an all-solid-state battery comprising the positive electrode material according to the first aspect of the present invention or the positive electrode material prepared by the method for preparing the positive electrode material according to the second aspect of the present invention. Compared with the prior art, the invention has at least the following beneficial effects: The positive