CN-122025572-A - Ternary positive electrode material, preparation method thereof and solid-state battery

CN122025572ACN 122025572 ACN122025572 ACN 122025572ACN-122025572-A

Abstract

The application discloses a ternary positive electrode material, a preparation method thereof and a solid-state battery. The solid-state battery ternary positive electrode material comprises a core, a first coating layer and a second coating layer, wherein the core comprises a ternary positive electrode material with a chemical formula of LiNi x Co y N z M 1‑x‑y‑z O 2 , N is Mn or Al, M is at least one of Li, na, B, mg, al, ni, fe, mn, K, ca, co, V, cr, cu, zn, zr, nb, sr, sn, la, ce, pr, nd, sm, eu, gd, tb, dy, ho, er, tm, yb, lu, x is 0.8< x <1, y is 0.2, z is 0.2, x+y+z is less than or equal to 1, the first coating layer contains Al, ta and Mg elements, and the second coating layer contains Ti and Nb elements. The application solves the core technical problems of unstable interface, poor structure/heat stability, high interface impedance and the like inherent in the high-nickel positive electrode material in the solid-state battery by constructing the composite structure with the high-nickel ternary material as the inner core, the functionalized Al-Ta-Mg layer as the inner coating layer and the Ti-Nb layer as the outer coating layer.

Inventors

CHEN YIMENG
YU QINGJIANG
HAN JINLONG
JIANG KECHENG
YU HONGJIANG

Assignees

江苏正力新能电池技术股份有限公司

Dates

Publication Date: 20260512
Application Date: 20251230

Claims (10)

1. A ternary positive electrode material is characterized by comprising an inner core, a first coating layer and a second coating layer from inside to outside; The inner core comprises a ternary positive electrode material with a chemical formula of LiNi x Co y N z M 1-x-y-z O 2 , wherein N is Mn or Al, M is at least one of Li, na, B, mg, al, ni, fe, mn, K, ca, co, V, cr, cu, zn, zr, nb, sr, sn, la, ce, pr, nd, sm, eu, gd, tb, dy, ho, er, tm, yb, lu, x is more than or equal to 0.6 and less than or equal to 1, y is more than or equal to 0.2, z is more than or equal to 0.2, and x+y+z is more than or equal to 1; the first coating layer contains an Al element, a Ta element and an Mg element; The second cladding layer contains Ti element and Nb element.
2. The ternary cathode material according to claim 1, wherein the molar ratio of the Al element, the Ta element and the Mg element is 5-20:2-8:1-5, and the molar ratio of the Ti element and the Nb element is 1:0.5-3.
3. The ternary cathode material of claim 1, wherein the first coating layer has a thickness of 2-5nm and the second coating layer has a thickness of 3-10nm.
4. The ternary cathode material of claim 1, wherein the D50 of the ternary cathode material in the core is 3-6 μm.
5. The preparation method of the ternary positive electrode material is characterized by comprising the following steps of: A. Adding the ternary positive electrode material into the first coating liquid to perform a first coating reaction to obtain a ternary positive electrode material with a first coating layer; B. Dispersing the ternary positive electrode material with the first coating layer in lithium salt solution, and carrying out microwave heating; C. and immersing the material heated by microwaves into the second coating liquid to carry out a second coating reaction, thus obtaining the ternary anode material with the first coating layer and the second coating layer.
6. The method of manufacturing according to claim 5, wherein: the Al source comprises at least one of AlCl 3 ·6H 2 O、Al 2 (SO 4 ) 3 and aluminum isopropoxide; The Ta source comprises at least one of Ta (OEt) 5 、TaF 5 、LiTaO 5 ; The Mg source comprises Mg (at least one of NO 3 ) 2 , magnesium acetylacetonate, mgSO 4 ; the Ti source comprises at least one of Ti (OC 4 H 9 ) 4 、Ti(OC 3 H 7 ) 4 、TiCl 4 ; The Nb source comprises Nb (at least one of OC 2 H 5 ) 5 、NbCl 5 ).
7. The method of preparing a coating solution according to claim 5, wherein in step A, the preparation method of the first coating solution comprises the steps of dissolving an Al source, a Ta source and a Mg source in a solvent, adding a complexing agent, dispersing, and adjusting the pH of the first coating solution to 4-5 during the dispersing process, wherein the complexing agent comprises at least one of citric acid, gluconic acid, sodium alginate and ethylenediamine tetraacetic acid.
8. The method according to claim 5, wherein in the step B, the lithium salt contains at least one of Li 3 PO 4 、Li 2 CO 3 、LiOH、LiNO 3 , and the microwave heating comprises a first stage of heating at 200W for 3 to 5min, a second stage of heating at 500W for 3 to 5min, and a third stage of heating at 300W for 2 to 4min.
9. The method according to claim 5, wherein after the step C, a lithium salt is used as an evaporation source, the anode material after the second coating reaction is subjected to chemical vapor deposition in an inert atmosphere, the lithium salt is at least one of Li 3 PO 4 、Li 2 CO 3 、LiOH、LiNO 3 , and the temperature of the chemical vapor deposition is 150-350 ℃ for 2-5 hours.
10. A solid-state battery comprising the ternary cathode material according to any one of claims 1 to 4, or the ternary cathode material produced by the production method according to any one of claims 5 to 9.

Description

Ternary positive electrode material, preparation method thereof and solid-state battery Technical Field The application belongs to the technical field of solid-state batteries, and particularly relates to a ternary positive electrode material, a preparation method thereof and a solid-state battery. Background With the rapid development of new energy automobiles, portable electronic devices and large-scale energy storage systems, higher and higher requirements are being placed on the energy density, safety, cycle life and reliability of lithium ion batteries. The traditional lithium ion battery adopts liquid organic electrolyte as an ion transmission medium, and has the outstanding problems of flammability, explosiveness, high leakage risk, poor high-temperature performance, limited compatibility with high-voltage positive electrode materials and the like although the technology is mature and the energy density is high, and particularly has outstanding potential safety hazards in high-safety requirement scenes such as electric automobiles, energy storage power stations and the like. The solid-state battery adopts the solid electrolyte to replace the traditional liquid electrolyte, fundamentally solves the problems of electrolyte leakage, combustion, corrosion and the like, has higher safety, potential higher energy density and wider working temperature range, and is an important development direction of the next-generation high-specific-energy battery system. However, the performance of the solid-state battery depends not only on the intrinsic characteristics of the solid-state electrolyte, but also on the interface properties between the positive electrode material and the solid-state electrolyte, which are one of the key factors determining the cycle stability, rate performance and overall energy efficiency thereof. Ternary cathode materials, such as LiNi xCoyMn1-x-yO2 (NCM, x≥0.6) or LiNi xCoyAl1-x-yO2 (NCA), have become the dominant cathode materials for current high energy density lithium ion batteries due to their high specific capacity (150-220 mAh/g), higher operating voltage plateau and good energy density, and are considered as important candidate systems for solid state battery cathode materials. However, when such materials are used in solid state batteries, there are several key challenges in that (1) the interfacial side reaction is serious, the ternary positive electrode material generally has high surface activity, particularly under high pressure (> 4.3V), surface oxygen is easy to precipitate out, chemical reaction is carried out on the ternary positive electrode material and solid electrolyte (particularly sulfide electrolyte) to lead to electrolyte decomposition, gas generation and interfacial impedance rise, and the conventional liquid electrolyte can passivate the positive electrode surface to a certain extent, and the solid electrolyte lacks such self-repairing capability, so that the interface is difficult to recover once instable. (2) Poor solid-solid contact, poor interface wettability, difficulty in forming close physical contact, poor ion transmission channel, and capacity change (expansion/contraction) of the positive electrode material caused by lithium ion deintercalation in the circulation process, further aggravation of interface separation and contact deterioration, and increase of polarization and reduction of rate capability. (3) The high-nickel ternary material has unstable structure and short cycle life, is easy to change from a layered structure to spinel or rock salt phase in the cycle process, particularly causes collapse of a crystal structure and loss of electrochemical active sites under high-voltage and high-temperature conditions, and takes a crystal boundary as a weak link in the material, so that cracks are easy to generate in the cycle process, and capacity attenuation and interface failure are accelerated. (4) The electrolyte has poor chemical/electrochemical compatibility with solid electrolytes, different types of solid electrolytes (such as sulfides, oxides and polymers) have different requirements on the chemical stability of the cathode material, for example, sulfide electrolytes are very sensitive to moisture and the activity of oxygen on the surface of the cathode and are easy to cause adverse reactions, and oxide electrolytes are stable but have poor wettability with a high-nickel cathode and weak interface ion conduction capability. In summary, the existing anode material modification technology still has obvious defects in the aspects of interface stability, ion transmission efficiency, structural reliability, process suitability and the like, and is difficult to meet the comprehensive performance requirements of high-safety and high-energy-density solid-state batteries on anode materials. Disclosure of Invention The application aims to provide a ternary positive electrode material of a solid-state battery, a preparation method of the ternary positi