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CN-115911297-B - Double-coated nickel ternary positive electrode material and preparation method thereof

CN115911297BCN 115911297 BCN115911297 BCN 115911297BCN-115911297-B

Abstract

The invention provides a double-coated nickel ternary positive electrode material and a preparation method thereof, wherein the preparation raw material comprises a nickel ternary material, a coating layer coated on the surface of the nickel ternary material, a fast ion conductor of boride and an alloy boride are included in the coating layer, the fast ion conductor of boride is selected from one or more of LiBO 2 、Li 2 B 4 O 7 、Li 3 BO 3 and H 3 BO 3 , the content of the fast ion conductor of boride in the nickel ternary material is more than 0 and less than or equal to 1%, and the content of the alloy boride in the nickel ternary material is more than 0 and less than or equal to 0.5%. The boride fast ion conductor exists on the surface of the positive electrode material in a glass shape after being heated, primary particles are bonded together, ionic and electronic conductivity is effectively improved, and in the circulation process, the boride fast ion conductor and the boride fast ion conductor have the advantages of better capacity exertion, capacity retention rate, lower DCR growth rate and better gas production performance in the storage process.

Inventors

  • SUN GUOZHENG
  • YU JIAN
  • WANG ZUNZHI
  • QI HONGLIANG
  • LUO SHUAI

Assignees

  • 宁波容百新能源科技股份有限公司

Dates

Publication Date
20260508
Application Date
20220930

Claims (7)

  1. 1. The double-coated nickel ternary cathode material is prepared from the following raw materials in percentage by weight; And a coating layer coated on the surface of the nickel ternary material; a fast ion conductor including boride and alloy boride in the coating layer; The fast ion conductor of the boride is selected from one or more of LiBO 2 、Li 2 B 4 O 7 、Li 3 BO 3 and H 3 BO 3 , and is coated on the surface of the nickel ternary positive electrode material in a glassy state; The content of the boride fast ion conductor in the nickel ternary material is more than or equal to 0.2% and less than or equal to 0.8%, and the content of the alloy boride in the nickel ternary material is more than or equal to 0.1% and less than or equal to 0.4%; the nickel ternary material has a general formula shown in a formula I: li z Ni x Co y A 1-x-y O 2 formula I; 0.7≤x≤0.9,0.05≤y≤0.3,0.95≤z≤1.07;x+y<1; The A is selected from one or more of Mn, al, ta, ti, nb, ge, Y, nb, W, zr, B, ce, ca, V, si, sr, mg and Mo.
  2. 2. The double-coated nickel ternary positive electrode material according to claim 1, wherein a mass ratio of the alloy boride located at the surface layer of the nickel ternary material to the alloy boride penetrating into the interior of the nickel ternary material is 2 or more.
  3. 3. The double-coated nickel ternary positive electrode material of claim 1, wherein the mass ratio of fast ion conductor to alloy boride of the boride is greater than 2.
  4. 4. The double-coated nickel ternary cathode material of claim 1 or 2, wherein the alloy boride is selected from one or more of ZrB 2 、MgB、CaB 6 、TiB 2 、NiB 2 、SiB 6 、AlB 2 、MnB 2 、NbB 2 、VB 2 、MoB、WB、TaB 2 and CoB.
  5. 5. The double-coated nickel ternary positive electrode material according to claim 1, wherein the molar content of nickel in the nickel ternary material is 60-94%.
  6. 6. A method for preparing the double-coated nickel ternary cathode material according to any one of claims 1-5, comprising the following steps: Ball milling the nickel ternary material, the alloy boride and the fast ion conductor of the boride to obtain a ball grinding material; and sintering the ball abrasive in an oxygen atmosphere to obtain the double-coated nickel ternary anode material.
  7. 7. The method according to claim 6, wherein the temperature is raised from room temperature to a temperature required for sintering at a temperature-raising rate of 1.8 to 2.3 ℃ per minute; The sintering temperature is 280-350 ℃, and the sintering heat preservation time is 9-12 h.

Description

Double-coated nickel ternary positive electrode material and preparation method thereof Technical Field The invention belongs to the technical field of anode materials, and particularly relates to a double-coated nickel ternary anode material and a preparation method thereof. Background Currently, a high-nickel ternary lithium ion battery is widely paid attention to as a green battery with high energy density, no memory effect, high working voltage platform and excellent performance, but as the interface of the high-nickel ternary lithium ion battery is easy to be corroded by electrolyte to fail and the ternary surface is easy to generate a passivation layer to reduce capacity and circulation, the modification of the surface of the high-nickel ternary material is particularly important, but at present, a coating substance is subjected to disproportionation reaction in the high-temperature storage or circulation process, mn is dissolved to cause the change of a positive electrode structure, meanwhile, the dissolved Mn passes through CEI and SEI films to damage the stability of a negative electrode to cause gas production and capacity attenuation. The cathode material for the lithium battery comprises a lithium metal composite oxide with a layered structure and a boron coating layer formed on the surface of the lithium metal composite oxide, wherein the boron coating layer comprises boron and/or boride, and the boride is lithium borate and/or boron oxide. The above patent uses the lithium borate fast ion conductor structured on the ternary surface to effectively improve the material capacity, but the coating layer can improve the interface stability to a certain extent by bonding primary particles, isolating the positive electrode material and electrolyte, but the fast ion conductor does not have excellent corrosion resistance, and the positive electrode manganese can undergo disproportionation reaction to damage the positive electrode and negative electrode interface by increasing the cycle times, so that the cycle attenuation and capacity reduction are caused. Therefore, it is urgent to search for a stable coating substance to improve the cycle stability of the battery. Disclosure of Invention In view of the above, the present invention aims to provide a double-coated nickel ternary positive electrode material and a preparation method thereof, and a battery prepared from the ternary positive electrode material has excellent cycle stability. The invention provides a double-coated nickel ternary anode material, which is prepared from the following raw materials in parts by weight; And a coating layer coated on the surface of the nickel ternary material; a fast ion conductor including boride and alloy boride in the coating layer; The fast ion conductor of the boride is selected from one or more of LiBO 2、Li2B4O7、Li3BO3 and H 3BO3; the content of the boride fast ion conductor in the nickel ternary material is more than 0 and less than or equal to 1%; the alloy boride accounts for more than 0 and less than or equal to 0.5 percent of the nickel ternary material. The preparation raw materials of the double-coated nickel ternary cathode material provided by the invention comprise a nickel ternary material, wherein the nickel ternary material preferably has a general formula shown in a formula I: li zNixCoyA1-x-yO2 formula I; 0.6≤x≤1,0≤y≤0.4,0.9≤z≤1.1;x+y<1; the A is selected from one or more of Mn, al, ta, ti, nb, ge, Y, nb, W, zr, B, ce, ca, V, si, sr, mg and Mo; In the invention, the value of x is preferably 0.7-0.9, more preferably 0.8-0.85, the value of y is preferably 0.05-0.3, more preferably 0.1-0.2, and the value of z is preferably 0.95-1.07, more preferably 0.98-1.03. In a specific embodiment, the nickel ternary material is Li 1.03Ni0.83Co0.12Mn0.05O2. In the invention, the molar content of nickel in the nickel ternary material is 60-94 mol%, preferably 70-90%, more preferably 80-85%, and in a specific embodiment, the nickel ternary material is preferably a nickel ternary material prepared by a continuous method. The nickel ternary material is in a sphere-like shape, wherein a radius of 2/3 of the center of the circle outwards is defined as an inner part, and the rest radius of 1/3 is defined as an outer layer. The preparation raw materials of the double-coated nickel ternary positive electrode material comprise a coating layer coated on the surface of the nickel ternary material, wherein the coating layer comprises a boride fast ion conductor and an alloy boride. In the present invention, the fast ion conductor of the boride is selected from one or more of LiBO 2、Li2B4O7、Li3BO3 and H 3BO3. The fast ion conductor of boride is coated on the surface of the nickel ternary positive electrode material in a glassy state. In the invention, the alloy boride has strong oxidation resistance and stable chemical property, and the introduction of the alloy boride can stabilize the surface interface of the nickel ternar