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CN-116344759-B - Lithium cobalt composite oxide and preparation method and application thereof

CN116344759BCN 116344759 BCN116344759 BCN 116344759BCN-116344759-B

Abstract

The invention provides a lithium cobalt composite oxide and a preparation method and application thereof, and belongs to the technical field of lithium ion batteries. The general formula of the lithium cobalt composite oxide is ：Li c Co 1d e‑ f M d Q e E f O 2 ·r Li a Co 1‑b T b O 4/3 ,(a×r+c)/(1+r)≤1;, the M, Q, E is at least one of Mg, al, ni, mn, Y, la, zr, F, P, B, ti, cu, na, and the T is at least one of Y, al, B, ni, mn. According to the invention, elements in different doping forms are introduced, and the precursor is utilized for in-situ doping, self-doping and cladding, so that the synergistic effect of various elements is utilized, the irreversible phase change of the T-element-containing cobalt substance cladding positive electrode material under high voltage is inhibited, and the structural stability of the positive electrode material is improved, so that the electrochemical performance with good cycle performance under high voltage is realized.

Inventors

  • LI BIN
  • LI CHANGDONG
  • DU RUI
  • RUAN DINGSHAN

Assignees

  • 广东邦普循环科技有限公司
  • 湖南邦普循环科技有限公司

Dates

Publication Date
20260505
Application Date
20230213

Claims (15)

  1. 1. A lithium cobalt composite oxide, characterized in that the general formula of the lithium cobalt composite oxide is: , wherein, r is more than or equal to 0.001 and less than or equal to 0.05, a is more than or equal to 0 and less than or equal to 0.02,0.006, b is more than or equal to 0.025,0.98 and c is more than or equal to 0 and less than or equal to 0.025,0.98 1.12,0.005 d is more than or equal to 0.02,0.002 e is more than or equal to 0.015,0.006 f is more than or equal to 0.025, and (a x r+c)/(1+r) is less than or equal to 1; Each M, Q, E is independently selected from at least one of Mg, al, ni, mn, Y, la, zr, F, P, B, ti, cu, na; the T is at least one of Zr and Al; The preparation method of the lithium cobalt composite oxide comprises the following steps: s1, mixing a Li-containing precursor, an E-doped Co-containing precursor and an M-containing precursor, and sintering to obtain an E-doped and M-doped matrix; s2, mixing the doped substrate prepared in the step S1, the precursor containing Co doped with the element T and the precursor containing the element Q, and sintering to obtain the lithium cobalt composite oxide.
  2. 2. The lithium cobalt composite oxide according to claim 1, wherein M is at least one of Mg, al, ni, mn, Y, la, zr, F, P, B.
  3. 3. The lithium cobalt composite oxide according to claim 1, wherein Q is at least one of Mg, al, ti, cu, Y, la, zr, F, P, B.
  4. 4. The lithium cobalt composite oxide according to claim 1, wherein E is at least one of Mg, al, ti, Y, zr, ni, mn, na, cu, B.
  5. 5. The lithium cobalt composite oxide according to claim 1, wherein a ratio of a sum of molar amounts of the Co, M, Q, E, T elements to a molar amount of the Li element is 0.98 to 1.1:1.
  6. 6. The lithium cobalt composite oxide according to claim 1, wherein (a×r+c)/(1+r) is 0.985 to 0.995.
  7. 7. The method for producing a lithium cobalt composite oxide according to any one of claims 1 to 6, comprising the steps of: s1, mixing a Li-containing precursor, an E-doped Co-containing precursor and an M-containing precursor, and sintering to obtain an E-doped and M-doped matrix; s2, mixing the doped substrate prepared in the step S1, the precursor containing Co doped with the element T and the precursor containing the element Q, and sintering to obtain the lithium cobalt composite oxide.
  8. 8. The method according to claim 7, wherein in the step S1, the molar ratio of Li to Co is adjusted to 1-1.1:1.
  9. 9. The method of claim 8, wherein the molar ratio of Li to Co is 1.03 to 1.07:1.
  10. 10. The method of claim 7, wherein the Co-containing precursor is at least one of Co (OH) 2 、CoCO 3 、Co 3 O 4 .
  11. 11. The method according to claim 7, wherein the Li-containing precursor is at least one of lithium carbonate, lithium hydroxide, lithium nitrate, and lithium chloride.
  12. 12. The method of claim 7, wherein the M element-containing precursor is an oxide of M element.
  13. 13. The method according to claim 7, wherein the Q-element-containing precursor is at least one of an oxide of Q element, a salt of Q element, and an acid of Q element.
  14. 14. The preparation method according to claim 7, wherein in the step S1, the sintering temperature is 900-1100 ℃ and the sintering time is 8-12 h, and the sintering is performed in an oxygen-containing atmosphere, and in the step S2, the sintering temperature is 800-1000 ℃ and the sintering time is 8-12 h, and the sintering is performed in an oxygen-containing atmosphere.
  15. 15. The use of the lithium cobalt composite oxide according to any one of claims 1 to 6 as a positive electrode material for a lithium ion battery.

Description

Lithium cobalt composite oxide and preparation method and application thereof Technical Field The invention relates to the technical field of lithium ion batteries, in particular to a lithium cobalt composite oxide and a preparation method and application thereof. Background The rechargeable lithium ion battery is a new generation green energy storage battery, has the outstanding advantages of high power density, high voltage, high energy density, no memory effect, stable circulation, long service life and the like, and is widely applied to products such as mobile phones, computers, new energy automobiles, intelligent networking, distributed energy storage and the like. Lithium ion batteries are various in types and mainly comprise lithium cobaltate, lithium manganate, lithium iron phosphate, lithium nickelate, lithium nickel cobalt manganate and the like, wherein the lithium cobaltate has the highest theoretical density value, so that the tap density and the compaction density of the lithium cobaltate in practical application are outstanding in the existing materials, and the volume energy density of the lithium cobaltate is superior to that of other anode materials until now. With the continuous and intensive research on lithium cobaltate, the charging voltage of lithium cobaltate gradually increases from 4.2V to 4.35V at that time, and continues to increase to 4.4V, 4.45V or even higher. The use voltage of the first generation lithium cobalt oxide battery is approximately 4.2-4.3V, the use voltage of the second generation lithium cobalt oxide battery is 4.35V in 2013, the use voltages of the third and fourth generation lithium ion batteries which are subsequently developed are respectively 4.4V and 4.45V, and the specific capacity of the second generation lithium cobalt oxide battery is 180-185 mAh/g. Lithium cobaltate is one of the most ideal positive electrode materials in the 3C field, along with the development of electronic technology, 3C products are more frequently updated with new generations, and the 3C products are light, thin and durable, so that the development trend is that the energy density of the lithium ion battery is higher. Volumetric energy density = discharge capacity x discharge voltage plateau x compacted density of lithium ion batteries currently the energy density of lithium cobaltate batteries is increased by increasing the compacted density and cut-off voltage. The method for improving the compaction density through the size particle grading is close to the limit at present, the lifting space is small, the cut-off voltage is improved, the specific discharge capacity is further improved, but more lithium ions are extracted from crystal lattices along with the increase of the charging voltage, the instability of a structure is caused, the lithium extraction degree on the surface of a material is increased, the structural phase change is expanded from the surface of the material to the inside of particles, high-valence cobalt is unstable, the cobalt has strong oxidizing property and is easy to react with electrolyte, the extraction of cobalt is accompanied with the extraction of oxygen, the extraction of oxygen is easy to cause gas production, the factors can shorten the cycle life, the safety is reduced, and the practical application of high-voltage lithium cobalt oxide is affected. The main stream optimization method at present is doping, cladding, synthesis improvement, process optimization and the like. Excessive lithium burning promotes particle growth, but excessive lithium exists in crystal lattices, so that the cycle performance is affected, the gas production risk at high temperature is increased, and the safety performance is not guaranteed. The micro-nano cobalt is used for coating, sintering is performed under the high temperature condition to absorb redundant lithium, residual lithium is reduced, the high temperature safety performance of the material is improved, and gas production is reduced, but under the high voltage condition, the valence state of cobalt is easy to rise along with the increase of the quantity of lithium ions, side reaction is easy to occur with electrolyte, and the cycle performance is attenuated, the capacity and the storage performance are deteriorated. Therefore, it is desirable to provide a lithium cobalt composite oxide material having few interfacial side reactions and good cycle performance at voltages of 4.45V/4.48V/4.50V or even higher. Disclosure of Invention The invention aims to overcome the defects in the prior art and provide the lithium cobalt composite oxide with few interface side reactions and good cycle performance under the voltage of 4.45V/4.48V/4.50V or even higher. Another object of the present invention is to provide a method for producing the above lithium cobalt composite oxide. Another object of the present invention is to provide an application of the above lithium cobalt composite oxide as a positive electrode materia