CN110336006B - Lithium cobaltate cathode material with high structural stability and preparation method thereof - Google Patents

Lithium cobaltate cathode material with high structural stability and preparation method thereof Download PDF

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CN110336006B
CN110336006B CN201910599936.3A CN201910599936A CN110336006B CN 110336006 B CN110336006 B CN 110336006B CN 201910599936 A CN201910599936 A CN 201910599936A CN 110336006 B CN110336006 B CN 110336006B
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lithium cobaltate
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崔光磊
马君
王龙龙
姜丰
虞鑫润
孙兴伟
徐红霞
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Qingdao Institute of Bioenergy and Bioprocess Technology of CAS
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Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a high-structure-stability lithium cobaltate positive electrode material and a preparation method thereof. The anode material has a layered structure formed by alternately arranging a lithium layer, an oxygen layer and a transition metal layer, and the transition metal layer contains a cluster structure; namely, the general formula of the cathode material is: liaCoxMoyMzO2+δIn the formula, a is more than or equal to 0.9 and less than or equal to 1.1, x is more than or equal to 0.8 and less than or equal to 1.0, y is less than or equal to 0 and less than or equal to 0.1, z is more than or equal to 0 and less than or equal to 0.1, and delta is more than or equal to-0.25 and less than or equal to 0.25; wherein the element M is selected from one or more of Na, K, Mg, Al, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Y, Zr, Nb, La, B, F and P. The high-structure-stability lithium cobalt oxide cathode material disclosed by the invention can greatly improve the energy density, coulombic efficiency, cycle performance and safety of a lithium ion battery, and the preparation method of the material is simple and feasible, and is suitable for large-scale production.

Description

Lithium cobaltate cathode material with high structural stability and preparation method thereof
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a high-structure-stability lithium cobaltate positive electrode material and a preparation method thereof.
Background
Lithium ion batteries have become a research hotspot in the fields of portable electronic products, electric tools and electric automobiles due to the advantages of high energy density, high volume density, no memory effect, long service life and the like. In particular to a lithium ion battery which takes lithium cobaltate as the most mainstream anode material, and is a lithium ion battery system which is most widely applied in portable electronic products. This is because lithium cobaltate positive electrode material has high operating voltage (>3.9V), high tap density, high volumetric energy density, high mass energy density and long cycle life, making it an irreplaceable place in high-end portable electronic products. However, with the development of the portable electronic products, the power consumption of the lithium ion battery is greatly increased, which results in that the energy density of the existing cobalt acid lithium battery is difficult to meet the requirement of the electronic products for long standby time. Therefore, development of lithium cobaltate cathode materials with higher energy density becomes a hotspot of development of lithium ion batteries.
Lithium cobaltate has a typical alpha-NaFeO2Structure, hexagonal system, belongs to
Figure BDA0002118864970000011
And (4) space group. Wherein the oxygen ions at the 6c position are in cubic close-packed, the lithium ions at the 3a position and the cobalt ions at the 3b position occupy octahedral voids of the oxygen ions, respectively, and are in a layered arrangement in the (111) crystal plane (as shown in fig. 1). In recent years, the solution to improve the energy density of lithium cobaltate positive electrode materials is to improve the specific discharge capacity by improving the charge cut-off voltage. However, increasing the charge cut-off voltage significantly increases the specific capacity of lithium cobaltate, and also causes structural damage to lithium cobaltate, reducing the cycle life of the battery. This is because, at high cut-off voltage operation, the lithium cobaltate layered structure changes as follows: (1) in the lithium layer, Li-O bonds are broken, so that lithium ions at the position 3a are extracted from crystal lattices, and O ions originally bonded with Li at the position 6c are mutually far away along the c-axis direction of the layered structure due to Coulomb repulsion force; (2) the oxidation state of cobalt ions at the 3b position of the cobalt layer is greatly increased, resulting in a significant shortening of the Co-O bond length, resulting in a shortening of O ions at the 6c position along the c-axis of the layered structure. In general, the degree of remoteness of O ions along the c-axis direction of the layered structure is much greater than the degree of shrinkage. (3) Oxygen evolution occurs during the oxidation of O ions, so that O vacancies occur in the lithium cobaltate layered structure, the number of O in a Co-O coordination polyhedron is reduced, and Co ions are dissolved out of the lithium cobaltate layered structure. Therefore, the resultant force of the lithium layer and the cobalt layer to O ions causes irreversible slippage or distortion of the arrangement of O ions, destroying the cobaltStructural stability of lithium oxide. When discharged, the extracted lithium ions cannot be inserted back into the crystal lattice of lithium cobaltate, thereby reducing the battery life. Furthermore, Co elution and oxygen evolution due to oxidation of O ions reduce battery safety. In order to solve the above problems, many experts or scholars have done a lot of work on how to improve the structural stability of the lithium cobaltate positive electrode material, wherein element doping on different ion sites of lithium cobaltate is one of the main solutions for improving the structural stability of lithium cobaltate. However, in the transition metal layer of the crystal structure of the doped lithium cobaltate, only the chemical bond between the transition metal and the anion (such as oxygen) exists, and the chemical bond between the transition metal and the anion (such as oxygen) changes with the desorption of lithium ions during the charging process, which still causes irreversible slippage and distortion of the oxygen atom layer, and destroys the structural stability of the lithium cobaltate. Chinese scientists report a high specific capacity lithium molybdate anode material Li2MoO3(chem. mater.,2014,26,3256-3262.) indicating the presence of Mo-Mo metal bonds in the transition metal layer of the lattice structure of the lithium molybdate material, wherein these Mo-Mo metal bonds have Mo in the transition metal layer3O13And (4) cluster structure. The Mo-Mo metal bonds can be reversibly broken and formed in the charge and discharge processes without oxygen evolution, and Mo ions can be reversibly transferred between the transition metal layer and lithium ion vacancies of the lithium layer, so that the lithium molybdate material has excellent structural stability, reversibility and safety, and is a high-energy-density lithium ion battery cathode material with great development potential. However, due to Li2MoO3Discharge cut-off voltage (2.0V) and discharge average voltage (C:)<3.5V) is low, and the requirement of consumer electronics products, particularly mobile phones, on the high working voltage of lithium batteries cannot be met.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the defects and shortcomings mentioned in the background technology, and provide a high-structure-stability lithium cobalt oxide positive electrode material with high specific capacity and excellent cycle performance under high voltage and a preparation method thereof.
In order to realize the purpose, the invention adopts the technical scheme that:
a lithium cobaltate positive electrode material with high structural stability is provided, the positive electrode material has a layered structure formed by alternately arranging a lithium layer, an oxygen layer and a transition metal layer, and the transition metal layer contains a cluster structure; namely, the general formula of the cathode material is: liaCoxMoyMzO2+δIn the formula, a is more than or equal to 0.9 and less than or equal to 1.1, x is more than or equal to 0.8 and less than or equal to 1.0, y is less than or equal to 0 and less than or equal to 0.1, z is more than or equal to 0 and less than or equal to 0.1, and delta is more than or equal to-0.25 and less than or equal to 0.25; wherein the element M is selected from one or more of Na, K, Mg, Al, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Y, Zr, Nb, La, B, F and P; preferably, the desired element M is selected from one or more of Mg, Al, Ti, Zr, Nb, La, F.
The element Mo is Mo in a transition metal layer of a lithium cobaltate lattice structure of the anode material3O13In the form of cluster structures, in which Mo is present3O13The cluster structure contains Mo-Mo metal bonds with bond lengths of
Figure BDA0002118864970000021
Mo in the transition metal layer3O13The cluster structure exists in an ordered or disordered form; preferably, Mo of said element Mo3O13The cluster structure exists in the transition metal layer in a disordered form.
The element M is distributed in any one or more layers of a lithium layer, an oxygen layer and a transition metal layer of the lithium cobaltate cathode material. Preferably, the metal element of the element M is located in the lithium layer and/or the transition metal layer, and the non-metal element is located in the oxygen layer. More preferably, the adjustment of the oxidation state of the metal element M is realized by controlling the element proportion, the synthesis atmosphere and the temperature in the preparation process of the material, when the ionic radius of the metal element M is less than or equal to Co3+At an ionic radius of 130%, the metal element M tends to be located in the transition metal layer; when the ionic radius of the metal element M is larger than that of Co3+At an ionic radius of 130%, the metal element M tends to be located in the lithium layer.
Co in the positive electrode material exists basically in a trivalent state, and Mo exists basically in a tetravalent state. Co3+And Mo4+Can be made into the form of powderThe specific capacity, the structural stability and the structural reversibility of the lithium cobaltate positive electrode material are improved, and oxygen evolution and Co dissolution are inhibited.
The anode material and the high polymer material are 90-99.9 parts by mass: 0.1-10 to obtain the core-shell type cathode material. The high polymer material is one or more of Polycyanoacrylate (PECA), poly (N-methyl-malonic acid amide) (PMA), Polymethacrylate (PMMA), Polyacrylonitrile (PAN), polypropylene carbonate (PPC), polyethylene carbonate (PEC), polyethylene carbonate (PVCA) and Polyoxyethylene (PEO).
The preparation method of the lithium cobaltate cathode material comprises the following steps:
a1) according to the general formula of lithium cobaltate cathode material LiaCoxMoyMzO2+δAnd (3) Li: co: mo: m ═ 1.0a-1.05 a: x: y: z preparing a precursor containing lithium, cobalt, molybdenum and M;
b1) synthesizing the precursor obtained in the step a) for 5-24 h at 600-1100 ℃ in an oxidizing or inert atmosphere to perform high-temperature reaction to obtain a sintered product;
c1) and c) carrying out powder treatment on the sintered product obtained in the step b) to obtain the high-voltage lithium cobaltate cathode material containing the cluster structure.
In the above preparation method, the lithium source used in the precursor containing lithium, cobalt, molybdenum and M in step a1) is an oxide or lithium salt of lithium, the cobalt source used is cobalt oxide or cobalt hydroxide or a cobalt salt, the molybdenum source used is molybdenum oxide or molybdenum salt, and the M source used is an oxide or hydroxide or salt of element M.
Or, the preparation method comprises the following steps:
a2) according to the general formula of lithium cobaltate cathode material LiaCoxMoyMzO2+δAnd (3) Li: co: m ═ (0.95a-1.05 a): x: z preparing a precursor containing lithium, cobalt and M;
b2) synthesizing the precursor obtained in the step a) in the air at 600-1100 ℃ for 5-24 h to carry out a first high-temperature reaction;
c2) cooling the material synthesized by the first high-temperature reaction obtained in the step b), and then, according to the ratio of Co: x represents Mo: ratio of y to Li2MoO3Pulverizing and uniformly mixing;
d2) synthesizing the mixture obtained in the step c) for 2-24 h at 600-1100 ℃ in an inert atmosphere to perform a second high-temperature reaction;
e2) and d) performing powder treatment on the material synthesized by the second high-temperature reaction obtained in the step d) to obtain the high-voltage lithium cobalt oxide cathode material containing the cluster structure.
In the preparation method, the precursor containing lithium, cobalt and M in the step a2) is a material obtained by mixing a lithium source, a cobalt source and an M source, or a material obtained by mixing a coprecipitation product of the cobalt source and the M source with the lithium source, or a material obtained by synthesizing gel products of the lithium source, the cobalt source and the M source at 200-500 ℃ in an air atmosphere for 1-24 h and then performing powder treatment;
in the preparation method, at least one element in the precursor containing lithium, cobalt and M in the step a2) is uniformly or gradiently distributed;
in the above preparation method, the lithium source used in the precursor containing lithium, cobalt and M in step a2) is an oxide or lithium salt of lithium, the cobalt source used is cobalt oxide or cobalt hydroxide or a cobalt salt, and the M source used is an oxide or hydroxide or salt of element M.
In the above production method, Li in the step c2)2MoO3Is commercial Li2MoO3Or self-synthesized Li2MoO3。
Or, the preparation method comprises the following steps:
a3) according to the general formula Li of lithium cobaltate cathode materialaCoxMoyMzO2+δAnd (3) medium Li: co: mo: m ═ (1.0a-1.05 a): x: y: z, preparing a precursor containing lithium, cobalt and molybdenum;
b3) synthesizing the precursor obtained in the step a) for 5-24 h at 600-1100 ℃ in an oxidizing or inert atmosphere to carry out a first high-temperature reaction;
c3) cooling the material synthesized by the first high-temperature reaction obtained in the step b), and then, according to the ratio of Co: m ═ x: the proportion of z and the source M are crushed and uniformly mixed;
d3) synthesizing the mixture obtained in the step c) for 2-24 h at 600-1100 ℃ in an oxidizing or inert atmosphere to perform a second high-temperature reaction;
e3) and d) performing powder treatment on the material synthesized by the second high-temperature reaction obtained in the step d) to obtain the high-voltage lithium cobalt oxide cathode material containing the cluster structure.
In the preparation method, the precursor containing lithium, cobalt and molybdenum in the step a3) is a material obtained by mixing a lithium source, a cobalt source and a molybdenum source, or a material obtained by mixing a coprecipitation product of a cobalt source and a molybdenum source with a lithium source, or a material obtained by synthesizing gel products of a lithium source, a cobalt source and a molybdenum source at 200-500 ℃ in an air atmosphere for 1-24 h and then performing powder treatment;
in the preparation method, at least one element in the precursor containing lithium, cobalt and molybdenum in the step a3) is uniformly distributed or gradiently distributed;
in the above preparation method, the lithium source used in the lithium, cobalt and molybdenum containing precursor in step a3) is lithium oxide or lithium salt, the cobalt source used is cobalt oxide or cobalt hydroxide or cobalt salt, the molybdenum source is molybdenum oxide or molybdenum salt,
in the above preparation method, the M source in step c3) is an oxide or hydroxide or salt of element M.
The precursor is a mixture of substances containing several elements; gel products containing several elements are synthesized for 1 to 24 hours at the temperature of between 200 and 500 ℃ in the air atmosphere, and then the materials are obtained by powder treatment; alternatively, a coprecipitation product of elements other than the lithium source is mixed with the lithium source.
The lithium source is an oxide or lithium salt of lithium, the cobalt source is cobalt oxide, cobalt hydroxide or cobalt salt, the molybdenum source is molybdenum oxide or molybdenum salt, and the M source is an oxide or hydroxide or salt of an element M.
The anode material and the high molecular substance are 90-99.9 parts by mass: 0.1-10 to obtain the core-shell type cathode material.
The positive electrode material obtained as described above may be a doped (further, may be an element gradient distribution) and/or coated material having a cluster structure; more preferably, the positive electrode material is a core-shell type material and/or an element gradient distribution material containing a cluster structure, so as to avoid the occurrence of potential interface side reactions at the interface of the electrolyte and the electrode material; the element gradient distribution process is only according to the preparation process, the adding sequence, the adding amount and the synthesis temperature of the materials are controlled, and the core-shell or gradient distribution can be realized.
The material of the invention is mainly based on the following principle: cluster structure Mo3O13The metal-metal bond in the lithium cobaltate anode material can be reversibly broken and formed in the charging and discharging process, the problem of oxygen evolution is avoided, the structural stability and reversibility are improved, the Mo element has electrochemical activity and can provide more specific capacity, and therefore the specific capacity, the coulombic efficiency, the cycle performance and the safety performance of the lithium cobaltate anode material are improved.
The invention has the following technical advantages:
the method can improve the specific capacity, the structural stability and the structural reversibility of the lithium cobaltate cathode material, and improve the energy density, the coulombic efficiency, the cycle life and the safety of the lithium ion battery; the lithium cobaltate positive electrode material has a layered structure formed by alternately arranging a lithium layer, an oxygen layer and a transition metal layer, wherein the transition metal layer contains a cluster structure; when lithium ions are removed from lithium cobaltate crystal lattices, part of cluster structures can be transferred to the lithium layer from the transition metal layer, the degree of separation between the upper oxygen layer and the lower oxygen layer of the lithium layer due to repulsion is inhibited, and the structural stability is improved; the method comprises the following specific steps:
1. according to the invention, the reversibility of the cluster structure of the doping element molybdenum is utilized to improve the structural stability and reversibility of the lithium cobaltate positive electrode material in the charging and discharging processes, so that the cycle performance and the coulombic efficiency are improved.
2. The invention utilizes the high working voltage characteristic of lithium cobaltate to make up Li2MoO3The disadvantage of low working voltage;
3. the invention utilizes the advantages of the electrochemical activity and the non-oxygen evolution of the doping element molybdenum to improve the specific capacity of the lithium cobaltate, thereby being beneficial to improving the energy density and the safety;
3. the element M and the molybdenum are utilized to cooperatively improve the stability and the specific capacity of the lithium cobaltate, and the energy density, the cycle performance and the safety of the lithium cobaltate are further improved.
Drawings
Fig. 1 is a schematic diagram of a lattice structure of lithium cobaltate having a layered structure according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of a cluster structure according to an embodiment of the present invention.
FIG. 3 is an X-ray diffraction analysis pattern of the material prepared in example 1.
FIG. 4 is an expanded X-ray fine structure spectrum of the material prepared in example 1 of the present invention.
FIG. 5 shows the DEMS results of the material prepared in example 1 of the present invention, and the charge cut-off voltage is 4.6V.
FIG. 6 is a TEM photograph of the material prepared in example 8 of the present invention.
FIG. 7 shows the results of the spectrum test of the material prepared in example 9 of the present invention.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects solved by the present invention more apparent, the present invention is described in detail below.
Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention are commercially available or can be prepared by existing methods.
The general formula of the high-structure-stability lithium cobalt oxide cathode material is LiaCoxMoyMzO2+δThe Mo element exists in a transition metal layer of a lithium cobaltate lattice structure in a cluster structure form, and has the function of stabilizing the structure, so that the lithium cobaltate cathode material has higher structural stability and safety. The high-structure-stability lithium cobalt oxide cathode material disclosed by the invention can greatly improve the energy density, coulombic efficiency, cycle performance and safety of a lithium ion battery, and the preparation method of the material is simple and feasible, and is suitable for large-scale production.
Examples
The present invention will be described in further detail with reference to examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the invention.
Example 1：
A cluster structure-containing lithium cobaltate cathode material has a general formula: LiCo0.99Mo0.01O2.005. The anode material is Mo-doped lithium cobaltate anode material.
The preparation method of the cluster structure-containing lithium cobalt oxide positive electrode material of the embodiment includes the following steps:
taking battery-grade lithium carbonate, cobalt hydroxide and molybdenum oxide as raw materials, controlling the element molar ratio of Li to Co to Mo to be 1.05:0.99:0.01, and then placing the raw materials in a ball milling tank to be uniformly mixed to obtain a precursor; putting the uniformly mixed precursor into a muffle furnace for sintering treatment, wherein the temperature of a main sintering temperature zone is 850 ℃, the sintering time is 24 hours, and the sintering atmosphere is air; and crushing, sieving and the like the sintered lithium cobaltate to obtain a product with a general formula: LiCo0.99Mo0.01O2.005The positive electrode material of (1) (see fig. 1, fig. 2, and table 1).
Comparative example 1：
Taking battery-grade lithium carbonate and cobalt hydroxide as raw materials, controlling the element molar ratio of Li to Co to be 1.05:1.00, and then placing the raw materials in a ball milling tank to be uniformly mixed to obtain a precursor; putting the uniformly mixed precursor into a muffle furnace for sintering treatment, wherein the temperature of a main sintering temperature zone is 850 ℃, the sintering time is 24 hours, and the sintering atmosphere is air; crushing and sieving the sintered lithium cobaltate to obtain the product LiCoO2。
The products prepared in example 1 and comparative example 1 were characterized and tested. An X-ray diffraction analysis pattern of the lithium cobaltate cathode material prepared in example 1 is shown in fig. 3, and it can be seen that the lithium cobaltate cathode material contains a lithium cobaltate crystal structure and no other impurity phase exists. FIG. 4 is an expanded X-ray fine structure spectrum of the lithium cobaltate positive electrode material prepared in example 1, in which Mo-Mo metal bonds are visible and the fitted bond length is about
Figure BDA0002118864970000061
Prove Mo3O13The existence of cluster structure. The cell data of the products obtained in example 1 and comparative example 1 are shown in table 1. As can be seen from Table 1, under the high voltage condition of 3.0V-4.6V, the first discharge specific capacity reaches 228.2mAh g-1, and the coulombic efficiency is 97.1%. Compared with comparative example 1, the first discharge specific capacity of the lithium ion battery reaches 201.5mAh g < -1 >, and the coulombic efficiency is 89.9%. The 200-week capacity retention ratio of example 1 was 75.1%, and the 200-week capacity retention ratio thereof was 22.6% as compared with comparative example 1. Fig. 5 shows the DEMS results of the product obtained in example 1, and it can be seen that no oxygen evolution occurred in example 1 upon charging to 4.6V. Therefore, the lithium cobalt oxide with the cluster structure has higher specific capacity, coulombic efficiency and cycle performance, which shows that the cluster structure is favorable for improving the structural stability and reversibility of the lithium cobalt oxide and improving the energy density, cycle performance and safety of the battery.
Example 2:
a cluster structure-containing lithium cobaltate cathode material has a general formula: LiCo0.97Mo0.03O2.015. The anode material is Mo-doped lithium cobaltate anode material.
The preparation method of the cluster structure-containing lithium cobalt oxide positive electrode material of the embodiment includes the following steps:
taking battery-grade lithium carbonate, cobalt hydroxide and molybdenum oxide as raw materials, controlling the element molar ratio of Li to Co to Mo to be 1.05:0.97:0.03, and then placing the raw materials in a ball milling tank to be uniformly mixed to obtain a precursor; putting the uniformly mixed precursor into a muffle furnace for sintering treatment, wherein the temperature of a main sintering temperature zone is 850 ℃, the sintering time is 24 hours, and the sintering atmosphere is air; and crushing, sieving and the like the sintered lithium cobaltate to obtain a product, which is shown in figure 1, figure 2 and table 1).
The cell data of the product obtained in example 2 are shown in table 1. It can be seen that the increase of the Mo doping amount contributes to further improving the specific capacity, coulombic efficiency and cycle performance of the lithium cobaltate.
Example 3:
a cluster structure-containing lithium cobalt oxide positive electrode material has a general formula: LiCo0.95Mo0.05O2.025. The anode material is Mo-doped lithium cobaltate anode material.
The preparation method of the cluster structure-containing lithium cobalt oxide positive electrode material of the embodiment includes the following steps:
taking battery-grade lithium carbonate, cobalt hydroxide and molybdenum oxide as raw materials, controlling the element molar ratio of Li to Co to Mo to be 1.05:0.95:0.05, and then placing the raw materials in a ball milling tank to be uniformly mixed to obtain a precursor; putting the uniformly mixed precursor into a muffle furnace for sintering treatment, wherein the temperature of a main sintering temperature zone is 850 ℃, the sintering time is 24 hours, and the sintering atmosphere is air; and crushing, sieving and the like the sintered lithium cobaltate to obtain a product, which is shown in figure 1, figure 2 and table 1).
The cell data of the product obtained in example 3 are shown in table 1. It can be seen that, with the increase of the Mo doping amount, the specific capacity, the coulombic efficiency and the cycle performance of the lithium cobaltate are further improved.
Example 4:
a cluster structure-containing lithium cobaltate cathode material has a general formula: LiCo0.90Mo0.10O2.05. The anode material is Mo-doped lithium cobaltate anode material.
The preparation method of the cluster structure-containing lithium cobalt oxide positive electrode material of the embodiment includes the following steps:
taking battery-grade lithium carbonate, cobalt hydroxide and molybdenum oxide as raw materials, controlling the element molar ratio of Li to Co to Mo to be 1.05:0.90:0.10, and then placing the raw materials in a ball milling tank to be uniformly mixed to obtain a precursor; putting the uniformly mixed precursor into a muffle furnace for sintering treatment, wherein the temperature of a main sintering temperature zone is 850 ℃, the sintering time is 24 hours, and the sintering atmosphere is air; and crushing, sieving and the like the sintered lithium cobaltate to obtain a product (see figure 1, figure 2 and table 1).
The cell data of the product obtained in example 4 are shown in table 1. It can be seen that the increase in Mo doping amount contributes to the improvement of the specific capacity, coulomb efficiency and cycle performance of lithium cobaltate, but when the Mo doping amount reaches 0.10, the specific capacity is rather reduced than when the Mo doping amount is 0.05.
Example 5:
a cluster structure-containing lithium cobalt oxide positive electrode material has a general formula: LiCo0.97Mo0.02Ti0.01O2.015. The anode material is a Mo and Ti co-doped lithium cobaltate anode material.
The preparation method of the cluster structure-containing lithium cobalt oxide positive electrode material of the embodiment includes the following steps:
using battery grade lithium carbonate, cobalt hydroxide, molybdenum oxide and TiO2The preparation method comprises the following steps of (1) controlling the molar ratio of Li to Co to Mo to Ti to be 1.05:0.97:0.02:0.01, and then uniformly mixing the raw materials in a ball milling tank to obtain a precursor; putting the uniformly mixed precursor into a muffle furnace for sintering treatment, wherein the temperature of a main sintering temperature zone is 850 ℃, the sintering time is 24 hours, and the sintering atmosphere is air; and crushing, sieving and the like the sintered lithium cobaltate to obtain a product (see fig. 1, fig. 2 and table 1).
The cell data of the product obtained in example 5 are shown in table 1. It can be seen that co-doping of Mo and Ti is helpful for improving the specific capacity, coulombic efficiency and cycle performance of lithium cobaltate.
Example 6:
a cluster structure-containing lithium cobaltate cathode material has a general formula: li0.95Na0.05Co0.99Mo0.01O2.005. The anode material is a Mo and Na co-doped lithium cobaltate anode material.
The preparation method of the cluster structure-containing lithium cobalt oxide positive electrode material of the embodiment includes the following steps:
taking battery-grade lithium carbonate, cobalt hydroxide, molybdenum oxide and sodium carbonate as raw materials, controlling the molar ratio of Li to Na to Co to Mo to be 0.95:0.05:0.99:0.01, and then placing the raw materials in a ball milling tank to be uniformly mixed to obtain a precursor; putting the uniformly mixed precursor into a muffle furnace for sintering treatment, wherein the temperature of a main sintering temperature zone is 800 ℃, the sintering time is 15h, and the sintering atmosphere is air; and crushing, sieving and the like the sintered lithium cobaltate to obtain a product (see figure 1, figure 2 and table 1).
The cell data of the product obtained in example 6 are shown in table 1. It can be seen that co-doping of Mo and Na is helpful for improving the specific capacity, coulombic efficiency and cycle performance of lithium cobaltate.
Example 7:
a cluster structure-containing lithium cobaltate cathode material has a general formula: LiCo0.99Mo0.01F0.1O1.955. The cathode material is a Mo and F co-doped lithium cobaltate cathode material.
The preparation method of the cluster structure-containing lithium cobalt oxide positive electrode material of the embodiment includes the following steps:
taking battery-grade lithium carbonate, lithium fluoride and cobalt hydroxide as raw materials, controlling the element molar ratio of Li to Co to F to be 0.95:0.99:0.1, and then placing the raw materials in a ball milling tank to be uniformly mixed to obtain a precursor; putting the uniformly mixed precursor into a muffle furnace for sintering treatment, wherein the temperature of a main sintering temperature zone is 800 ℃, the sintering time is 5 hours, and the sintering atmosphere is air; crushing and sieving the sintered lithium cobaltate, and performing other treatments on the lithium cobaltate and Li according to the element molar ratio of Co to Mo of 0.99:0.012MoO3Placing the materials in a ball milling tank, uniformly mixing, placing the uniformly mixed materials in a muffle furnace for sintering treatment, wherein the temperature of a main sintering temperature zone is 850 ℃, the sintering time is 15h, and the sintering atmosphere is argon; and crushing, sieving and the like the sintered lithium cobaltate to obtain a product (see figure 1, figure 2 and table 1).
While Li was used in the present example2MoO3Is made of commercial Li2MoO4The raw materials are synthesized by self, and the adopted synthesis method is a hydrogen reduction method. Firstly, Li is added2MoO4Grinding for 1H, then at H2Carrying out heat treatment at 650 ℃ in a tubular furnace with an atmosphere of/Ar (10:90v/v) for 12h, cooling along with the furnace, grinding the product to obtain black Li2MoO3And (3) powder.
The cell data of the product obtained in this example 7 are shown in Table 1. It can be seen that co-doping of Mo and F is helpful for improving the specific capacity, coulombic efficiency and cycle performance of lithium cobaltate.
Example 8:
a cluster structure-containing lithium cobalt oxide positive electrode material has a general formula: LiCo0.99Mo0.01O2.005@ PECA @ represents that the material has a core-shell structure, and the core is LiCo0.99Mo0.01O2.005The shell is PECA. The anode material is a Co-modified lithium cobaltate anode material doped with Mo and coated with PECA.
The preparation method of the cluster structure-containing lithium cobalt oxide positive electrode material of the embodiment includes the following steps:
lithium cobaltate cathode material LiCo prepared in example 10.99Mo0.01O2.005Preparing lithium cobaltate material LiCo coated with PECA by adopting an in-situ polymerization method as a raw material0.99Mo0.01O2.005@ PECA, where the components preceding @ are the core material to be coated and the components following @ are the shell material of the coating. First, as Ethyl Cyanoacrylate (ECA): preparing a solution in a closed container with the mass ratio of acetone to acetone being 1:3, and then mixing the solution according to the weight ratio of ECA: adding LiCo as the positive electrode material of lithium cobaltate into the solution at the mass ratio of 1:1000.99Mo0.01O2.005And continuously stirring for 2 hours after the container is closed, then opening the cover of the container, stirring in a fume hood until the solvent is volatilized, finally taking out the materials, drying in an oven at 60 ℃ for 5 hours, and grinding to obtain the product.
The product prepared in example 8 was characterized by transmission electron microscopy, and the results are shown in fig. 6. As can be seen from fig. 6, the surface of lithium cobaltate was uniformly coated with PECA, and the thickness of the coating layer was about 50 nm. The battery data of the product obtained in this example 8 are shown in table 1. It can be seen that the PECA coating is carried out on the basis of Mo doping, which is beneficial to further improving the coulombic efficiency and the cycle performance of lithium cobaltate.
Example 9:
a cluster structure-containing lithium cobaltate cathode material has a general formula: LiCo0.99Mo0.01O2.005@ PECA, core-shell gradient structure, wherein the core is Mo-gradient-doped lithium cobaltate, the content of Mo is gradually reduced from the center of the particle to the surface, and the shell is PECA. The anode material is a lithium cobaltate anode material which is subjected to Mo gradient doping and PECA coating co-modification.
The preparation method of the cluster structure-containing lithium cobalt oxide positive electrode material of the embodiment includes the following steps:
(1) preparing a molybdenum gradient doped cobalt oxide precursor. Firstly, battery-grade cobalt sulfate and ammonium molybdate are taken as raw materials, the molar ratio of Co to Mo is controlled to be 0.985:0.015, and the raw materials are dissolved in deionized water to prepare a salt solution 1 with the concentration of metal ions of 1 mol/L; preparing 2mol/L alkaline solution by taking battery-grade sodium hydroxide as a raw material; ammonia water is used as a raw material, and metal ions are controlled: 1mol/L ammonia water solution is prepared with the molar ratio of the elements of the ammonia being 1: 0.1. Adding equivalent deionized water and ammonia water solution into a reaction kettle, then simultaneously adding the salt solution 1, the alkali solution and the ammonia water solution into the reaction kettle according to a certain flow rate, simultaneously controlling the pH value to be 11.5, stirring at the speed of 500r/min, reacting at the temperature of 50 ℃, and carrying out coprecipitation reaction for 12 hours; and then aging for 12h, washing to neutrality by using deionized water, and drying to obtain the molybdenum-doped cobalt oxide. Then putting the molybdenum-doped cobalt oxide and a certain amount of the ammonia water solution into a reaction kettle, controlling the element molar ratio of Co to Mo to be 0.995:0.005, dissolving in deionized water, and preparing a salt solution 2 with the metal ion concentration of 1 mol/L; simultaneously adding the salt solution 2, the alkali solution and the ammonia water solution into a reaction kettle according to a certain flow rate, simultaneously controlling the pH value to be 11.5, stirring at the speed of 500r/min, reacting at the temperature of 50 ℃, and carrying out coprecipitation reaction for 12 hours; and aging for 12h, washing to neutrality by using deionized water, and drying to obtain the molybdenum gradient-doped cobalt oxide.
(2) Preparing the molybdenum gradient doped lithium cobaltate cathode material. Taking battery-grade lithium carbonate and the molybdenum-gradient-doped cobalt oxide as raw materials, controlling the molar ratio of Li (Co + Mo) to be 1.05:1.0, and then placing the raw materials in a ball-milling tank to be uniformly mixed to obtain a precursor; putting the uniformly mixed precursor into a muffle furnace for sintering treatment, wherein the temperature of a main sintering temperature zone is 850 ℃, the sintering time is 8h, and the sintering atmosphere is air; and crushing, sieving and the like the sintered product to obtain the molybdenum gradient doped lithium cobaltate cathode material.
(3) And (5) coating the surface. Molybdenum gradient doped LiCo cathode material and ECA are taken as raw materials, and the coating method of the embodiment 8 is adopted to carry out coating on the molybdenum gradient doped LiCo0.99Mo0.01O2.005Performing PECA surface coating, wherein ECA: the mass ratio of lithium cobaltate is 1:100, and the product LiCo is obtained0.99Mo0.01O2.005@ PECA, core-shell gradient structure, wherein the core is Mo-gradient-doped lithium cobaltate, the content of Mo is gradually reduced from the center of the particle to the surface, and the shell is PECA.
The product prepared in example 9 was subjected to energy spectrum testing, and the results are shown in FIG. 7. As can be seen from fig. 7, the distribution of Mo element is such that the content gradually decreases from the center of the particle toward the surface. The cell data of the product obtained in this example 9 are shown in Table 1. It can be seen that the co-modified lithium cobaltate prepared by Mo gradient doping and PECA coating has higher specific capacity, coulombic efficiency and cycle performance.
Example 10:
a cluster structure-containing lithium cobaltate cathode material has a general formula: LiCo0.99Mo0.01O2.005@AlF3Core-shell structures, in which the core is LiCo0.99Mo0.01O2.005The shell is AlF3. The anode material is Mo-doped AlF3Coating the co-modified lithium cobaltate cathode material.
The preparation method of the cluster structure-containing lithium cobalt oxide positive electrode material of the embodiment includes the following steps:
lithium cobaltate cathode material LiCo prepared in example 10.99Mo0.01O2.005Is used as a raw material. First, 100ml of 0.01g/ml aluminum nitrate solution was prepared, and then 10g of LiCo, a lithium cobaltate positive electrode material, LiCo, was added0.99Mo0.01O2.005Adding into aluminum nitrate solution, stirring in 50 deg.C water bath, slowly adding 0.01g/ml ammonium fluoride solution 100ml dropwise, stirring for 3 hr, filtering, washing, and drying at 100 deg.C for 2 hr. Drying the obtained productAnd (3) placing the material in a tubular furnace, carrying out heat treatment for 5h at 400 ℃ in a nitrogen atmosphere, and crushing to obtain the product.
The cell data of the product obtained in this example 10 are shown in Table 1. It can be seen that Mo-doped, AlF is comparable to Mo-doped lithium cobaltate3The coating co-modification is beneficial to further improving the specific capacity, the coulombic efficiency and the cycle performance of the lithium cobaltate.
Example 11:
a cluster structure-containing lithium cobalt oxide positive electrode material has a general formula: LiCo0.997La0.001Al0.002O2@Li2MoO3Core-shell structures, in which the core is LiCo0.997La0.001Al0.002O2The shell being Li2MoO3. The anode material is La and Al co-doped Li2MoO3Coating the co-modified lithium cobaltate cathode material.
The preparation method of the cluster structure-containing lithium cobalt oxide positive electrode material of the embodiment includes the following steps:
taking battery-grade lithium carbonate, cobalt hydroxide, lanthanum oxide and aluminum hydroxide as raw materials, controlling the molar ratio of Li to Co to La to Al to be 1.05:0.997:0.001:0.002, and then placing the raw materials in a ball milling tank for uniform mixing to obtain a precursor; putting the uniformly mixed precursor into a muffle furnace for sintering treatment, wherein the temperature of a main sintering temperature zone is 850 ℃, the sintering time is 20h, and the sintering atmosphere is air; crushing and sieving the sintered lithium cobaltate, and then processing according to LiCo0.997La0.001Al0.002O2:Li2MoO3In a mass ratio of 100:5 LiCo0.997La0.001Al0.002O2Uniformly mixing the materials with lithium carbonate and molybdenum oxide in a ball milling tank, putting the uniformly mixed materials into a tubular furnace, and performing high-temperature treatment in an argon atmosphere, wherein the temperature of a main sintering temperature zone is 650 ℃, and the sintering time is 2 hours; and crushing, sieving and the like the sintered lithium cobaltate to obtain the product.
The cell data of the product obtained in this example 11 are shown in Table 1. As can be seen,co-doping of La and Al and Li2MoO3The coated co-modified lithium cobaltate cathode material has high specific capacity and cycle performance.
Example 12:
a cluster structure-containing lithium cobaltate cathode material has a general formula: LiCo0.98Mo0.01Fe0.01O2@LiCo0.9Mg0.05Al0.05O1.975Core-shell structure, the core being LiCo0.98Mo0.01Fe0.01O2The shell is LiCo0.9Mg0.05Al0.05O1.975. The anode material is Mo and Fe co-doped LiCo0.9Mg0.05Al0.05O1.975Coating the co-modified lithium cobaltate cathode material.
The preparation method of the cluster structure-containing lithium cobalt oxide positive electrode material of the embodiment includes the following steps:
taking battery-grade lithium carbonate, cobalt hydroxide, molybdenum oxide and iron oxide as raw materials, controlling the element molar ratio of Li to Co to Mo to Fe to be 1.05:0.98:0.01:0.01, and then placing the raw materials in a ball milling tank to be uniformly mixed to obtain a precursor; putting the uniformly mixed precursor into a muffle furnace for sintering treatment, wherein the temperature of a main sintering temperature zone is 850 ℃, the sintering time is 20h, and the sintering atmosphere is air; crushing and sieving the sintered lithium cobaltate to obtain a first high-temperature reaction product LiCo0.98Mo0.01Fe0.01O2. Then, using battery-grade lithium carbonate, cobalt hydroxide, magnesium oxide and aluminum oxide as raw materials, controlling the element molar ratio of Li to Co to Mg to Al to be 1.05:0.90:0.05:0.05, and controlling LiCo0.98Mo0.01Fe0.01O2:LiCo0.9Mg0.05Al0.05O1.975In a mass ratio of 100:3 LiCo0.997La0.001Al0.002O2Adding, namely placing the materials in a ball milling tank, uniformly mixing, then placing in a muffle furnace for sintering treatment, wherein the temperature of a main sintering temperature zone is 800 ℃, the sintering time is 5 hours, and the sintering atmosphere is air; crushing and sieving the sintered lithium cobaltateAnd (5) carrying out treatment to obtain the product.
The cell data of the product obtained in this example 12 are shown in Table 1. It can be seen that Mo and Fe are codoped and LiCo is added0.9Mg0.05Al0.05O1.975The coated co-modified lithium cobaltate positive electrode material has higher specific capacity, coulombic efficiency and cycle performance.
Example 13:
a cluster structure-containing lithium cobalt oxide positive electrode material has a general formula: LiCo0.9Mo0.05Mg0.05O2The gradient structure has the surface Mo content higher than the bulk phase and the surface Mg content lower than the bulk phase. The cathode material is a Mo and Mg gradient co-doped lithium cobaltate cathode material.
The preparation method of the cluster structure-containing lithium cobalt oxide positive electrode material of the embodiment includes the following steps:
(1) preparing a cobalt oxide precursor doped with Mo and Mg in a gradient manner. Firstly, taking battery-grade cobalt sulfate, ammonium molybdate and magnesium sulfate as raw materials, controlling the element molar ratio of Co to Mo to Mg to be 0.9:0.01:0.09, dissolving the raw materials in deionized water, and preparing a salt solution 1 with the metal ion concentration of 1 mol/L; preparing 2mol/L alkali solution by taking battery-grade sodium hydroxide as a raw material; ammonia water is used as a raw material, and metal ions are controlled: an ammonia aqueous solution of 1mol/L was prepared with an elemental molar ratio of ammonia of 1: 0.1. Adding equivalent deionized water and ammonia water solution into a reaction kettle, then simultaneously adding the salt solution 1, the alkali solution and the ammonia water solution into the reaction kettle according to a certain flow rate, simultaneously controlling the pH value to be 11.5, stirring at the speed of 500r/min, reacting at the temperature of 50 ℃, and carrying out coprecipitation reaction for 12 hours; and then aging for 12h, washing to neutrality by using deionized water, and drying to obtain the molybdenum and magnesium co-doped cobalt oxide. Then putting the molybdenum and magnesium Co-doped cobalt oxide and a certain amount of the ammonia water solution into a reaction kettle, controlling the element molar ratio of Co to Mo to Mg to be 0.9:0.09:0.01, dissolving the cobalt oxide and the Mg in deionized water, and preparing a salt solution 2 with the metal ion concentration of 1 mol/L; simultaneously adding the salt solution 2, the alkali solution and the ammonia water solution into a reaction kettle according to a certain flow rate, simultaneously controlling the pH value to be 11.5, stirring at the speed of 500r/min, reacting at the temperature of 50 ℃, and carrying out coprecipitation reaction for 12 hours; and aging for 12h, washing to neutrality by using deionized water, and drying to obtain the molybdenum and magnesium gradient co-doped cobalt oxide.
(2) Preparing the molybdenum and magnesium gradient co-doped lithium cobaltate cathode material. Taking battery-grade lithium carbonate and the molybdenum-gradient-doped cobalt oxide as raw materials, controlling the molar ratio of Li (Co + Mo + Mg) to be 1.05:1.0, and then placing the raw materials in a ball-milling tank to be uniformly mixed to obtain a precursor; putting the uniformly mixed precursor into a muffle furnace for sintering treatment, wherein the temperature of a main sintering temperature zone is 900 ℃, the sintering time is 6 hours, and the sintering atmosphere is air; and crushing, sieving and the like the sintered product to obtain the molybdenum and magnesium gradient co-doped lithium cobaltate cathode material.
The cell data of the product obtained in this example 12 are shown in Table 1. The Mo and Mg gradient co-doped lithium cobalt oxide cathode material with the surface Mo content higher than that of the bulk phase and the surface Mg content lower than that of the bulk phase has higher specific capacity, coulombic efficiency and cycle performance.
Example 14:
a cluster structure-containing lithium cobalt oxide positive electrode material has a general formula: LiCo0.9Mo0.05Mg0.05O2And in the gradient structure, the surface Mg content is higher than that of a bulk phase, and the surface Mo content is lower than that of the bulk phase. The cathode material is a Mo and Mg gradient co-doped lithium cobaltate cathode material.
The preparation method of the cluster structure-containing lithium cobalt oxide positive electrode material of the embodiment includes the following steps:
(1) preparing a cobalt oxide precursor doped with Mo and Mg in a gradient manner. Firstly, taking battery-grade cobalt sulfate, ammonium molybdate and magnesium sulfate as raw materials, controlling the element molar ratio of Co to Mo to Mg to be 0.9:0.09:0.01, dissolving the raw materials in deionized water, and preparing a salt solution 1 with the metal ion concentration of 1 mol/L; preparing 2mol/L alkali solution by taking battery-grade sodium hydroxide as a raw material; ammonia water is used as a raw material, and metal ions are controlled as follows: 1mol/L ammonia water solution is prepared with the molar ratio of the elements of the ammonia being 1: 0.1. Adding equivalent deionized water and ammonia water solution into a reaction kettle, then simultaneously adding the salt solution 1, the alkali solution and the ammonia water solution into the reaction kettle according to a certain flow rate, simultaneously controlling the pH value to be 11.5, stirring at the speed of 500r/min, reacting at the temperature of 50 ℃, and carrying out coprecipitation reaction for 12 hours; and then aging for 12h, washing to neutrality by using deionized water, and drying to obtain the molybdenum and magnesium co-doped cobalt oxide. Then putting the molybdenum and magnesium Co-doped cobalt oxide and a certain amount of the ammonia water solution into a reaction kettle, controlling the element molar ratio of Co to Mo to Mg to be 0.9:0.01:0.09, dissolving the cobalt oxide and the Mg in deionized water, and preparing a salt solution 2 with the metal ion concentration of 1 mol/L; simultaneously adding the salt solution 2, the alkali solution and the ammonia water solution into a reaction kettle according to a certain flow rate, simultaneously controlling the pH value to be 11.5, stirring at the speed of 500r/min, reacting at the temperature of 50 ℃, and carrying out coprecipitation reaction for 12 hours; and then aging for 12h, washing to neutrality by using deionized water, and drying to obtain the molybdenum and magnesium gradient co-doped cobalt oxide.
(2) Preparing the molybdenum and magnesium gradient co-doped lithium cobaltate cathode material. Taking battery-grade lithium carbonate and the molybdenum-gradient-doped cobalt oxide as raw materials, controlling the molar ratio of Li (Co + Mo + Mg) to be 1.05:1.0, and then placing the raw materials in a ball-milling tank to be uniformly mixed to obtain a precursor; putting the uniformly mixed precursor into a muffle furnace for sintering treatment, wherein the temperature of a main sintering temperature zone is 900 ℃, the sintering time is 6 hours, and the sintering atmosphere is air; and crushing, sieving and the like the sintered product to obtain the molybdenum and magnesium gradient co-doped lithium cobaltate cathode material.
The cell data of the product obtained in this example 12 are shown in Table 1. The Mo and Mg gradient co-doped lithium cobaltate cathode material with the surface Mg content higher than that of the bulk phase and the surface Mo content lower than that of the bulk phase has higher specific capacity, coulombic efficiency and cycle performance, and the Mg gradient co-doped lithium cobaltate cathode material on the surface is more favorable for improving the specific capacity, the coulombic efficiency and the cycle performance of lithium cobaltate than the Mo surface.
Example 15:
a cluster structure-containing lithium cobalt oxide positive electrode material has a general formula: li0.95Mg0.05Co0.95Mo0.05O2.05. The anode material is a Mo and Mg co-doped lithium cobaltate anode material.
The preparation method of the cluster structure-containing lithium cobalt oxide positive electrode material of the embodiment includes the following steps:
taking battery-grade lithium carbonate, cobalt hydroxide and molybdenum oxide as raw materials, controlling the element molar ratio of Li to Co to Mo to be 1.0:0.9:0.05, and then placing the raw materials in a ball milling tank to be uniformly mixed to obtain a precursor; putting the uniformly mixed precursor into a muffle furnace for sintering treatment, wherein the temperature of a main sintering temperature zone is 800 ℃, the sintering time is 15h, and the sintering atmosphere is air; crushing, sieving and the like the sintered lithium cobaltate, uniformly mixing the treated powder and magnesium sulfate in a ball milling tank according to the element molar ratio of Co to Mg of 0.95:0.05, putting the uniformly mixed material into a muffle furnace for sintering treatment, wherein the temperature of a main sintering temperature zone is 850 ℃, the sintering time is 15 hours, and the sintering atmosphere is argon; and crushing, sieving and the like the sintered lithium cobaltate to obtain a product (see figure 1, figure 2 and table 1).
The cell data of the product obtained in this example 15 are shown in Table 1. It can be seen that co-doping of Mo and Mg is helpful for improving the specific capacity, coulombic efficiency and cycle performance of lithium cobaltate.
The materials obtained in the above examples are lithium cobaltate with a layered structure, the lattice structure of which is schematically shown in fig. 1, from top to bottom along the z axis, respectively, oxygen-cobalt-oxygen-lithium-oxygen-cobalt-oxygen layers, wherein oxygen ions at the 6c position are in cubic close packing, lithium ions at the 3a position and cobalt ions at the 3b position respectively occupy octahedral gaps of the oxygen ions, and the cobalt layers and the lithium layers are alternately distributed on both sides of the oxygen layers, and CoO is formed between the cobalt ions of the cobalt layers and the oxygen ions of the upper and lower layers6Octahedrons, which are connected by Co-O covalent bonds.
And Mo is seen in the positive electrode material3O13The cluster structure is schematically shown (figure 2), the cluster structure is formed by connecting three Mo-Mo metal bonds into a triangular structure, and molybdenum ions and oxygen ions are connected into MoO through Mo-O bonds6Octahedra, each MoO6Mo formed between octahedrons by sharing two edges3O13And (4) cluster structure.
TABLE 1
Figure BDA0002118864970000141
Figure BDA0002118864970000151
Table 1 above shows data on batteries according to examples of the present invention and comparative examples; further, the material obtained in the embodiment of the invention is assembled into a CR2032 button cell, and under the test temperature of room temperature, the first cycle charge-discharge multiplying power is 0.1C, the charge-discharge multiplying power in the cycle process is 0.5C, and the charge-discharge voltage range is 3.0V-4.6V.
All documents referred to herein are incorporated by reference into this application as if each were individually incorporated by reference. Furthermore, it should be understood that various changes and modifications of the present invention can be made by those skilled in the art after reading the above teachings of the present invention, and these equivalents also fall within the scope of the present invention as defined by the appended claims.
It is to be understood that within the scope of the present invention, the above-described features of the present invention and those specifically described below (e.g., in the examples) may be combined with each other to form new or preferred embodiments. Not to be reiterated herein, but to the extent of space.

Claims (10)

1. A lithium cobaltate cathode material with high structural stability is characterized in that the cathode material has a layered structure formed by alternately arranging a lithium layer, an oxygen layer and a transition metal layer, and the transition metal layer contains a cluster structure; namely, the general formula of the cathode material is: liaCoxMoyMzO2+δIn the formula, a is more than or equal to 0.9 and less than or equal to 1.1, x is more than or equal to 0.8 and less than or equal to 1.0, y is less than or equal to 0 and less than or equal to 0.1, z is more than or equal to 0 and less than or equal to 0.1, and delta is more than or equal to-0.25 and less than or equal to 0.25; wherein the element M is selected from one or more of Na, K, Mg, Al, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Y, Zr, Nb, La, B, F and P;
the element Mo is Mo in a transition metal layer of a lithium cobaltate lattice structure of the anode material3O13Of cluster structureForm (I) wherein Mo is3O13The cluster structure contains Mo-Mo metal bonds with bond lengths of
Figure FDA0003653993910000011
2. The lithium cobaltate positive electrode material according to claim 1, wherein the Mo is3O13The cluster structure exists in an ordered or disordered form.
3. The lithium cobaltate positive electrode material according to claim 1, wherein the element M is distributed in any one or more of a lithium layer, an oxygen layer, and a transition metal layer of the lithium cobaltate positive electrode material.
4. The lithium cobaltate positive electrode material according to claim 1, wherein the ratio of the positive electrode material to the high molecular substance is, by mass, 90-99.9: 0.1-10 to obtain the core-shell type cathode material.
5. The method of preparing a lithium cobaltate positive electrode material according to claim 1, wherein:
a) according to the general formula of lithium cobaltate cathode material LiaCoxMoyMzO2+δAnd (3) Li: co: mo: m ═ (1.0a-1.05 a): x: y: z, preparing a precursor containing lithium, cobalt, molybdenum and M;
b) synthesizing the precursor obtained in the step a) for 5-24 h at 600-1100 ℃ in an oxidizing or inert atmosphere to perform high-temperature reaction to obtain a sintered product;
c) and c) carrying out powder treatment on the sintered product obtained in the step b) to obtain the high-voltage lithium cobaltate cathode material containing the cluster structure.
6. The method for preparing a lithium cobaltate positive electrode material according to claim 1, comprising the steps of:
a) according to the general formula of lithium cobaltate cathode material LiaCoxMoyMzO2+δAnd (3) Li: co: m ═ 0.95a-1.05 a: x: z, preparing a precursor containing lithium, cobalt and M;
b) synthesizing the precursor obtained in the step a) for 5-24 h at 600-1100 ℃ in air to carry out first high-temperature reaction;
c) cooling the material synthesized by the first high-temperature reaction obtained in the step b), and then, according to the ratio of Co: x represents Mo: ratio of y to Li2MoO3Pulverizing and uniformly mixing;
d) synthesizing the mixture obtained in the step c) for 2-24 h at 600-1100 ℃ in an inert atmosphere to perform a second high-temperature reaction;
e) and d) performing powder treatment on the material synthesized by the second high-temperature reaction obtained in the step d) to obtain the high-voltage lithium cobalt oxide cathode material containing the cluster structure.
7. The method of preparing a lithium cobaltate positive electrode material according to claim 1, wherein:
a) according to the general formula of lithium cobaltate cathode material LiaCoxMoyMzO2+δAnd (3) Li: co: mo: m ═ (1.0a-1.05 a): x: y: z, preparing a precursor containing lithium, cobalt and molybdenum;
b) synthesizing the precursor obtained in the step a) for 5-24 h at 600-1100 ℃ in an oxidizing or inert atmosphere to carry out a first high-temperature reaction;
c) cooling the material synthesized by the first high-temperature reaction obtained in the step b), and then, according to the ratio of Co: m ═ x: the proportion of z and the source M are crushed and uniformly mixed;
d) synthesizing the mixture obtained in the step c) for 2-24 h at 600-1100 ℃ in an oxidizing or inert atmosphere to perform a second high-temperature reaction;
e) and d) performing powder treatment on the material synthesized by the second high-temperature reaction obtained in the step d) to obtain the high-voltage lithium cobalt oxide cathode material containing the cluster structure.
8. The method for preparing a lithium cobaltate positive electrode material according to any one of claims 5 to 7, wherein the precursor is a mixture of substances containing several elements; gel products containing several elements are synthesized for 1 to 24 hours at the temperature of between 200 and 500 ℃ in the air atmosphere, and then the materials are obtained by powder treatment; alternatively, the coprecipitate product of elements other than the lithium source is mixed with the lithium source.
9. The method for producing a lithium cobaltate positive electrode material according to any one of claims 5 to 7, wherein the lithium source is an oxide or lithium salt of lithium, the cobalt source is cobalt oxide, cobalt hydroxide or a cobalt salt, the molybdenum source is molybdenum oxide or a molybdenum salt, and the M source is an oxide or hydroxide or salt of an element M.
10. The method for preparing the lithium cobaltate positive electrode material according to any one of claims 5 to 7, wherein the ratio of the positive electrode material to the high molecular substance is, in parts by mass, 90 to 99.9: 0.1-10, and obtaining the core-shell type cathode material.
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