A Li3Al 1-x M x High-nickel layered oxide positive electrode material coated with F6 layer and preparation method

Abstract

The application provides a Li3Al 1‑x M x The application provides a high-nickel layered oxide positive electrode material coated with a F6 layer and a preparation method, wherein the high-nickel layered oxide is LiNi x1 Co y1 Mn 1‑x1‑y1 O2, M is one or more of Mg, Fe, Cr, La, Ce and Y, 0 < x ≤ 0.1, and the coating layer has high conductivity; in the preparation, the high-nickel layered oxide powder is added into a mixed aqueous solution of metal salt, lithium salt, ammonium fluoride and aluminum salt, the molar ratio of the lithium salt, the ammonium fluoride and the aluminum salt is 3:6:(0.9-1), the metal salt is one or more of magnesium salt, iron salt, chromium salt, lanthanum salt, cerium salt and yttrium salt, the mixed system is stirred, and then centrifuged and dried in sequence to obtain a precursor; the precursor is subjected to high-temperature calcination treatment at 300-800 DEG C under a protective atmosphere, and the electrochemical performance of the high-nickel layered oxide of the high-nickel ternary lithium ion battery positive electrode material under high pressure can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lithium ion batteries, in particular to a Li3Al 1-x M x F6-layer high-nickel layered oxide positive electrode material and preparation method. BACKGROUND

[0002] In recent years, the environmental problems caused by the use of traditional fossil fuels have attracted much attention, so new energy vehicles have replaced current fuel vehicles, bringing new opportunities for the development and application of lithium ion batteries, and higher requirements for energy density, service life, safety and cost. At present, the research and development of new lithium battery materials, battery structure design, battery performance improvement and battery cost control have become the key technologies for the development of lithium ion batteries in the future. Among them, the positive electrode material has a crucial influence on the safety performance, cycle performance and energy density of lithium ion batteries. Therefore, high-performance positive electrode material is one of the important directions in the field of lithium ion batteries.

[0003] Ternary positive electrode material LiNi x Co y Mn z O2(NCM) is considered to be the most promising high-performance positive electrode material candidate due to its high energy density and rate performance. At present, the development direction of ternary materials is to improve the working voltage, but there are still many serious problems with ternary materials under high voltage, such as the short service life of the battery caused by the deterioration of the bulk structure and the deterioration of the interface environment of the ternary positive electrode material under high voltage; and the stability is poor and the capacity decay is serious, which restricts the application of the material.

[0004] One or more methods such as structural modification of the secondary agglomerate particles of the high-voltage ternary positive electrode material, doping other elements in the layered structure, coating a stable thin film layer on the surface of the material, and adjusting the excellent high-voltage electrolyte can achieve the purpose of alleviating and inhibiting the serious problems of high-voltage ternary materials. Among them, surface coating as one of the most common modification methods can physically block the direct contact of the electrode active material with the electrolyte, which is conducive to inhibiting the decomposition of the electrolyte, reducing the dissolution of active transition metal ions in the electrode material, and weakening the interface side reaction. For example, patent CN 112366297 A discloses a surface coating modification method for high-nickel ternary positive electrode material, which adopts a wet chemical method and high-temperature sintering to prepare a layered high-voltage-resistant positive electrode material with a molecular formula of Li(Ni 0.8 Co 0.1 Mn 0.1 ) 1-x M xO2@Z, 0.005≤x≤0.02, the doping element M is one or more of Ti, Cr, V, Al, Mg, F, B, and Z is a material capable of forming lithium oxide with lithium. This modification method focuses on the surface improvement of high-nickel ternary materials, while being able to slow down the side reaction between the electrolyte and the material surface, stabilize the crystal structure of the positive electrode material, and reduce lithium-nickel mixing. However, due to the reliance on doping and coating for joint modification, the sample preparation process is complex and not suitable for large-scale production. Patent CN 117254015 A reports a preparation method of a cadmium sulfide nanorod coated substrate material LiNi x Co y Mn z O2, the cadmium sulfide nanorod has a large specific surface area, which is beneficial to improve the reactivity and adsorption performance; the high-nickel ternary positive electrode material coated with cadmium sulfide nanorod can effectively realize the regulation of electronic structure, improve the stability of the material, and improve the electronic conductivity of the positive electrode material. Therefore, the capacity retention rate of the battery assembled by the positive electrode material prepared by the invention is high, and the stability is improved. However, the invention has certain limitations for improving the electrochemical performance of high-nickel ternary materials, especially the coating layer has almost no ionic conductivity. SUMMARY

[0005] In view of the problems existing in the prior art, the present application provides a high-nickel layered oxide positive electrode material coated with a Li3Al 1-x M x F6 layer and a preparation method thereof. The coating layer Li3Al 1-x M x F6 has high electronic conductivity and ionic conductivity, which can improve the electrochemical performance of high-nickel layered oxide positive electrode material of high-nickel ternary lithium ion battery under high pressure.

[0006] The present application is realized by the following technical solutions:

[0007] A high-nickel layered oxide positive electrode material coated with a Li3Al 1-x M x F6 layer, the high-nickel layered oxide is LiNi x1 Co y1 Mn 1-x1-y1 O2, M is one or more of Mg, Fe, Cr, La, Ce and Y, and 0

[0008] Preferably, x1 and y1 satisfy the following relationships respectively:

[0009] 0.5≤x1<1, 0≤y1≤0.2.

[0010] A high-nickel layered oxide positive electrode material coated with a Li3Al 1-x Mx The preparation method of the F6-layer high-nickel layered oxide positive electrode material comprises the following steps:

[0011] S1, the high-nickel layered oxide powder is added into a mixed aqueous solution of metal salt, lithium salt, ammonium fluoride and aluminum salt, the molar ratio of lithium salt, ammonium fluoride and aluminum salt is 3:6:(0.9-1), the metal salt is one or more of magnesium salt, iron salt, chromium salt, lanthanum salt, cerium salt and yttrium salt, and a mixed system is obtained;

[0012] S2, the mixed system is stirred, and then centrifuged and dried in sequence to obtain a precursor;

[0013] S3, the precursor is subjected to high-temperature calcination treatment at 300-800°C under a protective atmosphere to obtain the Li3Al 1-x M x The F6-layer high-nickel layered oxide positive electrode material.

[0014] Preferably, the magnesium salt, iron salt, chromium salt, lanthanum salt, cerium salt, yttrium salt, lithium salt and aluminum salt in S1 are all nitrate salts.

[0015] Further, the aluminum nitrate is Al(NO3)3·9H2O, and the mass ratio of the high-nickel layered oxide powder, lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O in S1 is 1:(0.001-0.1):(0.001-0.1):(0.001-0.05).

[0016] Preferably, when the metal salt in S1 is magnesium salt, iron salt, chromium salt, lanthanum salt, cerium salt or yttrium salt, the molar ratio of aluminum salt to magnesium salt, iron salt, chromium salt, lanthanum salt, cerium salt or yttrium salt is (0.9-1):(0-0.1);

[0017] When the metal salt in S1 is multiple of magnesium salt, iron salt, chromium salt, lanthanum salt, cerium salt and yttrium salt, the molar ratio of aluminum salt to the corresponding salt is (0.9-1):(0-0.1).

[0018] Preferably, the stirring in S2 is carried out at 20-90°C for 1-6h.

[0019] Preferably, the drying in S2 is carried out at 60-70°C for 11-13h.

[0020] Preferably, the precursor in S3 is subjected to high-temperature calcination at 300-800°C for 2-12h.

[0021] Preferably, the temperature of 300-800°C in S3 is increased from room temperature, and the temperature increasing rate is 2-10°C / min.

[0022] Compared with the prior art, the application has the following beneficial technical effects:

[0023] The application is a high-nickel layered oxide positive electrode material coated with a Li3Al 1-x M x F6 layer 1-x M x F6 as a coating layer can effectively isolate the high-nickel layered oxide LiNi x1 Co y1 Mn 1-x1-y1 O2 and the electrolyte, and at the same time, the coating layer can weaken the volume change of the bulk phase structure of the electrode material, which will help to maintain the stability of the layered structure and improve the lithium ion transmission environment, so as to achieve the goal of stabilizing the electrode material structure and improving the cycle stability. In addition, the Li3Al 1-x M x F6 coating layer is more suitable for use as a high-voltage coating material than the traditional inert coating layer, because the doping of magnesium and more transition metal elements (Fe, Y and Cr) and rare earth elements La and Ce on the basis of Li3AlF6 can further improve the positive electrode interface thermal stability, ionic conductivity and electronic conductivity of Li3AlF6. Especially under high voltage, Li3Al 1-x M x F6 shows great potential as a high-voltage positive electrode coating material, and can successfully increase the charge cut-off voltage to 4.5 V. Under the voltage range of 2.7-4.5 V, the capacity retention rate of 200 cycles is as high as 80% or more.

[0024] The application is a high-nickel layered oxide positive electrode material coated with a Li3Al 1-x M x F6 layer 1-x M x F6 layer and the high-nickel layered oxide LiNi x1 Co y1 Mn 1-x1-y1 O2 precursor, and then high-temperature calcination is performed at 300-800 DEG C to obtain a Li3Al 1-x M x F surface coating layer, because when the temperature is lower than 300 DEG C, the Li3Al 1-x M x F6 layer cannot be formed on the NCM surface, and when the temperature exceeds 800 DEG C, the excessively high calcination temperature will cause a side reaction to occur during the calcination process, transition metal oxide particles are generated and attached to the surface of the high-nickel layered oxide, which affects the performance of the coating layer and hinders the transmission of lithium ions. The calcination is performed in a protective atmosphere to avoid the formation of excessive Li3Al 1-x Mx F6 particles, serious agglomeration phenomenon is generated. Li3Al 1-x M x F6 layer is evenly coated on the surface of LiNi x1 Co y1 Mn 1-x1-y1 O2, as a physical barrier to isolate LiNi x1 Co y1 Mn 1-x1-y1 O2 and electrolyte, thereby inhibiting the occurrence of side reactions and the dissolution of transition metals, improving the ionic conductivity, electronic conductivity and structural stability of the material, thereby improving the specific capacity of the high-voltage lithium ion battery anode material and the cycle life of the material. The preparation method of the present application is simple, controllable, high-yield, good repeatability, easy to realize industrialization, and can meet the application demand of high-voltage and high-specific-capacity materials on the market. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is the SEM diagram of the target substance synthesized by the embodiment 7 of the present application.

[0026] Figure 2 is the constant current charge-discharge curve diagram of the target substance synthesized by the embodiment 7 of the present application under high voltage of 2.7-4.5V.

[0027] Figure 3 is the SEM diagram of the target substance synthesized by the comparative example 1 of the present application.

[0028] Figure 4 is the constant current charge-discharge curve diagram of the target substance synthesized by the comparative example 1 of the present application under high voltage of 2.7-4.5V.

[0029] Figure 5 is the cycle-capacity diagram of the embodiment 7 and the comparative example 1 of the present application under high voltage of 2.7-4.5V for long cycle of 200 cycles. DETAILED DESCRIPTION

[0030] The present application will be further described in detail below with reference to the accompanying drawings. It should be understood that the following embodiments are only used to illustrate the present application, but not to limit the present application. Any technology realized based on the above description of the present application is covered within the scope intended to be protected by the present application.

[0031] The present application is a high-nickel layered oxide anode material coated with Li3Al 1-x M x F6 layer, which is a high-voltage lithium ion battery anode material based on surface coating modification, and the coating layer is Li3Al 1-x M x F6, 0 x Coy Mn 1-x-y O2, wherein 0.5≤x<1, 0≤y≤0.2, 0<z≤0.3, x+y+z=1), wherein the element M is one or more of Mg, Fe, Cr, La, Ce and Y, doping magnesium on the basis of Li3AlF6, and more transition metal elements (Fe, Y and Cr) and rare earth elements La, Ce can further improve the electrical conductivity of Li3AlF6, and help to improve the electrochemical stability of high-nickel ternary lithium-ion battery cathode material at high voltage, and the prepared modified cathode material shows higher capacity and better cycle stability at high cut-off voltage (2.7-4.5V).

[0032] The application is a high-nickel layered oxide cathode material coated with a Li3Al 1-x M x F6 layer, comprising the following steps:

[0033] (1) adding high-nickel layered oxide cathode material powder (chemical formula is LiNi x Co y Mn 1-x-y O2, wherein 0.5≤x<1, 0≤y≤0.2, 0<z≤0.3, x+y+z=1) into an aqueous solution of nitrate (one or more of Fe(NO3)3·9H2O, Mg(NO3)2·6H2O and Cr(NO3)3·9H2O) and lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O, and the mass ratio of the cathode material powder to lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O is 1:(0.001-0.1):(0.001-0.1):(0.001-0.05), and the molar ratio of Al(NO3)3·9H2O, Fe(NO3)3·9H2O, Mg(NO3)2·6H2O and Cr(NO3)3·9H2O, Ce(NO3)3·6H2O, Y(NO3)3·6H2O, La(NO3)3·6H2O is (0.9-1):(0-0.1):(0-0.1):(0-0.1):(0-0.1):(0-0.1):(0-0.1).

[0034] (2) stirring the mixed system obtained in step (1) at a temperature of 20-90℃ for 1-6h, then centrifuging, and then drying at 60-70℃ for 11-13h.

[0035] (3) placing the powder obtained in step (2) into a tube furnace, and performing high-temperature calcination treatment at 300-800℃ under a nitrogen atmosphere, the calcination time is 2-12h, the temperature is raised from room temperature, and the temperature rising rate is 2-10℃ / min, and finally the modified high-nickel ternary layered oxide cathode material is obtained.

[0036] Example 1

[0037] The present embodiment provides a coated modified lithium ion battery cathode material. The cathode material comprises a high-nickel layered oxide cathode material powder as an inner core and a coating layer coating the inner core; the high-nickel layered oxide is LiNi 0.8 Co 0.1 Mn 0.1 O2(referred to as NCM811), with an average particle size of 5 μm; the coating layer is Li3Al 0.9 Mg 0.1 F6.

[0038] The preparation method of the coated lithium ion battery cathode material comprises the following steps:

[0039] First step:

[0040] The high-nickel layered oxide cathode material powder is added to an aqueous solution of lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O and Mg(NO3)2·6H2O, and all the powders are weighed according to a certain proportion. Among them, the mass ratio of the cathode material powder to lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O and Mg(NO3)2·6H2O is 1:0.001:0.001:0.001. At the same time, the molar ratio of Al(NO3)3·9H2O and Mg(NO3)2·6H2O is 0.9:0.1.

[0041] Second step:

[0042] The mixed system obtained in the first step is stirred at a temperature of 20°C for 1 h, then centrifuged, and then dried at 65°C for 12 h.

[0043] Third step:

[0044] The powder obtained in the second step is placed in a tube furnace and subjected to high-temperature calcination treatment under a nitrogen atmosphere. The calcination temperature is 300°C, the calcination time is 2 h, and the heating rate is 2°C / min. Finally, the modified high-nickel ternary layered oxide cathode material is obtained.

[0045] The obtained coated modified lithium ion battery cathode material is subjected to electrochemical performance test. The cathode material, super-p and PVDF are mixed at a mass ratio of 8:1:1 to prepare lithium ion battery. A lithium metal sheet is used as a counter electrode, a polypropylene microporous membrane Celgard 2400 is used as a separator, and a 1 mol / L LiPF6 aqueous solution (containing EC, DEC and DMC at a volume ratio of 1:1:1) is used as an electrolyte to prepare a CR2032 type button cell. The battery is subjected to constant current charge and discharge test by using a LAND battery test system. The initial cycle discharge specific capacity is 209.9 mAh / g at a current density of 0.1 C in a voltage window of 2.7-4.5 V, and the capacity retention rate is 80.28% after 200 cycles at a current density of 1 C.

[0046] Example 2

[0047] The present embodiment provides a coated modified lithium ion battery cathode material. The cathode material comprises a high-nickel layered oxide cathode material powder as an inner core and a coating layer coating the inner core; the inner core is LiNi 0.6 Co 0.2 Mn 0.2 O2 (denoted as NCM622), and the average particle size is 2.5 μm; the coating layer is Li3Al 0.93 Cr 0.07 F6;

[0048] The preparation method of the coated lithium ion battery cathode material comprises the following steps:

[0049] First step:

[0050] The high-nickel layered oxide cathode material powder is added into an aqueous solution of lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O and Cr(NO3)2·9H2O, and all the powders are weighed according to a certain proportion. The mass ratio of the cathode material powder to lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O and Cr(NO3)2·9H2O is 1:0.1:0.1:0.05. Meanwhile, the molar ratio of Al(NO3)3·9H2O to Cr(NO3)2·9H2O is 0.93:0.07.

[0051] Second step:

[0052] The mixed system obtained in the first step is stirred at a temperature of 90°C for 5 h, then centrifuged, and dried at 65°C for 12 h.

[0053] Third step:

[0054] The powder obtained in the second step is placed in a tube furnace and subjected to high-temperature calcination treatment under a nitrogen atmosphere. The calcination temperature is 600 DEG C, the calcination time is 12 h, and the temperature rising rate is 10 DEG C / min. The modified high-nickel ternary layered oxide positive electrode material is finally obtained.

[0055] The obtained coated modified lithium ion battery positive electrode material is subjected to electrochemical performance testing. The positive electrode material, super-p and PVDF are mixed at a mass ratio of 8:1:1 to prepare an electrode. A lithium metal sheet is used as a counter electrode, a polypropylene microporous membrane Celgard 2400 is used as a separator, and a 1 mol / L LiPF6 aqueous solution (containing EC, DEC and DMC at a volume ratio of 1:1:1) is used as an electrolyte to prepare a CR2032 type button cell. The button cell is subjected to constant current charge and discharge testing using a LAND battery testing system. The initial cycle discharge specific capacity is 203.78 mAh / g at a current density of 0.1 C in a voltage window of 2.7-4.5 V, and the capacity retention rate after 200 cycles is 81.53% at a current density of 1 C.

[0056] Example 3

[0057] The present embodiment provides a coated modified lithium ion battery positive electrode material. The positive electrode material comprises a high-nickel layered oxide positive electrode material powder as an inner core and a coating layer coating the inner core; the inner core is LiNi 0.9 Co 0.05 Mn 0.05 O2 (denoted as NCM955), and the average particle size is 4.5 μm; the coating layer is Li3Al 0.95 Fe 0.05 F6;

[0058] The preparation method of the coated lithium ion battery positive electrode material comprises the following steps:

[0059] First step:

[0060] The high-nickel layered oxide positive electrode material powder is added into an aqueous solution of lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O and Fe(NO3)3·9H2O, and all the powders are weighed according to a certain proportion. The mass ratio of the positive electrode material powder to lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O and Fe(NO3)3·9H2O is 1:0.003:0.006:0.00. Meanwhile, the molar ratio of Al(NO3)3·9H2O to Fe(NO3)3·9H2O is 0.95:0.05.

[0061] Second step:

[0062] The mixed system obtained in the first step is stirred at a temperature of 70 DEG C for 3 h, then centrifuged, and then dried at 65 DEG C for 12 h.

[0063] Third step:

[0064] The powder obtained in the second step is placed in a tube furnace and subjected to high-temperature calcination treatment under a nitrogen atmosphere. The calcination temperature is 500℃, the calcination time is 10h, and the heating rate is 8℃ / min. Finally, the modified high-nickel ternary layered oxide positive electrode material is obtained.

[0065] The obtained coated modified lithium ion battery positive electrode material is subjected to electrochemical performance testing. The electrode sheet ratio is 8:1:1 of lithium ion battery positive electrode material, super-p and PVDF; lithium metal sheet is the counter electrode, polypropylene microporous membrane Celgard2400 is the separator, and 1mol / L LiPF6 aqueous solution (containing EC, DEC and DMC in a volume ratio of 1:1:1) is the electrolyte to prepare CR2032 type button cell. The battery is subjected to constant current charge and discharge test by LAND battery test system. Under the voltage window of 2.7-4.5V and the current density of 0.1C, the initial cycle discharge specific capacity is 212.64mAh / g, and the capacity retention rate after 200 cycles under the current density of 1C is 80.76%.

[0066] Example 4

[0067] The present embodiment provides a coated modified lithium ion battery positive electrode material. The positive electrode material comprises a high-nickel layered oxide positive electrode material powder as an inner core and a coating layer coating the inner core; the inner core is LiNi 0.8 Co 0.1 Mn 0.1 O2 (denoted as NCM811), with an average particle size of 5μm; the coating layer is Li3Al 0.96 Cr 0.02 Mg 0.02 F6;

[0068] The preparation method of the coated lithium ion battery positive electrode material comprises the following steps:

[0069] First step:

[0070] The high-nickel layered oxide positive electrode material powder is added into an aqueous solution of lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O, Cr(NO3)3·9H2O and Mg(NO3)2·6H2O, and all the powders are weighed according to a certain proportion. Among them, the mass ratio of the positive electrode material powder to lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O and Mg(NO3)2·6H2O is 1:0.03:0.06:0.01. At the same time, the molar ratio of Al(NO3)3·9H2O, Cr(NO3)3·9H2O and Mg(NO3)2·6H2O is 0.96:0.02:0.02.

[0071] Second step:

[0072] The mixed system obtained in the first step was stirred at a temperature of 60°C for 2h, then centrifuged, and dried at 65°C for 12h.

[0073] Third step:

[0074] The powder obtained in the second step was placed in a tube furnace and subjected to high-temperature calcination treatment under a nitrogen atmosphere. The calcination temperature was 450°C, the calcination time was 8h, and the heating rate was 6°C / min. The modified high-nickel ternary layered oxide positive electrode material was finally obtained.

[0075] The obtained coated modified lithium ion battery positive electrode material was subjected to electrochemical performance testing. The electrode sheet ratio was 8:1:1 of lithium ion battery positive electrode material, super-p, and PVDF; the metal lithium sheet was the counter electrode, the polypropylene microporous membrane Celgard 2400 was the separator, and the 1 mol / L LiPF6 aqueous solution (containing EC, DEC, and DMC in a volume ratio of 1:1:1) was the electrolyte to prepare CR2032 type button cells. The LAND battery test system was used to test the battery for constant current charge and discharge. Under a voltage window of 2.7-4.5V and a current density of 0.1C, the initial cycle discharge specific capacity was 210.10mAh / g, and the capacity retention rate after 200 cycles at a current density of 1C was 80.56%.

[0076] Example 5

[0077] The present embodiment provides a coated modified lithium ion battery positive electrode material. The positive electrode material includes a high-nickel layered oxide positive electrode material powder as an inner core and a coating layer coating the inner core; the inner core is LiNi 0.6 Co 0.2 Mn 0.2 O2 (denoted as NCM622), with an average particle size of 2.5μm; the coating layer is Li3Al 0.96 Cr 0.02 Fe 0.02 F6;

[0078] The preparation method of the coated lithium ion battery positive electrode material includes the following steps:

[0079] First step:

[0080] The high-nickel layered oxide cathode material powder is added into an aqueous solution of lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O, Cr(NO3)3·9H2O and Fe(NO3)3·9H2O, and the amounts of all the powders are weighed according to a certain ratio. Among them, the mass ratio of the cathode material powder to lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O and Al(NO3)3·9H2O is 1:0.03:0.06:0.01. At the same time, the molar ratio of Al(NO3)3·9H2O, Cr(NO3)3·9H2O and Fe(NO3)3·9H2O is 0.96:0.02:0.02.

[0081] Second step:

[0082] The mixed system obtained in the first step is stirred at a temperature of 40℃ for 4h, and then centrifuged and dried at 65℃ for 12h.

[0083] Third step:

[0084] The powder obtained in the second step is placed in a tube furnace and subjected to high-temperature calcination treatment under a nitrogen atmosphere. The calcination temperature is 350℃, the calcination time is 5h, and the heating rate is 3℃ / min. Finally, the modified high-nickel ternary layered oxide cathode material is obtained.

[0085] The obtained coated modified lithium ion battery cathode material is subjected to electrochemical performance test. The electrode sheet ratio is 8:1:1 of lithium ion battery cathode material, super-p and PVDF; lithium metal sheet is the counter electrode, polypropylene microporous membrane Celgard2400 is the separator, and 1mol / L LiPF6 aqueous solution (containing EC, DEC and DMC in a volume ratio of 1:1:1) is the electrolyte to prepare CR2032 type button cell. The battery is subjected to constant current charge and discharge test by using LAND battery test system. Under the voltage window of 2.7-4.5V and the current density of 0.1C, the initial cycle discharge specific capacity is 204.23mAh / g, and the capacity retention rate after 200 cycles under the current density of 1C is 81.92%.

[0086] Example 6

[0087] The present embodiment provides a coated modified lithium ion battery cathode material. The cathode material comprises a high-nickel layered oxide cathode material powder as an inner core and a coating layer coating the inner core; the inner core is LiNi 0.5 Co 0.2 Mn 0.3 O2 (denoted as NCM523), and the average particle size is 1.5μm; the coating layer is Li3Al 0.94 Cr 0.02 Fe 0.02 Mg 0.02 F6;

[0088] The preparation method of the coated lithium ion battery cathode material comprises the following steps:

[0089] First step:

[0090] The high-nickel layered oxide cathode material powder is added into an aqueous solution of lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O, Cr(NO3)3·9H2O, Fe(NO3)3·9H2O and Mg(NO3)2·6H2O, and the amounts of all the powders are weighed according to a certain proportion. Among them, the mass ratio of the cathode material powder to lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O and Cr(NO3)3·9H2O is 1:0.03:0.06:0.01. At the same time, the molar ratio of Al(NO3)3·9H2O, Cr(NO3)3·9H2O, Mg(NO3)2·6H2O and Fe(NO3)3·9H2O is 0.94:0.02:0.02:0.02.

[0091] Second step:

[0092] The mixed system obtained in the first step is stirred at a temperature of 30℃ for 4h, and then centrifuged and dried at 65℃ for 12h.

[0093] Third step:

[0094] The powder obtained in the second step is placed in a tube furnace and subjected to high-temperature calcination treatment under a nitrogen atmosphere. The calcination temperature is 550℃, the calcination time is 10h, and the heating rate is 5℃ / min. Finally, the modified high-nickel ternary layered oxide cathode material is obtained.

[0095] The obtained coated modified lithium ion battery cathode material is subjected to electrochemical performance test. The electrode sheet ratio is 8:1:1 of lithium ion battery cathode material, super-p and PVDF; the metal lithium sheet is the counter electrode, the polypropylene microporous membrane Celgard2400 is the separator, and the 1mol / L LiPF6 aqueous solution (containing EC, DEC and DMC in a volume ratio of 1:1:1) is the electrolyte to prepare CR2032 type button cell. The battery is subjected to constant current charge and discharge test by using LAND battery test system. Under the voltage window of 2.7-4.5V and the current density of 0.1C, the initial cycle discharge specific capacity is 214.78mAh / g, and the capacity retention rate after 200 cycles under the current density of 1C is 82.23%.

[0096] Example 7

[0097] The present embodiment provides a coated modified lithium ion battery cathode material. The cathode material comprises a high-nickel layered oxide cathode material powder as an inner core and a coating layer coating the inner core; the inner core is LiNi 0.5 Co 0.2Mn 0.3 O2(abbreviated as NCM523), and the average particle size is 1.5 μm; the coating layer is Li3Al 0.96 Fe 0.02 Mg 0.02 F6;

[0098] The preparation method of the coated lithium ion battery cathode material comprises the following steps:

[0099] First step:

[0100] The high-nickel layered oxide cathode material powder is added into an aqueous solution of lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O, Fe(NO3)3·9H2O and Mg(NO3)2·6H2O, and the amounts of all the powders are weighed according to a certain proportion. Among them, the mass ratio of the cathode material powder to lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O and Mg(NO3)2·6H2O is 1:0.03:0.06:0.01. At the same time, the molar ratio of Al(NO3)3·9H2O, Fe(NO3)3·9H2O and Mg(NO3)2·6H2O is 0.96:0.02:0.02.

[0101] Second step:

[0102] The mixed system obtained in the first step is stirred at a temperature of 80℃ for 6h, and then centrifuged and dried at 65℃ for 12h.

[0103] Third step:

[0104] The powder obtained in the second step is placed in a tube furnace and subjected to high-temperature calcination treatment under a nitrogen atmosphere. The calcination temperature is 400℃, the calcination time is 6h, and the heating rate is 5℃ / min. Finally, the modified high-nickel ternary layered oxide cathode material is obtained.

[0105] The target product obtained in this embodiment is coated with a Li3Al 0.96 Fe 0.02 Mg 0.02 F6 layer of the high-nickel layered oxide LiNi 0.5 Co 0.2 Mn 0.3 O2 cathode material is subjected to electron microscope scanning, and the results are shown in Figure 1 It can be seen from Figure 1 that the high-nickel layered oxide LiNi 0.5 Co 0.2 Mn 0.3 O2 still maintains a good polygonal structure, and the modification of the Li3Al 0.96 Fe 0.02 Mg 0.02 F6 layer does not affect the high-nickel layered oxide LiNi 0.5 Co0.2 Mn 0.3 The crystal structure of O2 has an impact.

[0106] The obtained coated modified lithium ion battery cathode material was subjected to electrochemical performance test. The mass ratio of the lithium ion battery cathode material, super-p and PVDF was 8:1:1. Lithium metal sheet was used as the counter electrode, polypropylene microporous membrane Celgard 2400 was used as the separator, and 1 mol / L LiPF6 aqueous solution (containing EC, DEC and DMC in a volume ratio of 1:1:1) was used as the electrolyte to prepare CR2032 type button cell. The battery was subjected to constant current charge and discharge test using LAND battery test system. As shown in Figure 2 , the first cycle discharge specific capacity was 215.50 mAh / g, and as shown in Figure 5 , the capacity retention rate after 200 cycles was 85.89%.

[0107] Example 8

[0108] The present embodiment provides a coated modified lithium ion battery cathode material. The cathode material comprises a high-nickel layered oxide cathode material powder as an inner core and a coating layer coating the inner core; the inner core is LiNi 0.6 Co 0.2 Mn 0.2 O2 (denoted as NCM622), with an average particle size of 2.5 μm; the coating layer is Li3Al 0.96 Cr 0.02 Ce 0.02 F6;

[0109] The preparation method of the coated lithium ion battery cathode material comprises the following steps:

[0110] First step:

[0111] The high-nickel layered oxide cathode material powder was added into an aqueous solution of lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O, Cr(NO3)3·9H2O and Ce(NO3)3·6H2O, and all the powders were weighed according to a certain proportion. Among them, the mass ratio of the cathode material powder to lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O and Ce(NO3)3·6H2O was 1:0.03:0.06:0.01. At the same time, the molar ratio of Al(NO3)3·9H2O, Cr(NO3)3·9H2O and Ce(NO3)3·6H2O was 0.96:0.02:0.02.

[0112] Second step:

[0113] The mixed system obtained in the first step was stirred at a temperature of 50℃ for 3h, then centrifuged, and dried at 65℃ for 12h.

[0114] Third step:

[0115] The powder obtained in the second step was placed in a tube furnace and subjected to high-temperature calcination treatment under a nitrogen atmosphere. The calcination temperature was 400℃, the calcination time was 4h, and the heating rate was 5℃ / min. Finally, the modified high-nickel ternary layered oxide positive electrode material was obtained.

[0116] The obtained coated modified lithium ion battery positive electrode material was subjected to electrochemical performance testing. The electrode sheet ratio was 8:1:1 of lithium ion battery positive electrode material, super-p and PVDF; lithium metal sheet was the counter electrode, polypropylene microporous membrane Celgard2400 was the separator, and 1mol / L LiPF6 aqueous solution (containing EC, DEC and DMC in a volume ratio of 1:1:1) was the electrolyte to prepare CR2032 type button cell. The battery was subjected to constant current charge and discharge test using LAND battery test system. Under the voltage window of 2.7-4.5V and the current density of 0.1C, the initial cycle discharge specific capacity was 204.79mAh / g, and the capacity retention rate after 200 cycles under the current density of 1C was 82.22%.

[0117] Example 9

[0118] The present embodiment provides a coated modified lithium ion battery positive electrode material. The positive electrode material comprises high-nickel layered oxide positive electrode material powder as an inner core and a coating layer coating the inner core; the inner core is LiNi 0.8 Co 0.1 Mn 0.1 O2 (denoted as NCM811), with an average particle size of 5μm; the coating layer is Li3Al 0.96 Y 0.02 Mg 0.02 F6;

[0119] The preparation method of the coated lithium ion battery positive electrode material comprises the following steps:

[0120] First step:

[0121] The high-nickel layered oxide cathode material powder is added into an aqueous solution of lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O, Y(NO3)3·6H2O and Mg(NO3)2·6H2O, and the amounts of all the powders are weighed according to a certain ratio. Among them, the mass ratio of the cathode material powder to lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O and Mg(NO3)2·6H2O is 1:0.03:0.06:0.01. At the same time, the molar ratio of Al(NO3)3·9H2O, Y(NO3)3·6H2O and Mg(NO3)2·6H2O is 0.96:0.02:0.02.

[0122] Second step:

[0123] The mixed system obtained in the first step is stirred at a temperature of 50°C for 5h, and then centrifuged and dried at 65°C for 12h.

[0124] Third step:

[0125] The powder obtained in the second step is placed in a tube furnace and subjected to high-temperature calcination treatment under a nitrogen atmosphere. The calcination temperature is 450°C, the calcination time is 5h, and the heating rate is 6°C / min. Finally, the modified high-nickel ternary layered oxide cathode material is obtained.

[0126] The obtained coated modified lithium ion battery cathode material is subjected to electrochemical performance test. The electrode sheet ratio is 8:1:1 of lithium ion battery cathode material, super-p and PVDF; lithium metal sheet is the counter electrode, polypropylene microporous membrane Celgard2400 is the separator, and 1 mol / L LiPF6 aqueous solution (containing EC, DEC and DMC in a volume ratio of 1:1:1) is the electrolyte to prepare CR2032 type button cell. The battery is subjected to constant current charge and discharge test by using LAND battery test system. Under the voltage window of 2.7-4.5V and the current density of 0.1C, the initial cycle discharge specific capacity is 211.12mAh / g, and the capacity retention rate after 200 cycles under the current density of 1C is 81.26%.

[0127] Example 10

[0128] The present embodiment provides a coated modified lithium ion battery cathode material. The cathode material comprises a high-nickel layered oxide cathode material powder as an inner core and a coating layer coating the inner core; the inner core is LiNi 0.6 Co 0.2 Mn 0.2 O2 (denoted as NCM622), and the average particle size is 2.5μm; the coating layer is Li3Al 0.93 La 0.07 F6;

[0129] The preparation method of the coated lithium ion battery cathode material comprises the following steps:

[0130] First step:

[0131] The high-nickel layered oxide cathode material powder is added into an aqueous solution of lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O and La(NO3)3·6H2O, and the amounts of all the powders are weighed according to a certain proportion. Among them, the mass ratio of the cathode material powder to lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O and La(NO3)3·6H2O is 1:0.1:0.1:0.05. At the same time, the molar ratio of Al(NO3)3·9H2O to La(NO3)3·6H2O is 0.93:0.07.

[0132] Second step:

[0133] The mixed system obtained in the first step is stirred at a temperature of 80°C for 4h, and then centrifuged and dried at 65°C for 12h.

[0134] Third step:

[0135] The powder obtained in the second step is placed in a tube furnace and subjected to high-temperature calcination treatment under a nitrogen atmosphere. The calcination temperature is 500°C, the calcination time is 10h, and the heating rate is 10°C / min. Finally, the modified high-nickel ternary layered oxide cathode material is obtained.

[0136] The obtained coated modified lithium ion battery cathode material is subjected to electrochemical performance test. The electrode sheet ratio is 8:1:1 of lithium ion battery cathode material, super-p and PVDF; the metal lithium sheet is the counter electrode, the polypropylene microporous membrane Celgard2400 is the separator, and the 1mol / L LiPF6 aqueous solution (containing EC, DEC and DMC in a volume ratio of 1:1:1) is the electrolyte to prepare CR2032 type button cell. The battery is subjected to constant current charge and discharge test by using LAND battery test system. Under the voltage window of 2.7-4.5V and the current density of 0.1C, the initial cycle discharge specific capacity is 202.92mAh / g, and the capacity retention rate after 200 cycles under the current density of 1C is 81.22%.

[0137] Comparative Example 1

[0138] This comparative example provides a coated modified lithium ion battery cathode material. The cathode material comprises a high-nickel layered oxide cathode material powder as an inner core and a coating layer coating the inner core; the inner core is LiNi 0.5 Co 0.2 Mn 0.3 O2 (denoted as NCM523), with an average particle size of 1.5μm; and the coating layer is Li3AlF6.

[0139] The preparation method of the coated lithium ion battery cathode material comprises the following steps:

[0140] First step:

[0141] The high-nickel layered oxide cathode material powder is added into an aqueous solution of lithium nitrate, ammonium fluoride and Al(NO3)3·9H2O, and the amounts of all the powders are weighed according to a certain ratio. Among them, the mass ratio of the cathode material powder to lithium nitrate, ammonium fluoride and Al(NO3)3·9H2O is 1:0.03:0.06:0.01.

[0142] Second step:

[0143] The mixed system obtained in the first step is stirred at a temperature of 80°C for 6h, and then centrifuged and dried at 65°C for 12h.

[0144] Third step:

[0145] The powder obtained in the second step is placed in a tube furnace and subjected to high-temperature calcination treatment under a nitrogen atmosphere. The calcination temperature is 400°C, the calcination time is 6h, and the heating rate is 5°C / min. Finally, the modified high-nickel ternary layered oxide cathode material is obtained.

[0146] The high-nickel layered oxide LiNi 0.5 Co 0.2 Mn 0.3 O2 cathode material obtained in the comparative example is coated with a Li3AlF6 layer, and the target product is subjected to scanning electron microscopy, and the results are shown in Figure 3 It can be seen from Figure 3 that the high-nickel layered oxide LiNi 0.5 Co 0.2 Mn 0.3 O2 still maintains a good polygonal structure, and the modification of the Li3AlF6 layer does not affect the crystal structure of the high-nickel layered oxide LiNi 0.5 Co 0.2 Mn 0.3 O2.

[0147] The obtained coated and modified lithium ion battery cathode material is subjected to electrochemical performance test, and the electrode piece ratio is 8:1:1 of lithium ion battery cathode material, super-p and PVDF; the metal lithium piece is the counter electrode, the polypropylene microporous membrane Celgard2400 is the separator, and the 1mol / L LiPF6 aqueous solution (containing EC, DEC and DMC in a volume ratio of 1:1:1) is the electrolyte to prepare CR2032 type button cell. The LAND battery test system is used to test the battery, and the constant current charge and discharge test is carried out at a voltage window of 2.7-4.5V and a current density of 0.1C, and the results are shown in Figure 4As shown, the first cycle discharge specific capacity is 199.70 mAh / g, and the capacity retention rate after 200 cycles at a current density of 1C is 78.57%, while the capacity retention rate of NCM523 after 200 cycles at a current density of 1C is only 46.0%. Figure 5 As shown, the capacity retention rate after 200 cycles is 78.57%, while the capacity retention rate of NCM523 after 200 cycles at a current density of 1C is only 46.0%.

[0148] It can be seen from the comparison of Example 7 and Comparative Example 1 that the modified material doped with Fe and Mg elements in the Li3AlF6 coating layer has higher capacity and higher capacity retention rate after 200 cycles than the modified material coated with pure Li3AlF6.

[0149] In summary, the present application introduces Li3Al 1-x M x The Li3AlF6 coating layer modifies the high-nickel ternary lithium ion battery positive electrode material, improves the ionic conductivity and structural stability of the material, and thus improves the specific capacity of the material and the cycle life of the material. The uniform Li3AlF6 coating layer can act as a physical barrier to isolate the positive electrode material and the electrolyte, thereby inhibiting the occurrence of side reactions and the dissolution of transition metals. After the above modification strategy, the coated positive electrode material obtained by the present application has better conductivity, specific capacity and longer cycle life when used as a lithium ion battery positive electrode material. 1-x M x The Li3AlF6 coating layer can act as a physical barrier to isolate the positive electrode material and the electrolyte, thereby inhibiting the occurrence of side reactions and the dissolution of transition metals. After the above modification strategy, the coated positive electrode material obtained by the present application has better conductivity, specific capacity and longer cycle life when used as a lithium ion battery positive electrode material.

[0150] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought of by those skilled in the art, and all fall within the protection scope and disclosure scope of the present application.

Claims

1. A Li3Al 1-x M x F6-coated high-nickel layered oxide cathode material characterized by, The high nickel layered oxide is LiNi x1 Co y1 Mn 1-x1-y1 O2, M is one or more of Mg, Fe, Cr, La, Ce and Y, and 0 2. The Li3Al 1-x M x A high-nickel layered-oxide cathode material of F6 layer characterized in that, x1 and y1 satisfy the following relationships respectively: 0.5≤x1<1, 0≤y1≤0.

2.

3. The Li3Al0.5Co0.5O2-coated positive electrode active material according to any one of claims 1 to 2, wherein the Li3Al0.5Co0.5O2-coated positive electrode active material is coated with Li3Al0.5Co0.5O2 at a coating amount of 0.01 to 0.5 mass% based on the mass of the positive electrode active material. 1-x M x A method for producing a high-nickel layered oxide positive electrode material of F6 layer, characterized by, Comprising the following steps: S1, adding high-nickel layered oxide powder into a mixed aqueous solution of metal salt, lithium salt, ammonium fluoride and aluminum salt, the molar ratio of lithium salt, ammonium fluoride and aluminum salt being 3:6:(0.9-1), the metal salt being one or more of magnesium salt, iron salt, chromium salt, lanthanum salt, cerium salt and yttrium salt, to obtain a mixed system; S2, stirring the mixed system, and then centrifuging and drying in sequence to obtain a precursor; S3, high-temperature calcination treatment of the precursor under a protective atmosphere at 300-800 DEG C, to obtain coated with Li3Al 1- x M x F6 layer of high nickel layer of oxide cathode material.

4. The Li3Al 1-x M x A method for producing a high-nickel layered-oxide positive electrode material of F6 layer, characterized by, The magnesium salt, iron salt, chromium salt, lanthanum salt, cerium salt, yttrium salt, lithium salt and aluminum salt in S1 are all nitrate salts.

5. The Li3Al 1-x M x A method for producing a high-nickel layered-oxide positive electrode material of F6 layer, characterized by, The aluminum nitrate is Al(NO3)3·9H2O, and the mass ratio of high-nickel layered oxide powder, lithium nitrate, ammonium fluoride, Al(NO3)3·9H2O in S1 is 1:(0.001-0.1):(0.001-0.1):(0.001-0.05).

6. The Li3Al 1-x M x A method for producing a high-nickel layered-oxide positive electrode material of F6 layer, characterized by, When the metal salt in S1 is magnesium salt, iron salt, chromium salt, lanthanum salt, cerium salt or yttrium salt, the molar ratio of aluminum salt to magnesium salt, iron salt, chromium salt, lanthanum salt, cerium salt or yttrium salt is (0.9-1):(0-0.1); When the metal salt in S1 is multiple of magnesium salt, iron salt, chromium salt, lanthanum salt, cerium salt and yttrium salt, the molar ratio of aluminum salt to the corresponding salt is (0.9-1):(0-0.1).

7. The Li3Al 1-x M x A method for producing a high-nickel layered-oxide positive electrode material of F6 layer, characterized by, The stirring in S2 is carried out at 20-90℃ for 1-6h.

8. The Li3Al 1-x M x A method for producing a high-nickel layered-oxide positive electrode material of F6 layer, characterized by, The drying in S2 is carried out at 60-70℃ for 11-13h.

9. The Li3Al 1-x M x A method for producing a high-nickel layered-oxide positive electrode material of F6 layer, characterized by, The precursor in S3 is high-temperature calcined at 300-800℃ for 2-12h.

10. The Li3Al 1-x M x A method for producing a high-nickel layered-oxide positive electrode material of F6 layer, characterized by, The temperature of 300-800℃ in S3 is raised from room temperature, and the raising rate is 2-10℃ / min.

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