Battery

Abstract

The invention relates to the field of batteries, in particular to a battery. The battery comprises a positive plate and an electrolyte, the positive plate comprises a positive current collector and a positive active material layer on at least one side surface of the positive current collector, an XRD diffraction pattern of the positive active material layer has a 012 diffraction peak and a 006 diffraction peak, and a difference value gt of an angle value of the 012 diffraction peak and an angle value of the 006 diffraction peak; 0.1 degree; the electrolyte comprises a first additive, and the first additive comprises an element O and a cyano group. The positive plate and the electrolyte in the battery have a synergistic effect, so that the cycle performance and the safety performance of the battery can be improved.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and particularly to a battery. Background Art

[0002] The electrolyte of a lithium-ion battery is a very important component in the battery. Its function is to provide an ion transport channel between the positive and negative electrodes of the battery, and at the same time, it also determines the capacity, rate performance, and safety performance of the battery. Nitrile additives are a common type of electrolyte additive, which can improve the capacity and rate performance of the battery. Therefore, their research in the field of lithium-ion batteries has received much attention. However, nitrile additives have a poor adsorption protection effect on the positive electrode sheet, and their chemical stability is also poor. They are prone to decomposition and generate harmful gases, which affect the cycle performance and safety performance of the battery. Summary of the Invention

[0003] The purpose of the present invention is to overcome the above problems existing in the prior art and provide a battery. In the battery of the present invention, the positive electrode sheet and the electrolyte can produce a synergistic effect, improving the cycle performance and safety performance of the battery.

[0004] The present invention provides a battery, which includes a positive electrode sheet and an electrolyte. The positive electrode sheet includes a positive current collector and a positive active material layer on at least one surface of the positive current collector. The XRD diffraction pattern of the positive active material layer has a 012 diffraction peak and a 006 diffraction peak, and the difference between the angular values of the 012 diffraction peak and the 006 diffraction peak > 0.1°; the electrolyte includes a first additive, and the first additive includes element O and a cyano group.

[0005] Through the above technical solutions, the present invention has at least the following advantages compared with the prior art: The battery of the present invention has a specially designed positive electrode sheet and electrolyte, and the two can produce a synergistic effect. The additive in the electrolyte can form a stable adsorption on the surface of the positive electrode sheet, thereby reducing the risk of side reactions between the electrolyte and the positive electrode sheet, improving the stability of the positive electrode sheet, and improving the safety performance and cycle performance of the battery.

[0006] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein. Brief Description of the Drawings

[0007] Figure 1 Shown is the XRD diffraction pattern of the positive active material layer in an example of the present invention. Detailed Description

[0008] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not used to limit the present invention.

[0009] The present invention provides a battery, and the battery may include a positive electrode sheet and an electrolyte.

[0010] The positive electrode sheet may include a positive electrode current collector and a positive electrode active material layer on at least one surface of the positive electrode current collector. The XRD diffraction pattern of the positive electrode active material layer has a 012 diffraction peak and a 006 diffraction peak, and the difference between the angular value of the 012 diffraction peak and the angular value of the 006 diffraction peak > 0.1° (for example, 0.11°, 0.15°, 0.2°, 0.25°, 0.3°, 0.35°, 0.4°, 0.45°, 0.5°, 0.55°, 0.6°, 0.65°, 0.7°, 0.75°, 0.8°, 0.85°, 0.9°, 0.95°, 1°, 1.1°, 1.2°, 1.3°, 1.4°, 1.5°, 1.6°, 1.7°, 1.8°, 1.9° or 2°). As Figure 1 The XRD diffraction pattern of the positive electrode active material layer in an example of the present invention is shown. It can be seen from the figure that the XRD diffraction pattern of the positive electrode active material layer has a 012 diffraction peak and a 006 diffraction peak. Among them, the angular value of the 012 diffraction peak is 39.09°, the angular value of the 006 diffraction peak is 38.42°, and the difference between the two is 0.67°, which is greater than 0.1°.

[0011] The electrolyte may include a first additive, and the first additive may include element O and a cyano group.

[0012] Since nitrile additives can improve the capacity and rate performance of batteries, they are often used as electrolyte additives. However, nitrile additives have poor adsorption protection for the positive electrode sheet and poor chemical stability. The inventors of the present invention found that by using a specific positive electrode sheet in combination with the electrolyte, a synergistic effect can be produced between the two, which can not only improve the adsorption protection of the first additive (nitrile additive) for the positive electrode sheet, but also make the first additive and the positive electrode sheet have excellent electrochemical stability. It is mainly that the nitrile additive adsorbs on the surface of the positive electrode sheet, isolating other components in the electrolyte from directly contacting the positive electrode sheet, reducing the oxidation of the positive electrode sheet by the electrolyte, thereby improving the cycle performance and safety performance of the battery. The reason may be that: the XRD diffraction pattern of the positive electrode active material layer of the battery of the present invention has 012 diffraction peaks and 006 diffraction peaks. The transition metals on these two crystal planes are easily exposed and come into contact with the electrolyte, resulting in side reactions. And because the positions of the transition metals exposed on these two crystal planes are different, the adsorption strengths of different functional groups for them are also different. The inventors of the present invention found that the cyano group in the first additive is easily adsorbed on the 012 crystal plane, while the element O in the first additive is easily adsorbed on the 006 crystal plane. Therefore, by specially designing the positive electrode sheet and the electrolyte, the first additive molecules can be closely adsorbed on the surface of the positive electrode sheet, thereby reducing the contact with the positive electrode sheet in the electrolyte, inhibiting the oxidation and consumption of other components in the electrolyte, and further improving the cycle performance and safety performance of the battery. The inventors of the present invention further found that the cycle performance and safety performance of the battery can be further improved by controlling the diffraction angles of the 012 diffraction peak and the 006 diffraction peak. When the difference in the diffraction peak angles is too small (for example, less than or equal to 0.1°), the transition metal is easily exposed, increasing the risk of side reactions with the electrolyte; when the difference in the diffraction peak angles is too large (for example, greater than 1.05°), the functional groups in the electrolyte additive are difficult to adsorb on the surface, and the adsorption force weakens, and the electrolyte cannot be effectively isolated. The range of the difference in the angles of the 012 diffraction peak and the 006 diffraction peak in the XRD diffraction pattern of the positive electrode active material layer of the battery of the present invention is conducive to the adsorption of the element O and the cyano group in the electrolyte on the surface of the positive electrode sheet to form a stable interfacial film, which can effectively isolate the electrolyte.

[0013] In one example, the difference between the angle value of the 012 diffraction peak and the angle value of the 006 diffraction peak is 0.2° - 0.99°.

[0014] In one example, the difference between the angle value of the 012 diffraction peak and the angle value of the 006 diffraction peak is 0.5° - 0.9°.

[0015] In the present invention, in the first additive, the molar ratio of the cyano group to the element O is ≤4, such as 4, 3.5, 3, 2.5, 2, 1.5, 1 or 0.5.

[0016] The inventors of the present invention have found that when the ratio of the number of moles of cyano groups to the number of moles of element O is within a specific range, the adsorption ability of the first additive on the surface of the positive electrode sheet can be improved, thereby improving the cycle performance and safety performance of the battery.

[0017] In one example, in the first additive, the ratio of the number of moles of cyano groups to the number of moles of element O ≤ 1.5.

[0018] In one example, in the first additive, the ratio of the number of moles of cyano groups to the number of moles of element O ≤ 1.

[0019] In the present invention, the first additive may include

[0020]

[0021]

[0022] at least one of

[0023] In the present invention, based on the total mass of the electrolyte, the content of the first additive may be 0.23 - 5.34% by weight, such as 0.23, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 or 5.34% by weight.

[0024] In one example, based on the total mass of the electrolyte, the content of the first additive is 1 - 3% by weight.

[0025] In the present invention, the content of the first additive in the electrolyte can be obtained by testing using conventional methods in the art, such as gas chromatography.

[0026] In the present invention, the positive electrode active material layer may include a positive electrode active material. The positive electrode active material may include doped and / or undoped lithium cobaltate. The doped lithium cobaltate may include doping elements, and the doping elements may include at least one of Al, Mg, Ti, Zr, Ni, Mn, Y, La, Sr, W and Sc.

[0027] In the present invention, the mass content of the doping element in the cathode active material can be 100 ppm - 10,000 ppm, such as 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, 1,000 ppm, 1,500 ppm, 2,000 ppm, 2,500 ppm, 3,000 ppm, 3,500 ppm, 4,000 ppm, 4,500 ppm, 5,000 ppm, 5,500 ppm, 6,000 ppm, 6,500 ppm, 7,000 ppm, 7,500 ppm, 8,000 ppm, 8,500 ppm, 9,000 ppm, 9,500 ppm or 10,000 ppm.

[0028] In one example, the mass of the doping element in the cathode active material is 2,000 ppm - 9,000 ppm.

[0029] In the present invention, the electrolyte may further include a second additive, and the second additive may include

[0030] In the present invention, based on the total weight of the electrolyte, the content of the second additive can be 0.1 - 5 wt%, such as 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 or 5 wt%.

[0031] In the present invention, the electrolyte may further include a third additive, and the third additive may include fluoroethylene carbonate.

[0032] In the present invention, the electrolyte may further include a lithium salt, and the lithium salt may include at least one of lithium perchlorate (LiClO4), lithium hexafluorophosphate (LiPF6), lithium difluorophosphate (LiPO2F2), lithium difluorooxalate borate (LiDFOB), lithium tetrafluorooxalate phosphate (LiOTFP), lithium bis(fluorosulfonyl)imide (LiTFSI), lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium difluorobis(oxalate)phosphate (LiDFBP), lithium tetrafluoroborate (LiBF4), lithium bis(oxalate)borate (LiBOB), lithium hexafluoroantimonate (LiSbF6), lithium hexafluoroarsenate (LiAsF6), 4,5-dicyano-2-trifluoromethylimidazole lithium (LiTDI), lithium bis(pentafluoroethylsulfonyl)imide, lithium tris(trifluoromethylsulfonyl)methyl and lithium bis(trifluoromethylsulfonyl)imide.

[0033] In the present invention, based on the total weight of the electrolyte, the content of the lithium salt can be 11 - 18 wt%, such as 11, 12, 13, 14, 15, 16, 17 or 18 wt%.

[0034] In the present invention, the electrolyte may further include an organic solvent; the organic solvent may include a carbonate compound and / or a carboxylate compound. The carbonate compound may include at least one of the following solvents with or without fluorine substitution: ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC). The carboxylate compound may include at least one of the following solvents with or without fluorine substitution: propyl acetate, n-butyl acetate, isobutyl acetate, n-pentyl acetate, isopentyl acetate, propyl propionate (PP), ethyl propionate (EP), methyl butyrate, and ethyl n-butyrate.

[0035] In the present invention, the positive electrode active material layer may further include a positive electrode conductive agent and a positive electrode binder.

[0036] The positive electrode conductive agent may include one or more of conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nanotubes (including single-walled carbon nanotubes and multi-walled carbon nanotubes), metal powder, and carbon fiber. The positive electrode binder may include at least one or more of polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose, styrene-butadiene latex, polytetrafluoroethylene, and polyethylene oxide.

[0037] In the present invention, based on the total weight of the positive electrode active material layer, the content of the positive electrode active material may be 80-99.8% by weight (such as 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 99.8% by weight), the content of the positive electrode conductive agent may be 0.1-10% by weight (such as 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5, or 0.1% by weight), and the content of the positive electrode binder may be 0.1-10% by weight (such as 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5, or 0.1% by weight).

[0038] In one example, based on the total weight of the positive electrode active material layer, the content of the positive electrode active material is 90-99.6% by weight, the content of the positive electrode conductive agent is 0.2-5% by weight, and the content of the positive electrode binder is 0.2-5% by weight.

[0039] In the present invention, components of the battery other than the positive electrode sheet and the electrolyte (such as the negative electrode sheet and the separator, etc.) can all be conventional selections in the art.

[0040] In one example, the battery further includes a negative electrode sheet and a separator.

[0041] In the present invention, the negative electrode sheet may include a negative electrode current collector and a negative electrode coating on at least one surface of the negative electrode current collector. The negative electrode coating includes a negative electrode active material, a negative electrode conductive agent, and a negative electrode binder.

[0042] The negative electrode active material may include a carbon-based material and / or a silicon-based material. The carbon-based material may include one or more of artificial graphite, natural graphite, mesocarbon microbeads, hard carbon, and soft carbon. The silicon-based material may include one or more of silicon oxide materials or silicon carbide materials, such as including one or more of Si, SiC, and SiO x (0 < x < 2). The negative electrode conductive agent may include one or more of conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nanotubes (including single-walled carbon nanotubes and multi-walled carbon nanotubes), metal powder, and carbon fiber. The negative electrode binder may include at least one or more of sodium carboxymethyl cellulose, styrene-butadiene rubber, polytetrafluoroethylene, and polyethylene oxide.

[0043] In the present invention, based on the total weight of the negative electrode coating, the content of the negative electrode active material may be 80-99.8% by weight (such as 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, or 99.8% by weight), the content of the negative electrode conductive agent may be 0.1-10% by weight (such as 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5, or 0.1% by weight), and the content of the negative electrode binder may be 0.1-10% by weight (such as 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5, or 0.1% by weight).

[0044] In one example, based on the total weight of the negative electrode coating, the content of the negative electrode active material is 90-99.6% by weight, the content of the negative electrode conductive agent is 0.2-5% by weight, and the content of the negative electrode binder is 0.2-5% by weight.

[0045] In the present invention, the separator may be selected from the separators commonly used in the art, such as at least one of a polyethylene film or a polypropylene film (PP).

[0046] In the present invention, the battery can be assembled in a conventional manner in the art.

[0047] The present invention also provides a method for preparing the positive electrode active material, which at least includes the following steps:

[0048] (1) Mix a cobalt source, a complexing agent, and an alkali evenly in a solvent and carry out a first reaction;

[0049] (2) Carry out a first calcination on the product obtained in step (1);

[0050] (3) Calcinate the lithium source, the product obtained in step (2), and the compound containing the doping element for the second time.

[0051] In the present invention, in step (1), the cobalt source may include at least one of cobalt acetate, cobalt oxalate, cobalt nitrate, cobalt sulfate, cobalt chloride, and cobalt hydroxide.

[0052] In the present invention, in step (1), the complexing agent may include ammonia water.

[0053] In one example, the mass concentration of the ammonia water is 20%-25%.

[0054] In the present invention, in step (1), the base may include a soluble base containing carbonate. The soluble base containing carbonate may include at least one of Na2CO3, NH4HCO3, and (NH4)2CO3.

[0055] In the present invention, in step (1), the solvent may include deionized water.

[0056] In the present invention, in step (1), the temperature of the first reaction is 30°C - 80°C (such as 30°C, 40°C, 50°C, 60°C, 70°C, or 80°C), and the time of the first reaction is 10 hours - 20 hours (such as 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, or 20 hours).

[0057] In the present invention, in step (1), dissolve the cobalt source, the complexing agent, and the base in water. The concentration of the cobalt source may be 0.8 mol / L - 3.8 mol / L (such as 0.8 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, or 3.8 mol / L), the concentration of the base may be 0.8 mol / L - 3.8 mol / L (such as 0.8 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, or 3.8 mol / L), and the concentration of the complexing agent may be 0.1 mol / L - 4 mol / L (such as 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, or 4 mol / L). Under the action of the complexing agent, the base reacts with the cobalt source in the first reaction to form cobalt carbonate.

[0058] In the present invention, in step (2), the temperature of the first calcination can be 920°C - 1000°C (such as 920°C, 930°C, 940°C, 950°C, 960°C, 970°C, 980°C, 990°C or 1000°C); the time of the first calcination can be 8 hours - 12 hours (such as 8 hours, 9 hours, 10 hours, 11 hours or 12 hours).

[0059] In the present invention, in step (3), the lithium source includes one or more of lithium hydroxide, lithium nitrate, lithium carbonate, lithium oxalate, lithium acetate, lithium oxide and lithium citrate.

[0060] In the present invention, in step (3), the compound containing a doping element includes one or more of an oxide, a chloride, a hydroxide, a carbonate, a sulfate, a nitrate, an oxalate and an acetate containing the doping element.

[0061] In the present invention, the doping element can include at least one of Al, Mg, Ti, Zr, Ni, Mn, Y, La, Sr, W and Sc.

[0062] In one example, the compound containing a doping element includes one or more of Al2(SO4)3, AlCl3 and Al2O3.

[0063] In the present invention, in step (3), the temperature of the second calcination can be 900°C - 1200°C (such as 900°C, 910°C, 920°C, 930°C, 940°C, 950°C, 960°C, 970°C, 980°C, 990°C, 1000°C, 1010°C, 1020°C, 1030°C, 1040°C, 1050°C, 1060°C, 1070°C, 1080°C, 1090°C, 1100°C, 1150°C or 1200°C); the time of the second calcination can be 8 hours - 15 hours (such as 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours or 15 hours).

[0064] It should be noted that in the present invention, the numerical representation methods such as "first" and "second" are only used to distinguish different substances or usage methods, and do not represent the difference in order.

[0065] The present invention will be described in detail below through examples. The examples described in the present invention are only a part of the examples of the present invention, rather than all of the examples. All other examples obtained by those of ordinary skill in the art based on the examples in the present invention without making creative efforts fall within the scope of protection of the present invention.

[0066] In the following examples, unless otherwise specified, the materials used are commercially available analytical pure.

[0067] Preparation Example 1

[0068] The positive electrode active material was prepared according to the following method:

[0069] (1) Cobalt acetate, ammonia water (mass concentration: 22%) and Na2CO3 were mixed evenly at a mass ratio of 177:35.05:106, and deionized water was added (wherein, the concentration of cobalt acetate was 2.5 mol / L and the concentration of Na2CO3 was 2.5 mol / L), and the reaction was carried out at 50 °C for 15 hours;

[0070] (2) The product prepared in step (1) was calcined at 950 °C for 10 hours;

[0071] (3) Lithium hydroxide, the product prepared in step (2) and Al2(SO4)3 were mixed at a molar ratio of 1:1:0.1 and calcined at 1000 °C for 10 hours.

[0072] Preparation Example 2

[0073] (1) Cobalt acetate, ammonia water (mass concentration: 22%) and Na2CO3 were mixed evenly at a mass ratio of 177:35.05:106, and deionized water was added (wherein, the concentration of cobalt acetate was 2.5 mol / L and the concentration of Na2CO3 was 2.5 mol / L), and the reaction was carried out at 50 °C for 15 hours;

[0074] (2) The product prepared in step (1) was calcined at 950 °C for 10 hours;

[0075] (3) Lithium hydroxide, the product prepared in step (2) and Al2(SO4)3 were mixed at a molar ratio of 1:1:0.1 and calcined at 1000 °C for 8 hours.

[0076] Preparation Example 3

[0077] (1) Cobalt acetate, ammonia water (mass concentration: 22%) and Na2CO3 were mixed evenly at a mass ratio of 177:35.05:106, and deionized water was added (wherein, the concentration of cobalt acetate was 2.5 mol / L and the concentration of Na2CO3 was 2.5 mol / L), and the reaction was carried out at 50 °C for 15 hours;

[0078] (2) The product prepared in step (1) was calcined at 950 °C for 12 hours;

[0079] (3) Lithium hydroxide, the product prepared in step (2) and Al2(SO4)3 were mixed at a molar ratio of 1:1:0.1 and calcined at 1050 °C for 12 hours.

[0080] Preparation Example 4

[0081] The positive electrode active material is prepared by the following method:

[0082] (1) Cobalt chloride, ammonia water (mass concentration: 20%), and NH4HCO3 are mixed evenly in a mass ratio of 177:35.05:79, and deionized water is added (wherein, the concentration of cobalt chloride is 3.5 mol / L, and the concentration of NH4HCO3 is 3.5 mol / L), and the reaction is carried out at 30 °C for 20 hours;

[0083] (2) The product prepared in step (1) is calcined at 920 °C for 12 hours;

[0084] (3) Lithium carbonate, the product prepared in step (2), and AlCl3 are mixed in a molar ratio of 1:1:0.1, and calcined at 920 °C for 8.2 hours.

[0085] Preparation Example 5

[0086] The positive electrode active material is prepared by the following method:

[0087] (1) Cobalt hydroxide, ammonia water (mass concentration: 25%), and (NH4)2CO3 are mixed evenly in a mass ratio of 177:35.05:96, and deionized water is added (wherein, the concentration of cobalt hydroxide is 2.5 mol / L, and the concentration of (NH4)2CO3 is 2.5 mol / L), and the reaction is carried out at 80 °C for 10 hours;

[0088] (2) The product prepared in step (1) is calcined at 1000 °C for 8 hours;

[0089] (3) Lithium oxide, the product prepared in step (2), and Al2O3 are mixed in a molar ratio of 1:1:0.1, and calcined at 1200 °C for 14 hours.

[0090] Preparation Example 6

[0091] The positive electrode active material is prepared by the following method:

[0092] (1) Cobalt chloride, ammonia water (mass concentration: 20%), and NH4HCO3 are mixed evenly in a mass ratio of 177:35.05:79, and deionized water is added (wherein, the concentration of cobalt chloride is 3.5 mol / L, and the concentration of NH4HCO3 is 3.5 mol / L), and the reaction is carried out at 30 °C for 20 hours;

[0093] (2) The product prepared in step (1) is calcined at 900 °C for 11 hours;

[0094] (3) Mix lithium carbonate, the product prepared in step (2), and AlCl3 in a molar ratio of 1:1:0.1, and calcine at 900 °C for 8 hours.

[0095] Preparation Example 7

[0096] Prepare the positive electrode active material according to the following method:

[0097] (1) Mix cobalt hydroxide, ammonia water (mass concentration of 25%), and (NH4)2CO3 evenly in a mass ratio of 177:35.05:96, add deionized water (wherein the concentration of cobalt hydroxide is 2.5 mol / L and the concentration of (NH4)2CO3 is 2.5 mol / L), and react at 80 °C for 10 hours;

[0098] (2) Calcinate the product prepared in step (1) at 1000 °C for 10 hours;

[0099] (3) Mix lithium oxide, the product prepared in step (2), and Al2O3 in a molar ratio of 1:1:0.1, and calcine at 1200 °C for 15 hours.

[0100] Preparation Example 8

[0101] Refer to Preparation Example 1, except that in step (3), mix lithium oxide, the product prepared in step (2), and Al2O3 in a molar ratio of 1:1:0.01.

[0102] Comparative Preparation Example

[0103] Refer to Preparation Example 1, except that in step (3), calcine at 700 °C for 7 hours.

[0104] Example

[0105] Prepare the battery according to the following method:

[0106] (1) Prepare the electrolyte

[0107] In a glove box filled with argon (H2O < 0.1 ppm, O2 < 0.1 ppm), mix EC, PC, DEC, and PP evenly in a mass ratio of 1:2:4:3; add 1 mol / L of fully dried lithium hexafluorophosphate (LiPF6) to the above mixed solution, add fluoroethylene carbonate based on 5% of the total mass of the electrolyte, add different contents of the substances in Table 1, stir evenly, and obtain the electrolyte after passing the moisture and free acid tests.

[0108] (2) Prepare the positive electrode sheet

[0109] The cathode active material, PVDF, conductive carbon black (SP), and single-walled carbon nanotubes (SWCNTs) obtained in Preparation Example were mixed at a weight ratio of 96:2:1.5:0.5, and N-methylpyrrolidone (NMP) was added, with a solid content of 70%. The cathode slurry was obtained under the action of a vacuum mixer; the above cathode slurry was uniformly coated on aluminum foil; the coated aluminum foil was dried, rolled, and slit to obtain a cathode sheet.

[0110] (3) Preparation of the anode sheet

[0111] Artificial graphite, silicon monoxide, sodium carboxymethyl cellulose (CMC-Na), styrene-butadiene rubber, conductive carbon black (SP), and single-walled carbon nanotubes (SWCNTs) were mixed at a weight ratio of 79.5:15:2.5:1.5:1:0.5, and deionized water was added, with a solid content of 50%. The anode slurry was obtained under the action of a vacuum mixer; the above anode slurry was uniformly coated on copper foil, dried, rolled, and slit to obtain an anode sheet.

[0112] (4) Preparation of the battery

[0113] The cathode sheet obtained in step (2), the separator (a 9-μm-thick PP film), and the anode sheet obtained in step (3) were stacked in sequence and wound to obtain an electrode core. The above bare electrode core was placed in an outer packaging aluminum foil, and the electrolyte obtained in step (1) was injected into the outer packaging. After vacuum packaging, standing, formation, shaping, and sorting, the battery was obtained (the charge-discharge range was 3.0 V - 4.5 V).

[0114] Table 1

[0115]

[0116]

[0117] Test Example

[0118] (1) XRD test

[0119] Using an XRD of the Shimadzu XRD-6100 type in Japan, the test conditions were: voltage 40 KV, current 30 mA, scanning range 10 - 90 degrees, step size 0.02 degrees, scanning speed 4 degrees / minute. The batteries prepared in Example 1, Examples 4a - 4f, Example 7, and Comparative Example 1 were disassembled, and the cathode active material layer was subjected to XRD testing. The test results were recorded in Table 2.

[0120] (2) Cycle performance test

[0121] The batteries prepared in the examples and the comparative examples were subjected to cycle performance testing. The specific testing method was as follows:

[0122] At 25°C, charge and discharge cycles are carried out at a rate of 1C for 100 weeks; the capacity of the 100th week is divided by the capacity of the 1st week to obtain the cycle capacity retention rate, and the results are recorded in Table 2.

[0123] (3) Thermal shock test

[0124] The batteries prepared in the examples and comparative examples are subjected to a thermal shock test. The specific test method is as follows:

[0125] The battery in the 4.5V state is placed in an oven and heated from room temperature (25°C) to 180°C at a rate of 5°C / min, and the time when the battery catches fire is measured. The results are recorded in Table 2

[0126] Table 2

[0127]

[0128]

[0129] As can be seen from Table 2, compared with the comparative examples, the battery of the present invention has a higher cycle capacity retention rate and ignition temperature.

[0130] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A battery, characterized in that, The battery includes a positive electrode sheet and an electrolyte. The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer on at least one surface of the positive electrode current collector. The XRD diffraction pattern of the positive electrode active material layer has a 012 diffraction peak and a 006 diffraction peak, and the difference between the angular value of the 012 diffraction peak and the angular value of the 006 diffraction peak > 0.1°; the electrolyte includes a first additive, and the first additive includes element O and a cyano group.

2. The battery according to claim 1, wherein, The difference between the angular value of the 012 diffraction peak and the angular value of the 006 diffraction peak is 0.2° - 0.99°; preferably 0.5° - 0.9°.

3. The battery according to claim 1, wherein, In the first additive, the molar ratio of the cyano group to the molar number of element O ≤ 4; preferably, the molar ratio of the cyano group to the molar number of element O ≤ 1.

4. The battery according to claim 1, wherein, The first additive includes at least one of 5. The battery according to claim 1, wherein, Based on the total mass of the electrolyte, the content of the first additive is 0.23 - 5.34% by weight; preferably 1 - 3% by weight.

6. The battery according to claim 1, wherein, The positive electrode active material layer includes a positive electrode active material, and the positive electrode active material includes doped and / or undoped lithium cobaltate; Preferably, the doped lithium cobaltate includes a doping element, and the doping element includes at least one of Al, Mg, Ti, Zr, Ni, Mn, Y, La, Sr, W, and Sc.

7. The battery according to claim 6, wherein, The mass of the doping element in the positive electrode active material is 100 ppm - 10,000 ppm; preferably 2,000 ppm - 5,000 ppm.

8. The battery according to claim 1, wherein, The electrolyte further includes a second additive, and the second additive includes Preferably, based on the total weight of the electrolyte, the content of the second additive is 0.1 - 5% by weight.

9. The battery according to claim 1, wherein, The electrolyte further includes a lithium salt, and the lithium salt includes at least one of lithium perchlorate, lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorooxalate borate, lithium tetrafluorooxalate phosphate, lithium bisfluorosulfonimide, lithium bis(trifluoromethylsulfonyl)imide, lithium difluorobis(oxalato)phosphate, lithium tetrafluoroborate, lithium bis(oxalato)borate, lithium hexafluoroantimonate, lithium hexafluoroarsenate, 4,5-dicyano-2-trifluoromethyl-imidazole lithium, bis(pentafluoroethylsulfonyl)imide lithium, tris(trifluoromethylsulfonyl)methyl lithium, and bis(trifluoromethylsulfonyl)imide lithium.

10. The battery according to claim 1, wherein, The electrolyte further includes an organic solvent; the organic solvent includes a carbonate compound and / or a carboxylate compound; and / or, the carbonate compound includes at least one of the following fluorine-substituted or unsubstituted solvents: ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; and / or, the carboxylate compound includes at least one of the following fluorine-substituted or unsubstituted solvents: propyl acetate, n-butyl acetate, isobutyl acetate, n-pentyl acetate, isopentyl acetate, propyl propionate, ethyl propionate, methyl butyrate, and n-butyl acetate.

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