battery

Abstract

The present disclosure relates to the field of batteries, and in particular to a battery. The battery comprises a positive electrode sheet and an electrolyte. The positive electrode sheet comprises a positive electrode active material layer, the XRD diffraction pattern of the positive electrode active material layer has a 012 diffraction peak and a 006 diffraction peak, and the angle value difference between the 012 diffraction peak and the 006 diffraction peak is greater than 0.1°. The electrolyte comprises a first additive, and the first additive comprises an element O and a cyano group. According to the battery of the present disclosure, the positive electrode sheet and the electrolyte synergistically improve the cycle performance and safety performance of the battery.

Description

Battery Technical Field

[0001] The present disclosure relates to the field of batteries, and in particular to a battery. Background Art

[0002] The electrolyte of lithium-ion batteries is a crucial component, providing a pathway for ion transport between the positive and negative electrodes and determining the battery's capacity, rate capability, and safety. Nitrile additives are a common electrolyte additive, known for their ability to improve battery capacity and rate performance, and therefore attract considerable research interest in lithium-ion batteries. However, nitrile additives offer limited protection for the positive electrode and exhibit poor chemical stability, leading to their proneness to decomposition and the generation of harmful gases, which can negatively impact the battery's cycling performance and safety. Summary of the Invention

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

[0004] The present disclosure provides a battery, comprising a positive electrode sheet and an electrolyte, wherein the positive electrode sheet comprises a positive electrode current collector and a positive electrode active material layer on at least one side of the positive electrode current collector, wherein the XRD diffraction pattern of the positive electrode active material layer comprises a 012 diffraction peak and a 006 diffraction peak, and the difference between the angle value of the 012 diffraction peak and the angle value of the 006 diffraction peak is greater than 0.1°; the electrolyte comprises a first additive, wherein the first additive comprises the element O and a cyano group.

[0005] Through the above technical solution, the present disclosure has at least the following advantages compared with the prior art: the battery disclosed in the present disclosure has a specially designed positive electrode sheet and electrolyte, the two of which can produce a synergistic effect, and the additives in the electrolyte can form 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] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG1 shows an XRD diffraction pattern of a positive electrode active material layer in an example of the present disclosure. DETAILED DESCRIPTION

[0008] The following describes the specific embodiments of the present disclosure in detail. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure and are not intended to limit the present disclosure.

[0009] The present disclosure provides a battery, which 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 side of the positive electrode current collector, the XRD diffraction pattern of the positive electrode active material layer having a 012 diffraction peak and a 006 diffraction peak, and the difference between the angle value of the 012 diffraction peak and the angle value of the 006 diffraction peak is greater than 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° or 1.05°). As shown in Figure 1, this is the XRD diffraction pattern of the positive electrode active material layer in an example of the present disclosure. 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, wherein the angle value of the 012 diffraction peak is 39.09°, and the angle value of the 006 diffraction peak is 38.42°. 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 elemental 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 and protection effects on positive electrode sheets, and their chemical stability is also poor. The inventors of the present disclosure have found that by combining a specific positive electrode sheet with an electrolyte, the two can produce a synergistic effect, which can not only improve the adsorption and protection effect of the first additive (nitrile additive) on the positive electrode sheet, but also make the first additive and the positive electrode sheet have excellent electrochemical stability. The main reason is that the nitrile additive is adsorbed on the surface of the positive electrode sheet, isolating other components in the electrolyte from direct contact with the positive electrode sheet, reducing the oxidation effect of the electrolyte on the positive electrode sheet, thereby improving the cycle performance and safety performance of the battery. The reason may be that the XRD diffraction pattern of the positive active material layer of the battery disclosed in the present disclosure has 012 diffraction peaks and 006 diffraction peaks. The transition metals of these two crystal planes are easily exposed and come into contact with the electrolyte, resulting in the occurrence of side reactions, and since the positions of the transition metal exposure on the two crystal planes are different, the adsorption strength of different functional groups on them is also different. The inventors of the present disclosure have found that the cyanide 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 between the electrolyte and the positive electrode sheet, inhibiting the oxidation and consumption of other components in the electrolyte, and thus improving the cycle performance and safety performance of the battery. The inventors of the present disclosure have 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 angle 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 angle is too large (for example, greater than 1.05°), the functional groups in the electrolyte additive are difficult to adsorb on the surface, the adsorption force is weakened, and the electrolyte cannot be effectively isolated. The angle difference range between the 012 diffraction peak and the 006 diffraction peak of the XRD diffraction pattern of the positive electrode active material layer in the battery disclosed herein is conducive to the adsorption of element O and cyanide in the electrolyte on the surface of the positive electrode to form a stable interface 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 disclosure, in the first additive, the ratio of the number of moles of cyano groups to the number of moles of element O is ≤4, for example, 4, 3.5, 3, 2.5, 2, 1.5, 1 or 0.5.

[0016] The inventors of the present disclosure have discovered that when the ratio of the molar number of cyano groups to the molar number of element O is within a specific range, the adsorption capacity 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 molar number of cyano groups to the molar number of element O is ≤1.5.

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

[0019] In the present disclosure, the first additive may include At least one of .

[0020] In one example, the first additive includes At least one of .

[0021] In the present disclosure, based on the total weight of the electrolyte, the content of the first additive may be 0.23%-5.34%, for example, 0.23%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% or 5.34%.

[0022] In one example, based on the total weight of the electrolyte, the content of the first additive is 1-3%.

[0023] In the present disclosure, the content of the first additive in the electrolyte can be measured by conventional methods in the art, such as gas chromatography.

[0024] In the present disclosure, 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 cobalt oxide. The doped lithium cobalt oxide may include a doping element, and the doping element may include at least one of Al, Mg, Ti, Zr, Ni, Mn, Y, La, Sr, W, and Sc.

[0025] In the present disclosure, the mass content of the doping element in the positive electrode active material can be 100ppm-10000ppm, for example, 100ppm, 200ppm, 300ppm, 400ppm, 500ppm, 600ppm, 700ppm, 800ppm, 900ppm, 1000ppm, 1500ppm, 2000ppm, 2500ppm, 3000ppm, 3500ppm, 4000ppm, 4500ppm, 5000ppm, 5500ppm, 6000ppm, 6500ppm, 7000ppm, 7500ppm, 8000ppm, 8500ppm, 9000ppm, 9500ppm or 10000ppm.

[0026] In one example, the mass content of the doping element in the positive electrode active material is 2000 ppm-9000 ppm.

[0027] In one example, the mass content of the doping element in the positive electrode active material is 2000 ppm-5000 ppm.

[0028] In the present disclosure, the type of the doping element and the mass content of the doping element in the positive electrode active material can be measured by conventional testing methods in the art, for example, the type of the doping element can be measured by an energy dispersive spectrometer (EDS), and the mass content of the doping element can be measured by inductively coupled plasma (ICP).

[0029] In the present disclosure, the electrolyte may further include a second additive, which may include

[0030] In the present disclosure, based on the total weight of the electrolyte, the content of the second additive may be 0.1%-5%, for example, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%.

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

[0032] In the present disclosure, the electrolyte may further include a lithium salt, which may include at least one of lithium perchlorate (LiClO4), lithium hexafluorophosphate (LiPF6), lithium difluorophosphate (LiPO2F2), lithium difluorooxalatoborate (LiDFOB), lithium tetrafluorooxalatophosphate (LiOTFP), lithium bisfluorosulfonyl imide (LiTFSI), lithium bistrifluoromethylsulfonyl imide (LiTFSI), lithium difluorobisoxalatophosphate (LiDFBP), lithium tetrafluoroborate (LiBF4), lithium bisoxalatoborate (LiBOB), lithium hexafluoroantimonate (LiSbF6), lithium hexafluoroarsenate (LiAsF6), 4,5-dicyano-2-trifluoromethyl-imidazole lithium (LiTDI), lithium bis(pentafluoroethylsulfonyl)imide, tris(trifluoromethylsulfonyl)methyl lithium, and lithium bis(trifluoromethylsulfonyl)imide.

[0033] In the present disclosure, based on the total weight of the electrolyte, the content of the lithium salt may be 11%-18%, for example, 11%, 12%, 13%, 14%, 15%, 16%, 17% or 18%.

[0034] In the present disclosure, the type of the lithium salt and its content in the electrolyte can be measured by conventional testing methods in the art, such as ion chromatography (IC) or gas chromatography (GC).

[0035] In the present disclosure, 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 substituted or unsubstituted with fluorine and 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 substituted or unsubstituted with fluorine: propyl acetate, n-butyl acetate, isobutyl acetate, n-amyl acetate, isoamyl acetate, propyl propionate (PP), ethyl propionate (EP), methyl butyrate and ethyl butyrate.

[0036] In the present disclosure, the positive electrode active material layer may further include a positive electrode conductor and a positive electrode binder.

[0037] The positive electrode conductive agent may include at least one 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 of polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose, styrene-butadiene latex, polytetrafluoroethylene, and polyethylene oxide.

[0038] In the present disclosure, based on the total weight of the positive electrode active material layer, the content of the positive electrode active material can be 80% - 99.8% (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%), the content of the positive electrode conductive agent can be 0.1% - 10% (such as 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5% or 0.1%), and the content of the positive electrode binder can be 0.1% - 10% (such as 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5% or 0.1%).

[0039] 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%, the content of the positive electrode conductive agent is 0.2% - 5%, and the content of the positive electrode binder is 0.2% - 5%.

[0040] In the present disclosure, 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.

[0041] In one example, the battery further includes a negative electrode sheet and a separator.

[0042] In the present disclosure, 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.

[0043] The negative electrode active material may include a carbon-based material and / or a silicon-based material. The carbon-based material may include at least one of artificial graphite, natural graphite, mesocarbon microbeads, hard carbon, and soft carbon. The silicon-based material may include at least one of silicon oxide material or silicon carbon material, such as including at least one of Si, SiC, and SiO x (0 < x < 2). The negative electrode conductive agent may include at least one 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 of sodium carboxymethyl cellulose, styrene-butadiene rubber, polytetrafluoroethylene, and polyethylene oxide.

[0044] In the present disclosure, based on the total weight of the negative electrode coating, the content of the negative electrode active material may be 80%-99.8% (for example, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 99.8%), the content of the negative electrode conductor may be 0.1%-10% (for example, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5% or 0.1%), and the content of the negative electrode binder may be 0.1%-10% (for example, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5% or 0.1%).

[0045] 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%, the content of the negative electrode conductor is 0.2%-5%, and the content of the negative electrode binder is 0.2%-5%.

[0046] In the present disclosure, the separator may be a separator commonly used in the art, such as at least one of a polyethylene film and a polypropylene film (PP).

[0047] In the present disclosure, the battery can be assembled in a conventional manner in the art.

[0048] The present disclosure also provides a method for preparing the positive electrode active material, which comprises at least the following steps:

[0049] (1) adding a cobalt source, a complexing agent, and a base into a solvent and mixing them uniformly to perform a first reaction;

[0050] (2) subjecting the product obtained in step (1) to a first calcination;

[0051] (3) subjecting the lithium source, the product obtained in step (2) and the compound containing the doping element to a second calcination.

[0052] In the present disclosure, 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.

[0053] In the present disclosure, in step (1), the complexing agent may include aqueous ammonia.

[0054] In the present disclosure, the mass concentration of the ammonia water is 20%-25%, for example, 20%, 21%, 21.5%, 22%, 22.5%, 23%, 23.5%, 24%, 24.5% or 25%.

[0055] In the present disclosure, 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.

[0056] In the present disclosure, in step (1), the solvent may include deionized water.

[0057] In the present disclosure, in step (1), the temperature of the first reaction is 30°C-80°C (e.g., 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 (e.g., 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours or 20 hours).

[0058] In the present disclosure, in step (1), the cobalt source, the complexing agent and the alkali are dissolved in water, the concentration of the cobalt source can be 0.8mol / L-3.8mol / L (e.g., 0.8mol / L, 1mol / L, 2mol / L, 3mol / L or 3.8mol / L), the concentration of the alkali can be 0.8mol / L-3.8mol / L (e.g., 0.8mol / L, 1mol / L, 2mol / L, 3mol / L or 3.8mol / L), the concentration of the complexing agent can be 0.1mol / L-3.8mol / L (e.g., 0.8mol / L, 1mol / L, 2mol / L, 3mol / L or 3.8mol / L), and the concentration of the complexing agent can be 0.1mol / L-3.8mol / L. mol / L-4mol / L (for example, 0.1mol / L, 0.2mol / L, 0.3mol / L, 0.4mol / L, 0.5mol / L, 0.6mol / L, 0.7mol / L, 0.8mol / L, 0.9mol / L, 1mol / L, 1.5mol / L, 2mol / L, 2.5mol / L, 3mol / L, 3.5mol / L or 4mol / L), and under the action of the complexing agent, the base and the cobalt source undergo the first reaction to generate cobalt carbonate.

[0059] In the present disclosure, in step (2), the temperature of the first calcination can be 920°C-1000°C (e.g., 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 (e.g., 8 hours, 9 hours, 10 hours, 11 hours or 12 hours).

[0060] In the present disclosure, in step (3), the lithium source includes at least one of lithium hydroxide, lithium nitrate, lithium carbonate, lithium oxalate, lithium acetate, lithium oxide and lithium citrate.

[0061] In the present disclosure, in step (3), the compound containing the doping element includes at least one of oxides, chlorides, hydroxides, carbonates, sulfates, nitrates, oxalates and acetates containing the doping element.

[0062] In the present disclosure, the doping element may include at least one of Al, Mg, Ti, Zr, Ni, Mn, Y, La, Sr, W, and Sc.

[0063] In one example, the compound containing the doping element includes at least one of Al2(SO4)3, AlCl3, and Al2O3.

[0064] In the present disclosure, in step (3), the temperature of the second calcination may be 900°C-1200°C (e.g., 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 may be 8 hours-15 hours (e.g., 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours or 15 hours).

[0065] It should be noted that the numerical expressions such as "first" and "second" in the present disclosure are only used to distinguish different substances or usage methods, and do not represent a difference in order.

[0066] The present disclosure will be described in detail below through examples. The examples described in this disclosure are only a portion of the examples of the present disclosure, not all of the examples. Based on the examples in this disclosure, all other examples obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this disclosure.

[0067] In the following examples, unless otherwise specified, all materials used were commercially available analytical grade.

[0068] Preparation Example 1

[0069] Prepare the positive electrode active material as follows:

[0070] (1) Cobalt acetate, ammonia (mass concentration of 22%), and Na2CO3 were mixed uniformly in a mass ratio of 177:35.05:106, deionized water (wherein the concentration of cobalt acetate was 2.5 mol / L and the concentration of Na2CO3 was 2.5 mol / L) was added, and the mixture was reacted at 50°C for 15 hours;

[0071] (2) calcining the product obtained in step (1) at 950° C. for 10 hours;

[0072] (3) lithium hydroxide, the product prepared in step (2) and Al2(SO4)3 in terms of Al are mixed in a molar ratio of 1:1:0.1 and calcined at 1000°C for 10 hours.

[0073] Preparation Example 2

[0074] (1) Cobalt acetate, ammonia (mass concentration of 22%), and Na2CO3 were mixed uniformly in a mass ratio of 177:35.05:106, deionized water (wherein the concentration of cobalt acetate was 2.5 mol / L and the concentration of Na2CO3 was 2.5 mol / L) was added, and the mixture was reacted at 50°C for 15 hours;

[0075] (2) calcining the product obtained in step (1) at 950° C. for 10 hours;

[0076] (3) lithium hydroxide, the product prepared in step (2) and Al2(SO4)3 calculated as Al are mixed in a molar ratio of 1:1:0.1 and calcined at 1000°C for 8 hours.

[0077] Preparation Example 3

[0078] (1) Cobalt acetate, ammonia (mass concentration of 22%), and Na2CO3 were mixed uniformly in a mass ratio of 177:35.05:106, deionized water (wherein the concentration of cobalt acetate was 2.5 mol / L and the concentration of Na2CO3 was 2.5 mol / L) was added, and the mixture was reacted at 50°C for 15 hours;

[0079] (2) calcining the product obtained in step (1) at 950° C. for 12 hours;

[0080] (3) lithium hydroxide, the product prepared in step (2) and Al2(SO4)3 in terms of Al are mixed in a molar ratio of 1:1:0.1 and calcined at 1050°C for 12 hours.

[0081] Preparation Example 4

[0082] Prepare the positive electrode active material as follows:

[0083] (1) Cobalt chloride, ammonia water (mass concentration of 20%) and NH4HCO3 were mixed uniformly in a mass ratio of 177:35.05:79, deionized water (wherein the concentration of cobalt chloride was 3.5 mol / L and the concentration of NH4HCO3 was 3.5 mol / L) was added, and the mixture was reacted at 30°C for 20 hours;

[0084] (2) calcining the product obtained in step (1) at 920° C. for 12 hours;

[0085] (3) Lithium carbonate, the product prepared in step (2) and AlCl3 calculated as Al were mixed in a molar ratio of 1:1:0.1 and calcined at 920°C for 8.2 hours.

[0086] Preparation Example 5

[0087] Prepare the positive electrode active material as follows:

[0088] (1) Cobalt hydroxide, ammonia water (mass concentration of 25%) and (NH4)2CO3 were mixed uniformly in a mass ratio of 177:35.05:96, deionized water (wherein the concentration of cobalt hydroxide was 2.5 mol / L and the concentration of (NH4)2CO3 was 2.5 mol / L) was added, and the mixture was reacted at 80°C for 10 hours;

[0089] (2) calcining the product obtained in step (1) at 1000° C. for 8 hours;

[0090] (3) Lithium oxide, the product prepared in step (2) and Al2O3 calculated as Al were mixed in a molar ratio of 1:1:0.1 and calcined at 1200°C for 14 hours.

[0091] Preparation Example 6

[0092] Prepare the positive electrode active material as follows:

[0093] (1) Cobalt chloride, ammonia water (mass concentration of 20%) and NH4HCO3 were mixed uniformly in a mass ratio of 177:35.05:79, deionized water (wherein the concentration of cobalt chloride was 3.5 mol / L and the concentration of NH4HCO3 was 3.5 mol / L) was added, and the mixture was reacted at 30°C for 20 hours;

[0094] (2) calcining the product obtained in step (1) at 900° C. for 11 hours;

[0095] (3) lithium carbonate, the product prepared in step (2) and AlCl3 calculated as Al were mixed in a molar ratio of 1:1:0.1 and calcined at 900°C for 8 hours.

[0096] Preparation Example 7

[0097] Prepare the positive electrode active material as follows:

[0098] (1) Cobalt hydroxide, ammonia water (mass concentration of 25%) and (NH4)2CO3 were mixed uniformly in a mass ratio of 177:35.05:96, deionized water (wherein the concentration of cobalt hydroxide was 2.5 mol / L and the concentration of (NH4)2CO3 was 2.5 mol / L) was added, and the mixture was reacted at 80°C for 10 hours;

[0099] (2) calcining the product obtained in step (1) at 1000° C. for 10 hours;

[0100] (3) Lithium oxide, the product prepared in step (2) and Al2O3 calculated as Al were mixed in a molar ratio of 1:1:0.1 and calcined at 1200°C for 15 hours.

[0101] Preparation Example 8

[0102] Preparation Example 8a

[0103] The method is carried out in accordance with Preparation Example 1, except that, in step (3), lithium oxide, the product prepared in step (2), and Al2O3 calculated as Al are mixed in a molar ratio of 1:1:0.01;

[0104] Preparation Example 8b

[0105] The method is carried out in accordance with Preparation Example 1, except that, in step (3), lithium oxide, the product prepared in step (2), and Al2O3 calculated as Al are mixed in a molar ratio of 1:1:0.007;

[0106] Preparation Example 8c

[0107] The method is carried out in accordance with Preparation Example 1, except that, in step (3), lithium oxide, the product prepared in step (2), and Al2O3 calculated as Al are mixed in a molar ratio of 1:1:0.018;

[0108] Preparation Example 8d

[0109] The process is carried out in accordance with Preparation Example 1, except that in step (3), lithium oxide, the product prepared in step (2) and Al2O3 calculated as Al are mixed in a molar ratio of 1:1:0.032.

[0110] Preparation Example 9

[0111] Preparation Example 9a

[0112] The method is carried out in accordance with Preparation Example 1, except that in step (3), Al2(SO4)3 is replaced by NiSO4, and the molar ratio of lithium hydroxide, the product prepared in step (2) and NiSO4 calculated as Ni is 1:1:0.0045;

[0113] Preparation Example 9b

[0114] The method is carried out in accordance with Preparation Example 1, except that in step (3), Al2(SO4)3 is replaced by MgSO4, and the molar ratio of lithium hydroxide, the product prepared in step (2) and MgSO4 calculated as Mg is 1:1:0.011;

[0115] Preparation Example 9c

[0116] The method is carried out in accordance with Preparation Example 1, except that in step (3), Al2(SO4)3 is replaced by MnSO4, and the molar ratio of lithium hydroxide, the product prepared in step (2) and MnSO4 calculated as Mn is 1:1:0.005;

[0117] Preparation Example 9d

[0118] The process is carried out in accordance with Preparation Example 1, except that in step (3), Al2(SO4)3 is replaced by TiSO4, and the molar ratio of lithium hydroxide, the product prepared in step (2) and TiSO4 calculated as Ti is 1:1:0.0055.

[0119] Comparative Preparation Example

[0120] The process was carried out in accordance with Preparation Example 1, except that in step (3), the calcination was carried out at 700°C for 7 hours.

[0121] Example

[0122] Prepare the battery as follows:

[0123] (1) Preparation of electrolyte

[0124] In an argon-filled glove box (H2O<0.1ppm, O2<0.1ppm), EC, PC, DEC and PP were mixed in a mass ratio of 1:2:4:3; 1 mol / L of fully dried lithium hexafluorophosphate (LiPF6) was added to the above mixed solution, 5% of fluoroethylene carbonate based on the total mass of the electrolyte was added, and different contents of substances in Table 1 were added, stirred evenly, and the electrolyte was obtained after passing the moisture and free acid tests.

[0125] (2) Preparation of positive electrode sheet

[0126] The positive electrode active material prepared in the preparation example, PVDF, conductive carbon black (SP) and single-walled carbon nanotubes (SWCNTs) were mixed in a weight ratio of 96:2:1.5:0.5, and N-methylpyrrolidone (NMP) was added with a solid content of 70%. A positive electrode slurry was obtained under the action of a vacuum mixer; the above-mentioned positive electrode slurry was evenly coated on an aluminum foil; and the above-mentioned coated aluminum foil was dried, rolled, and cut to obtain a positive electrode sheet.

[0127] (3) Preparation of negative electrode sheet

[0128] Artificial graphite, silicon oxide, sodium carboxymethyl cellulose (CMC-Na), styrene-butadiene rubber, conductive carbon black (SP) and single-walled carbon nanotubes (SWCNTs) are mixed in a weight ratio of 79.5:15:2.5:1.5:1:0.5, deionized water is added, and the solid content is 50%. A negative electrode slurry is obtained under the action of a vacuum mixer; the above negative electrode slurry is evenly coated on a copper foil, dried, rolled, and cut to obtain a negative electrode sheet.

[0129] (4) Preparation of batteries

[0130] The positive electrode sheet obtained in step (2), the separator (9 μm thick PP film) and the negative electrode sheet obtained in step (3) are stacked in sequence and wound to obtain a battery cell. The above-mentioned bare battery cell is placed in an outer packaging aluminum foil, and the electrolyte obtained in step (1) is injected into the outer packaging. After vacuum packaging, standing, forming, shaping and sorting, a battery (charging and discharging range is 3.0V-4.5V) is obtained.

[0131] Table 1

[0132] Test Case

[0133] (1) XRD test

[0134] A Shimadzu XRD-6100 was used with the following test conditions: 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 XRD tests were performed on the positive electrode active material layer. The test results are recorded in Table 2.

[0135] (2) Cyclic performance test

[0136] The batteries prepared in the examples and comparative examples were subjected to cycle performance tests, and the specific test methods are as follows:

[0137] At 25°C, charge and discharge cycles were performed for 100 cycles at a rate of 1C. The capacity at the 100th cycle was divided by the capacity at the 1st cycle to obtain the cycle capacity retention rate. The results are recorded in Table 2.

[0138] (3) Temperature shock test

[0139] The batteries prepared in the examples and comparative examples were subjected to temperature shock tests. The specific test method is as follows:

[0140] The battery at 4.5V was placed in an oven and heated from room temperature (25°C) to 180°C at a rate of 5°C / min. The time it took for the battery to catch fire was measured. The results are recorded in Table 2.

[0141] Table 2

[0142] It can be seen from Table 2 that the battery of the present disclosure has higher cycle capacity retention rate and ignition temperature than the comparative example.

[0143] The preferred embodiments of the present disclosure are described in detail above, but the present disclosure is not limited thereto. Within the technical concept of the present disclosure, various simple variations of the technical solution of the present disclosure may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed by the present disclosure and fall within the scope of protection of the present disclosure.

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 or 2, 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 ≤ 1.5; More preferably, the molar ratio of the cyano group to the molar number of element O ≤ 1.

4. The battery according to any one of claims 1 to 3, wherein, The first additive includes at least one of; Preferably, the first additive includes At least one of.

5. The battery according to any one of claims 1-4, wherein, Based on the total weight of the electrolyte, the content of the first additive is 0.23% - 5.34%; preferably 1% - 3%.

6. The battery according to any one of claims 1-5, 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 content of the doping element in the positive electrode active material is 100 ppm - 10000 ppm; preferably 2000 ppm - 5000 ppm.

8. The battery according to any one of claims 1-7, 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%.

9. The battery according to any one of claims 1-8, wherein, The electrolyte further includes a third additive, and the third additive includes fluoroethylene carbonate.

10. The battery according to any one of claims 1-9, 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 bis(fluorosulfonyl)imide, lithium bis(trifluoromethylsulfonyl)imide, lithium difluorobis(oxalate)phosphate, lithium tetrafluoroborate, lithium bis(oxalate)borate, lithium hexafluoroantimonate, lithium hexafluoroarsenate, 4,5-dicyano-2-trifluoromethyl-imidazole lithium, lithium bis(pentafluoroethylsulfonyl)imide, lithium tris(trifluoromethylsulfonyl)methyl, and lithium bis(trifluoromethylsulfonyl)imide.

11. The battery according to any one of claims 1-10, wherein, Based on the total weight of the electrolyte, the content of the lithium salt is 11% - 18%.

12. The battery according to any one of claims 1-11, wherein, The electrolyte further includes an organic solvent; the organic solvent includes a carbonate compound and / or a carboxylate compound.

13. The battery according to claim 12, wherein, The carbonate compound includes at least one of the following solvents with or without fluorine substitution and ethylene carbonate: propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; And / or, the carboxylate compound includes 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, ethyl propionate, methyl butyrate, and n-butyl acetate.

14. The battery according to any one of claims 1-13, wherein, The positive electrode active material layer further includes a positive electrode binder and a positive electrode conductive agent; Preferably, the positive electrode conductive agent includes at least one of conductive carbon black, acetylene black, Ketjen black, conductive graphite, conductive carbon fiber, carbon nanotube, metal powder, and carbon fiber; Preferably, the positive electrode binder includes at least one of polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene-butadiene latex, polytetrafluoroethylene, and polyethylene oxide.

15. The battery according to claim 14, wherein, Based on the total weight of the positive electrode active material layer, the content of the positive electrode active material is 80% - 99.8%, the content of the positive electrode conductive agent is 0.1% - 10%, and the content of the positive electrode binder is 0.1% - 10%; Preferably, the content of the positive electrode active material is 90% - 99.6%, the content of the positive electrode conductive agent is 0.2% - 5%, and the content of the positive electrode binder is 0.2% - 5%.

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