Positive electrode active material, positive electrode sheet, secondary battery, and power using device

Abstract

The application relates to the technical field of secondary batteries, and particularly provides a positive electrode active material, a positive electrode sheet, a secondary battery and a power utilization device. The positive electrode active material comprises a lithium-containing phosphate and a lithium-containing metal oxide. The mass percentage of the lithium-containing metal oxide in the positive electrode active material is 1%-20%. The X-ray diffraction spectrum of the lithium-containing metal oxide comprises a diffraction peak of a (003) crystal face and a diffraction peak of a (104) crystal face, and the diffraction peak of the (003) crystal face and the diffraction peak of the (104) crystal face satisfy the condition that the value of I(003) / I(104) is less than or equal to 1.2, wherein I(003) represents the intensity of the diffraction peak of the (003) crystal face, and I(104) represents the intensity of the diffraction peak of the (104) crystal face. The application provides a positive electrode sheet which comprises a current collector and a positive electrode film layer arranged on the current collector. The positive electrode film layer comprises the positive electrode active material as described above. The mass percentage of the positive electrode active material in the positive electrode film layer is 90%-97%. The positive electrode active material provided by the application can provide the cycle performance of the secondary battery.

Description

Technical Field

[0001] This application relates to the field of secondary battery technology, and in particular to a positive electrode active material, a positive electrode sheet, a secondary battery, and an electrical device. Background Technology

[0002] Rechargeable batteries are widely used in various consumer electronics and electric vehicles due to their outstanding advantages of being lightweight, pollution-free, and having no memory effect. With the continuous development of the new energy industry, users are placing higher demands on the reliability of rechargeable batteries. However, the charging and discharging process of rechargeable batteries leads to the loss of active lithium, thus reducing their cycle performance. Summary of the Invention

[0003] In view of the technical problems existing in the background art, this application provides a positive electrode active material, a positive electrode sheet, a secondary battery, and an electrical device, aiming to solve the cycle performance of the secondary battery.

[0004] To solve the above-mentioned technical problems, the first technical solution adopted in this application is: to provide a positive electrode active material, which includes a lithium-containing phosphate and a lithium-containing metal oxide. The lithium-containing metal oxide accounts for 1%-20% of the mass percentage of the positive electrode active material. The X-ray diffraction pattern of the lithium-containing metal oxide includes diffraction peaks of the (003) crystal plane and diffraction peaks of the (104) crystal plane. The diffraction peaks of the (003) crystal plane and the (104) crystal plane satisfy: I(003) / I(104)≤1.2, where I(003) represents the intensity of the diffraction peak of the (003) crystal plane, and I(104) represents the intensity of the diffraction peak of the (104) crystal plane. + When lithium-containing metal oxides are extracted, they readily transform from a layered structure to a spinel / rock salt phase structure. This structure can increase the yield of Li. + Intercalation impedance affects lithium intercalation capability, meaning that the extracted Li+ ions cannot be transferred back into the lithium-containing metal oxide during discharge. Therefore, lithium-containing metal oxides with high cation mixing exhibit low capacity retention, as they can delithiate during each charge-discharge cycle, causing Li+ ions to be lost. + The lithium is irreversibly released and transferred to the negative electrode to replenish the active lithium. Therefore, during cycling, without increasing the charging voltage, the active lithium of the battery can be continuously replenished, improving the cycle performance of the secondary battery.

[0005] In any embodiment of this application, lithium phosphate includes those with the molecular formula Li x A y Me a M b P 1-c X c Y zCompounds and their modified compounds, where 0 < x ≤ 1.3, 0 ≤ y < 1.3, and 0.9 ≤ x + y ≤ 1.3, 0 < a ≤ 1.5, 0 ≤ b ≤ 0.7, 0.6 ≤ a + b ≤ 1.5, 0 ≤ c ≤ 0.5, 3 ≤ z ≤ 5; A includes one or more of Na, K, Mg; Me includes one or more of Mn, Fe, Co, Ni; M includes one or more of Al, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce; X includes one or more of S, Si, Cl, B, C, N; Y includes one or more of O, F; Optionally, the lithium-containing phosphate includes at least one of lithium iron phosphate and lithium vanadium phosphate; Optionally, the lithium-containing phosphate includes one or more of LiFePO4, LiNiPO4, LiCoPO4, LiV 0.67 PO4, LiMnPO4, LiMn 0.2 Fe 0.8 PO4, and LiMn 0.5 Fe 0.5 PO4.

[0006] In the technical solution of the embodiment of the present application, limiting the lithium-containing phosphate within the above range can continuously supplement the active lithium of the battery without increasing the charging voltage, and improve the cycling performance of the secondary battery.

[0007] In any implementation manner of the present application, the lithium-containing metal oxide includes compounds and their modified compounds with the molecular formula Li d Ni g Co h R k Q j O r T t where 0.8 ≤ d ≤ 1.2, 0 < g < 1, 0 < h < 1, 0 < k < 1, 0 ≤ j ≤ 0.1, 1 ≤ r ≤ 2, 0 ≤ t ≤ 1, t + r ≤ 2; R includes at least one of Mn and Al; Q includes one or more of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, Nb; T includes one or more of N, F, S, Cl; Optionally, the lithium-containing metal oxide includes at least one of lithium nickel cobalt manganate and lithium nickel cobalt aluminate; Optionally, the lithium-containing metal oxide includes LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2O2 and LiNi 0.8 Co 0.1 Mn 0.1 At least one of O2; optionally, lithium-containing metal oxides include LiNi. 0.85 Co 0.15 Al 0.05 O2, LiNi 0.8 Co 0.1 Al 0.1 O2, LiNi 0.5 Co 0.2 Al 0.3 O2 and LiNi 1 / 3 Co 1 / 3Al 1 / 3 At least one of O2.

[0008] In the technical solution of this application embodiment, the lithium-containing metal oxide is limited to the above-mentioned range, which enables the continuous replenishment of active lithium in the battery without increasing the charging voltage, thereby improving the cycle performance of the secondary battery.

[0009] In any embodiment of this application, in the lithium-containing metal oxide, the molar ratio of nickel to all metal elements except lithium is greater than or equal to 50%.

[0010] In the technical solution of this application embodiment, by making the nickel content greater than or equal to 50%, a sufficient amount of Ni can be obtained. 2+ Occupy Li + Its position in the crystal lattice prevents the extracted Li+ from being transferred back to the lithium-containing metal oxide through discharge, thus playing a role in replenishing lithium.

[0011] In any embodiment of this application, the lithium metal oxide accounts for 1%-5% of the mass percentage of the positive electrode active material.

[0012] In the technical solution of this application embodiment, the mass percentage of lithium metal oxide is controlled within the above range, which can both maintain the role of lithium phosphate as a positive electrode active material and enable it to play a role in lithium replenishment.

[0013] In any embodiment of this application, the value of the XRD diffraction peak I(003) / I(104) of the lithium metal oxide is ≤1.

[0014] In the technical solution of this application embodiment, the value of the XRD diffraction peak I(003) / I(104) of the lithium metal oxide is further limited to the above range, which can further improve the effect of the lithium metal oxide as a lithium replenishing agent, that is, can further improve the cycle performance of the secondary battery.

[0015] The second technical solution adopted in this application is: providing a positive electrode sheet, which includes a current collector and a positive electrode film layer disposed in the current collector. The positive electrode film layer includes the positive electrode active material as described above. Optionally, the positive electrode active material accounts for 90%-97% of the mass of the positive electrode film layer.

[0016] In the technical solution of this application embodiment, controlling the mass percentage of the positive electrode active material within the above-mentioned range can improve the energy density of the secondary battery, thereby improving the cycle performance of the secondary battery.

[0017] The third technical solution adopted in this application is: providing a secondary battery, which includes a positive electrode, a negative electrode, and a separator as described above. The separator is disposed between the positive electrode and the negative electrode.

[0018] In the technical solution of this application embodiment, the secondary battery contains the above-mentioned positive electrode active material, and therefore has the same advantage of good cycle performance.

[0019] In any embodiment of this application, the input voltage of the secondary battery is 2.0V-3.8V.

[0020] In the technical solution of this application embodiment, the secondary battery can continuously replenish lithium during each charge and discharge process when the input voltage is between 2.0V and 3.8V, without needing to increase the charging voltage to replenish lithium.

[0021] In any embodiment of this application, the charging temperature of the secondary battery is 30-45°C.

[0022] In the technical solution of this application embodiment, when the charging temperature of the secondary battery is within the above-mentioned temperature range, the lithium battery has the highest charging efficiency, the shortest charging time, and good lithium replenishment effect, which can also improve the reliability and lifespan of the battery.

[0023] The fourth technical solution adopted in this application is: to provide an electrical device that includes a secondary battery as described above.

[0024] In the technical solution of this application embodiment, the electrical device includes the above-mentioned secondary battery, and thus has the same advantage of good cycle performance.

[0025] In any embodiment of this application, the electrical device further includes a temperature regulator for adjusting the ambient temperature of the secondary battery to 30-45°C.

[0026] In the technical solution of this application embodiment, by setting a temperature regulator in the electrical device, the ambient temperature of the secondary battery can be adjusted, thereby enabling it to charge within the corresponding temperature range and improving charging efficiency.

[0027] The above description is merely an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, specific embodiments of this application are given below. Attached Figure Description

[0028] To more clearly illustrate the technical solution of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without any creative effort.

[0029] Figure 1 This is a schematic diagram of one embodiment of a secondary battery.

[0030] Figure 2 yes Figure 1 The exploded diagram.

[0031] Figure 3 This is a schematic diagram of one embodiment of the battery module.

[0032] Figure 4 This is a schematic diagram of one embodiment of the battery pack.

[0033] Figure 5 yes Figure 4 The exploded diagram.

[0034] Figure 6 This is a schematic diagram of one embodiment of a device that uses a secondary battery as a power source. Detailed Implementation

[0035] The present application will be further described below with reference to specific embodiments. It should be understood that these specific embodiments are for illustrative purposes only and are not intended to limit the scope of the present application.

[0036] For the sake of brevity, this article only discloses some specific numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0037] In this description, unless otherwise stated, the term "or" is inclusive. That is, the phrase "A or (or) B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0038] In the description of this article, it should be noted that, unless otherwise stated, "above" and "below" include the number itself, and "several" in "one or more" means two or more.

[0039] Unless otherwise stated, the terms used in this application have their common meanings as commonly understood by those skilled in the art. Unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0040] [Positive electrode active material]

[0041] The positive electrode active material provided in this application is used in secondary batteries. The positive electrode active material of a secondary battery includes lithium phosphate and lithium metal oxide, and therefore it can also be called a lithium-ion battery or lithium battery. The positive electrode active material is a decisive factor in the electrochemical performance of a lithium battery, directly determining the battery's energy density and reliability, and thus affecting the battery's overall performance. In addition to lithium phosphate and lithium metal oxide, the positive electrode active material of a lithium battery may also include conductive agents, solvents, binders, additives, and auxiliary materials.

[0042] The lithium metal oxide accounts for 1%-20% of the mass percentage of the positive electrode active material. For example, the mass percentage of lithium metal oxide in the positive electrode active material can be 1%, 3%, 5%, 8%, 10%, 11.5%, 12%, 14%, 15%, 16%, 18%, 20%, etc., or any range of any two of the above values, such as 1%-8%, 3%-12%, 8%-12%, 3%-16%, 16%-20%, etc.

[0043] The X-ray diffraction pattern of lithium-containing metal oxides includes diffraction peaks of the (003) crystal plane and diffraction peaks of the (104) crystal plane. The diffraction peaks of the (003) crystal plane and the diffraction peaks of the (104) crystal plane satisfy the following condition: I(003) / I(104)≤1.2, where I(003) represents the intensity of the diffraction peak of the (003) crystal plane and I(104) represents the intensity of the diffraction peak of the (104) crystal plane. For example, the value of I(003) / I(104) of the XRD diffraction peaks of lithium-containing metal oxides can be 0.3, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, etc., or a range consisting of any two of the above values, such as 0.3-0.5, 0.5-0.7, 0.7-0.9, 0.9-1.1, 1.0-1.2, etc.

[0044] In the embodiments of this application, the intensity I(003) of the diffraction peak of the (003) crystal plane and the intensity I(104) of the diffraction peak of the (104) crystal plane are expressed as the integral area of ​​the corresponding diffraction peaks. They can be tested using instruments and methods known in the art, with reference to the standard JIS K0131-1996 General Rules for X-ray Diffraction Analysis.

[0045] The XRD diffraction peak I(003) / I(104) value (referred to as R value) of lithium metal oxides is a semi-quantitative and semi-empirical measure of cationic disorder. The (003) crystal plane diffraction peak reflects the hexagonal structure, while the (104) crystal plane diffraction peak reflects the sum of the hexagonal and cubic structures. The larger the R value, the higher the degree of hexagonal cell ordering of the lithium metal oxide, the closer it is to the ideal hexagonal structure, and the more complete the crystal structure. An R value greater than 1.2 indicates that the lithium metal oxide has a good layered structure, while when the R value is less than or equal to 1.2, it indicates that the degree of cation disorder in the layered cathode material is relatively high. During the cyclic charging process at the working voltage, Li + Upon extraction from lithium-containing metal oxides, the lithium-containing metal oxide transforms from a layered structure to a spinel / rock salt phase structure. Compared to the layered structure, the spinel / rock salt phase structure can increase the Li... + Intercalation impedance affects its lithium intercalation capability, i.e., the ability to extract Li-. + It is impossible for the lithium to be transferred back to the lithium-containing metal oxide through discharge. Therefore, lithium-containing metal oxides with a high degree of cation mixing have low capacity retention, and they can delithigate during each charge-discharge cycle, causing Li to... +脱出 in an irreversible manner and transferred to the negative electrode to supplement the formation of the SEI (solid electrolyte interface) film and the active lithium lost during the charge-discharge process. Thus, during the cycling process, without increasing the charging voltage, the active lithium of the battery can be continuously supplemented, improving the cycling performance of the secondary battery.

[0046] In some embodiments, the lithium-containing phosphate includes a compound with the molecular formula Li x A y Me a M b P 1-c X c Y z and its modified compounds, where 0 < x ≤ 1.3, 0 ≤ y < 1.3, and 0.9 ≤ x + y ≤ 1.3, 0 < a ≤ 1.5, 0 ≤ b ≤ 0.7, 0.6 ≤ a + b ≤ 1.5, 0 ≤ c ≤ 0.5, 3 ≤ z ≤ 5; A includes one or more of Na, K, Mg; Me includes one or more of Mn, Fe, Co, Ni; M includes one or more of Al, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce; X includes one or more of S, Si, Cl, B, C, N; Y includes one or more of O, F; optionally, the lithium-containing phosphate includes at least one of lithium iron phosphate and lithium vanadium phosphate; optionally, the lithium-containing phosphate includes one or more of LiFePO4, LiNiPO4, LiCoPO4, LiV 0.67 PO4, LiMnPO4, LiMn 0.2 Fe 0.8 PO4 and LiMn 0.5 Fe 0.5 PO4.

[0047] LiFePO₄ belongs to lithium iron phosphate (Lithium Iron Phosphate, abbreviated as LFP). The crystal form of lithium iron phosphate is usually an olivine structure. The charge-discharge process of lithium iron phosphate occurs between the two phases of LiFePO₄ and FePO₄. During charging, Li + detaches from LiFePO₄, and Fe 2+ becomes Fe 3+ , forming the FePO₄ phase; during discharging, Li + embeds into FePO₄, and Fe 3+ becomes Fe 2+ , forming the LiFePO₄ phase. During the charge-discharge process, the reversible insertion and extraction of Li + corresponds to Fe 3+ / Fe2+ The voltage plateau during the conversion between these phases is approximately 3.45V and is relatively long. During charging, the voltage of a lithium-ion battery changes in a pattern of rising, stabilizing, and rising again. During discharging, the voltage also experiences a stabilizing phase, and this stable voltage value is the charging / discharging voltage plateau. Because the PO bond energy is very large, the PO4 tetrahedron is very stable and provides structural support during charging and discharging. Therefore, LiFePO4 has excellent resistance to high temperatures and overcharge. Furthermore, since the structure of LiFePO4 is very similar to that of FePO4 in its fully delithiated state, LiFePO4 also exhibits excellent cycle performance. + When completely extracted, the volume decreases while the density increases; after multiple charge-discharge cycles, the olivine structure remains stable, and the iron atoms remain in octahedral positions. Furthermore, when the lithium-containing phosphate is lithium iron phosphate, its cycle decay is slower than that of lithium-containing metal oxides. Specifically, because the olivine structure of lithium iron phosphate is more stable than the layered structure of lithium-containing metal oxides, the Li in lithium iron phosphate... + Li in lithium-containing metal oxides + After being released during each charge and discharge cycle, the Li in lithium iron phosphate... + It is easier to return to the positive electrode. Conversely, lithium-containing metal oxides, due to their tendency to transform from a layered structure to a spinel / rock salt phase, have a spinel / rock salt phase structure that can increase the Li-to-metal content. + Intercalation impedance, then Li in lithium-containing metal oxides + Since it can no longer be transferred back to the lithium-containing metal oxide through discharge, the lithium-containing metal oxide can play a role in replenishing lithium in the positive electrode active material.

[0048] LiV 0.67 PO4 belongs to the lithium vanadium phosphate family. Lithium vanadium phosphate is an inorganic compound, a monoclinic crystal. PO4 tetrahedra and VO6 octahedra are interconnected by oxygen atoms at shared vertices, forming a lantern-like structural unit. Each metal V atom is surrounded by six PO4 tetrahedra, and each PO4 tetrahedra is surrounded by four VO6 octahedra. This structure forms a three-dimensional network. Li atoms occupy the cavities within this framework, with three quadruple crystal positions occupied by Li, resulting in 12 Li positions within a single structural unit. In this open three-dimensional structure, it resembles PO4. 3- Such a large anion replaces the position of the oxygen atom, thus making the structure more stable, and Li +Ions can move faster therein. As a lithium-containing phosphate, lithium vanadium phosphate can reversibly deintercalate and intercalate two lithium ions, and it has good electrochemical and thermodynamic stability and a relatively high specific capacity. In addition, when the lithium-containing phosphate is lithium vanadium phosphate, the cycle attenuation of lithium vanadium phosphate is slower than that of the lithium-containing metal oxide. Specifically, due to the more stable monoclinic crystal structure of lithium vanadium phosphate compared to the layered structure of the lithium-containing metal oxide, the Li + in lithium vanadium phosphate and the Li + in the lithium-containing metal oxide are more likely to return to the positive electrode after being deintercalated during each charge-discharge process. On the contrary, since the crystal phase of the lithium-containing metal oxide is prone to change from the layered structure to the spinel / rock salt phase, and the spinel / rock salt phase structure can increase the Li + intercalation impedance, the Li + in the lithium-containing metal oxide cannot return to the lithium-containing metal oxide through discharge transfer anymore, which enables the lithium-containing metal oxide to play a role in supplementing lithium in the positive electrode active material.

[0049] In some embodiments, the lithium-containing metal oxide includes a compound with the molecular formula Li d Ni g Co h R k Q j O r T t and its modified compounds, where 0.8 ≤ d ≤ 1.2, 0 < g < 1, 0 < h < 1, 0 < k < 1, 0 ≤ j ≤ 0.1, 1 ≤ r ≤ 2, 0 ≤ t ≤ 1, and t + r ≤ 2; R includes at least one of Mn and Al; Q includes one or more of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, Nb; T includes one or more of N, F, S, Cl; optionally, the lithium-containing metal oxide includes at least one of lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide; optionally, the lithium-containing metal oxide includes LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM622) and LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM81) at least one of; optionally, the lithium-containing metal oxide includes LiNi 0.85 Co 0.15 Al​​0.05 O2, LiNi 0.8 Co 0.1 Al 0.1 O2(NCA811), LiNi 0.7 Co 0.2 Al 0.1 O2(NCA721), LiNi 0.5 Co 0.2 Al 0.3 O2(NCA523), LiNi 0.6 Co 0.2 Al 0.2 O2 (NCA622) and LiNi 1 / 3 Co 1 / 3 Al 1 / 3 At least one of O2 (NCA333).

[0050] The aforementioned lithium-containing metal oxides can also be referred to as ternary materials. Among them, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2(NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM622) and LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811) belongs to lithium nickel cobalt manganese oxide, LiNi 0.85 Co 0.15 Al 0.05 O2, LiNi 0.8 Co 0.1 Al 0.1 O2(NCA811), LiNi 0.7 Co 0.2 Al 0.1 O2(NCA721), LiNi 0.5 Co 0.2 Al 0.3 O2(NCA523), LiNi 0.6 Co 0.2 Al 0.2 O2 (NCA622) and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3O2 (NCA333) belongs to lithium nickel cobalt aluminum oxide. Lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide possess advantages such as good cycle performance, high voltage platform, good thermal stability, long cycle life, ideal crystal structure, low self-discharge, and no memory effect. For example, lithium-containing metal oxides can include lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide, or a mixture of the two. Both lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide have a layered structure.

[0051] In some embodiments, the lithium-containing metal oxide includes lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide, and the molar ratio of lithium nickel cobalt manganese oxide to lithium nickel cobalt aluminum oxide can be 0.01-100:100:0.01. For example, it can be 0.01:100, 1:100, 1:2, 1:1, 5:1, 7:100, 100:7, 2:1, 50:1, 100:1, 100:0.01, etc., or a range consisting of any two of the above values, for example, it can be 0.01:100-1:2, 1:1-7:100, 100:7-50:1, 100:1-100:0.01, etc.

[0052] During the cyclic charging process of lithium nickel cobalt manganese oxide and / or lithium nickel cobalt aluminum oxide at the operating voltage, Ni 2+ With Li + With similar radii, due to the high degree of cation mixing, in Li + When Ni is extracted from lithium nickel cobalt manganese oxide and / or lithium nickel cobalt aluminum oxide 2+ Will occupy Li + The position of ions within the crystal lattice. This ion dislocation phenomenon reduces the interlattice thickness and alters the lattice type; for example, lithium nickel cobalt manganese oxide and / or lithium nickel cobalt aluminum oxide transform from a layered structure to a spinel / rock salt phase structure. Compared to a layered structure, the spinel / rock salt phase structure can increase the density of Li. + Intercalation impedance affects its lithium intercalation capability, i.e., the ability to extract Li-. + It is impossible for the lithium to be transferred back to lithium nickel cobalt manganese oxide and / or lithium nickel cobalt aluminum oxide through discharge. Therefore, lithium nickel cobalt manganese oxide and / or lithium nickel cobalt aluminum oxide with a high degree of cation mixing have low capacity retention and can delithigate during each charge-discharge cycle, causing Li to... + The lithium is irreversibly extracted and transferred to the negative electrode to replenish the active lithium lost during SEI film formation and charging / discharging. Thus, without increasing the charging voltage during cycling, the active lithium in the battery can be continuously replenished, improving the cycle performance of the secondary battery.

[0053] In some embodiments, in lithium-containing metal oxides, the molar ratio of nickel to all metal elements except lithium is greater than or equal to 50%. For example, the nickel content can be 50%, 52%, 54%, 56%, 58%, 60%, 65%, 68%, 70%, 80%, etc., or a range consisting of any two of the above values, such as 50%-60%, 52%-56%, 56%-60%, 52%-68%, 68%-80%, etc. The proportions of nickel, cobalt, and manganese in lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide can be adjusted according to actual needs, ensuring that the nickel content is greater than or equal to 50%. During the cyclic charging process of lithium nickel cobalt manganese oxide and / or lithium nickel cobalt aluminum oxide at the operating voltage, Ni... 2+ With Li + With similar radii, due to the high degree of cation mixing, in Li + When Ni is extracted from lithium-containing metal oxides, 2+ Will occupy Li + Its position in the crystal lattice. Limiting the nickel content to the above range allows for a sufficient amount of Ni... 2+ Occupy Li + Its position within the crystal lattice promotes a reduction in the interlattice thickness of lithium-containing metal oxides, leading to a transformation from a layered structure to a spinel / rock salt phase structure, thereby increasing the Li... + Embedding impedance, causing the extracted Li + It can no longer be transferred back to the lithium-containing metal oxide through discharge.

[0054] In some embodiments, the lithium metal oxide accounts for 1%-5% of the mass percentage of the positive electrode active material. For example, the mass percentage of the lithium metal oxide in the positive electrode active material can be 1%, 1.5%, 2%, 2.6%, 3%, 3.3%, 4%, 4.7%, 5%, etc., or a range consisting of any two of the above values, such as 1%-3.3%, 1.5%-2.6%, 2.6%-3.3%, 1.5%-4.7%, 3.3%-5%, etc. In the positive electrode active material, the lithium metal oxide acts as a lithium supplement agent. Controlling the mass percentage of the lithium metal oxide within the above range ensures that the function of the lithium phosphate as a positive electrode active material is not affected, while simultaneously providing lithium supplementation.

[0055] In some embodiments, the value of the XRD diffraction peak I(003) / I(104) of the lithium-containing metal oxide is ≤1. For example, the value of the XRD diffraction peak I(003) / I(104) of the lithium-containing metal oxide can be 0.3, 0.5, 0.6, 0.7, 0.73, 0.8, 0.86, 0.9, 0.94, 1.0, etc., or a range consisting of any two of the above values, such as 0.3-0.5, 0.5-0.8, 0.5-0.73, 0.7-0.86, 0.94-1.0, etc. As mentioned above, the larger the R value, the higher the degree of hexagonal cell ordering of the lithium-containing metal oxide, the closer it is to the ideal hexagonal structure, and the more complete the crystal structure. Generally, an R value greater than 1.20 indicates that the lithium-containing metal oxide has a good layered structure, which is conducive to the diffusion of lithium ions. However, when the R value is less than or equal to 1.2, it indicates that the degree of cation mixing in the layered cathode material is high, and the insertion / extraction of lithium ions in the material is hindered. Further limiting the values ​​of the XRD diffraction peaks I(003) / I(104) of the lithium-containing metal oxide to the above range can further improve the effect of the lithium-containing metal oxide as a lithium replenishing agent, that is, it can further improve the cycle performance of the secondary battery.

[0056] [Positive electrode plate]

[0057] The secondary battery provided in this application embodiment includes a positive electrode sheet comprising a positive current collector and a positive electrode film layer disposed on the current collector. The positive electrode film layer comprises the positive electrode active material as described above. Optionally, the positive electrode active material accounts for 90%-97% of the mass percentage of the positive electrode film layer. For example, the mass percentage of the positive electrode active material in the positive electrode film layer can be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, etc., or a range consisting of any two of the above values, such as 90%-91%, 91%-93%, 92%-95%, 94%-97%, etc. As mentioned above, the positive electrode active material is a decisive factor in the electrochemical performance of lithium batteries, directly determining the energy density and reliability of the battery, and thus affecting the overall performance of the battery. By controlling the mass percentage of the positive electrode active material within the above range in this application embodiment, the energy density of the secondary battery can be improved, thereby improving the cycle performance of the secondary battery.

[0058] The positive electrode current collector can be a conventional metal foil or a composite current collector (a composite current collector can be formed by setting metal material on a polymer substrate). As an example, the positive electrode current collector can be aluminum foil.

[0059] The positive electrode film layer typically includes binders, conductive agents, and other optional additives.

[0060] As an example, the conductive agent can be one or more of the following: superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, conductive carbon black (Super P, SP), graphene, and carbon nanofibers.

[0061] As an example, the adhesive may be one or more of the following: polymerized styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0062] As an example, other optional additives include, but are not limited to, one or more combinations of acids, dispersants, surfactants, chelating agents, etc. The acids in the additives can be inorganic acids and / or organic acids. Inorganic acids in the additives include, but are not limited to, one or more combinations of hydrochloric acid, nitric acid, sulfuric acid, perchloric acid, chloric acid, etc., and organic acids in the additives preferably include, but are not limited to, one or more combinations of 2,4,6-trinitrophenol, 2,4,6-trinitrobenzoic acid, trifluoroacetic acid, trichloroacetic acid, methanesulfonic acid, benzenesulfonic acid, KMD acid, etc. Dispersants can be, but are not limited to, one or more combinations of water, ethanol, acetone, propanol, isopropanol, methanol, n-butanol, acetonitrile, tetrahydrofuran, dichloromethane ether, chloroform, dimethyl sulfoxide, dimethylformamide, etc. Surfactants can be, but are not limited to, one or more combinations of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, polyethylene glycol, polyethylene oxide, polyacrylamide or carboxymethyl cellulose, polyvinylpyrrolidone, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, etc. The chelating agent can be one or more of the following: aminetriacetic acid, 1,2-cyclohexanediaminetetraacetic acid, ethylenediaminetetraacetic acid, citric acid, malic acid, oxalic acid, acetic acid, salicylic acid, etc.

[0063] [Negative electrode plate]

[0064] In a secondary battery, the negative electrode typically includes a negative current collector and a negative electrode film layer disposed on the negative current collector, the negative electrode film layer including a negative electrode active material.

[0065] The negative electrode current collector can be a conventional metal foil or a composite current collector (for example, a composite current collector can be formed by setting a metal material on a polymer substrate). As an example, the negative electrode current collector can be a copper foil.

[0066] The specific type of negative electrode active material is not limited; any active material known in the art that can be used as the negative electrode of a secondary battery can be used. Those skilled in the art can select according to actual needs. As an example, the negative electrode active material may include, but is not limited to, one or more of artificial graphite, natural graphite, hard carbon, soft carbon, silicon-based materials, and tin-based materials. Silicon-based materials may be selected from one or more of elemental silicon, silicon oxide compounds (e.g., silicon suboxide), silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from one or more of elemental tin, tin oxide compounds, and tin alloys. All of these materials are commercially available.

[0067] In some implementations, the negative electrode active material may include a silicon-based material in order to further improve the energy density of the battery.

[0068] The negative electrode film layer typically includes binders, conductive agents, and other optional additives.

[0069] As an example, the conductive agent can be one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0070] As an example, the adhesive may be one or more of styrene-butadiene rubber (SBR), water-based acrylic resin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-vinyl acetate copolymer (EVA), polyvinyl alcohol (PVA), and polyvinyl butyral (PVB).

[0071] As an example, other optional additives may be thickeners and dispersants (such as sodium carboxymethylcellulose, CMC-Na) and PTC thermistor materials.

[0072] Electrolyte

[0073] A secondary battery may include an electrolyte, which acts as a conductor of ions between the positive and negative electrodes. The electrolyte may include an electrolyte salt and a solvent.

[0074] As an example, the electrolyte salt may be selected from one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0075] As an example, the solvent may be selected from ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl ethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), diisopropyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (n-Propyl Acetate (PA), methyl propionate (MP), and ethyl propionate (Ethyl... One or more of the following: Propanoate (EP), n-PropylPropionate (PP), Methyl Butyrate (MB), Ethyl Butyrate (EB), 1,4-Butyrolactone (GBL), Tetramethylene Sulfone (SF), Methyl Sulfone (MSM), Methyl Ethyl Sulfone (EMS), and Diethyl Sulfone (ESE).

[0076] In some embodiments, the electrolyte also includes additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, and additives that improve battery low-temperature performance.

[0077] This application does not impose any particular limitation on the shape of the secondary battery; it can be cylindrical, square, or any other arbitrary shape. Figure 1 This is an example of a square-structured secondary battery 5.

[0078] In some embodiments, the secondary battery may include an outer packaging. This outer packaging encapsulates the positive electrode, the negative electrode, and the electrolyte. A separator faces the positive electrode.

[0079] In some embodiments, the outer packaging of the secondary battery can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the secondary battery can also be a soft pack, such as a pouch-type soft pack. The material of the soft pack can be plastic, including one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0080] In some implementations, refer to Figure 2 The outer packaging may include a housing 51 and a cover 53. The housing 51 may include a bottom plate and side plates connected to the bottom plate, the bottom plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 can be placed on the opening to close the receiving cavity.

[0081] The method for preparing the secondary battery described in this application is well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a secondary battery. As an example, the positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process and / or a stacking process. The electrode assembly is placed in an outer packaging, dried, and then injected with an electrolyte. After vacuum sealing, settling, formation, and shaping processes, a battery cell is obtained. Multiple battery cells can be further connected in series, parallel, or a combination thereof to form a battery module. Multiple battery modules can also be connected in series, parallel, or a combination thereof to form a battery pack. In some embodiments, multiple battery cells can also be directly assembled into a battery pack.

[0082] Figure 3 This is battery module 4, used as an example. (See reference...) Figure 5In battery module 4, multiple secondary batteries 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple secondary batteries 5 can be fixed in place using fasteners.

[0083] The battery module 4 may also include a housing with a receiving space in which multiple secondary batteries 5 are received.

[0084] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0085] Figure 4 and Figure 5 This is battery pack 1 as an example. (See reference...) Figure 4 and Figure 5 The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0086] [Rechargeable Battery]

[0087] A rechargeable battery is a battery that can be recharged after discharge to reactivate its active materials and continue to be used. Typically, a rechargeable battery includes a positive electrode, a negative electrode, a separator, and an electrolyte. During charging and discharging, active ions repeatedly insert and extract between the positive and negative electrodes. The separator, positioned between the positive and negative electrodes, serves as a barrier. The electrolyte, acting as a conductor of ions, lies between the positive and negative electrodes.

[0088] The secondary battery provided in the application embodiment includes a lithium battery, in which the active ion is lithium ion. The lithium ion is inserted and extracted back and forth between the positive electrode and the negative electrode to realize the charging and discharging process.

[0089] In related technologies, the operating voltage range of secondary batteries with lithium metal oxide as the positive electrode active material is 2.8V-4.4V, with a voltage plateau of around 3.2V. The operating voltage range of lithium iron phosphate batteries is 2V-3.8V, with a voltage plateau of around 3.7V. Therefore, only by increasing the charging voltage can the lithium metal oxide be activated and delithiated. However, increasing the charging voltage may trigger side reactions at the electrodes, leading to increased electrode interface impedance, increased polarization, and affecting cell performance. Furthermore, using this strategy, lithium replenishment to the negative electrode can only be performed during charging activation within the aforementioned activation voltage range, making continuous lithium replenishment impossible during each charge-discharge cycle. Moreover, to stabilize the structure of the lithium metal oxide, the precursor is typically modified through doping, coating, or structural improvements, which increases manufacturing costs and complexity.

[0090] The secondary battery provided in this application embodiment includes the positive electrode active material as described above, which includes lithium phosphate and lithium metal oxide.

[0091] In some embodiments, the input voltage of the secondary battery is 2.0V-3.8V. Compared with secondary batteries in related technologies where the positive electrode active material is a lithium metal oxide, the secondary battery provided in this application embodiment can continuously replenish lithium during each charge and discharge process when the input voltage is between 2.0V and 3.8V, without needing to increase the charging voltage to replenish lithium.

[0092] In any embodiment of this application, the charging temperature of the secondary battery is 30-45°C. If the charging temperature is too high, overcharging and discharging of the secondary battery will damage the positive and negative electrodes. For example, collapse may prevent lithium ions from inserting into the negative electrode during charging, or some lithium ions in the negative electrode may no longer be released, thus shortening the lifespan of the secondary battery. If the charging temperature is too low, the lithium battery's lithium replenishment rate will be slow. Within the above temperature range, the lithium battery has high charging efficiency, short charging time, and good lithium replenishment effect, which can also improve the battery's reliability and lifespan.

[0093] [Device]

[0094] This application also provides an electrical device, which includes the secondary battery of this application. A single battery cell, battery module, or battery pack can serve as a power source for the device, or as an energy storage unit. The device can be, but is not limited to, mobile devices (e.g., mobile phones, laptops), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks), electric trains, ships and satellites, and energy storage systems.

[0095] The device can be configured to use individual battery cells, battery modules, or battery packs depending on its application requirements.

[0096] In any embodiment of this application, the electrical device further includes a temperature regulator for adjusting the ambient temperature of the secondary battery to 30-45°C. If the charging temperature is too high, overcharging and discharging of the secondary battery can damage the positive and negative electrodes. For example, collapse can prevent lithium ions from inserting into the negative electrode during charging, or cause some lithium ions in the negative electrode to become unable to be released, thus shortening the battery's lifespan. If the charging temperature is too low, the lithium battery's lithium replenishment rate is slow. Within the aforementioned temperature range, the lithium battery has high charging efficiency, short charging time, and good lithium replenishment effect, which also improves battery reliability and lifespan.

[0097] Figure 6 This is an example of an electrical device 6. This electrical device 6 can be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery for this electrical device 6, a battery pack or battery module can be used.

[0098] As another example, the power device 6 could be a mobile phone, tablet, or laptop. This power device typically requires a slim and lightweight design and can use a single battery cell as its power source.

[0099] The beneficial effects of this application are further illustrated below with reference to the embodiments.

[0100] To make the technical problems, technical solutions, and beneficial effects solved by the embodiments of this application clearer, the following will provide a more detailed description in conjunction with the embodiments and accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0101] Preparation of primary and secondary batteries

[0102] 1. Preparation of negative electrode sheet

[0103] Preparation of the negative electrode sheet: Graphite, sodium carboxymethyl cellulose (CMC), conductive carbon (SP), and binder (SBR) were mixed at high speed in water at a ratio of 96:1:1:2 to obtain a slurry with a solid content of 53%. The weight of the obtained slurry was controlled to be 0.209 g / 1540.25 mm. 2 The paste is uniformly coated onto a 10μm thick copper foil. After the paste on the copper foil is fully dried in an environment with an average temperature of 85℃, it is cold-pressed with a compaction of 1.7g / cc to obtain a negative electrode sheet with a thickness of 0.1694mm, which is then cut into 97mm wide pieces for later use.

[0104] 2. Preparation of the positive electrode sheet

[0105] Lithium iron phosphate (LFP), lithium metal oxide NCM622 (R value 1.2), binder PVDF, and conductive carbon SP were mixed at high speed in an NMP solution at a ratio of 97:1:1:1 to obtain a slurry with a solid content of 62%. The weight of the obtained slurry was controlled at 0.45 g / 1540.25 mm. 2 The paste is uniformly coated onto a 15μm thick aluminum foil. After the paste on the aluminum foil is fully dried in an environment with an average temperature of 85℃, it is cold-pressed with a compaction of 2.6g / cc to obtain a positive electrode sheet with a thickness of 0.2384mm, which is then cut into 100mm wide pieces for later use.

[0106] 3. Secondary battery assembly

[0107] A 7μm separator was cut into 106mm wide pieces, and the positive and negative electrodes and separator were wound together using a 322mm circumference needle to obtain a dry cell. Then, an electrolyte solution with 1M LiPF6 as the lithium salt and an EC / DMC / PC ratio of 1:1:1 was added to obtain a 169.9Ah secondary battery.

[0108] 4. Charging method

[0109] It can be used in charge-discharge cycles between 2V and 3.8V.

[0110] The secondary batteries of Examples 2-8 and Comparative Examples 1-5 are prepared in a similar manner to the secondary battery of Example 1, except that the types and proportions of lithium metal oxides are different, as well as the cycling temperature is different. In Examples 6 / 11 / 16 and Comparative Example 3, the molar ratio of NCM622 to NCA622 is 1:1.

[0111] See Table 1 for details.

[0112] II. Battery Performance Testing

[0113] Battery cycle performance (cycles):

[0114] At 25°C, the secondary batteries prepared in the examples and comparative examples were charged at a constant current rate of 1C to the charging cutoff voltage V1, then charged at a constant voltage until the current ≤0.05C, allowed to stand for 5 minutes, and then discharged at a constant current rate of 0.33C to the discharge cutoff voltage V2, allowed to stand for 5 minutes. This constitutes one charge-discharge cycle. The batteries were subjected to cyclic charge-discharge tests according to this method until the battery capacity decreased to 80%. The number of cycles at this point is the cycle life of the battery at 25°C.

[0115]

[0116]

[0117] As shown in Table 1, compared with Comparative Examples 1-3, Examples 1-26 with a mass ratio of 1%-20% containing lithium metal oxide and an R value less than or equal to 1.2 have better lithium replenishment effect and better cycle performance of secondary batteries.

[0118] Comparing Example 7 with Example 1, Example 8 with Example 2, Example 9 with Example 3, Example 10 with Example 4, and Example 11 with Example 6, when the value of the XRD diffraction peak I(003) / I(104) of the lithium metal oxide is ≤1, the lithium replenishment effect is good and the cycle performance of the secondary battery is excellent.

[0119] Compared with Examples 7-8 and 17, Examples 12-16 show that when the mass percentage of lithium metal oxide in the positive electrode active material is 1%-5%, the lithium replenishment effect is good and the cycle performance of the secondary battery is excellent.

[0120] Compared with Example 18, Examples 8, 19, and 20 show that when the molar ratio of nickel to all metal elements except lithium in lithium-containing metal oxides is greater than or equal to 50%, the lithium replenishment effect is good and the cycle performance of the secondary battery is excellent.

[0121] Compared with Examples 8, 25, and 26, Examples 21-24 show better lithium replenishment and better cycle performance of the secondary battery when the charging temperature is 30-45℃.

[0122] In summary, the positive electrode active material provided in this application includes lithium phosphate and lithium metal oxide. The lithium metal oxide comprises lithium-containing metal oxides, and the lithium metal oxide accounts for 1%-20% of the mass percentage of the positive electrode active material. The XRD diffraction peak I(003) / I(104) value of the lithium metal oxide is ≤1.2. Li + When lithium-containing metal oxides are extracted, they readily transform from a layered structure to a spinel / rock salt phase structure. This structure can increase the yield of Li. + Intercalation impedance affects its lithium intercalation capability, i.e., the ability to extract Li-. + It is impossible for the lithium to be transferred back to the lithium-containing metal oxide through discharge. Therefore, lithium-containing metal oxides with a high degree of cation mixing have low capacity retention, and they can delithigate during each charge-discharge cycle, causing Li to... + The lithium is irreversibly released and transferred to the negative electrode to replenish the active lithium. Therefore, during cycling, without increasing the charging voltage, the active lithium of the battery can be continuously replenished, improving the cycle performance of the secondary battery.

[0123] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A positive electrode active material, characterized in that, Including lithium-containing phosphates and lithium-containing metal oxides; The lithium-containing metal oxide accounts for 1%-20% of the mass percentage of the positive electrode active material. The X-ray diffraction pattern of the lithium-containing metal oxide includes diffraction peaks of the (003) crystal plane and diffraction peaks of the (104) crystal plane. The diffraction peaks of the (003) crystal plane and the diffraction peaks of the (104) crystal plane satisfy the following: 0.6≤I(003) / I(104)≤0.8, where I(003) represents the intensity of the diffraction peak of the (003) crystal plane and I(104) represents the intensity of the diffraction peak of the (104) crystal plane. The lithium-containing metal oxide has a hexagonal unit cell structure, and the diffraction peaks of the (003) crystal plane reflect the hexagonal structure, while the diffraction peaks of the (104) crystal plane reflect the sum of the hexagonal and cubic structures. In the lithium-containing metal oxide, the molar ratio of nickel to all metal elements except lithium is greater than or equal to 50%.

2. The positive electrode active material as described in claim 1, characterized in that, The lithium-containing phosphate includes a compound with the formula Li x A y Me a M b P 1-c X c Y z and its modified compounds, where 0 < x ≤ 1.3, 0 ≤ y < 1.3, and 0.9 ≤ x + y ≤ 1.3, 0 < a ≤ 1.5, 0 ≤ b ≤ 0.7, 0.6 ≤ a + b ≤ 1.5, 0 ≤ c ≤ 0.5, 3 ≤ z ≤ 5; A includes one or more of Na, K, and Mg; Me includes one or more of Mn, Fe, Co, and Ni; M includes one or more of Al, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X includes one or more of S, Si, Cl, B, C, and N; Y includes one or more of O and F.

3. The positive electrode active material as described in claim 2, characterized in that, The lithium-containing phosphate includes at least one of lithium iron phosphate and lithium vanadium phosphate.

4. The positive electrode active material as described in claim 2, characterized in that, The lithium-containing phosphates include LiFePO4, LiNiPO4, LiCoPO4, and LiV. 0.67 PO4, LiMnPO4, LiMn 0.2 Fe 0.8 PO4 and LiMn 0.5 Fe 0.5 One or more of PO4.

5. The positive electrode active material according to any one of claims 1 to 4, characterized in that, The lithium-containing metal oxide includes those with the molecular formula Li. d Ni g Co h R k Q j O r T t Compounds and their modified compounds, wherein 0.8 ≤ d ≤ 1.2, 0.5 ≤ g < 1, 0 <h<1,0<k<1,0≤j≤0.1,1≤r≤2,0≤t≤1,t+r≤2; R includes at least one of Mn and Al; Q includes one or more of Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, and Nb; T includes one or more of N, F, S, and Cl.

6. The positive electrode active material as described in claim 5, characterized in that, The lithium-containing metal oxide includes at least one of lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide.

7. The positive electrode active material as described in claim 5, characterized in that, The lithium-containing metal oxide includes LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2 and LiNi 0.8 Co 0.1 Mn 0.1 At least one of O2.

8. The positive electrode active material as described in claim 5, characterized in that, The lithium-containing metal oxide includes LiNi 0.85 Co 0.15 Al 0.05 O2, LiNi 0.8 Co 0.1 Al 0.1 O2 and LiNi 0.5 Co 0.2 Al 0.3 At least one of O2.

9. The positive electrode active material according to any one of claims 1 to 8, characterized in that, The lithium-containing metal oxide accounts for 10%-20% of the mass percentage of the positive electrode active material.

10. A positive electrode plate, characterized in that, It includes a current collector and a positive electrode film layer disposed on the current collector, the positive electrode film layer comprising the positive electrode active material as described in any one of claims 1 to 9.

11. The positive electrode sheet as described in claim 10, characterized in that, The positive electrode active material accounts for 90%-97% of the mass of the positive electrode film.

12. A secondary battery, characterized in that, Includes the positive electrode sheet as described in claim 10 or 11.

13. The secondary battery as described in claim 12, characterized in that, The input voltage of the secondary battery is 2.0 V-3.8 V.

14. The secondary battery as described in claim 12 or 13, characterized in that, The charging temperature of the secondary battery is 30-45 ℃.

15. An electrical appliance, characterized in that, Includes the secondary battery as described in any one of claims 12-14.

16. The electrical appliance as described in claim 15, characterized in that, It also includes a temperature regulator, which is used to adjust the ambient temperature of the secondary battery to 30-45 ℃.

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