Battery cell, battery device and electric device

Abstract

The invention discloses a battery cell, a battery device and a power utilization device. The battery monomer comprises a positive pole piece and a negative pole piece, in the positive pole piece, a positive active material layer comprises a positive active material, the positive active material comprises a multi-element active material and a lithium supplement agent, the multi-element active material comprises a layered metal oxide containing nickel, cobalt and manganese elements, and based on the total molar weight of the nickel, cobalt and manganese elements, the lithium supplement agent is a lithium supplement agent. The molar ratio of the nickel element is greater than or equal to 80%; or the multi-element active material comprises a layered metal oxide containing nickel, cobalt and aluminum elements, and based on the total molar weight of the nickel, cobalt and aluminum elements, the molar ratio of the nickel element is larger than or equal to 80%; the lithium supplement agent comprises a nickel-containing metal oxide and / or an iron-containing metal oxide; in the negative pole piece, the negative active material layer comprises a negative active material, and the negative active material comprises graphite and a silicon-based material. Therefore, the battery has relatively high energy density and relatively long cycle life.

Description

Technical Field

[0001] The present application belongs to the field of battery technology, and specifically relates to battery cells, battery devices and electrical devices. Background Art

[0002] Secondary batteries are not only used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles, electric cars, as well as military equipment and aerospace and other fields. With the development of current society, people's requirements for batteries are getting higher and higher, such as high energy density or long service life. Summary of the invention

[0003] In view of the technical problems existing in the background technology, the present application provides a battery cell, aiming to obtain high energy density and long cycle life.

[0004] In order to achieve the above object, in a first aspect of the present application, a battery cell is provided, comprising:

[0005] A positive electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector, the positive electrode active material layer comprising a positive electrode active material, the positive electrode active material comprising a multi-element active material and a lithium supplement, wherein:

[0006] The multi-element active material comprises a layered metal oxide containing nickel, cobalt and manganese elements, wherein the molar proportion of the nickel element in the layered metal oxide containing nickel, cobalt and manganese elements is ≥80% based on the total molar amount of the nickel, cobalt and manganese elements; or, the multi-element active material comprises a layered metal oxide containing nickel, cobalt and aluminum elements, wherein the molar proportion of the nickel element in the layered metal oxide containing nickel, cobalt and aluminum elements is ≥80% based on the total molar amount of the nickel, cobalt and aluminum elements;

[0007] The lithium supplement comprises a metal oxide containing nickel and / or a metal oxide containing iron;

[0008] A negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector, wherein the negative electrode active material layer comprises a negative electrode active material, and the negative electrode active material comprises graphite and a silicon-based material.

[0009] The battery cell of the first aspect of the present application has at least the following beneficial effects: on the basis of improving the battery energy density, the content of active lithium on the negative electrode side can be effectively increased, and the problem of increased loss of active lithium when forming SEI film due to the small particle size of silicon-containing materials affecting the first cycle efficiency can be improved, as well as the problem of easy destruction or pulverization of silicon-containing materials during the cycle due to their large expansion, which leads to the rupture and regeneration of SEI film, resulting in active lithium consumption and reduced battery cell cycle performance. Thus, the battery can have both high energy density and long cycle life.

[0010] In some embodiments of the present application, the silicon-based material includes silicon-oxygen compounds and / or silicon-carbon compounds, thereby further improving the energy density of the battery.

[0011] In some embodiments of the present application, based on the total mass of the negative electrode active material, the mass proportion of the silicon element is 0.3% to 10%, which is conducive to making the battery have higher energy density, first efficiency and cycle life.

[0012] In some embodiments of the present application, the silicon-based material includes silicon oxides, and the mass proportion of the silicon element is 0.5% to 5% based on the total mass of the negative electrode active material, thereby facilitating the battery to have a higher energy density, first efficiency and cycle life.

[0013] In some embodiments of the present application, the silicon-based material includes a silicon-carbon compound, and the mass proportion of the silicon element is 3% to 10% based on the total mass of the negative electrode active material, thereby facilitating the battery to have a higher energy density, first efficiency and cycle life.

[0014] In some embodiments of the present application, the longitudinal section of the positive electrode sheet along the thickness direction includes multi-active material particles and lithium supplement particles, the lithium supplement particles include transition metal elements, the transition metal elements include nickel elements, and in a single lithium supplement particle, based on the total molar amount of the transition metal elements, the molar proportion of the nickel element is n1; the multi-active material particles include layered metal oxides containing nickel, cobalt and manganese elements, and in a single multi-active material particle, based on the total molar amount of the nickel, cobalt and manganese elements, the molar proportion of the nickel element is n2, and the ratio of n1 to n2 is 1:(0.8~0.96), or the multi-active material particles include layered metal oxides containing nickel, cobalt and aluminum elements, and in a single multi-active material particle, based on the total molar amount of the nickel, cobalt and aluminum elements, the molar proportion of the nickel element is n3, and the ratio of n1 to n3 is 1:(0.8~0.96).

[0015] In some embodiments of the present application, the positive electrode active material further comprises one or more of the following elements: P, Al, Mg, Zr, B, Ti, and based on the total mass of the positive electrode active material, the content of the P element, the Al element, the Mg element, the Zr element, the B element, and the Ti element is independently less than or equal to 7000 ppm, thereby further enabling the battery to have a higher energy density and better cycle performance.

[0016] In some embodiments of the present application, the positive electrode active material includes P element, and the content of P element is 50 ppm to 3000 ppm based on the total mass of the positive electrode active material.

[0017] In some embodiments of the present application, the positive electrode active material includes Al element, and based on the total mass of the positive electrode active material, the content of Al element is 50 ppm to 3000 ppm, and can be optionally 300 ppm to 2000 ppm.

[0018] In some embodiments of the present application, the positive electrode active material includes Mg element, and the content of Mg element is 50 ppm to 3000 ppm based on the total mass of the positive electrode active material.

[0019] In some embodiments of the present application, the positive electrode active material includes a Zr element. Based on the total mass of the positive electrode active material, the content of the Zr element is 50 ppm to 4000 ppm, and can be optionally 2000 ppm to 4000 ppm.

[0020] In some embodiments of the present application, the positive electrode active material includes element B, and the content of element B is 50 ppm to 7000 ppm, optionally 500 ppm to 7000 ppm, based on the total mass of the positive electrode active material.

[0021] In some embodiments of the present application, the positive electrode active material includes a Ti element, and the content of the Ti element is 5 ppm to 3000 ppm based on the total mass of the positive electrode active material.

[0022] In some embodiments of the present application, at least part of the surface of the lithium supplement is provided with a coating layer, and the coating layer includes one or more of the following elements: C, Al, Zr, P, S. This is beneficial to improve the air stability of the lithium supplement and reduce the generation of lithium impurities on the surface.

[0023] In some embodiments of the present application, the coating layer includes one or more of carbon material, aluminum oxide, zirconium oxide, lithium phosphide, and lithium sulfide, which is beneficial to further improve the electrochemical performance of the battery.

[0024] In some embodiments of the present application, the multi-active material includes secondary particles, and the surface roughness of the secondary particles is greater than the surface roughness of the lithium supplement particles.

[0025] In some embodiments of the present application, the secondary particles are spherical or quasi-spherical.

[0026] In some embodiments of the present application, the positive electrode active material layer further includes a conductive agent, and the conductive agent includes conductive carbon black and carbon nanotubes. This not only improves the conductivity of the electrode, but also facilitates the decomposition of the lithium supplement and the improvement of the battery dynamics.

[0027] In some embodiments of the present application, the lithium supplement comprises Li x M1 y M2 g O z , wherein 1≤x≤6, 1≤y≤6, 2≤z≤12, 0≤g≤0.05, M1 includes one or more elements of Na, Ni, Co, Mn, and Fe, and M2 includes one or more elements of Al, Zr, and B. Thus, a better lithium supplementation effect can be achieved, so that the battery has both higher energy density, first efficiency, and cycle life.

[0028] In some embodiments of the present application, the lithium supplement includes Li2NiO2 and / or Li5FeO4. Thus, the first efficiency and energy density of the battery can be improved, so that the battery has higher energy density, first efficiency and cycle life.

[0029] In some embodiments of the present application, the lithium supplement comprises Li n NiO m and / or Li p FeO q , where 0≤n≤2, 0<m≤2, 0<p≤5, 0<q≤4.

[0030] In some embodiments of the present application, the lithium supplement comprises NiO m and / or Li p FeO q , where 0<m≤2, 0<p≤1, 0<q≤2.

[0031] In some embodiments of the present application, the general formula of the multi-active material is Li a Ni b Co c M3 d M4 e O f, wherein 0.5≤a≤1.2, 0.8≤b≤0.96, 0<c<1, 0<d<1, 0≤e≤0.03, b+c+d+e=1, 1.8≤f≤3.5, M3 includes Mn element or Al element; M4 includes one or more of the following elements: Na, K, Mg, B, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, F. In this way, the energy density and cycle performance of the battery can be better taken into account, and the service life of the battery can be extended.

[0032] In some embodiments of the present application, M4 includes one or more of the following elements: Al, Mg, Zr, B, P, Ti. Thus, the battery can further have both higher energy density and better cycle stability, thereby extending the battery life.

[0033] In some embodiments of the present application, the battery cell is a soft-pack battery, a square battery or a cylindrical battery.

[0034] A second aspect of the present application provides a battery device, which includes: the battery cell described in the first aspect of the present application, and the battery device includes at least one of a battery module, a battery pack, and an energy storage device.

[0035] The third aspect of the present application provides an electrical device, which includes: the battery cell described in the first aspect of the present application or the battery device described in the second aspect of the present application, and the battery cell or the battery device is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0037] Figure 1 It is a schematic structural diagram of a battery cell according to one embodiment of the present application.

[0038] Figure 2 It is a schematic structural diagram of a battery module according to one embodiment of the present application.

[0039] Figure 3 It is a schematic diagram of the structure of a battery pack according to one embodiment of the present application.

[0040] Figure 4 yes Figure 3 Exploded diagram of .

[0041] Figure 5 It is a schematic diagram of an embodiment of an electrical device using the battery device of the present application as a power source.

[0042] Description of reference numerals:

[0043] 1: Battery cell; 2: Battery module; 3: Battery pack; 4: Upper case; 5: Lower case. DETAILED DESCRIPTION

[0044] The present application is further described below in conjunction with specific implementations. It should be understood that these specific implementations are only used to illustrate the present application and are not used to limit the scope of the present application.

[0045] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0046] "Scope" disclosed in the present application is defined in the form of lower limit and / or upper limit, and a given range is defined by selecting a lower limit and / or an upper limit, and the selected lower limit and / or the rear upper limit define the boundary of a special range. The scope defined in this way can be including or excluding end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a scope that is not clearly recorded, and any lower limit can be combined with other lower limits to form a scope that is not clearly recorded, and any upper limit can be combined with any other upper limit to form a scope that is not clearly recorded. In addition, each separately disclosed point or single numerical value itself can be used as a lower limit or upper limit and any other point or single numerical value combination or with other lower limits or upper limits to form a scope that is not clearly recorded.

[0047] If not otherwise specified, all embodiments and optional embodiments of the present application may be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of the present application.

[0048] Unless otherwise specified, all technical features and optional technical features of the present application may be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of the present application.

[0049] If there is no special explanation, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps S1 and S2, which means that the method may include steps S1 and S2 performed sequentially, or may include steps S2 and S1 performed sequentially. For example, the method may also include step S3, which means that step S3 may be added to the method in any order. For example, the method may include steps S1, S2 and S3, or may include steps S1, S3 and S2, or may include steps S3, S1 and S2, etc.

[0050] If there is no special explanation, in this application, the term "and / or" is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0051] In the present application, the terms "plurality" and "multiple" refer to two or more.

[0052] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by technicians in the technical field of this application; the terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and any variations thereof are intended to cover non-exclusive inclusions. Unless otherwise specified, the terms used in this application have the well-known meanings commonly understood by those skilled in the art. Unless otherwise specified, the numerical values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (for example, they can be tested according to the methods given in the embodiments of this application).

[0053] With the continuous advancement of green environmental protection, the application of batteries has penetrated into all aspects of life, including vehicles, electronic equipment, energy storage devices, etc. However, with the continuous promotion of battery applications, people's requirements for batteries are getting higher and higher. For example, taking lithium-ion batteries as an example, secondary batteries with high energy density and long cycle life have become an important research direction in the battery industry.

[0054] The present application aims to develop a battery cell with both high energy density and long cycle life by comprehensively controlling the composition of the positive electrode sheet and the negative electrode sheet, using high-nickel multi-active materials and lithium supplements as positive electrode active materials in the positive electrode sheet, using graphite and silicon-based materials as negative electrode active materials in the negative electrode sheet, and regulating the nickel content in the multi-active materials, so as to develop a battery cell with high energy density and long cycle life.

[0055] In the positive electrode plate of the present application, the positive electrode active material includes a multi-active material and a lithium supplement, the multi-active material includes a layered metal oxide containing nickel, cobalt and manganese elements, and in the layered metal oxide containing nickel, cobalt and manganese elements, based on the total molar amount of nickel, cobalt and manganese elements, the molar proportion of nickel element is ≥80%; or, the multi-active material includes a layered metal oxide containing nickel, cobalt and aluminum elements, and in the layered metal oxide containing nickel, cobalt and aluminum elements, based on the total molar amount of nickel, cobalt and aluminum elements, the molar proportion of nickel element is ≥80%; the lithium supplement includes a metal oxide containing nickel and / or a metal oxide containing iron; in the negative electrode plate, the negative electrode active material uses graphite and silicon-based materials. Therefore, on the basis of improving the energy density of the battery, the content of active lithium on the negative electrode side can be effectively increased, and the problem of increased loss of active lithium when forming the SEI film due to the small particle size of the silicon-containing material, which affects the first cycle efficiency, and the problem of easy destruction or pulverization of the silicon-containing material during the cycle due to its large expansion, which leads to the rupture and regeneration of the SEI film, resulting in active lithium consumption and reduced battery cell cycle performance, can be improved, so that the battery has both high energy density and long cycle life.

[0056] The battery cells disclosed in the embodiments of the present application can be used in electrical equipment that uses the battery cells or battery devices with the battery cells as power sources or various energy storage systems that use the battery cells or battery devices with the battery cells as energy storage elements. Electrical equipment may include, but is not limited to, mobile phones, tablets, laptops, electric toys, electric tools, battery cars, electric cars, ships, spacecraft, and the like. Among them, electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, and the like, and spacecraft may include airplanes, rockets, space shuttles, and spacecraft, and the like.

[0057] The first aspect of the present application provides a battery cell, which includes: a positive electrode plate and a negative electrode plate. The positive electrode plate includes a positive current collector and a positive active material layer provided on at least one side of the positive current collector, the positive active material layer includes a positive active material, the positive active material includes a multi-active material and a lithium supplement, wherein the multi-active material includes a layered metal oxide containing nickel, cobalt and manganese elements, in which the molar proportion of nickel element in the layered metal oxide containing nickel, cobalt and manganese elements is ≥80% based on the total molar amount of nickel, cobalt and manganese elements; or, the multi-active material includes a layered metal oxide containing nickel, cobalt and aluminum elements, in which the molar proportion of nickel element in the layered metal oxide containing nickel, cobalt and aluminum elements is ≥80% based on the total molar amount of nickel, cobalt and aluminum elements; the lithium supplement includes a metal oxide containing nickel element and / or a metal oxide containing iron; the negative electrode plate includes a negative current collector and a negative active material layer provided on at least one side of the negative current collector, the negative active material layer includes a negative active material, and the negative active material includes graphite and silicon-based materials.

[0058] In silicon-containing battery systems, it is difficult to achieve both high energy density and long cycle life. Among them, although the system of high-nickel positive electrode active materials and silicon-based negative electrode active materials helps to increase the gram capacity of active materials in positive and negative electrode sheets, the introduction of silicon materials has the following problems: First, compared with graphite, the particle size of silicon materials is relatively small, and the loss of active lithium when forming the SEI film will increase, resulting in the inability of the active lithium from the positive electrode to be sufficiently embedded back into the positive electrode active material during the first cycle, resulting in a decrease in the first efficiency of the battery. Therefore, after the introduction of the lithium supplement, the active lithium content on the negative electrode side can be effectively increased, and the problem of low first efficiency caused by the introduction of silicon materials can be reduced, thereby reducing the cycle capacity attenuation caused by the battery in the long-term cycle process; second, compared with graphite, the silicon material itself expands greatly, and is easily broken or pulverized during the cycle process, resulting in the exposure of new phase interfaces, thereby promoting the formation of new SEI films, and the formation of new SEI films will lead to continued loss of active lithium, reducing the battery cycle performance. Therefore, after the introduction of the lithium supplement, the active lithium content on the negative electrode side can be effectively increased, and sufficient lithium can be supplied to form a new SEI film to improve the cycle performance.

[0059] Therefore, the battery cell of the first aspect of the present application has at least the following beneficial effects: on the basis of improving the battery energy density, the first efficiency and cycle performance of the battery can be taken into account, so that the battery has both higher energy density and longer cycle life.

[0060] Exemplarily, the multi-active material may include a layered metal oxide containing nickel, cobalt and manganese elements, in which the molar percentage of nickel element based on the total molar amount of nickel, cobalt and manganese elements may be 80%, 82%, 85%, 88%, 90%, 92%, 95% or 96%, etc.

[0061] Exemplarily, the multi-active material may include a layered metal oxide containing nickel, cobalt, and aluminum, in which the molar percentage of nickel element based on the total molar amount of nickel, cobalt, and aluminum elements may be 80%, 82%, 85%, 88%, 90%, 92%, 95%, or 96%, etc.

[0062] In the present application, the composition of the multi-active material in the positive electrode active material layer can be analyzed in combination with one or more characterization methods such as X-ray diffraction (XRD), energy spectrum analysis (EDS), inductively coupled plasma emission spectroscopy (ICP), etc.; the analysis method of the relative molar content of nickel in the multi-active material can include but is not limited to inductively coupled plasma emission spectroscopy (ICP) test, such as EPA6010D-2014 "Inductively Coupled Plasma Atomic Emission Spectrometry", after disassembling the battery, separating the positive electrode active material sample from the pole piece, and treating the sample to be tested by chemical methods to dissolve it into a solution, atomizing it into plasma to excite the characteristic spectrum of the element, and qualitatively and quantitatively analyzing the element content according to the wavelength and intensity (proportional to the concentration) of the spectrum line. In the actual operation process, when testing the element composition in the multi-active material, one or more conventional methods such as mechanical stripping method and chemical dissolution method can be used to obtain the positive electrode active material sample from the pole piece.

[0063] In some embodiments of the present application, one or more conventional instruments and conventional methods such as a scanning electron microscope, an EDS spectrometer, an X-ray diffractometer, and an inductively coupled plasma emission spectrometer can be combined to perform qualitative and quantitative analysis on the positive electrode active material to determine whether a lithium supplement is present in the positive electrode active material and the type of the lithium supplement.

[0064] For example, in the positive electrode active material layer, the lithium supplement agent and the multi-active material particles used as positive electrode active materials have different elemental compositions as well as usually different sizes and particle morphologies. The lithium supplement agent does not completely disappear after delithiation, but residual elements and particle skeletons remain. The lithium supplement agent usually shrinks in volume after delithiation, so that a certain gap is formed between the residual particle skeleton and the surrounding area. Based on the above differences, the possible locations of the lithium supplement agent can be quickly screened in the scanning electron microscope test, and the elemental composition and content of the lithium supplement agent can be analyzed in combination with the EDS energy spectrometer.

[0065] For another example, the surface roughness of the multi-active material particles and the lithium supplement agent particles are usually different. This difference can also be used to quickly screen the location of the lithium supplement agent in the scanning electron microscope test. In addition, the X-ray diffractometer can be further combined to perform XRD characterization on the positive electrode active material sample to determine the crystal structure of the lithium supplement agent, and combined with the ICP test to further determine the content of the lithium supplement agent.

[0066] For another example, lithium supplements usually do not completely remove lithium after formation. The diffraction peak changes (such as peak position, peak intensity, etc.) of the XRD spectrum of the positive electrode active material sample to be tested before and after charging and discharging can be compared to determine whether a lithium supplement is added to the positive electrode active material and the type of lithium supplement added. In addition, due to the difference in lithium content between the lithium supplement and the multi-active material and the different lithium deintercalation efficiency during charging and discharging, their lithium content in the full charged and discharged state is also different. For example, in the charged state, the lithium deintercalation efficiency of the lithium supplement in the positive electrode active material is usually lower than the lithium deintercalation efficiency of the multi-active material. The cross-section of the positive electrode active material layer can be characterized and distinguished by FIB (focused ion beam) combined with SIMS (secondary ion mass spectrometry) testing to determine whether there is a lithium supplement in the positive electrode active material and the type of lithium supplement; and in a charging and discharging process, the lithium supplement and the multi-active material have different lithium deintercalation efficiencies, resulting in obvious differences in volume expansion between material particles, which can be observed and characterized by in-situ confocal microscopy.

[0067] [Positive electrode]

[0068] In some embodiments of the present application, on the longitudinal section of the positive electrode sheet along the thickness direction, it includes multi-active material particles and lithium supplement particles, the lithium supplement particles include transition metal elements, the transition metal elements may include nickel elements, in a single lithium supplement particle, based on the total molar amount of the transition metal elements, the molar ratio of the nickel element is n1; the multi-active material particles include layered metal oxides containing nickel, cobalt and manganese elements, in a single multi-active material particle, based on the total molar amount of nickel, cobalt and manganese elements, the molar ratio of the nickel element is n2, and the ratio of n1 to n2 can be 1: (0.8-0.96), such as 1: 0.96, 1:0.95, 1:0.92, 1:0.9, 1:0.88, 1:0.85, 1:0.82 or 1:0.8, etc.; or, the multi-active material particles include layered metal oxides containing nickel, cobalt, and aluminum elements, and in a single multi-active material particle, based on the total molar amount of nickel, cobalt, and aluminum elements, the molar proportion of nickel element is n3, and the ratio of n1 to n3 can be 1:(0.8-0.96), such as 1:0.96, 1:0.95, 1:0.92, 1:0.9, 1:0.88, 1:0.85, 1:0.82 or 1:0.8, etc. The relative molar content of Ni in a single multi-active material particle and a single lithium supplement particle can be obtained by EDS analysis independently in combination with a scanning electron microscope and an energy dispersive spectrometer. Taking the initial state of the lithium supplementer as Li2NiO2 as an example, the multi-element active material particles include Co, Mn or Al in addition to Ni, and the non-lithium metal element in the residual elements after partial or complete delithiation of the lithium supplementer is Ni, that is, n2 or n3 can be 1. Making the ratio of n1 to n2 or n1 to n3 satisfy the given range is conducive to making the battery have both high energy density, initial efficiency and long cycle life.

[0069] In some embodiments of the present application, the positive electrode active material may also include one or more of the following elements: P, Al, Mg, Zr, B, Ti. Based on the total mass of the positive electrode active material, the content of the P element, the Al element, the Mg element, the Zr element, the B element, and the Ti element may be independently less than or equal to 7000ppm, for example, independently ≤7000ppm, ≤6000ppm, ≤5000ppm, ≤4000ppm, ≤3000ppm, ≤2000ppm, ≤1000ppm, ≤500ppm, etc. The elements P, Al, Mg, Zr, B, and Ti in the positive electrode active material may be qualitatively and quantitatively analyzed in combination with conventional characterization methods such as ICP testing. The positive electrode active material includes a multi-element active material and a lithium supplement. The P, Al, Mg, Zr, B, and Ti elements are mainly derived from the doping elements in the multi-element active material and the lithium supplement. The contents of the elements in the positive electrode active material meet the given range, which is conducive to further making the battery have a higher energy density and a longer cycle life.

[0070] In some embodiments of the present application, the positive electrode active material may include P element. Based on the total mass of the positive electrode active material, the content of P element may be 50ppm to 3000ppm, for example, 50ppm, 200ppm, 500ppm, 1000ppm, 1500ppm, 2000ppm, 2500ppm or 3000ppm, etc.

[0071] In some embodiments of the present application, the positive electrode active material may include Al element, and the content of Al element may be 50ppm to 3000ppm based on the total mass of the positive electrode active material, for example, 50ppm, 200ppm, 500ppm, 1000ppm, 1500ppm, 2000ppm, 2500ppm or 3000ppm, etc. Further, based on the total mass of the positive electrode active material, the content of Al element may be 300ppm to 2000ppm.

[0072] In some embodiments of the present application, the positive electrode active material may include Mg element. Based on the total mass of the positive electrode active material, the content of Mg element may be 50ppm to 3000ppm, for example, 50ppm, 200ppm, 500ppm, 1000ppm, 1500ppm, 2000ppm, 2500ppm or 3000ppm, etc.

[0073] In some embodiments of the present application, the positive electrode active material may include a Zr element, and the content of the Zr element is 50ppm to 4000ppm based on the total mass of the positive electrode active material, for example, 50ppm, 200ppm, 500ppm, 1000ppm, 1500ppm, 2000ppm, 2500ppm, 3000ppm, 3500ppm or 4000ppm, etc. Further, based on the total mass of the positive electrode active material, the content of the Zr element may be 2000ppm to 4000ppm.

[0074] In some embodiments of the present application, the positive electrode active material may include a B element, and the content of the B element may be 50 ppm to 7000 ppm based on the total mass of the positive electrode active material, for example, 50 ppm, 200 ppm, 500 ppm, 1000 ppm, 200 ppm, 3000 ppm, 4000 ppm, 5000 ppm, 6000 ppm or 7000 ppm, etc. Further, based on the total mass of the positive electrode active material, the content of the B element may be 500 ppm to 7000 ppm.

[0075] In some embodiments of the present application, the positive electrode active material may include Ti element. Based on the total mass of the positive electrode active material, the content of Ti element may be 5ppm to 3000ppm, for example, 5ppm, 50ppm, 200ppm, 500ppm, 1000ppm, 1500ppm, 2000ppm, 2500ppm or 3000ppm, etc.

[0076] In some embodiments of the present application, at least part of the surface of the lithium supplement may be provided with a coating layer, and the coating layer includes one or more of the following elements: C, Al, Zr, P, S. The types of elements in the coating layer of the lithium supplement may be qualitatively analyzed by combining EDS energy spectrum analysis, FIB (focused ion beam) combined with SIMS (secondary ion mass spectrometry) testing and other characterization methods. The air stability of lithium supplements is generally poor. Taking Li2NiO2 as an example, it has strong alkalinity and is easy to react with water and CO2. Forming a coating layer on the surface of the lithium supplement can improve its air stability and reduce the generation of lithium impurities on the surface.

[0077] In some embodiments of the present application, the coating layer may include one or more of carbon materials, aluminum oxides, zirconium oxides, lithium phosphides, and lithium sulfides. The type of coating layer material can be determined by combining one or more analytical methods such as EDS energy spectrum analysis, X-ray diffraction, FIB (focused ion beam) combined with SIMS (secondary ion mass spectrometry) testing. Among them, the lithium supplement has relatively poor conductivity. Carbon materials, aluminum oxides, and zirconium oxides as coating layer materials are beneficial to improving the air stability of the lithium supplement and reducing the generation of lithium-containing impurities on the surface. In addition, the use of carbon materials as coating layer materials is beneficial to improving the conductivity of the positive electrode; the use of fast ion conductor lithium phosphide or lithium sulfide as a coating layer material is beneficial to improving the lithium ion transfer rate and improving the kinetic performance, which is further beneficial to the lithium supplement delithiation and improving the lithium supplement capacity. This is conducive to further improving the electrochemical performance of the battery.

[0078] In some embodiments of the present application, the multi-active material may include secondary particles, the secondary particles include primary particles, the lithium supplement agent is usually irregular particles, and the surface roughness of the secondary particles is greater than the surface roughness of the lithium supplement agent particles. The microscopic morphology of the multi-active material and lithium supplement agent particles can be combined with conventional equipment such as scanning electron microscopes to characterize the surface or cross-section of the positive electrode active material layer. The surface of the secondary particles is relatively rough, and the surface of the lithium supplement agent particles is relatively smooth. Combining multi-active material particles and lithium supplement agent particles with different morphologies is beneficial to improving the compaction density of the positive electrode sheet. In addition, the secondary particles can be spherical or quasi-spherical. In the present application, the quasi-spherical refers to a particle shape with a high sphericity and no obvious edges and corners. Optionally, the sphericity of the quasi-spherical particle can be 0.9 to 1, and can be 0.95 to 1.

[0079] In some embodiments of the present application, the positive electrode active material layer may further include a conductive agent, and the conductive agent may include conductive carbon black and carbon nanotubes. The conductivity of the lithium supplement is poor, and the conductivity of carbon nanotubes is better than that of conductive carbon black, but the cost is relatively high. Using zero-dimensional conductive carbon black and one-dimensional carbon nanocomposites as conductive agents is not only conducive to the dispersion of carbon nanotubes, but also to the formation of a better conductive network and the realization of better conductive properties. In this way, not only the conductive properties of the pole piece can be improved, but also the decomposition of the lithium supplement and the improvement of the battery kinetics can be facilitated, which in turn helps to further improve the energy density and cycle life of the battery cell.

[0080] In some embodiments of the present application, the lithium supplement may include Li x M1 y M2 g O z, wherein 1≤x≤6, 1≤y≤6, 2≤z≤12, 0≤g≤0.05, M1 may include one or more elements of Na, Ni, Co, Mn, Fe, and M2 may include one or more elements of Al, Zr, and B. Exemplarily, the value of x may be 1, 2, 3, 4, 5, or 6, or may be a range consisting of any of the above values. Optionally, the value of x may be 1<x≤6, such as 2≤x≤5; the value of y may be 1, 2, 3, 4, 5, or 6, or may be a range consisting of any of the above values. The value of z may be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12, or may be a range consisting of any of the above values. Optionally, the value of z may be 1<z≤8, such as 2≤z≤8; the value of g may be 0, 0.01, 0.02, 0.03, 0.04, or 0.05, etc. Wherein, Li x M1 y O z The charge capacity is 1 to 5 times that of the multi-active material, which can provide additional lithium during the first charge. x M1 y O z , can play a better positive electrode lithium supplement effect. In addition, in the lithium supplement agent Li x M1 y O z Doping one or more of Al, Zr, and B in the lithium supplement is not only beneficial to reducing the decomposition voltage of the lithium supplement, improving the decomposition ability of the lithium supplement, so that it can play a greater role in capacity compensation, but also beneficial to stabilizing the crystal structure of the lithium supplement after decomposition, reducing the dissolution of transition metals and possible side reactions with the electrolyte, and thus further helping the battery to have a higher energy density, initial efficiency, and cycle life. It is understandable that during the formation and use of the battery, as the lithium supplement process proceeds, the lithium in the lithium supplement will be partially or completely released, causing the lithium supplement to change from the initial state to a partially delithiated state or a completely delithiated state, at which time x≤1 and / or z≤1 will occur.

[0081] In some embodiments of the present application, the lithium supplement Li x M1 y M2 g O z The value of g can be greater than 0, so that the lithium supplement Li x M1 y M2 g O z Based on the mass of , the content of the doping element M4 can be 50ppm to 1000ppm, such as 50ppm, 200ppm, 500ppm, 800ppm or 1000ppm, and so on.

[0082] In some embodiments of the present application, the lithium supplement may include but is not limited to Li2NiO2 and / or Li5FeO4. In the manufacturing process of the positive electrode sheet, Li2NiO2 and / or Li5FeO4 can be directly incorporated into the positive electrode active material layer along with the multi-active material. Li2NiO2 can form LiNiO2 with lithium deintercalation ability after lithium removal. LiNiO2 can become Li in the lithium removal state. 1-x1 NiO2, 0≤x1≤1, can be restored to LiNiO2 in the lithium-embedded state; Li5FeO4 has a strong lithium replenishment ability, and the LiFeO2 formed after lithium removal does not cause obvious side reactions. Therefore, the use of Li2NiO2 and / or Li5FeO4 as a lithium replenisher can achieve a better capacity compensation effect. Exemplarily, the lithium replenisher can be Li2NiO2, which can provide considerable lithium replenishment capacity only by changing the valence of Ni atoms at a lower potential, without the need to provide capacity through the valence change of oxygen atoms, which can reduce the risk of the electrolyte being oxidized by oxygen free radicals.

[0083] In some embodiments of the present application, the lithium supplement may include an initial state, a partially delithiated state, and a completely delithiated state. When the lithium supplement changes from the initial state to the partially delithiated state and the completely delithiated state, the lithium supplement may include Li n NiO m and / or Li p FeO q , wherein 0≤n≤2, 0<m≤2, 0<p≤5, 0<q≤4. For example, the value of n can be 0, 0.5, 1, 1.5 or 2, etc., or can be a range consisting of any of the above values; the value of m can be 0.5, 1, 1.5 or 2, etc., or can be a range consisting of any of the above values; the value of p can be 0.5, 1, 2, 3, 4 or 5, etc., or can be a range consisting of any of the above values; the value of q can be 1, 2, 3 or 4, etc., or can be a range consisting of any of the above values. Exemplarily, taking the lithium supplement whose initial state is Li2NiO2 as an example, when the lithium in Li2NiO2 is partially released, the lithium supplement Li n NiO m The composition may include one or more of the components of 0<n<1, n=1, 1<n<2; when the lithium in Li2NiO2 is completely removed, the lithium supplement Li n NiO m The composition may include NiO m Taking the lithium supplement agent with the initial state of Li5FeO4 as an example, when the lithium in Li5FeO4 is partially released, the lithium supplement agent Li p FeO qThe composition may include one or more of the components of 1<p<2, 2≤p<3, 3≤p<4, 4≤p<5; when the lithium in Li5FeO4 is completely removed, the lithium supplement Li p FeO q The composition may include LiFeO2. Under factors such as polarization, LiFeO2 may continue to delithiate, resulting in the appearance of Li with p < 1. p FeO q Component.

[0084] In some embodiments of the present application, when the lithium supplement agent changes from an initial state to a completely de-lithiated state, the lithium supplement agent may include NiO m and / or Li p FeO q , wherein 0<m≤2, 0<p≤1, 0<q≤2, for example, the value of m can be 0.5, 1, 1.5 or 2, or can be a range of any of the above values; the value of p can be 0.2, 0.5, 0.8 or 1, or can be a range of any of the above values; the value of q can be 0.2, 0.5, 1, 1.5 or 2, or can be a range of any of the above values. Exemplarily, taking the lithium supplement whose initial state is Li2NiO2 and Li5FeO4 as an example, when the lithium supplement is completely de-lithiated, the lithium supplement after de-lithiation can include but is not limited to NiO and / or LiFeO2.

[0085] In some embodiments of the present application, the general formula of the multi-active material can be Li a Ni b Co c M3 d M4 e O f, wherein 0.5≤a≤1.2, 0.8≤b≤0.96, 0<c<1, 0<d<1, 0≤e≤0.03, b+c+d+e=1, 1.8≤f≤3.5, M3 may include Mn element or Al element; M4 may include one or more of the following elements: Na, K, Mg, B, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, F. Exemplarily, the value of a can be 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1 or 1.2, or can be a range consisting of any of the above values; the value range of b can be 0.8, 0.82, 0.85, 0.88, 0.9, 0.92, 0.95 or 0.96, or can be a range consisting of any of the above values; the value of c can be 0.02, 0.05, 0.08, 0.1, 0.12, 0.15, 0.18 or 0.2, or can be any of the above values The value of d can be 0.02, 0.05, 0.08, 0.1, 0.12, 0.15, 0.18 or 0.2, etc., or can be a range composed of any of the above values; the value of e can be 0, 0.005, 0.01, 0.015, 0.02, 0.025 or 0.03, etc., or can be a range composed of any of the above values; the value of f can be 1.8, 1.9, 2, 2.1, 2.2, 2.5, 3 or 3.5, etc., or can be a range composed of any of the above values. As described in the previous section, the composition of the multi-active material can be analyzed in combination with one or more characterization methods such as X-ray diffraction (XRD), energy dispersive spectrum analysis (EDS), inductively coupled plasma emission spectroscopy (ICP), etc. The use of a multi-active material that satisfies the given general formula can better balance the energy density and cycle life of the battery and extend the service life of the battery.

[0086] In some embodiments of the present application, the multi-active material Li a Ni b Co c M3 d M4 e O f In the embodiment, M4 may include one or more of the following elements: Al, Mg, Zr, B, P, Ti. Among them, doping with Al is conducive to further improving the energy density of the battery, and doping with elements such as Zr or B is conducive to further stabilizing the structure of the high-nickel multi-active material and improving the cycle stability. In this way, the battery can further have both a higher energy density and a longer cycle life, thereby extending the service life of the battery.

[0087] In some embodiments of the present application, when M4 is doped in the multi-active material, on the longitudinal section of the positive electrode sheet along the thickness direction, in a single multi-active material particle, based on the total molar number of Ni, Co, M3, and M4, the molar percentage of Ni is n4; in a single lithium supplement particle, based on the total molar number of M1 and M2, the molar percentage of Ni is n1', and the ratio of n1' to n4 can be 1: (0.8-0.96), and can be 1: 0.96, 1: 0.95, 1: 0.92, 1: 0.9, 1: 0.88, 1: 0.85, 1: 0.82 or 1: 0.8, etc. Making the ratio of n1' to n4 satisfy the given range is conducive to making the battery have both high energy density, first efficiency and cycle life.

[0088] In some embodiments of the present application, the positive electrode current collector may be a conventional metal foil or a composite current collector (a metal material may be disposed on a polymer substrate to form a composite current collector). As an example, the positive electrode current collector may include at least one of copper foil, aluminum foil, nickel foil, stainless steel foil, stainless steel mesh, and carbon-coated aluminum foil.

[0089] In some embodiments of the present application, the positive electrode active material layer may also optionally include at least one of a binder and other optional auxiliary agents. Wherein, the binder and auxiliary agent can be conventionally selected in the art, for example, the binder may include but not limited to 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) One or more. These materials can be obtained through commercial channels.

[0090] [Negative electrode]

[0091] In some embodiments of the present application, the silicon-based material may include silicon oxide compounds and / or silicon carbon compounds. The gram capacity of silicon carbon materials and silicon oxide materials is 800mAh / g to 2000mAh / g, which is much higher than graphite. Selecting these two silicon-based materials and graphite as negative electrode active materials is beneficial to further improve the energy density of the battery. Among them, the type of silicon-based material can be qualitatively analyzed in combination with one or more conventional characterization methods such as X-ray diffraction analysis, X-ray photoelectron spectroscopy analysis, EDS spectroscopy analysis, spectroscopy, etc.

[0092] In some embodiments of the present application, based on the total mass of the negative electrode active material, the mass proportion of silicon in the negative electrode active material can be 0.3% to 10%, for example, 0.3%, 0.5%, 0.8%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, and so on. The analysis method of the silicon content in the negative electrode active material may include but is not limited to ICP testing. Appropriately increasing the amount of silicon-based material in the negative electrode pole piece is conducive to further improving the energy density of the battery, so that the content of silicon in the negative electrode active material meets the given range, and can reduce the proportional influence of silicon-based materials on the first efficiency and cycle performance of the battery on the basis of improving the battery energy density, thereby helping the battery to have both higher energy density, first efficiency and cycle life.

[0093] In some embodiments of the present application, the silicon-based material may include silicon oxides, and based on the total mass of the negative electrode active material, the mass proportion of silicon in the negative electrode active material may be 0.5% to 5%, for example, 0.5%, 0.8%, 1%, 2%, 3%, 4% or 5%, etc. This is conducive to making the battery have higher energy density, first efficiency and cycle life on the basis of lower silicon-based material usage.

[0094] In some embodiments of the present application, the silicon-based material may include a silicon-carbon compound, and based on the total mass of the negative electrode active material, the mass proportion of silicon in the negative electrode active material may be 3% to 10%, for example, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, etc. Thus, the battery can have a high energy density, first efficiency and cycle life.

[0095] In some embodiments of the present application, the negative electrode current collector may be a conventional metal foil or a composite current collector (for example, a metal material may be disposed on a polymer substrate to form a composite current collector). As an example, the negative electrode current collector may be a metal foil such as copper foil.

[0096] In some embodiments of the present application, the negative electrode active material layer generally further includes a binder and a conductive agent, the conductive agent is used to improve the conductivity of the negative electrode active material layer, and the binder is used to firmly bond the negative electrode active material and the binder to the negative electrode current collector. The present application does not specifically limit the types of negative electrode sheet conductive agents and binders, and can be selected according to actual needs. As an example, the conductive agent may include but is not limited to at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. As an example, the binder may include but is not limited to at least one of styrene butadiene rubber (SBR), styrene-butadiene rubber (SBCs), water-based acrylic resin (water-based acrylic resin) and carboxymethyl cellulose (CMC). In addition, the negative electrode active material layer may also optionally include a thickener, such as carboxymethyl cellulose (CMC) and the like. However, the present application is not limited thereto, and the present application may also use other materials that can be used as thickeners for negative electrode sheets of lithium-ion batteries.

[0097] [Electrolyte]

[0098] Typically, the battery cell further includes an electrolyte, which may include an organic solvent and an electrolyte salt.

[0099] Exemplarily, taking a lithium battery as an example, the electrolyte may include an organic solvent and a lithium salt, and the organic solvent may include a cyclic carbonate and a linear carbonate. Thus, it is further beneficial to obtain a battery with a high energy density. Exemplarily, the cyclic carbonate may include EC (ethylene carbonate) and / or PC (propylene carbonate), for example, EC. Exemplarily, the linear carbonate may include one or more of EMC (ethyl methyl carbonate), DMC (dimethyl carbonate), and DEC (diethyl carbonate). Exemplarily, the lithium salt may include, but is not limited to, at least one of lithium hexafluorophosphate, lithium difluorooxalate borate, lithium tetrafluoroborate, lithium bisoxalate borate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium trifluoromethylsulfonate, and lithium bis(trifluoromethylsulfonyl)imide.

[0100] In some embodiments of the present application, the electrolyte may optionally include other additives that can improve certain properties of the battery, for example, the additives may include negative electrode film-forming additives, may include positive electrode film-forming additives, may also include additives that can improve the overcharge performance of the battery, improve the high temperature performance of the battery, or improve the low temperature performance of the battery, and so on. Exemplarily, the additives may include but are not limited to FEC (fluoroethylene carbonate) and / or VC (vinyl carbonate), etc. The addition of FEC helps the positive electrode plate to form a stable CEI film, and forms a tough SEI film on the surface of the negative electrode plate, reducing the high Li consumption caused by the expansion of silicon-based materials. The addition of VC is conducive to the formation of a stable polycarbonate SEI film on the surface of the negative electrode plate, further improving the cycle performance of the battery.

[0101] It is understandable that the concentration of lithium salt in the electrolyte and the mass percentage of additives in the electrolyte can be flexibly selected according to actual needs and are not particularly limited here.

[0102] Typically, the battery cell also includes a separator. In the present application, there is no particular restriction on the material of the separator, and any known porous structure separator with electrochemical stability and mechanical stability can be selected according to actual needs, such as but not limited to a single-layer or multi-layer film containing at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.

[0103] The embodiments of the present application have no particular restrictions on the shape of the battery cell. For example, in some embodiments of the present application, the battery cell may be a soft-pack battery, a square battery, or a cylindrical battery. Figure 1 The battery cell 1 is a square structure as an example.

[0104] In some embodiments of the present application, the battery cell may be a cylindrical battery, which may include a shell, and the two ends of the shell are respectively a first end and a second end, and the first end may be connected to the negative electrode plate through the shell wall of the shell located at the first end, and illustratively, the pole ear of the negative electrode plate may be connected to the shell wall of the shell located at the first end through the first current collecting part; the second end may be provided with a cap, and the cap may include a pole, and the pole column may be connected to the positive electrode plate, and illustratively, the pole ear of the positive electrode plate may be connected to the pole column through the second current collecting part. Optionally, the cap may be a steel cap. Providing a cap structure not only facilitates the cylindrical battery to be connected by welding through the current collecting part (such as a collector bar, etc.), but also facilitates the pressure relief after the battery fails, and reduces the safety risks that may be caused by the high-nickel and high-silicon system batteries due to the large gas production due to thermal runaway.

[0105] In some embodiments, the battery cell may include an outer packaging for encapsulating the positive electrode sheet, the negative electrode sheet, and the electrolyte.

[0106] In some embodiments, the outer package may include a shell and a cover plate. The shell may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell has an opening connected to the receiving cavity, and the cover plate can be covered on the opening to close the receiving cavity.

[0107] The positive electrode sheet, the negative electrode sheet and the separator can be wound or laminated to form an electrode assembly. The electrode assembly is packaged in the receiving cavity. The number of electrode assemblies contained in the battery cell can include one or more, which can be adjusted according to demand.

[0108] In some embodiments, the outer packaging of the battery cell may include a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell.

[0109] The outer packaging of the battery cell may also include a soft package, such as a bag-type soft package. The material of the soft package may be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0110] The second aspect of the present application provides a battery device, which includes: the battery cell of the first aspect of the present application. Optionally, the battery device includes at least one of a battery module, a battery pack, and an energy storage device.

[0111] In some embodiments, the battery device may be a battery cell, or a battery module or battery pack assembled from battery cells. The battery module or battery pack may contain multiple battery cells, and the specific number may be adjusted according to the application and capacity of the battery module.

[0112] Figure 2 2 is an example of a battery module 2. Figure 2 In the battery module 2, a plurality of battery cells 1 may be arranged in sequence along the length direction of the battery module 2. Of course, they may also be arranged in any other manner. The plurality of battery cells 1 may further be fixed by fasteners. The battery module 2 may also include a housing having a storage space, and the plurality of battery cells 1 are stored in the storage space. In some embodiments, the battery modules may also be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0113] Figure 3 and 4 The battery pack 3 is used as an example. Figure 3 and 4The battery pack 3 may include a battery box and a plurality of battery modules 2 disposed in the battery box. The battery box includes an upper box body 4 and a lower box body 5. The upper box body 4 can cover the lower box body 5 and form a closed space for accommodating the battery modules 2. The plurality of battery modules 2 can be arranged in the battery box in any manner.

[0114] The third aspect of the present application provides an electrical device, which includes: the battery cell of the first aspect of the present application, the battery cell or the battery device is used to provide electrical energy.

[0115] Specifically, the battery cell or battery device can be used as a power source for the electrical device, or as an energy storage unit for the electrical device. The electrical device may include, 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, satellites, and energy storage systems.

[0116] Figure 5 As an example of an electric device, the electric device includes a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. As another example, the electric device may include a mobile phone, a tablet computer, and a laptop computer. The electric device is usually required to be light and thin, and a battery cell may be used as a power source.

[0117] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0118] Example 1

[0119] (1) Positive electrode

[0120] The invention comprises a positive electrode current collector aluminum foil, wherein positive electrode active material layers are arranged on two surfaces of the aluminum foil which are arranged opposite to each other, the thickness of the aluminum foil is 17 μm, the thickness of the positive electrode active material layers arranged on the two surfaces of the aluminum foil is equal, and the single-side coating surface density of the positive electrode active material layer is 0.393 g / 1540.25 mm 2The positive electrode active material includes a multi-active material and a lithium supplement. Based on the mass of the positive electrode active material layer, it includes 98% of the positive electrode active material by mass (wherein the multi-active material is lithium nickel cobalt manganese oxide (layered metal oxide), the lithium supplement is Li2NiO2, and the surface of the lithium supplement has aluminum oxide. Based on the total mass of the positive electrode active material, the mass of the lithium supplement accounts for 1.8%), 0.8% of the conductive agent (in terms of mass percentage, including 75% of conductive carbon black Super P and 25% of carbon nanotubes CNT), and 1.2% of the binder polyvinylidene fluoride (PVDF). The molar ratio of Ni, Co, and Mn in lithium nickel cobalt manganese oxide is 0.85:0.1:0.05.

[0121] (2) Negative electrode

[0122] The invention comprises a positive electrode current collector copper foil, wherein negative electrode active material layers are arranged on two oppositely arranged surfaces of the copper foil, the thickness of the copper foil is 11 μm, the thickness of the negative electrode active material layers arranged on the two surfaces of the copper foil is equal, and the single-sided coating surface density of the negative electrode active material layer is 0.216 g / 1540.25 mm 2 The negative electrode active material includes artificial graphite and silicon-based material SiO. Based on the mass of the negative electrode active material layer, the negative electrode active material layer includes 96% by mass of the negative electrode active material (based on the total mass of the negative electrode active material, the mass proportion of silicon in the negative electrode active material is 2.3%), 1% by mass of the conductive agent (Super P), 1.8% by mass of the binder styrene-butadiene rubber (SBR), and 1.2% by mass of the thickener sodium carboxymethyl cellulose (CMC-Na).

[0123] (3) Electrolyte

[0124] It includes organic solvents, electrolyte salts and additives. The solvent is prepared by EC, DMC and EMC in a mass ratio of 3:4:3. The electrolyte salt is LiPF6, and the concentration of LiPF6 in the electrolyte is 1 mol / L. The additives include fluoroethylene carbonate (FEC), and the mass proportion of FEC in the electrolyte is 1.5%.

[0125] (4) Isolation film: A polyethylene film with a ceramic coating on one side, with a total thickness of 14 μm.

[0126] (5) Battery cell: including the above-mentioned positive electrode sheet, negative electrode sheet, separator and electrolyte, with the ceramic coating of the separator facing the positive electrode sheet.

[0127] test:

[0128] (1) Elemental composition

[0129] The instrument standard refers to EPA6010D-2014 "Inductively Coupled Plasma Atomic Emission Spectrometry". The sample is treated by chemical methods to be digested into a solution, atomized into plasma and excited to produce characteristic spectral lines of the elements. The element content is qualitatively and quantitatively analyzed based on the wavelength and intensity of the spectral lines (which are proportional to the concentration).

[0130] (2) Energy density

[0131] At 25°C, the formed battery cell was charged at a constant current of 1 / 3C to 4.25V, then charged at a constant voltage of 4.25V to a current of 0.05C, left to stand for 5 minutes, and then discharged at 1 / 3C to 2.5V, and the discharge capacity was recorded as C; after measuring the size of the battery cell, its volume was calculated as V, and its volume energy density was obtained to be 3.7×C / V.

[0132] (3) Cycle performance

[0133] At 25°C, let the formed battery stand for 30 minutes, and discharge it to 2.5V at a constant current of 1 / 3C. Then, perform the charge and discharge cycle according to the following steps: let it stand for 5 minutes, charge it to 4.25V at a constant current of 1 / 3C, then charge it at a constant voltage until the current drops to 0.05C; let it stand for 5 minutes; discharge it to 2.5V at a constant current of 1 / 3C, and record the discharge capacity at this time as C0'. After 500 cycles, record the discharge capacity C at the 500th cycle. 500 The capacity retention rate after 500 cycles is calculated according to the following formula:

[0134] Capacity retention rate after 500 cycles (%): C 500 / C0'×100%.

[0135] Comparative Example 1

[0136] The negative electrode plate and electrolyte in the battery cell are the same as those in Example 1, except that in the positive electrode plate, the positive electrode active material only includes multiple active materials and does not contain a lithium supplement. However, the mass proportion of the positive electrode active material in the positive electrode active material layer is the same as that in Example 1.

[0137] Comparative Example 2

[0138] The positive electrode plate and electrolyte in the battery cell are the same as those in Example 1, except that in the negative electrode plate, the negative electrode active material only includes artificial graphite and does not contain silicon-based materials, but the mass proportion of the negative electrode active material in the negative electrode active material layer is the same as that in Example 1.

[0139] Example 2

[0140] The negative electrode plate and electrolyte in the battery cell are the same as those in Example 1, except that in the positive electrode plate, the multi-element active material is lithium nickel cobalt aluminum oxide (layered metal oxide), and the molar ratio of nickel, cobalt and aluminum in the lithium nickel cobalt aluminum oxide is 0.85:0.1:0.05.

[0141] Comparative Example 3

[0142] The negative electrode plate and electrolyte in the battery cell are the same as those in Example 2, except that in the positive electrode plate, the positive electrode active material only includes multiple active materials and does not contain a lithium supplement. However, the mass proportion of the positive electrode active material in the positive electrode active material layer is the same as that in Example 1.

[0143] Comparative Example 4

[0144] The positive electrode plate and electrolyte in the battery cell are the same as those in Example 2, except that in the negative electrode plate, the negative electrode active material only includes artificial graphite and does not contain silicon-based materials, but the mass proportion of the negative electrode active material in the negative electrode active material layer is the same as that in Example 1.

[0145] The differences between Example 1 and Example 2, and Comparative Examples 1 to 4 are shown in Table 1.

[0146] Table 1

[0147]

[0148] In combination with Example 1 and Example 2, as well as Comparative Examples 1 to Comparative Examples 4, it can be seen that the battery cell proposed in the present application has both high energy density and cycle capacity retention rate, indicating that the present application uses a high-nickel multi-active material lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide (layered metal oxide) in combination with a lithium supplement in the positive electrode plate, and uses graphite and silicon-based materials in combination in the negative electrode plate, so that the battery cell can have both high energy density and long cycle life.

[0149] Example 3, Example 4, Example 5

[0150] The negative electrode plate and electrolyte in the battery cell are the same as those in Example 1, except that the molar ratio of nickel, cobalt and manganese elements in the multi-element active material lithium nickel cobalt manganese oxide in the positive electrode plate is different.

[0151] The differences between Example 3, Example 4, Example 5 and Example 1 are shown in Table 2.

[0152] Table 2

[0153]

[0154] Combining Example 1 with Example 3, Example 4, and Example 5, it can be seen that with the increase of the Ni content in the multi-element active material in the positive electrode plate, the energy density of the battery cell also increases, and the cycle capacity retention rate of the battery cell shows a downward trend. The reason for this may be that with the increase of the Ni element content, the stability of the multi-element active material decreases, and the probability of lithium-nickel mixing increases, which affects the lithium insertion amount of the positive electrode plate and the cycle performance of the battery cell. This shows that controlling the nickel content in the high-nickel multi-element active material within an appropriate range is beneficial to further enable the battery cell to have both higher energy density and longer cycle life.

[0155] Example 6, Example 7, Example 8, Example 9

[0156] The positive electrode plate and electrolyte in the battery cell are the same as those in Example 1, except that in the negative electrode plate, the content of silicon-based material in the negative electrode active material is different, and the mass proportion of Si element in the negative electrode active material is also different, but the mass proportion of the negative electrode active material in the negative electrode active material layer is the same as that in Example 1.

[0157] The differences between Example 6, Example 7, Example 8, Example 9 and Example 1 are shown in Table 3.

[0158] Table 3

[0159]

[0160] It can be seen from Example 1, Comparative Example 2 and Examples 6 to 9 that as the content of silicon-based materials in the negative electrode active material increases, the energy density of the battery cell also increases, and the cycle capacity retention rate of the battery cell shows a downward trend, indicating that controlling the amount of silicon-based materials in the negative electrode active material within an appropriate range is beneficial to further enable the battery cell to have both higher energy density and longer cycle life.

[0161] Embodiment 10, Embodiment 11

[0162] The negative electrode plate and electrolyte in the battery cell are the same as those in Example 1, except that the composition of the conductive agent in the positive electrode active material layer in the positive electrode plate is different.

[0163] Example 12, Example 13, Example 14

[0164] The negative electrode plate and electrolyte in the battery cell are the same as those in Example 1, except that in the positive electrode plate, the surface of the lithium supplement agent has a coating material.

[0165] The differences between Examples 10 to 14 and Example 1 are shown in Table 4.

[0166] Table 4

[0167]

[0168]

[0169] Combining Example 1, Example 10 and Example 11, it can be seen that after adding carbon nanotubes to the conductive carbon black, the energy density and cycle capacity retention rate of the battery monomer are improved, indicating that the combination of conductive carbon black and an appropriate amount of carbon nanotubes as positive electrode conductive agents is further beneficial to improving the energy density and cycle life of the battery monomer.

[0170] It can be seen from the combination of Example 12, Example 13, Example 14 and Example 1 that after the surface of the lithium supplement agent is coated with lithium phosphide or lithium sulfide, the energy density of the battery cell is improved.

[0171] Embodiment 15

[0172] The positive electrode plate and electrolyte in the battery cell are the same as those in Example 6, except that in the negative electrode plate, the type and amount of silicon-based material in the negative electrode active material are different, and the mass proportion of Si element in the negative electrode active material is also different, but the mass proportion of the negative electrode active material in the negative electrode active material layer is the same as that in Example 6.

[0173] Example 16, Example 17

[0174] The electrolyte in the battery cell is the same as that in Example 15, except that in the positive electrode plate, the composition of the lithium replenisher is different, but the mass proportion of the lithium replenisher in the positive electrode active material is the same as that in Example 15; in the negative electrode plate, the amount of silicon-based material in the negative electrode active material is different, and the mass proportion of Si element in the negative electrode active material is also different, but the mass proportion of the negative electrode active material in the negative electrode active material layer is the same as that in Example 15.

[0175] Embodiment 18

[0176] The positive electrode plate and electrolyte in the battery cell are the same as those in Example 15, except that in the negative electrode plate, the amount of silicon-based material in the negative electrode active material is different, and the mass proportion of Si element in the negative electrode active material is also different, but the mass proportion of the negative electrode active material in the negative electrode active material layer is the same as that in Example 15.

[0177] The differences between Example 15, Example 16, Example 17, Example 18 and Example 6 are shown in Table 5.

[0178] Table 5

[0179]

[0180] It can be seen from Example 6, Example 15 and Comparative Example 2 that the use of silicon-carbon compounds instead of silicon-oxygen compounds in combination with artificial graphite can also improve the energy density of battery cells.

[0181] Combining Example 16, Example 17 and Example 18, it can be seen that using Li5FeO4 to replace part or all of the lithium supplement Li2NiO2 can also make the battery monomer have a higher energy density, indicating that using other lithium-rich materials can also achieve a good lithium supplement effect and improve the energy density and cycle life of the battery monomer. Further combining Comparative Example 2 and Example 18 can further illustrate that controlling the amount of silicon-based material in the negative electrode plate within an appropriate range is conducive to further making the battery monomer have both higher energy density and better cycle performance.

[0182] Example 19, Example 20

[0183] The negative electrode plate and electrolyte in the battery cell are the same as those in Example 1, except that the multi-element active material in the positive electrode plate has doping elements.

[0184] Example 21, Example 22, Example 23

[0185] The negative electrode plate and the electrolyte in the battery cell are the same as those in Example 1, except that in the positive electrode plate, the multi-element active material has a doping element, and the lithium supplement has a doping element.

[0186] Embodiment 24

[0187] The negative electrode plate and electrolyte in the battery cell are the same as those in Example 1, except that in the positive electrode plate, the multi-element active material has doping elements, the lithium supplement has doping elements, and the surface of the lithium supplement has carbon material and lithium phosphide coated on it.

[0188] The differences between Examples 19 to 24 and Example 1 are shown in Table 6.

[0189] Table 6

[0190]

[0191] In combination with Example 1, Example 19 to Example 24, it can be seen that in the positive electrode plate, introducing an appropriate amount of doping elements in the multi-active material or the lithium supplement can also adjust the energy density and / or cycle capacity retention rate of the battery cell. Further in combination with Example 21 to Example 24, it can be seen that in the positive electrode plate, by introducing an appropriate content and type of doping elements in the multi-active material and the lithium supplement, the energy density and cycle capacity retention rate of the battery cell can be further improved, which means that by introducing an appropriate amount of doping elements in the multi-active material and / or the lithium supplement of the positive electrode, the battery cell can have both higher energy density and better cycle performance, thereby extending the service life of the battery cell.

[0192] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that: include: A positive electrode sheet, the positive electrode sheet comprising a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector, the positive electrode active material layer comprising a positive electrode active material, the positive electrode active material comprising a multi-element active material and a lithium supplement, wherein: The multi-element active material comprises a layered metal oxide containing nickel, cobalt and manganese elements, wherein the molar proportion of the nickel element in the layered metal oxide containing nickel, cobalt and manganese elements is ≥80% based on the total molar amount of the nickel, cobalt and manganese elements; or, the multi-element active material comprises a layered metal oxide containing nickel, cobalt and aluminum elements, wherein the molar proportion of the nickel element in the layered metal oxide containing nickel, cobalt and aluminum elements is ≥80% based on the total molar amount of the nickel, cobalt and aluminum elements; The lithium supplement comprises a metal oxide containing nickel and / or a metal oxide containing iron; A negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer disposed on at least one side of the negative electrode current collector, wherein the negative electrode active material layer comprises a negative electrode active material, and the negative electrode active material comprises graphite and a silicon-based material.

2. The battery cell according to claim 1, characterized in that: The silicon-based material includes silicon-oxygen compounds and / or silicon-carbon compounds.

3. The battery cell according to claim 1 or 2, characterized in that: Based on the total mass of the negative electrode active material, the mass proportion of the silicon element is 0.3% to 10%.

4. The battery cell according to any one of claims 1 to 3, characterized in that: The silicon-based material includes a silicon-oxygen compound, and based on the total mass of the negative electrode active material, the mass proportion of the silicon element is 0.5% to 5%.

5. The battery cell according to any one of claims 1 to 3, characterized in that: The silicon-based material includes a silicon-carbon compound, and based on the total mass of the negative electrode active material, the mass proportion of the silicon element is 3% to 10%.

6. The battery cell according to any one of claims 1 to 5, characterized in that: The longitudinal section of the positive electrode sheet along the thickness direction includes multi-element active material particles and lithium supplement particles, the lithium supplement particles include transition metal elements, the transition metal elements include nickel elements, and in a single lithium supplement particle, based on the total molar amount of the transition metal elements, the molar proportion of the nickel element is n1; The multi-element active material particles include a layered metal oxide containing nickel, cobalt and manganese elements, and in a single multi-element active material particle, based on the total molar amount of the nickel, cobalt and manganese elements, the molar proportion of the nickel element is n2, and the ratio of n1 to n2 is 1:(0.8-0.96), or, The multi-active material particles include layered metal oxides containing nickel, cobalt, and aluminum elements. In a single multi-active material particle, based on the total molar amount of the nickel, cobalt, and aluminum elements, the molar proportion of the nickel element is n3, and the ratio of n1 to n3 is 1:(0.8-0.96).

7. The battery cell according to any one of claims 1 to 6, characterized in that: The positive electrode active material also includes one or more of the following elements: P, Al, Mg, Zr, B, and Ti. Based on the total mass of the positive electrode active material, the contents of P, Al, Mg, Zr, B, and Ti are each independently less than or equal to 7000 ppm.

8. The battery cell according to any one of claims 1 to 7, characterized in that: The positive electrode active material includes a P element, and the content of the P element is 50 ppm to 3000 ppm based on the total mass of the positive electrode active material.

9. The battery cell according to any one of claims 1 to 8, characterized in that: The positive electrode active material includes Al element. Based on the total mass of the positive electrode active material, the content of Al element is 50 ppm to 3000 ppm, and can be optionally 300 ppm to 2000 ppm.

10. The battery cell according to any one of claims 1 to 9, characterized in that: The positive electrode active material includes Mg element, and the content of Mg element is 50 ppm to 3000 ppm based on the total mass of the positive electrode active material.

11. The battery cell according to any one of claims 1 to 10, characterized in that: The positive electrode active material includes Zr element. Based on the total mass of the positive electrode active material, the content of Zr element is 50 ppm to 4000 ppm, and can be optionally 2000 ppm to 4000 ppm.

12. The battery cell according to any one of claims 1 to 11, characterized in that: The positive electrode active material includes B element. Based on the total mass of the positive electrode active material, the content of B element is 50 ppm to 7000 ppm, and can be optionally 500 ppm to 7000 ppm.

13. The battery cell according to any one of claims 1 to 12, characterized in that: The positive electrode active material includes a Ti element, and a content of the Ti element is 5 ppm to 3000 ppm based on the total mass of the positive electrode active material.

14. The battery cell according to any one of claims 1 to 13, characterized in that: At least part of the surface of the lithium supplement agent is provided with a coating layer, and the coating layer includes one or more of the following elements: C, Al, Zr, P, and S.

15. The battery cell according to claim 14, characterized in that: The coating layer includes one or more of carbon material, aluminum oxide, zirconium oxide, lithium phosphide, and lithium sulfide.

16. The battery cell according to any one of claims 1 to 15, characterized in that: The multi-element active material includes secondary particles, and the surface roughness of the secondary particles is greater than the surface roughness of the lithium supplement particles.

17. The battery cell according to claim 16, characterized in that: The secondary particles are spherical or quasi-spherical.

18. The battery cell according to any one of claims 1 to 17, characterized in that: The positive electrode active material layer further includes a conductive agent, and the conductive agent includes conductive carbon black and carbon nanotubes.

19. The battery cell according to any one of claims 1 to 18, characterized in that: The lithium supplement comprises Li x M1 y M2 g O z , Among them, 1≤x≤6, 1≤y≤6, 2≤z≤12, 0≤g≤0.05, M1 includes one or more elements of Na, Ni, Co, Mn, and Fe, and M2 includes one or more elements of Al, Zr, and B.

20. The battery cell according to any one of claims 1 to 18, characterized in that: The lithium supplement includes Li2NiO2 and / or Li5FeO4.

21. The battery cell according to any one of claims 1 to 18, characterized in that: The lithium supplement comprises Li n NiO m and / or Li p FeO q , where 0≤n≤2, 0<m≤2, 0<p≤5, 0<q≤4.

22. The battery cell according to any one of claims 1 to 18, characterized in that: The lithium supplement comprises NiO m and / or Li p FeO q , where 0<m≤2, 0<p≤1, 0<q≤2.

23. The battery cell according to any one of claims 1 to 22, characterized in that: The general formula of the multi-active material is Li a Ni b Co c M3 d M4 e O f , wherein 0.5≤a≤1.2, 0.8≤b≤0.96, 0<c<1, 0<d<1, 0≤e≤0.03, b+c+d+e=1, 1.8≤f≤3.5, M3 includes Mn element or Al element; M4 includes one or more of the following elements: Na, K, Mg, B, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, Ce, and F.

24. The battery cell according to claim 23, characterized in that: M4 includes one or more of the following elements: Al, Mg, Zr, B, P, Ti.

25. A battery device, characterized in that: The battery device comprises a battery cell as claimed in any one of claims 1 to 24, wherein the battery device comprises at least one of a battery module, a battery pack and an energy storage device.

26. An electrical device, characterized in that: The invention comprises the battery cell according to any one of claims 1 to 24 or the battery device according to claim 25, wherein the battery cell or the battery device is used to provide electrical energy.

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