Batteries and electrical equipment

Abstract

A battery and an electrical device are provided. The battery's positive plate, negative plate, and electrolyte are [0010] Meet JPEG2025509528000010.jpg21168. Ce represents the electrolyte retention capacity of the positive and negative plates, A is a correction coefficient, a is the viscosity of the electrolyte at room temperature, R is the capacity of the battery, and B is the capacity of the battery. i and B. ii are the capillary index of the pore size of the positive electrode material layer and the capillary index of the pore size of the negative electrode material layer, respectively, i and ii are the average pore size value in the pore size range of the positive electrode material layer and the average pore size value in the pore size range of the negative electrode material layer, respectively, m and n are the maximum value in the pore size range of the positive electrode material layer and the maximum value in the pore size range of the negative electrode material layer, respectively, Pc i and Pa ii are the ratios of the pore volume of the positive electrode material layer when the pore size is i to the total pore volume, and the ratios of the pore volume of the negative electrode material layer when the pore size is ii to the total pore volume, respectively. The battery has good cycle stability and high capacity retention.

Description

Technical Field

[0001] Cross - reference to Related Applications This disclosure claims the priority and benefit of Chinese Patent Application No. 202210251599.0, entitled "BATTERY AND ELECTRICAL DEVICE", filed on March 15, 2022. The entire content of the application referenced above is incorporated herein by reference.

[0002] This disclosure relates to the technical field of lithium batteries, and more particularly, to batteries and electrical devices.

Background Art

[0003] During the charge and discharge of a lithium battery, the positive and negative electrode plates undergo volume changes of different degrees. Such volume changes push out and reverse the flow of the electrolyte between the electrode plates of the battery core. However, the phenomenon that the electrolyte cannot flow back in a timely manner usually occurs, especially in batteries with a large volume such as wound batteries and laminated batteries. When the electrolyte cannot flow back in a timely manner, a part of the electrode plate in the battery core does not contact the electrolyte. As a result, local lithium plating occurs on the electrode plate during charging, and even safety problems occur.

[0004] Currently, in the industry, this problem is usually solved by adjusting the composition of the electrolyte to increase the force between the electrolyte and the electrode plate. However, this method has high requirements for the compatibility between the type of the electrolyte and the electrode plate, and is not general or universal.

Summary of the Invention

Problems to be Solved by the Invention

[0005] In view of this, in the present disclosure, in order to ensure that the positive electrode plate and the negative electrode plate have a strong liquid retention ability with respect to the electrolytic solution and reduce the generation of lithium plating during charging, the pore diameters and the respective pore size distributions of the positive electrode plate and the negative electrode plate are adjusted, and the viscosities of the positive electrode plate, the negative electrode plate, and the electrolytic solution are controlled. As a result, the battery has good cycle stability, a high capacity retention rate, and a long battery cycle life.

Means for Solving the Problems

[0006] According to a first aspect of the present disclosure, a battery is provided. The battery includes a positive electrode plate, a negative electrode plate, an electrolytic solution, and a separator positioned between the positive electrode plate and the negative electrode plate. The positive electrode plate includes a positive electrode current collector and a positive electrode material layer provided on the positive electrode current collector. The negative electrode plate includes a negative electrode current collector and a negative electrode material layer provided on the negative electrode current collector. The positive electrode plate, the negative electrode plate, and the electrolytic solution satisfy the following formula.

Number

[0007] In the formula, Ce is the liquid retention ability of the positive electrode plate and the negative electrode plate with respect to the electrolytic solution. The range of Ce is from 1.0 g / Ah to 5.0 g / Ah. A is a correction coefficient, a is the viscosity of the electrolytic solution at room temperature, measured in mPa·s, R is the capacity of the battery, measured in Ah, B i is the capillary index of the pore diameter of the positive electrode material layer, B ii is the capillary index of the pore diameter of the negative electrode material layer, B i and B ii are measured in meters. m is the maximum pore diameter of the pores in the positive electrode material layer, i is the average pore diameter of the pores in the positive electrode material layer, Pc i is the ratio of the volume of the pores in the positive electrode material layer having a pore diameter i to the volume of the positive electrode material layer. n is the maximum pore diameter of the pores in the negative electrode material layer, ii is the average pore diameter of the pores in the negative electrode material layer, Pa ii is the ratio of the volume of the pores in the negative electrode material layer having a pore diameter ii to the volume of the negative electrode material layer.

[0008] In some embodiments, R is in the range of 0.1Ah to 300Ah, and A is in the range of 0.01s to 100s.

[0009] In some embodiments, R is in the range of 10Ah to 200Ah.

[0010] In some embodiments, R is in the range of 10Ah to 100Ah.

[0011] In some embodiments, the pore size distribution range of the positive electrode material layer is 20 nm to 20,000 nm, and the pore size distribution range of the negative electrode material layer is 20 nm to 20,000 nm.

[0012] In some embodiments, the value of i is 20000nm, 18000nm, 15000nm, 12000nm, 10000nm, 7500nm, 6500nm, 5500nm, 5000nm, 3500nm, 2500nm, 1800nm, 1200nm, 750nm, 500nm, 320nm, 200nm, 140nm, 90nm, 65nm, 50nm, 40nm, 30nm, or 20nm. m is the value of ii, which is 20000nm, 18000nm, 15000nm, 12000nm, 10000nm, 7500nm, 6500nm, 5500nm, 5000nm, 3500nm, 2500nm, 1800nm, 1200nm, 750nm, 500nm, 320nm, 200nm, 140nm, 90nm, 65nm, 50nm, 40nm, 30nm, or 20nm.

[0013] In some embodiments, the porosity of the positive electrode material layer is 10% to 50%, and the porosity of the negative electrode material layer is 10% to 70%.

[0014] In some embodiments, the minimum values ​​of i and ii are both 50, and the values ​​of m and n are both 20000 nm.

[0015] In some embodiments, a is in the range of 0.5 mPa·s to 50 mPa·s.

[0016] In some embodiments, a is in the range of 0.5 mPa·s to 5 mPa·s.

[0017] In some embodiments, the electrolyte comprises an organic solvent and a lithium salt, the lithium salt comprising at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorophosphate, or lithium 4,5-dicyano-2-(trifluoromethyl)imidazole, and the organic solvent comprising at least one of ethylene carbonate, diethyl carbonate, dimethyl carbonate, or ethyl methyl carbonate.

[0018] In some embodiments, the electrolyte includes a viscosity modifier, the viscosity modifier includes at least one of polyimide, polyvinylidene difluoride, or polyacrylic acid.

[0019] In some embodiments, the positive electrode material layer comprises a positive electrode active material, a first conductive agent, and a first binder, and the negative electrode material layer comprises a negative electrode active material, a second conductive agent, or a second binder.

[0020] According to a second aspect of this disclosure, an electrical device is provided. The electrical device includes a battery provided in a first aspect of this disclosure. [Brief explanation of the drawing]

[0021] [Figure 1] This is a schematic diagram of the structure of a battery according to one embodiment of the present disclosure. [Figure 2] This is a schematic diagram of the structure of an electrical device according to one embodiment of the present disclosure. [Modes for carrying out the invention]

[0022] Generally, during the charge and discharge of a battery, when the volume of the active material in the positive electrode material layer and the negative electrode material layer expands, the distance between the electrode plates shrinks, and a part of the electrolyte is extruded. When the volume of the active material shrinks, the distance between the electrode plates expands, and the electrolyte flows back between the electrode plates. However, due to factors such as the flow characteristics of the electrolyte, the electrolyte cannot always flow back in a timely manner. As a result, a part of the electrode plate in the battery core does not come into contact with the electrolyte. As a result, local lithium plating occurs, affecting the safety of using the battery.

[0023] To solve the above technical problems, an embodiment of the present disclosure provides a battery. As shown in FIG. 1, the battery 10 includes a positive electrode plate 110, a negative electrode plate 120, an electrolyte 130, and a separator 140 between the positive electrode plate 110 and the negative electrode plate 120. The positive electrode plate 110 includes a positive electrode current collector 111 and a positive electrode material layer 112 disposed on the positive electrode current collector 111. The negative electrode plate 120 includes a negative electrode current collector 121 and a negative electrode material layer 122 disposed on the negative electrode current collector 121. The positive electrode plate, the negative electrode plate, and the electrolyte satisfy the following relational expressions.

Number

[0024] In the formula, Ce represents the liquid retention capacity of the positive electrode plate and the negative electrode plate with respect to the electrolyte. The value range of Ce is 1.0 g / Ah to 5.0 g / Ah. A is a correction coefficient. a is the viscosity of the electrolyte at room temperature, and the unit of viscosity is mPa·s. R is the capacity of the battery, and the unit of capacity is Ah. B i is the capillary index of the pore diameter of the positive electrode material layer. B ii is the capillary index of the pore diameter of the negative electrode material layer. B i and B ii are both measured in meters (m). m is the maximum pore diameter in the pore diameter range of the pores of the positive electrode material layer. i is the average pore diameter in the pore diameter range of the pores of the positive electrode material layer. Pc iii is the ratio of the volume of pores in the positive electrode material layer having pore size i to the volume of the positive electrode material layer, n is the maximum pore size in the pore size range of the negative electrode material layer, ii is the average pore size in the pore size range of the negative electrode material layer, and Pa ii m and n are the ratio of the volume of the pores in the negative electrode material layer having pore size ii to the volume of the negative electrode material layer, where i and ii may be the same, and m and n may also be the same.

[0025] In this disclosure, the pore size i of the positive electrode material layer, the pore size ii of the negative electrode material layer, and the pore size distribution Pc of the positive electrode material layer are described. i , and the pore size distribution of the negative electrode material layer Pa ii The device is configured such that the parameters and the viscosity a of the electrolyte satisfy the aforementioned relationship, thereby potentially significantly improving the electrolyte retention capacity of the positive and negative electrode plates (i.e., improving the interaction force between the electrode plates and the electrolyte). When the viscosity of the electrolyte and the pore structure of the positive and negative electrode plates satisfy the aforementioned relationship, the permeability of the electrolyte in the electrode plates may improve, and the electrolyte in the pores of the electrode plates cannot be easily pushed out of the electrode plates by the pressing force generated by the volume expansion of the active material. Therefore, electrolyte overflow caused by volume expansion of the electrode plates during battery charging and discharging may be reduced. Even if a small amount of electrolyte leaks out from the battery core, the strong interaction force between the electrode plates and the electrolyte, as well as the intermolecular forces of the electrolyte, allows the electrolyte to flow back between the electrode plates in a timely manner. Therefore, the battery provided by this disclosure significantly reduces the problem of lithium plating on the electrode plate surface caused by a portion of the electrode plate not coming into contact with the electrolyte due to the electrolyte not flowing back in a timely manner, and can further ensure that the battery has good cycle stability and safety and achieves high capacity.

[0026] m represents the largest pore size within the pore size range of the positive electrode material layer, i is the average pore size within the pore size range of the positive electrode material layer, and Pc iis the ratio of the volume of pores in the positive electrode material layer to the volume of the positive electrode material layer when the pore size is i. n represents the largest pore size in the negative electrode material layer within its pore size range, and ii is the average pore size in the negative electrode material layer within its pore size range. ii This is the ratio of the volume of the pores in the negative electrode material layer to the volume of the negative electrode material layer when the pore size is ii. i and ii may be the same, and m and n may also be the same. B i and B ii It is measured in units of m. The range of Ce values ​​is 1.0 g / Ah to 5.0 g / Ah.

[0027] In this disclosure, i is the average pore size value within the pore size range of the positive electrode material layer, and ii is the average pore size value within the pore size range of the negative electrode material layer. i and ii may be equal or positive integers. m is the maximum value within the pore size range of the positive electrode plate, and n is the maximum value within the pore size range of the negative electrode plate. Pci is the ratio of the pore size of the pores corresponding to the average pore size value within the pore size range of the positive electrode plate, and Pa ii This represents the ratio of pore diameters corresponding to the average pore diameter value within the pore diameter range of the negative electrode plate. i, ii, Pc i , and Pa ii This relates to the manufacturing conditions of the electrode plates, such as the compressive density of the active material, particle engineering, and / or various parameters in the coating and rolling techniques of the electrode plates. i and B ii This relates to the electrolyte composition and the start and end values ​​of the pore size range. Therefore, within the same pore size range, the value B of the positive electrode material layer i and the value B of the negative electrode material layer ii These are the same. It should be noted that in this disclosure, the positive electrode plate and the negative electrode plate are sometimes collectively referred to as electrode plates. Pore size refers to the gap between particles in the positive electrode material layer or the negative electrode material layer. Pore size range refers to the range of values ​​for the diameter of the pores. Pore volume refers to the volume corresponding to a specific pore size.

[0028] In the aforementioned relation, the value a is the viscosity of the electrolyte at room temperature, as measured by a viscometer. For example, the viscometer may be an Ubbelohde viscometer or a rotational rheometer. This is not limited to the present disclosure. It should be noted that viscosity in the present disclosure refers to the property of resisting deformation of adjacent fluid layers by a fluid, or preventing relative movement.

[0029] Under conditions where the composition of the electrolyte and the composition of the electrode plates do not change, the value B i (or B ii ) and the pore size di are inversely proportional: B i =k / di. Therefore, di-B is in two or more groups. i The value of is obtained through experimentation, the value k is obtained by fitting the corresponding inverse proportional relationship, and the value B under a different hole diameter value. i (or B ii To further obtain the following: Specifically, three groups of capillaries with different diameters (2 μm, 10 μm, and 20 μm) are selected and inserted into the selected electrolyte, and the increase in the height of the electrolyte in the capillaries is measured. The height value is the value of the corresponding pore diameter B. i k1, k2, and k3 are obtained, and the mean value k is obtained. Then, different values ​​di are substituted into the relation, and the corresponding value B is obtained. i To obtain.

[0030] In addition, the electrode plates i, ii, and Pc i , and Pa ii This may also be obtained through testing. Specifically, the pore size and pore size distribution of the positive and negative electrode plates are measured using the mercury intrusion method. Because the range of pore sizes is large, and the smaller the pore size value, the value B iBecause the values ​​differ significantly, the density increases as the pore size range decreases. In specific embodiments, based on the porosity results from experimental tests, i and ii are the following values: 20000nm, 18000nm, 15000nm, 12000nm, 10000nm, 7500nm, 6500nm, 5500nm, 5000nm, 3500nm, 2500nm, 1800nm, 1200nm, 750nm, 500nm, 320nm, 200nm, 140nm, 90nm, 65nm, 50nm, 40nm, 30nm, or 20nm. It should be noted that in the mercury intrusion method, the pore size and pore size distribution are measured by applying external pressure to the mercury so that the mercury can overcome surface tension and enter the pores. Porosity refers to the percentage of the volume of pores in a material relative to its total volume in its natural state.

[0031] The inventors of this disclosure have discovered through numerous experiments that the correction factor A is related to the material composition of the battery system, but A does not change with changes in the pore structure of the electrode plates. A larger value of A indicates a stronger force between the electrolyte and the positive and negative electrode plates. The correction factor A must be obtained by fitting initial simulation experiments. When the value A is fitted to the battery system (the battery is a physical object) through initial simulation experiments, i, ii, B i B ii PC i , and Pa ii The values ​​are actually measured, and Ce is also an actually measured value (denoted as Ce'). Ce' represents the actual electrolyte retention capacity of the electrode plates in the battery (specifically, a battery core with an opening is fabricated, an excess amount of electrolyte is injected into the battery core, the battery core is placed under a high vacuum level, and the electrolyte content in the battery is measured after a certain period of time; this value is the electrolyte retention capacity of the electrode plates Ce'). Then, the measured Ce' and values ​​i, ii, B are shown. i B ii PC i , and Pa ii This is substituted into the aforementioned relation to obtain the value A for the battery system.

[0032] The aforementioned relational expression provided in this disclosure may be used to fabricate a battery having a predetermined electrolyte retention capacity. Specifically, after the value A of the battery system is obtained, the pore parameter Pc of the electrode plate is obtained. i and Pa ii However, based on the value Ce required by the battery under design (i.e., the preset value), based on the aforementioned relation, and the actually measured value B i and B ii This may be obtained by referring to the relevant source and through calculations. Therefore, in the process of fabricating the positive and negative electrode plates, parameters such as the compressive density of the active material, particle engineering, and / or the coating and rolling techniques of the electrode plates are adjusted to obtain electrode plates and batteries that satisfy the aforementioned pore structure. In addition, the set electrolyte retention capacity of the battery substantially matches the actual electrolyte retention capacity of the battery.

[0033] In addition, in existing battery systems, B i and B ii The following parameters related to the battery (A, i, ii, Pc) were measured and measured. i , and Pa ii Once the values ​​A and C are learned and these parameters are substituted into the aforementioned relation, the electrolyte retention capacity Ce of the battery's electrode plates can be calculated. Then, electrochemical performance tests (e.g., tests for capacity retention, detection of lithium plating condition, or tests for rate characteristics) are performed on the battery to establish a correspondence between the battery's electrochemical performance and the value Ce. In this case, for other batteries in this series, only the battery value Ce needs to be calculated in advance in order to estimate the battery's cycle life. In some other cases, the battery value A and the actual electrolyte retention capacity value Ce' are obtained, and once these two values ​​are substituted into the aforementioned relation, the pore structure of the electrode plates can be obtained through calculation.

[0034] Specifically, fitting the correction factor A involves the following steps:

[0035] First, in the process of fabricating the positive and negative electrode plates of the battery, various parameters in the compression density of the active material on the positive and negative electrodes, particle engineering, and / or the coating and rolling techniques of the electrode plates are adjusted to produce five groups of positive and negative electrode plates with different pore structures. Then, the following tests are performed.

[0036] (1) Value B i and value B ii Measure.

[0037] (2) Electrode plates i, ii, Pc of the five groups i , and Pa ii Measure the value.

[0038] (3) The positive electrode plate, separator, and negative electrode plate are stacked in order, and the positive electrode plate, separator, and negative electrode plate are assembled in a glove box to prepare five battery core samples, and the electrolyte retention capacity of the electrode plates in the battery core is measured. It should be noted that in the above tests, all conditions are kept consistent except for the pore size and pore size distribution of the positive electrode material layer and the negative electrode material layer. Specifically, the following steps are included.

[0039] A hole of a certain size is drilled in the housing of the battery core, and the mass of the battery core is weighed and recorded as M1. Next, an excess amount of electrolyte is injected under these conditions, and the system is evacuated for 2 minutes under fixed vacuum conditions. Finally, the battery core is sealed, and the mass of the battery core is weighed and recorded as M2. The mass of the electrolyte in the test sample is recorded as Y, where Y = M2 - M1. The value of Y / M is calculated, where M is the sum of the mass of the positive electrode material layer in the positive electrode plate and the mass of the negative electrode material layer in the negative electrode plate, and the value of Y / M is the electrolyte retention capacity Ce' of the electrode plates.

[0040] (4) The values ​​Ce' of the five battery core samples are substituted into the aforementioned relation, and the values ​​of each correction coefficient A under these experimental conditions are calculated to obtain the value A of the battery system. The values ​​A of the five groups are approximately the same within the margin of error.

[0041] In this embodiment of the present disclosure, A is in the range of 0.01s to 100s. Controlling the value A to fall within this range helps to ensure the electrolyte retention capacity of the electrode plates, thereby helping to provide a battery with good cycle stability, high capacity retention, and long cycle life.

[0042] In this embodiment of the Disclosure, R is in the range of 0.1Ah to 300Ah. In some specific embodiments, R is in the range of 10Ah to 200Ah. In some other specific embodiments, R is in the range of 10Ah to 100Ah. The aforementioned relational expressions defined in the Disclosure are universal for batteries with different capacities.

[0043] In embodiments of this disclosure, the porosity of the positive electrode material layer is in the range of 10% to 50%, and the porosity of the negative electrode material layer is in the range of 10% to 70%. The porosities of the positive electrode material layer and the negative electrode material layer may be the same or different. Controlling the porosity of the positive and negative electrode plates within the aforementioned ranges helps to improve the electrolyte retention capacity of the electrode plates without affecting the performance of the positive and negative electrode plates.

[0044] In embodiments of this disclosure, the pore size distribution range of the positive electrode material layer and the negative electrode material layer is 20 nm to 20,000 nm. The actual distribution ranges of the pore size of the positive electrode material layer and the negative electrode material layer may be the same or different. Controlling the pore sizes of the positive electrode material layer and the negative electrode material layer to fall within the aforementioned ranges helps to improve the electrolyte retention capacity of the electrode plates and helps to construct a conductive network on the positive and negative electrode plates.

[0045] In the embodiments of this disclosure, the values ​​of m and n are 20,000 nm. Because the range of pore diameters in the porosity test results is large, and the smaller the pore diameter value, the lower the value of B. iBecause the values ​​differ significantly, the density increases as the pore size range decreases. In some embodiments, the length of the pore size range may be 20 nm to 100 nm. For example, the length of the pore size range may be the following values: 20000 nm, 18000 nm, 15000 nm, 12000 nm, 10000 nm, 7500 nm, 6500 nm, 5500 nm, 5000 nm, 3500 nm, 2500 nm, 1800 nm, 1200 nm, 750 nm, 500 nm, 320 nm, 200 nm, 140 nm, 90 nm, 65 nm, 50 nm, 40 nm, 30 nm, or 20 nm.

[0046] In embodiments of this disclosure, a is in the range of 0.5 mPa·s to 50 mPa·s. For example, the value of a may be 0.5 mPa·s, 1.0 mPa·s, 2.0 mPa·s, 3.0 mPa·s, 4.0 mPa·s, 5.0 mPa·s, 6.0 mPa·s, 7.0 mPa·s, 8.0 mPa·s, 9.0 mPa·s, 10.0 mPa·s, 20 mPa·s, 30 mPa·s, 40 mPa·s, or 50 mPa·s. In some embodiments, a is in the range of 0.5 mPa·s to 5 mPa·s. For example, a may be 0.5 mPa·s, 1.5 mPa·s, 2.5 mPa·s, 3.5 mPa·s, 4.5 mPa·s, or 5.0 mPa·s. The appropriate viscosity of the electrolyte helps improve the electrolyte retention capacity of the electrode plates, and the electrolyte helps wet the positive and negative electrode plates, maintaining the internal resistance of the battery core within an appropriate range.

[0047] In embodiments of this disclosure, the electrolyte comprises an organic solvent and a lithium salt. The lithium salt includes, but is not limited to, at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorophosphate, and lithium 4,5-dicyano-2-(trifluoromethyl)imidazole. The organic solvent includes, but is not limited to, at least one of ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC).

[0048] In embodiments of this disclosure, the electrolyte further comprises a viscosity modifier. The viscosity modifier comprises, but is not limited to, at least one of polyimide, polyvinylidene difluoride, and polyacrylic acid. The viscosity modifier is a high-viscosity inert organic liquid. By adding a viscosity modifier, the viscosity of the electrolyte can be adjusted to a predetermined value without altering other components of the electrolyte, thereby meeting the design requirements of the battery.

[0049] In embodiments of this disclosure, the positive electrode material layer comprises a positive electrode active material, a conductive agent (e.g., a first conductive agent), and a binder (e.g., a first binder). The negative electrode material layer comprises a negative electrode active material, a conductive agent (e.g., a second conductive agent), and a binder (e.g., a second binder). The positive electrode active material, negative electrode active material, conductive agent, and binder are all materials commonly used by those skilled in the art. For example, the positive electrode active material comprises, but is not limited to, at least one of lithium iron phosphate, lithium manganese phosphate, lithium iron manganese phosphate, lithium vanadium phosphate, lithium cobalt phosphate, lithium cobalt oxide, lithium manganese oxide, lithium nickel manganese oxide (NCM), lithium nickel cobalt aluminum oxide (NCA), and lithium-rich manganese-based materials. For example, the negative electrode active material comprises, but is not limited to, at least one of graphite, natural graphite, mesocarbon microbeads, and silicon carbon negative electrode materials.

[0050] The conductive agent includes, but is not limited to, at least one of carbon nanotubes (CNTs), carbon fibers (CF), carbon black (such as acetylene black or Ketjen black), furnace black, and graphene. The binder includes, for example, at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polyimide (PI), poly(acrylic acid) (PAA), polyacrylate, polyolefin (such as polyethylene, polypropylene, and polystyrene), carboxymethylcellulose (CMC), and sodium alginate.

[0051] In response to this, embodiments of the present disclosure further provide electrical equipment. As shown in Figure 2, electrical equipment 1 includes a battery 10. Electrical equipment may be a portable device (such as a mobile phone, notebook computer, or tablet computer) or a powered vehicle, but is not limited to this disclosure. Electrical equipment includes a load connected to the battery. For example, the load may be various elements within a portable device or the motor of a powered vehicle. The battery is configured to supply power to the load. Because a battery is used, electrical equipment has good battery life and safety performance.

[0052] The technical solutions of this disclosure will be described in detail by using several embodiments described below.

[0053] Embodiment 1 Preparation of electrolyte: EC, DMC, and DEC were mixed in a ratio of 4:3:3. Then, a certain amount of LiPF6 was added to the mixed solution so that the concentration of LiPF6 in the mixture was 1 mol / L. Next, a certain amount of viscosity modifier (polyimide) was added to obtain the electrolyte. The viscosity value a of the electrolyte at room temperature was tested using a viscometer. The pore size range length was set to 50 nm, and value B was obtained. i B was measured. i =B ii .

[0054] Cathode Plate Preparation: To prepare the positive electrode active material paste, a positive electrode active material (single crystal NCM811 with a D50 particle size of 3.87 μm), comprising 94% by mass, a conductive agent (carbon black + CNT), comprising 4% by mass, and a binder (PVDF), comprising 2% by mass, were uniformly mixed with N-methyl-2-pyrrolidone (NMP) to obtain the positive electrode active material paste. The prepared positive electrode active material paste was coated onto the aluminum foil of the positive electrode current collector using a coating machine, and after drying, it was rolled and die-cut to obtain the positive electrode plate.

[0055] Fabrication of the negative electrode plate: To prepare the negative electrode active material paste, a negative electrode active material (graphite) accounting for 96% of the mass, a conductive agent (acetylene black) accounting for 2% of the mass, and a binder (PVDF) accounting for 2% of the mass were uniformly mixed with NMP to obtain the negative electrode active material paste. The prepared negative electrode active material paste was coated onto the copper foil of the negative electrode current collector, and after drying, it was rolled and die-cut to obtain the negative electrode plate.

[0056] Measurement of the pore structure of electrode plates: Values ​​i, ii, Pc for positive and negative electrode plates. i , and Pa ii It was measured,

number

[0057] A dry cell core was fabricated by alternately stacking a positive electrode plate, a separator, and a negative electrode plate. The capacity R of the battery core was 9.2 Ah. The separator alternately isolates the positive electrode plate and the negative electrode plate. The dry cell core was placed in an aluminum laminated film enclosure, dried, and injected with electrolyte. After chemical formation, a battery of Embodiment 1 was obtained and denoted as S1.

[0058] According to the battery manufacturing method provided in Embodiment 1, batteries of Embodiments 2 to 14 were manufactured based on the ratios in Table 1, and batteries of Embodiments 2 to 14 were denoted as S2 to S14, respectively. [Table 2]

[0059] NCM811 specifically uses LiNi 0.8 Co 0.1 Mn 0.1It was O2. Specifically, NCM622 is LiNi 0.6 Co 0.2 Mn 0.2 It was O2. Specifically, NCM523 is LiNi 0.5 Co 0.2 Mn 0.3 It was O2.

[0060] To highlight the beneficial effects of the embodiments of this disclosure, the following three comparative examples are provided. Batteries of Comparative Examples 1 to 3 were manufactured according to the battery manufacturing method provided in Embodiment 1, based on the ratios in Table 2, and the batteries of Comparative Examples 1 to 3 were denoted as DS1 to DS3, respectively. [Table 3]

[0061] Electrochemical performance tests were performed on the batteries prepared in the embodiments and comparative examples described above. The details are as follows.

[0062] (1) Detection of lithium plating condition: A 0.5C / 0.5C cycle test was performed on the battery at 25°C, with a voltage range of 2.5V to 4.2V. The condition of the lithium plating on the negative electrode of the battery after 500 cycles was recorded, and the results are summarized in Table 3.

[0063] (2) Cycle performance test: A 0.5C / 0.5C cycle test was performed on the battery at 25°C, with a voltage range of 2.5V to 4.2V. The capacity retention rate of the battery after 500 cycles was recorded, and the results are summarized in Table 3.

[0064] (3) High-current performance test: A high-current charge-discharge test was performed on the battery at 25°C, with a voltage range of 2.5V to 4.2V, using a high current of 5C / 5C for charging and discharging. The battery's capacity retention rate was recorded, and the results are summarized in Table 3. [Table 4]

[0065] Referring to the battery parameters in Tables 1 and 2, and the battery test results in Table 3, it can be seen that batteries satisfying the relationships defined in this disclosure had excellent electrochemical performance. Specifically, batteries S1 to S14 of the embodiments all had good capacity retention rates. Comparing battery S1 and battery DS1, under the same experimental conditions, DS1 used an electrolyte with excessively low viscosity, resulting in an excessively low value of Ce for DS1. As a result, the lithium plating of the battery was in poor condition, and the battery capacity deteriorated rapidly. Comparing battery S1 and battery DS2, the value of Ce for battery DS2 exceeded the upper limit defined in this disclosure, resulting in a high internal resistance of the battery, and consequently, a very low capacity retention rate at a high rate of 5C current. Comparing battery S1 and battery DS3 under the same experimental conditions, the excessively small porosity of the electrode plates of DS3 led to a small value of Ce, resulting in severe lithium plating and rapid deterioration of the battery capacity.

[0066] The foregoing is an exemplary embodiment of the present application. Those skilled in the art should note that several improvements and modifications can be made without departing from the principles of the present disclosure, and such improvements and modifications will fall within the scope of the protection of the present disclosure. [Explanation of Symbols]

[0067] 1. Electrical equipment 10 batteries 110 Positive Plate 111 Positive electrode current collector 112 Cathode material layer 120 Negative plate 121 Negative electrode current collector 122 Negative electrode material layer 130 Electrolyte 140 Separator 150 Battery Case

Claims

1. A battery (10) comprising a positive electrode plate (110), a negative electrode plate (120), an electrolyte (130), and a separator (140) between the positive electrode plate and the negative electrode plate, wherein the positive electrode plate comprises a positive electrode current collector (111) and a positive electrode material layer (112) disposed on the positive electrode current collector, and the negative electrode plate comprises a negative electrode current collector (121) and a negative electrode material layer (122) disposed on the negative electrode current collector, and the relationship between the positive electrode plate, the negative electrode plate, and the electrolyte is given by the following equation: 【Number 1】 The following conditions are met, where Ce is the electrolyte retention capacity of the positive electrode plate and the negative electrode plate, the range of the value of Ce is 1.0 g / Ah to 5.0 g / Ah, A is a correction coefficient, a is the viscosity of the electrolyte at room temperature, measured in units of mPa·s, R is the capacity of the battery, measured in units of Ah, B ｉ is the capillary index of the pore size of the positive electrode material layer, and B ｉｉ is the capillary index of the pore size of the negative electrode material layer, and B ｉ and B ｉｉ Pc is measured in meters, where m is the maximum pore diameter of the pores in the positive electrode material layer, i is the average pore diameter of the pores in the positive electrode material layer, and Pc ｉ Pa is the ratio of the volume of the pores in the positive electrode material layer having pore diameter i to the volume of the positive electrode material layer, n is the maximum pore diameter of the pores in the negative electrode material layer, ii is the average pore diameter of the pores in the negative electrode material layer, and Pa ｉｉ A battery (10) is the ratio of the volume of pores in the negative electrode material layer having pore size ii to the volume of the negative electrode material layer.

2. The battery according to claim 1, wherein R is in the range of 0.1 Ah to 300 Ah and A is in the range of 0.01 s to 100 s.

3. The battery according to claim 1, wherein R is in the range of 10Ah to 100Ah.

4. The battery according to claim 1, wherein the distribution range of the pore size in the positive electrode material layer is 20 nm to 20,000 nm, and the distribution range of the pore size in the negative electrode material layer is 20 nm to 20,000 nm.

5. The battery according to claim 1, wherein the porosity of the positive electrode material layer is 10% to 50%, and the porosity of the negative electrode material layer is 10% to 70%.

6. The battery according to claim 1, wherein the minimum value of i and the minimum value of ii are 50, and the values ​​of m and n are 20,000 nm.

7. The value of i is 20000nm, 18000nm, 15000nm, 12000nm, 10000nm, 7500nm, 6500nm, 5500nm, 5000nm, 3500nm, 2500nm, 1800nm, 1200nm, 750nm, 500nm, 320nm, 200nm, 140nm, 90nm, 65nm, 50nm, 40nm, 30nm, or 20nm, and the value of ii is The battery according to claim 1, wherein the wavelength is 20,000 nm, 18,000 nm, 15,000 nm, 12,000 nm, 10,000 nm, 7,500 nm, 6,500 nm, 5,500 nm, 5,000 nm, 3,500 nm, 2,500 nm, 1,800 nm, 1,200 nm, 750 nm, 500 nm, 320 nm, 200 nm, 140 nm, 90 nm, 65 nm, 50 nm, 40 nm, 30 nm, or 20 nm.

8. The battery according to claim 1, wherein a is in the range of 0.5 mPa·s to 50 mPa·s.

9. The battery according to claim 1, wherein the electrolyte comprises an organic solvent and a lithium salt, the lithium salt comprising at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(oxalato)borate, lithium difluoro(oxalato)borate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorophosphate, or lithium 4,5-dicyano-2-(trifluoromethyl)imidazole, and the organic solvent comprising at least one of ethylene carbonate, diethyl carbonate, dimethyl carbonate, or ethyl methyl carbonate.

10. The battery according to claim 1, wherein the electrolyte comprises a viscosity modifier, and the viscosity modifier comprises at least one of polyimide, polyvinylidene fluoride, and polyacrylic acid.

11. The battery according to claim 1, wherein the positive electrode material layer comprises a positive electrode active material, a first conductive agent, and a first binder, and the negative electrode material layer comprises a negative electrode active material, a second conductive agent, and a second binder.

12. An electrical device (1) comprising a battery (10) according to any one of claims 1 to 11.

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