CN115020792A - Cylindrical lithium ion power battery and electric device - Google Patents

Cylindrical lithium ion power battery and electric device Download PDF

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Publication number
CN115020792A
CN115020792A CN202210755802.8A CN202210755802A CN115020792A CN 115020792 A CN115020792 A CN 115020792A CN 202210755802 A CN202210755802 A CN 202210755802A CN 115020792 A CN115020792 A CN 115020792A
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positive
mass
negative
active material
lithium ion
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Inventor
邓晓波
黄满湘
陈杰
项海标
李载波
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Huizhou Liwinon Energy Technology Co Ltd
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Huizhou Liwinon Energy Technology Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Inorganic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Secondary Cells (AREA)

Abstract

The invention provides a cylindrical lithium ion power battery and an electric device, wherein a material with a nickel-cobalt-manganese ratio of 5.2:2:2.8 is selected as a positive electrode material, and an optimized positive electrode active material layer and an optimized negative electrode active material layer are matched, so that the gram capacity of an active agent of the material can be effectively exerted; in addition, the positions of the positive electrode lug and the negative electrode lug are adjusted, so that the impedance can be effectively reduced. Therefore, the cylindrical lithium ion power battery has excellent cycle performance, particularly and preferably has capacity retention rate of over 90 percent after the battery is cycled for 1000 weeks, greatly meets the regulation of over 80 percent of the current industry, and is in the leading level of the industry.

Description

Cylindrical lithium ion power battery and electric device
Technical Field
The invention relates to the field of lithium batteries, in particular to a cylindrical lithium ion power battery and an electric device.
Background
With the continuous development of lithium ion secondary battery technology, the lithium ion secondary battery technology is widely applied to daily life; the cylindrical 18650 high-energy-density power battery is widely applied to electric bicycles and new energy vehicles. The industry requires that the service life of a cylindrical 18650 nickel cobalt lithium manganate power battery is 1000 weeks, and the capacity retention rate is more than or equal to 80%. Therefore, the design difficulty of the lithium ion battery is higher and higher, and in order to more effectively explore the use potential of the lithium ion battery, the preparation of the pole piece of the lithium ion battery needs to be innovated in various aspects so as to prolong the cycle life of the lithium ion battery as much as possible.
In view of the above, it is necessary to provide a technical solution to the above problems.
Disclosure of Invention
One of the objects of the present invention is: in view of the defects of the prior art, the cylindrical lithium ion power battery has the advantage of long cycle life.
In order to achieve the purpose, the invention adopts the following technical scheme:
a cylindrical lithium ion power battery comprising a core, an electrolyte, and a battery housing containing the core and the electrolyte, the core comprising:
the positive plate comprises a positive current collector and a positive active substance layer coated on at least one surface of the positive current collector, the positive current collector is provided with a positive lug welding area, a positive lug is welded on the positive lug welding area, and the positive active substance layer is provided with a positive lug groove in the positive lug welding area so as to expose the positive lug; the positive active material layer comprises 96-98% by mass of a positive active material, 1-2% by mass of a positive conductive agent and 1-2% by mass of a positive binder, and the positive active material is a nickel-cobalt-manganese positive material, wherein the molar ratio of nickel to cobalt to manganese is 5.2:2: 2.8;
the negative plate comprises a negative current collector and a negative active material layer coated on at least one surface of the negative current collector, the head and the tail of the negative current collector are both provided with a negative lug welding area, and a negative lug is welded on the negative lug welding area; the negative electrode active material layer comprises 95-97% by mass of a negative electrode active material, 1.5-3% by mass of a negative electrode binder and 1.5-2% by mass of a thickening agent;
and the diaphragm is spaced between the positive plate and the negative plate and is wound with the positive plate and the negative plate to manufacture the battery cell.
Preferably, the nickel-cobalt-manganese positive electrode material is nickel-cobalt-manganese lithium manganate or doped nickel-cobalt-manganese lithium manganate, and the doped material comprises one or a combination of more of Al, B, P, Zr, Si, Ti, Ge, Sn, Mg, Ce and W.
Preferably, the positive current collector is an aluminum foil, the thickness of the aluminum foil is 15-16 mu m, and the MD elongation of the aluminum foil is more than or equal to 2%.
Preferably, the positive tab is positioned at positions 1/4-3/4 of the head of the positive current collector.
Preferably, the positive tab is positioned at positions 1/3-2/3 of the head of the positive current collector.
Preferably, the negative electrode current collector is a copper foil, the thickness of the copper foil is 8-9 μm, the MD elongation of the copper foil is more than or equal to 3%, and the negative electrode lug is a copper-nickel composite belt.
Preferably, the negative active material is graphite, the negative binder is styrene butadiene rubber, and the negative thickener is sodium carboxymethylcellulose.
Preferably, the electrolyte is an electrolyte, the electrolyte comprises a lithium salt, an organic solvent and an additive, the mass of the lithium salt is 15-17% of the mass of the electrolyte, the mass of the organic solvent is 70-83% of the mass of the electrolyte, and the mass of the additive is 2-7% of the mass of the electrolyte.
Preferably, the organic solvent consists of 20-30% by mass of ethylene carbonate, 10-15% by mass of ethyl methyl carbonate and 40-50% by mass of dimethyl carbonate; the additive comprises 0.5-1% by mass of ethylene sulfite, 1-3% by mass of vinylene carbonate and 0.5-2% by mass of fluoroethylene carbonate.
Another object of the present invention is to provide an electric device including the cylindrical lithium-ion power battery according to any one of the above aspects.
Compared with the prior art, the invention has the beneficial effects that: according to the cylindrical lithium ion power battery provided by the invention, a material with a nickel-cobalt-manganese ratio of 5.2:2:2.8 is optimally selected as a positive electrode material, and the optimized positive electrode active material layer and the optimized negative electrode active material layer are matched, so that the exertion of gram capacity of an active agent of the material can be effectively promoted; in addition, the positions of the positive electrode lug and the negative electrode lug are adjusted, so that the impedance can be effectively reduced. Therefore, the cylindrical lithium ion power battery has excellent cycle performance, particularly and preferably has capacity retention rate of over 90 percent after the battery is cycled for 1000 weeks, greatly meets the regulation of over 80 percent of the current industry, and is in the leading level of the industry.
Drawings
Fig. 1 is a cycle life test chart of a battery according to example 1 of the present invention.
Detailed Description
The invention aims at providing a cylindrical lithium ion power battery, which comprises a battery core, electrolyte and a battery shell for accommodating the battery core and the electrolyte, wherein the battery core comprises:
the positive plate comprises a positive current collector and a positive active substance layer coated on at least one surface of the positive current collector, the positive current collector is provided with a positive lug welding area, a positive lug is welded on the positive lug welding area, and the positive active substance layer is provided with a positive lug groove in the positive lug welding area so as to expose the positive lug; the positive active material layer comprises 96-98% by mass of a positive active material, 1-2% by mass of a positive conductive agent and 1-2% by mass of a positive binder, and the positive active material is a nickel-cobalt-manganese positive material, wherein the molar ratio of nickel, cobalt and manganese is 5.2:2: 2.8;
the negative plate comprises a negative current collector and a negative active material layer coated on at least one surface of the negative current collector, the head and the tail of the negative current collector are both provided with a negative lug welding area, and a negative lug is welded on the negative lug welding area; the negative electrode active material layer comprises 95-97% by mass of a negative electrode active material, 1.5-3% by mass of a negative electrode binder and 1.5-2% by mass of a thickening agent;
and the diaphragm is spaced between the positive plate and the negative plate and is wound with the positive plate and the negative plate to manufacture the battery cell.
The inventor of the cylindrical lithium ion power battery provided by the invention verifies through repeated experiments, and finally obtains the cylindrical battery which can reduce the impedance of the battery, improve the energy density of the battery and prolong the cycle life through various improvements such as material selection, formula design, structural design and the like.
Compared with the conventional cathode material with the molar ratio of nickel to cobalt to manganese of 5:2:3, the nickel-cobalt-manganese cathode material is selected, the inventor finds that the content of Ni and Mn is finely adjusted to increase the content of Ni to 5.2 and reduce the content of Mn to 2.8, and after the formula of the corresponding active material layer is matched, the activity of the material can be effectively improved, the energy density of the battery is improved, and the foundation is filled for prolonging the cycle life of the cylindrical battery. Compared with the conventional positive active material with the proportion of 92-93%, the matched active material layer formula is matched with the active material with the high proportion, and is matched with the nickel-cobalt-manganese positive material with the proportion of 5.2:2:2.8, so that the matched active material layer formula is more favorable for exciting the activity of the material.
Specifically, the proportion of the positive electrode active material layer can be 96% of positive electrode active material, 2% of positive electrode conductive agent and 2% of positive electrode binder; 96.5 percent of positive active material, 1.5 percent of positive conductive agent and 2 percent of positive binder; 97% of positive active material, 1% of positive conductive agent and 2% of positive binder; 97% of positive active material, 2% of positive conductive agent and 1% of positive binder; 97% of positive active material, 1.5% of positive conductive agent and 1.5% of positive binder; 97.5 percent of positive active material, 1.5 percent of positive conductive agent and 1 percent of positive binder; the anode material can also be 98 percent of anode active material, 1 percent of anode conductive agent and 1 percent of anode binder.
More preferably, the positive active material is a nickel-cobalt-manganese positive electrode material, the nickel-cobalt-manganese positive electrode material is nickel-cobalt lithium manganate or doped nickel-cobalt lithium manganate, and the doped material comprises one or a combination of more of Al, B, P, Zr, Si, Ti, Ge, Sn, Mg, Ce, and W; the conductive agent is conductive carbon black; the positive electrode binder is polyvinylidene fluoride (PVDF).
On the premise of increasing the proportion of the positive active material, the proportion of the negative active material is synchronously increased, lithium precipitation caused by low content of the negative active material is avoided, and the capacity of the positive active material is inhibited from being exerted. Specifically, the proportion of the negative electrode active material layer can be 95% of the negative electrode active material, 3% of the negative electrode binder and 2% of the thickening agent by mass; the weight ratio of the negative electrode active material to the negative electrode binder can also be 95.5 percent, 2.5 percent and 2 percent of the thickening agent; the weight ratio of the anode active material to the cathode binder can also be 96%, 2% and 2% of the thickening agent; 96.5% of negative electrode active material, 2% of negative electrode binder and 1.5% of thickening agent in mass percentage; 97% of negative electrode active material, 1.5% of negative electrode binder and 1.5% of thickening agent in mass percentage can also be adopted. More preferably, the negative electrode active material is graphite, the negative electrode binder is styrene butadiene rubber, and the negative electrode thickener is sodium carboxymethylcellulose.
In addition, on the basis of improving the energy density, the design of low internal resistance of the battery is synchronously provided, the positive electrode tab is arranged between the positive electrode active material layers, and the negative electrode tab is arranged at the head and the tail of the negative electrode sheet by avoiding the negative electrode active material layers, so that the alternating current internal resistance of the battery can be reduced by at least 9-11 m omega. The head and the tail of the cell are relative to the cell after winding, the head of the cell is the position of the head circle of winding, the tail of the cell is the position of the last circle of winding, correspondingly, the head of the negative electrode sheet is the negative electrode sheet corresponding to the head circle of winding, and the tail of the negative electrode sheet is the negative electrode sheet corresponding to the last circle of winding.
In some embodiments, the positive current collector is an aluminum foil, the thickness of the aluminum foil is 15-16 μm, and the MD elongation of the aluminum foil is greater than or equal to 2%. Compared with the conventionally adopted aluminum foil with the thickness of 12-14 mu m and the MD elongation rate of more than or equal to 1.5 percent, the aluminum foil with higher thickness is beneficial to reducing the internal resistance of the battery. Meanwhile, the positive electrode lug is arranged between the positive electrode active material layers and synchronously matched with the negative electrode lugs arranged at the head part and the tail part, so that the internal resistance of the battery can be further reduced, but the energy density can be relatively reduced, therefore, the battery is also provided with the positive electrode material and the formula design of the positive electrode active material layer and the negative electrode active material layer, the influence of high aluminum foil on the energy density is buffered, and the energy density is further improved compared with the conventional cylindrical battery. In addition, after the tabs and the cover caps are welded by laser, the tabs are folded in a V shape, so that the risk that the tabs touch the inner wall of the steel shell to cause short circuit in the use process of the battery can be avoided. And the aluminum foil with higher elongation rate is beneficial to improving the compaction density of the pole piece, so that the energy density and the cycle performance of the battery can be further improved.
Preferably, the positive tab is positioned at 1/4-3/4 positions of the head of the positive current collector. More preferably, the positive tab is positioned at positions 1/3-2/3 of the head of the positive current collector. Further preferably, when the positive electrode current collector header 1/3 is provided, a more effective effect of reducing the internal resistance can be achieved, and the internal resistance can be reduced by 3-5 m Ω. Theoretically, when the electrode tab is arranged at the position 1/2 of the positive electrode current collector, the internal resistance is more favorably reduced, but in the research process, the inventor finds that the electrode tab is bent after being welded with a cap at 1/2, the cell is often damaged, and therefore, the 1/3 has better arrangement practicability for industrial mass production.
In some embodiments, the negative electrode current collector is a copper foil, the thickness of the copper foil is 8-9 μm, the MD elongation (i.e., longitudinal elongation) of the copper foil is greater than or equal to 3%, and the negative electrode tab is a copper-nickel composite tape. Compared with the conventionally adopted copper foil with the thickness of 6 microns and the MD elongation rate of more than or equal to 2.5 percent, the copper foil with thicker thickness and larger MD elongation rate is also adopted as the current collector in the invention; in addition, the cathode lug is made of a copper-nickel composite strip material, and is provided with the head part and the tail part, so that compared with the conventional cathode lug which is made of a pure nickel strip material, the cathode lug is more beneficial to reducing the internal resistance of the battery and improving the energy density and the cycle performance of the battery.
In some embodiments, the electrolyte is an electrolyte solution, the electrolyte solution includes a lithium salt, an organic solvent and an additive, the mass of the lithium salt is 15-17% of the mass of the electrolyte solution, the mass of the organic solvent is 70-83% of the mass of the electrolyte solution, and the mass of the additive is 2-7% of the mass of the electrolyte solution.
In some embodiments, the organic solvent consists of 20-30% by mass of ethylene carbonate, 10-15% by mass of ethyl methyl carbonate and 40-50% by mass of dimethyl carbonate; the additive comprises 0.5-1% by mass of ethylene sulfite, 1-3% by mass of vinylene carbonate and 0.5-2% by mass of fluoroethylene carbonate.
The second aspect of the invention aims to provide an electric device, which comprises the cylindrical lithium ion power battery. Through the application of the battery, the requirements of the industry on the service life of 1000 weeks and capacity retention rate of more than or equal to 80 percent of a cylindrical 18650 nickel cobalt lithium manganate power battery can be greatly met, and the application range of the battery is greatly widened.
The electric device can be a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool and the like. The vehicle can be a fuel oil vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid electric vehicle or a range-extended vehicle and the like; spacecraft include aircraft, rockets, space shuttles, and spacecraft, among others; electric toys include stationary or mobile electric toys, such as game machines, electric car toys, electric ship toys, electric airplane toys, and the like; the electric power tools include metal cutting electric power tools, grinding electric power tools, assembly electric power tools, and electric power tools for railways, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, electric impact drills, concrete vibrators, and electric planers.
In order to make the technical solutions and advantages of the present invention clearer, the present invention and its advantages will be described in further detail below with reference to the following detailed description and the accompanying drawings, but the embodiments of the present invention are not limited thereto.
Example 1
A cylindrical lithium ion power battery, which is a 18650 cylindrical battery, comprising a cell, an electrolyte, and a battery housing accommodating the cell and the electrolyte, the cell comprising:
the positive plate comprises a positive current collector aluminum foil and a positive active material layer coated on at least one surface of the positive current collector, a positive lug welding area is arranged on the positive current collector at the position of the head 1/3 of the positive plate, a positive lug is welded on the positive lug welding area, and the positive lug is an aluminum strip; the positive active material layer is provided with a positive lug groove in the positive lug welding area so as to expose the positive lug; the positive active material layer comprises 97% by mass of a positive active material, 1.5% by mass of positive conductive agent conductive carbon black and 1.5% by mass of a positive binder PVDF, wherein the positive active material is nickel cobalt lithium manganate, and the molar ratio of nickel, cobalt and manganese is 5.2:2: 2.8;
the negative plate comprises a negative current collector copper foil and a negative active material layer coated on at least one surface of the negative current collector, the head and the tail of the negative current collector are both provided with a negative lug welding area, a negative lug is welded on the negative lug welding area, and the negative lug is a copper-nickel composite belt; the negative electrode active material layer comprises 96% of negative electrode active material graphite, 2% of negative electrode binder SBR and 2% of thickening agent CMC by mass;
and the diaphragm is a single-sided ceramic coating diaphragm, is spaced between the positive plate and the negative plate, and is wound with the positive plate and the negative plate to form the battery cell.
The electrolyte of this embodiment includes a lithium salt, an organic solvent, and an additive, wherein the lithium salt is composed of 15% LiPF 6 The organic solvent consists of 25 mass percent of ethylene carbonate, 10 mass percent of methyl ethyl carbonate and 45 mass percent of dimethyl carbonate; the additive comprises 1 mass percent of ethylene sulfite, 2 mass percent of vinylene carbonate and 2 mass percent of fluoroethylene carbonate.
The preparation method of the cylindrical lithium ion power battery comprises the following steps: preparing a positive plate, a negative plate, a diaphragm and electrolyte according to the formula and the structural design by referring to the existing preparation method; and then, preparing the positive plate, the negative plate and the diaphragm into a battery core through a full-automatic winding machine, putting the battery core into a battery shell, adding electrolyte, and preparing the battery through a spot bottom welding, slot rolling, baking, liquid injection, cap laser welding, sealing, cleaning, X-Ray and film covering automatic assembly packaging line.
And finally, the battery is produced through the working procedures of aging, formation, OCV, capacity grading detection and sorting.
The specific process is as follows:
a. standing the battery at normal temperature for 48 +/-2 hours for aging;
b. after the battery is loaded, the battery is charged on a formation cabinet at a constant current of 0.5 ℃ for 3 min. The pre-charging process uses small current for short-time charging, and is firstly helpful for forming a stable solid electrolyte interface film-SEI film on the surface of the negative electrode; the trace moisture in the electrolyte is decomposed, and the performance of the battery is improved;
c. standing the lower battery cabinet for 24 +/-2 hours at normal temperature after the pre-charging is finished;
d. after standing at normal temperature, the battery is turned out, and then the battery is put into a cabinet for formation, and is charged to 4.2V at a constant current and a constant voltage of 0.2C, and the 0.02C is cut off; and after the formation is finished, screening the OCV1/IR1 voltage/internal resistance, and removing self-discharge high-internal-resistance defective products. When the short-time 0.5C pre-charging time is 3min, the metal impurities of the positive electrode at a lower potential are dissolved in the electrolyte, and the metal impurities are formed by small current 0.2C after being placed for 24h at normal temperature, so that the metal ions are tiled and separated out at the negative electrode, the self-discharge rate of the battery is reduced, and the safety performance of the battery is improved;
e. aging at 45 + -3 deg.C for 3 days; screening the voltage/internal resistance of OCV2/IR2 after the high-temperature aging is finished; rejecting self-discharge and high internal resistance defective products;
f. standing at the normal temperature of 25 +/-3 ℃ for 10 days; after standing at normal temperature, screening OCV3/IR3 voltage/internal resistance; rejecting self-discharge and high internal resistance defective products;
g. grading, charging to 4.2V at constant current and constant voltage of 0.5C, stopping charging at 0.05C, standing for 5min, and discharging to 3.0V at 0.5C;
h. the batteries are sorted according to the capacity, internal resistance, voltage and K value (delta OCV voltage difference method). Finally, the battery is obtained.
Example 2
Different from the embodiment 1, the formulation of the positive electrode active material layer comprises 98% by mass of the positive electrode active material, 1% by mass of the positive electrode conductive agent conductive carbon black and 1% by mass of the positive electrode binder PVDF.
The rest is the same as embodiment 1, and the description is omitted here.
Example 3
Different from the embodiment 1, the formulation of the positive electrode active material layer comprises 96 mass percent of positive electrode active material, 2 mass percent of positive electrode conductive agent conductive carbon black and 2 mass percent of positive electrode binder PVDF.
The rest is the same as embodiment 1, and the description is omitted here.
Example 4
Unlike example 1, the negative electrode active material layer was formulated to include 97% by mass of graphite as a negative electrode active material, 1.5% by mass of SBR as a negative electrode binder, and 1.5% by mass of CMC as a thickener.
The rest is the same as embodiment 1, and the description is omitted here.
Example 5
Unlike the embodiment 1, the welding position of the positive tab is located at 3/4 on the head of the positive tab.
The rest is the same as embodiment 1, and the description is omitted here.
Example 6
Unlike the embodiment 1, the welding position of the positive tab is located at 1/2 on the head of the positive tab.
The rest is the same as embodiment 1, and the description is omitted here.
Comparative example 1
Different from the embodiment 1, the formulation of the positive electrode active material layer comprises 92 mass percent of positive electrode active material, 4 mass percent of positive electrode conductive agent conductive carbon black and 4 mass percent of positive electrode binder PVDF.
The rest is the same as embodiment 1, and the description is omitted here.
Comparative example 2
Unlike example 1, the negative electrode active material layer was formulated to include 93% by mass of graphite as a negative electrode active material, 4% by mass of SBR as a negative electrode binder, and 3% by mass of CMC as a thickener.
The rest is the same as embodiment 1, and the description is omitted here.
Comparative example 3
The difference from the embodiment 1 is that the welding position of the positive electrode tab is located at the head of the positive electrode sheet, that is, the position of the positive electrode sheet corresponding to the winding head circle.
The rest is the same as embodiment 1, and the description is omitted here.
Comparative example 4
Different from the embodiment 1, the welding position and the material of the negative electrode tab are adopted, and the position of the negative electrode tab at the head part 1/2 of the negative electrode tab is a single electrode tab and is made of pure nickel strap.
The rest is the same as embodiment 1, and the description is omitted here.
The batteries obtained in the above examples 1 to 6 and comparative examples 1 to 4 were subjected to a cycle performance test, and were charged at a constant current and a constant voltage of 0.5C to 4.2V, and were cut off at 0.05C; standing for 30 min; and (5) discharging the mixture to 3.0V at a constant current at 1C, and calculating the capacity retention rate after 1000 weeks of circulation.
The test results are shown in table 1 below and fig. 1.
TABLE 1
Capacity retention (%) Capacity retention (%)
Example 1 91.1％ Example 2 90.2％
Example 3 91.3％ Example 4 91.2％
Example 5 90.1％ Example 6 91.2％
Comparative example 1 81.3％ Comparative example 2 73.4％
Comparative example 3 86.9％ Comparative example 4 83.5％
From the test results, the 18650 cylindrical battery provided by the invention can be improved in various aspects such as material selection, formula design and structural design synchronously, can obtain a cylindrical battery capable of reducing the impedance of the battery, improving the energy density of the battery and prolonging the cycle life, can still keep more than 90% of capacity retention rate after 1000 cycles, is far higher than the industry 80% standard, and is more beneficial to the wide application of lithium ion batteries.
Variations and modifications to the above-described embodiments may also occur to those skilled in the art, which fall within the scope of the invention as disclosed and taught herein. Therefore, the present invention is not limited to the above-mentioned embodiments, and any obvious improvement, replacement or modification made by those skilled in the art based on the present invention is within the protection scope of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims (10)

1. A cylindrical lithium ion power battery, includes electric core, electrolyte and holds the battery case of electric core and electrolyte, its characterized in that, electric core includes:
the positive plate comprises a positive current collector and a positive active substance layer coated on at least one surface of the positive current collector, the positive current collector is provided with a positive lug welding area, a positive lug is welded on the positive lug welding area, and the positive active substance layer is provided with a positive lug groove in the positive lug welding area so as to expose the positive lug; the positive active material layer comprises 96-98% by mass of a positive active material, 1-2% by mass of a positive conductive agent and 1-2% by mass of a positive binder, and the positive active material is a nickel-cobalt-manganese positive material, wherein the molar ratio of nickel, cobalt and manganese is 5.2:2: 2.8;
the negative plate comprises a negative current collector and a negative active material layer coated on at least one surface of the negative current collector, the head and the tail of the negative current collector are both provided with a negative lug welding area, and a negative lug is welded on the negative lug welding area; the negative electrode active material layer comprises 95-97% by mass of a negative electrode active material, 1.5-3% by mass of a negative electrode binder and 1.5-2% by mass of a thickening agent;
and the diaphragm is spaced between the positive plate and the negative plate and is wound with the positive plate and the negative plate to manufacture the battery core.
2. The cylindrical lithium ion power battery of claim 1, wherein the nickel cobalt manganese positive electrode material is nickel cobalt manganese oxide or doped nickel cobalt manganese oxide, and the doped material comprises a combination of one or more of Al, B, P, Zr, Si, Ti, Ge, Sn, Mg, Ce, and W.
3. The cylindrical lithium ion power battery as claimed in claim 1, wherein the positive electrode current collector is an aluminum foil, the thickness of the aluminum foil is 15-16 μm, and the MD elongation of the aluminum foil is not less than 2%.
4. The cylindrical lithium ion power battery as claimed in claim 1 or 3, wherein the positive tab is located at 1/4-3/4 of the head of the positive current collector.
5. The cylindrical lithium ion power battery as claimed in claim 4, wherein the positive tab is located at positions 1/3-2/3 of the head of the positive current collector.
6. The cylindrical lithium ion power battery as claimed in claim 1, wherein the negative electrode current collector is a copper foil, the thickness of the copper foil is 8-9 μm, the MD elongation of the copper foil is not less than 3%, and the negative electrode tab is a copper-nickel composite belt.
7. The cylindrical lithium ion power battery of claim 1 or 6, wherein the negative active material is graphite, the negative binder is styrene butadiene rubber, and the negative thickener is sodium carboxymethylcellulose.
8. The cylindrical lithium ion power battery as claimed in claim 1, wherein the electrolyte is an electrolyte solution, and the electrolyte solution comprises a lithium salt, an organic solvent and an additive, wherein the mass of the lithium salt is 15-17% of the mass of the electrolyte solution, the mass of the organic solvent is 70-83% of the mass of the electrolyte solution, and the mass of the additive is 2-7% of the mass of the electrolyte solution.
9. The cylindrical lithium ion power battery according to claim 8, wherein the organic solvent comprises 20-30% by mass of ethylene carbonate, 10-15% by mass of ethyl methyl carbonate and 40-50% by mass of dimethyl carbonate; the additive comprises 0.5-1% by mass of ethylene sulfite, 1-3% by mass of vinylene carbonate and 0.5-2% by mass of fluoroethylene carbonate.
10. An electric device comprising the cylindrical lithium ion power battery according to any one of claims 1 to 9.
CN202210755802.8A 2022-06-30 2022-06-30 Cylindrical lithium ion power battery and electric device Pending CN115020792A (en)

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