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CN-118983500-B - Cylindrical lithium ion battery and power utilization device

CN118983500BCN 118983500 BCN118983500 BCN 118983500BCN-118983500-B

Abstract

The application provides a cylindrical lithium ion battery and an electricity utilization device, wherein the cylindrical lithium ion battery comprises a shell, a winding core arranged in the shell and with the bottom end electrically connected with the shell, and a cover cap correspondingly covered on the top end of the winding core, the top end of the winding core is also provided with a current collecting piece which is electrically connected with the cover cap, the current collecting piece comprises a straight part, a bending part and a main body part which are sequentially connected, the straight part is electrically connected with the cover cap, the main body part is electrically connected with the electrode end face of the top end of the winding core, the alternating current internal resistance of the battery from the bending part to the cover cap is set to be a first internal resistance R1, the alternating current internal resistance of the battery from the bending part to the bottom end of the shell is set to be a second internal resistance R2, and the first internal resistance R1 and the second internal resistance R2 are 70% -R2/(R1+R2) 95%. By proportionally distributing R1 and R2, the overall internal resistance of the lithium battery is reduced, the short-circuit protection function of the current collecting sheet can be reserved, the balance of the low internal resistance performance and the tab short-circuit protection performance of the battery is realized, and the safety of the cylindrical lithium ion battery is improved.

Inventors

  • Wang Chitang
  • CHEN XUAN

Assignees

  • 江苏睿恩新能源科技有限公司

Dates

Publication Date
20260505
Application Date
20240801

Claims (7)

  1. 1. The cylindrical lithium ion battery comprises a shell, a winding core arranged in the shell and with the bottom electrically connected with the shell, and a cover cap correspondingly covered on the top end of the winding core, wherein the winding core is formed by winding a positive plate, a diaphragm and a negative plate which are sequentially stacked, electrolyte is filled in the shell to infiltrate the winding core, the cylindrical lithium ion battery is a full-tab cylindrical lithium ion battery, the top end of the winding core is also provided with a current collecting piece which is electrically connected with the cover cap, the overall internal resistance of the cylindrical lithium ion battery is R1+R2, the current collecting piece comprises a main body part, a first bending part, a straight part and a second bending part which are sequentially connected, the main body part is in welded connection with the top end of the winding core, the second bending part is electrically connected with the cover cap, the alternating current internal resistance of the battery between the first bending part and the cover cap is set to be the first internal resistance R1, the alternating current internal resistance of the battery between the first bending part and the bottom end of the shell is set to be the second internal resistance R2, and the first internal resistance R1 and R2 are less than or equal to or less than or equal to 2% (-1.R2%; the winding core is wrapped with an insulating material layer to be electrically insulated from the shell, the insulating material layer comprises a first adhesive tape wound on the middle section of the outer side wall of the winding core, the inner end of the first adhesive tape is adhered to the outer side wall of the winding core and wound round by round, the first adhesive tape of the outermost layer is abutted against the inner wall of the shell when the winding core is assembled into the shell to enable the winding core and the shell to be relatively fixed in the radial direction, the width of the first adhesive tape accounts for 50% -99% of the height of the winding core in the axial direction, the insulating material layer further comprises a third adhesive tape, the cylindrical lithium ion battery further comprises a fourth adhesive tape, the fourth adhesive tape is covered on the initial end of the positive electrode sheet, the initial end is located at the innermost side of the winding core, the fifth adhesive tape is covered on the tail end of the positive electrode sheet, the tail end is located at the outermost side of the winding core, the discharge retention rate of the cylindrical lithium ion battery at 10C is 83-97%, the charge retention rate at 3C is 62-85%, and the cyclic retention rate at 10C is 60-90%.
  2. 2. The cylindrical lithium ion battery according to claim 1, wherein one or more of an expansion adhesive tape, a PET adhesive tape, a PI adhesive tape, and a polyurethane adhesive tape can be used for each of the insulating material layer, the fourth adhesive tape, and the fifth adhesive tape.
  3. 3. The cylindrical lithium ion battery according to claim 1, wherein the positive electrode sheet comprises a positive electrode active material, a binder and a conductive agent, the positive electrode active material is a nickel-based layered lithium intercalation transition metal oxide material or a combination of a nickel-based layered lithium intercalation transition metal oxide material and a lithium iron phosphate material, the metal element in the nickel-based layered lithium intercalation transition metal oxide material further comprises one or more of cobalt, manganese and aluminum, and the proportion of the number of nickel atoms in the positive electrode active material to the total number of atoms of transition metal atoms is greater than or equal to 75%.
  4. 4. The cylindrical lithium ion battery according to claim 1, wherein the negative electrode sheet comprises a negative electrode active material, a binder and a conductive agent, the negative electrode active material comprises a silicon-based material and a carbon-based material, and the mass ratio of the silicon-based material in the negative electrode active material is 2% -30%.
  5. 5. The cylindrical lithium ion battery of claim 1, wherein the electrolyte comprises a solvent comprising one or more of ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, and an additive comprising one or more of vinylene carbonate, methyl formate, ethyl acetate, propyl propionate, and a lithium salt comprising one or more of lithium difluorophosphate, lithium hexafluorophosphate, lithium difluorosulfonimide, lithium bistrifluoromethylsulfonimide.
  6. 6. The cylindrical lithium ion battery of claim 1, wherein the area of the outer side wall of the winding core covered with the insulating material layer is further provided with a two-dimensional code for associating identity information of the cylindrical lithium ion battery.
  7. 7. An electrical device comprising a cylindrical lithium ion battery as defined in any one of claims 1-6.

Description

Cylindrical lithium ion battery and power utilization device Technical Field The application relates to the technical field of electricity utilization devices, in particular to a cylindrical lithium ion battery and an electricity utilization device. Background The internal resistance of a cylindrical lithium ion battery is an important factor affecting the functional performance and charge-discharge efficiency of the battery, and is also an important parameter for evaluating the life of the lithium battery. The cylindrical lithium ion battery needs smaller internal resistance to realize higher power application, and in recent years, the internal resistance of the battery is greatly reduced through the design of a full tab, so that the frequency of triggering temperature cutoff due to overheat of a battery core during heavy current discharging or charging is reduced, the energy loss in the battery core is reduced, and the quick charge and quick discharge performances of the cylindrical lithium ion battery are improved. The internal resistance of the cylindrical lithium ion battery mainly comprises two parts of internal resistance of a structural member and internal resistance of a winding core, wherein the internal resistance of the structural member comprises a cover cap, an anode and cathode current collecting piece, a steel shell and the like, and the internal resistance of the winding core comprises an anode and cathode lug, an anode and cathode pole piece, an anode and cathode active substance, a diaphragm and the like. The internal resistance of the positive current collecting plate is not only related to the heat generation of the head of the battery, but also affects the exertion of the short-circuit protection performance of the battery, and the integral internal resistance of the winding core affects the quick charge and quick discharge dynamics performance of the battery. Disclosure of Invention In order to solve the problems, the internal resistances of different parts in the battery are reasonably optimized, so that the performance of the battery in a high-rate charge-discharge application scene is greatly improved, and the short-circuit protection performance of the positive current collecting plate is greatly improved. The first aspect of the application provides a cylindrical lithium ion battery, which comprises a shell, a winding core arranged in the shell and with the bottom end electrically connected with the shell, and a cover cap correspondingly covered on the top end of the winding core, wherein electrolyte is filled in the shell to infiltrate the winding core, a current collecting piece is further arranged on the top end of the winding core and is electrically connected with the cover cap, the current collecting piece comprises a main body part, a first bending part, a straight part and a second bending part which are sequentially connected, the main body part is electrically connected with the top end of the winding core, the second bending part is electrically connected with the cover cap, the alternating current internal resistance of the battery between the first bending part and the cover cap is set to be a first internal resistance R1, the alternating current internal resistance of the battery between the first bending part and the bottom end of the shell is set to be a second internal resistance R2, and the first internal resistance R1 and the second internal resistance R2 meet the conditions that R2/(R1+R2) is less than or equal to 95%. The junction of the first bending part and the main body part of the current collecting piece is used as a boundary to divide the internal resistance of the battery into a first internal resistance R1 from the first bending part to the cap and a second internal resistance R2 from the first bending part to the bottom end of the shell, and the R1 and the R2 are further distributed in proportion, so that the ratio of R2/(R1+R2) is less than or equal to 70 percent and less than or equal to 95 percent, the ratio of R2 is controlled while the integral internal resistance (namely the sum of the R1 value and the R2 value) of the lithium battery is reduced, the short-circuit protection function of the current collecting piece is reserved, the balance of the low internal resistance performance and the tab short-circuit protection performance of the battery is realized, and the safety of the cylindrical lithium ion battery is improved. Preferably, the first internal resistance R1 and the second internal resistance R2 meet 72 percent or less of R2/(R1+R2) or less of 85 percent or less. In some alternative embodiments, the winding core is formed by winding a positive electrode sheet, a separator and a negative electrode sheet which are stacked, and the winding core is wrapped with an insulating material layer and is electrically insulated from the shell. Through wrapping up in insulating material layer on the book core, avoid battery manufacturing in-process