CN-121983642-A - Lithium ion secondary battery structure and lithium ion secondary battery module comprising same

CN121983642ACN 121983642 ACN121983642 ACN 121983642ACN-121983642-A

Abstract

The invention provides a lithium ion secondary battery structure and a lithium ion secondary battery module comprising the same, and relates to the technical field of lithium ion batteries. The battery structure comprises a first electrode unit and a second electrode unit which are stacked along the thickness direction of the battery, wherein a metal current collector is adopted as a negative electrode of the first electrode unit to ensure high conductivity and long-cycle stability, a polymer-based composite current collector with metal plating layers at two sides is adopted as a negative electrode of the second electrode unit to provide thermal runaway protection, and the outermost layer of the whole battery is the second electrode unit to realize safe starting priority. According to the battery structure, the conductivity and the circulation stability are guaranteed through the first electrode unit, and the thermal runaway early fusing and the current blocking are realized through the second electrode unit, so that the effects of cooperatively improving the safety, the output performance and the circulation service life of the battery are realized, and the problems that the internal resistance is improved, the circulation attenuation and the intrinsic safety of the metal current collector are difficult to consider due to the composite current collector in the prior art are effectively solved.

Inventors

LI ZHICHUN
XU HAO
LU CHENG
QIAN ZHIYU
BU SHAONING
WU JUNWEI
WENG WEIJIA

Assignees

江苏英联复合集流体有限公司

Dates

Publication Date: 20260505
Application Date: 20260228

Claims (10)

1. A lithium ion secondary battery structure is characterized by comprising a first electrode unit and a second electrode unit, wherein the first electrode unit and the second electrode unit respectively comprise a positive electrode (200), a negative electrode and a diaphragm (300) arranged between the positive electrode (200) and the negative electrode, and the first electrode unit and the second electrode unit are respectively arranged in a mode of independent connection, wherein: The negative electrode of the first electrode unit is called as a first electrode unit negative electrode (100), and the first electrode unit negative electrode (100) uses a metal current collector (110); The negative electrode of the second electrode unit is called as a second electrode unit negative electrode (400), and the second electrode unit negative electrode (400) uses a composite current collector (410), wherein the composite current collector (410) is composed of a polymer substrate (411) and metal plating layers (412) positioned on two sides of the polymer substrate (411); The first electrode unit and the second electrode unit are stacked along the thickness direction of the battery, a separator (300) is arranged between the positive electrode (200) and the negative electrode, and the outermost layers of the battery structure are the second electrode units.
2. The lithium ion secondary battery structure according to claim 1, wherein the number ratio of the first electrode unit to the second electrode unit in the whole battery is 10:1-1:10, preferably 3:1-1:3.
3. The lithium ion secondary battery structure according to claim 1, wherein the first electrode unit and the second electrode unit are stacked in a periodic sequence in a battery thickness direction; The periodic sequence arrangement comprises one of BABAB, BAAABB, BAAABAAAB, BABB, BABBB, BABBBB, BABABB, BABBBBB, wherein A is a first electrode unit and B is a second electrode unit.
4. The lithium ion secondary battery structure according to claim 1, wherein the metal current collector (110) substrate surface of the first electrode unit has a convex and concave structure; Preferably, the metal current collector (110) substrate is selected from one of copper foil, aluminum foil, stainless steel foil, nickel foil, titanium foil, silver foil, aluminum-cadmium alloy foil.
5. The lithium ion secondary battery structure according to claim 1, wherein the polymer substrate (411) of the composite current collector (410) in the second electrode unit is selected from at least one of a polyethylene terephthalate substrate, a polypropylene terephthalate substrate, a polybutylene terephthalate substrate, and a polyethylene naphthalate substrate.
6. The lithium ion secondary battery structure according to claim 1, wherein the composite current collector (410) of the second electrode unit is left blank in the tab region to form a second electrode unit tab (413); the metal current collector (110) of the first electrode unit is reserved with a blank in the lug area to form a first electrode unit lug (111); The length of the first electrode unit tab (111) is greater than the length of the second electrode unit tab (413).
7. The lithium ion secondary battery structure according to claim 6, wherein the length of the first electrode unit tab (111) is 10-20 mm longer than the length of the second electrode unit tab (413).
8. The lithium ion secondary battery structure of claim 6, further comprising a negative tab integrated welded structure and a positive (200) tab integrated welded structure, wherein: The negative electrode tab integrated welding structure comprises a first welding area (500) and a second welding area (600); The first welding area (500) is obtained by arranging and welding the second electrode unit lugs (413) and the first electrode unit lugs (111) side by side; The second welding area (600) is obtained by welding a redundant section of the first electrode unit lug (111) corresponding to the length difference based on the length difference of the first electrode unit lug (111) and the second electrode unit lug (413) as a conductive bridging path; the tab integrated welding structure of the positive electrode (200) comprises a third welding area (700), wherein the third welding area (700) is obtained by welding a first electrode unit positive electrode (200) and a second electrode unit positive electrode (200) which are arranged side by side.
9. The lithium ion secondary battery structure according to claim 8, wherein the width of the conductive bridging path of the second welding area (600) is 50-70% of the width of the tab of the negative metal current collector (110).
10. A lithium ion secondary battery module characterized in that the module comprises a plurality of lithium ion secondary battery structures according to any one of claims 1 to 9, and a module frame for fixing and electrically connecting the plurality of lithium ion secondary battery structures; the cathode lugs of each lithium ion secondary battery structure are welded and then are connected to the same external cathode busbar, and the anode lugs of each positive electrode (200) are connected to the same external anode (200) busbar.

Description

Lithium ion secondary battery structure and lithium ion secondary battery module comprising same Technical Field The present invention relates to the field of lithium ion battery technologies, and in particular, to a lithium ion secondary battery structure and a lithium ion secondary battery module including the same. Background Along with the development of technology, secondary batteries have been widely used in the traffic fields of portable electronic devices (such as mobile phones, digital cameras, notebook computers), electric vehicles, electric bicycles, and the like, and have shown a wide prospect in energy storage systems. In new energy automobiles and energy storage systems, the market demand for high power output capability and low internal resistance performance of the battery cell is continuously improved. At present, the conventional manufacturing process of the lithium ion secondary battery comprises the steps of coating slurry containing electrode active substances on an electrode current collector, drying, rolling, die cutting, winding (or lamination) to form an electrode, assembling a positive electrode, a negative electrode and a diaphragm to form an electrode assembly, injecting electrolyte, and packaging in a battery shell to form a complete battery core. Copper foil and aluminum foil are now common materials for electrode current collectors. Among them, copper foil is commonly used as current collector for the negative electrode. However, the conventional metal current collector has a safety hazard in that when an internal short circuit occurs in the battery, the aluminum positive current collector may directly contact with the negative active material (e.g., lithium metal or lithiated carbon material), causing a severe exothermic reaction, and even causing a fire or explosion. In order to improve safety, researchers have attempted to replace conventional metal current collectors with composite current collectors, such as composite conductive current collectors formed by plating a metal layer (e.g., copper) on the surface of a polymer film such as Polyester (PET) as a substrate. When the current collector is locally overheated, the polymer substrate can melt and shrink to cut off a current path, thereby inhibiting the thermal runaway from spreading. However, in practical applications, it is found that the composite current collector not only has an increased self resistance, but also has a significantly increased total resistance of the short circuit loop when the short circuit occurs in a state of contact with the negative electrode active material, which is theoretically beneficial to limiting short circuit current, but may delay the response of the protection circuit during safety verification, and more seriously, the increase of the ohmic internal resistance of the whole battery leads to the decrease of rate performance, the aggravation of polarization, the shortening of cycle life, and the obvious deterioration of output characteristics. Therefore, there is a need to develop a novel electrode structure that combines intrinsic safety characteristics with excellent electrochemical output performance while maintaining high structural stability and good processability. In view of this, the present invention has been made. Disclosure of Invention A first object of the present invention is to provide a lithium ion secondary battery structure having advantages of synergistically exerting the output characteristics of a metal current collector and the safety function of a composite current collector, effectively taking into consideration the safety performance, output characteristics and cycle life of the battery. A second object of the present invention is to provide a lithium ion secondary battery module. In order to achieve the above object of the present invention, the following technical solutions are specifically adopted: the invention provides a lithium ion secondary battery structure, which comprises a first electrode unit and a second electrode unit, wherein the first electrode unit and the second electrode unit respectively independently comprise a positive electrode, a negative electrode and a diaphragm arranged between the positive electrode and the negative electrode, and the battery structure comprises: The negative electrode of the first electrode unit is marked as a first electrode unit negative electrode, and the first electrode unit negative electrode uses a metal current collector; The negative electrode of the second electrode unit is marked as a negative electrode of the second electrode unit, and the negative electrode of the second electrode unit uses a composite current collector which consists of a polymer substrate and metal plating layers positioned on two sides of the polymer substrate; The first electrode unit and the second electrode unit are stacked along the thickness direction of the battery, a separator is arranged between the anode and the cathode, and t