Fig. 7 is a graph comparing the cycles of three groups of cells. As can be seen from table 1 and fig. 7, after the plain adhesive tape and the conductive swelling adhesive tape are applied to the empty foil region of the battery cell for the planarization treatment, after the battery cell of the plain adhesive tape group (including the plain adhesive tape group 1, the plain adhesive tape group 2, and the plain adhesive tape group 3) and the conductive swelling adhesive tape group (including the conductive swelling adhesive tape group 1, the conductive swelling adhesive tape group 2, and the conductive swelling adhesive tape group 3) is stored at 60 ℃ in the full power state for 35 days, the capacity retention rates are all as high as 75% or more, and excellent stability is exhibited, while after the battery cell of the comparative group without the planarization treatment of the adhesive tape (including the comparative group 1, the comparative group 2, and the comparative group 3) is stored at 60 ℃ in the full power state for 35 days, the maximum value of the capacity retention rate is 10.6%, and extremely poor stability is exhibited; although the capacity recovery rates of the three groups of batteries are all more than 80%, it can be seen from fig. 7 that the capacity retention rate of the battery cell of the comparative group without the adhesive paper for the flatness treatment after 320 weeks of circulation is 80%, while the capacity retention rate of the battery cell adopting the conductive sol adhesive paper for the flatness treatment after 400 weeks of circulation is 94%, and the capacity retention rate is also obviously better than the capacity retention rate of the battery cell adopting the ordinary adhesive paper for the flatness treatment after 400 weeks of circulation, which is 92%.

From the above results, the storage performance and the cycling stability of the battery core without the adhesive paper for the leveling treatment are both worse than those of the battery core adopting the adhesive paper for the leveling treatment, because after the formation, the two vacuum air extractions are performed, the aluminum-plastic film in the empty foil area is deformed, the edges of the first pole piece, the second pole piece and the diaphragm are subjected to uneven external force exerted by the deformed aluminum-plastic film, the expansion deformation of the pole pieces is obvious after the long-time cycle, the service life of the pole pieces is reduced, the aluminum-plastic film exerts uneven external force on the positions after the expansion deformation, the diaphragm is easily punctured, and the tiny self-discharge in the battery is caused, the stored electric quantity is accumulated, and the stored electric quantity is continuously consumed, and the stability is poor; the storage performance and the circulation stability of the battery core subjected to flatness processing by adopting the conductive swelling adhesive tape are better than those of a battery subjected to flatness shaping processing by adopting common adhesive tape, because the conductive swelling adhesive can play a constant expansion effect according to the thickness of the battery core and the capacity of electrolyte after expansion, and the relative movement of pole pieces in the circulating charge-discharge process is restrained, so that the phenomenon that welding points between the first hollow foil areas and the second hollow foil areas are broken or fall off due to the volume expansion of the battery core is effectively avoided.

Although the present disclosure has been described above, the scope of the present disclosure is not limited thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the spirit and scope of the present disclosure, and these changes and modifications are intended to be within the scope of the present disclosure.

Claims

1. A pole piece is characterized by comprising a current collector, wherein the current collector comprises a paste coating area and a hollow foil area which are sequentially arranged along the width direction, and an active substance layer is arranged in the paste coating area;

2. The pole piece of claim 1, wherein the rubberized region and the pasted region have the same thickness.

3. The pole piece of claim 1 wherein the length of the adhesive paper is no greater than the length of the empty foil area.

4. The pole piece of claim 1, wherein a single-sided surface or a double-sided surface of the empty foil area is provided with the adhesive paper.

5. The pole piece of claim 1, wherein the adhesive paper comprises an adhesive layer and a substrate layer, the substrate layer is sandwiched between the two adhesive layers, and the adhesive layer comprises at least one of water glue, oil glue, hot melt glue, natural rubber, synthetic rubber and conductive swelling glue.

6. The pole piece of claim 5, wherein the adhesive layer comprises a conductive swelling glue.

7. The pole piece of claim 1, wherein a distance between the gummed paper disposed on the gummed region and the pasting region is 0 to 0.5 mm.

8. An electrical core, comprising a first pole piece, a second pole piece, and a separator disposed between the first pole piece and the second pole piece, wherein the first pole piece and the second pole piece have opposite polarities;

the first and second pole pieces are the pole pieces of any one of claims 1 to 7.

9. The cell of claim 8, wherein the first pole piece, the separator, and the second pole piece are stacked and wound or alternately stacked along a length direction of the first pole piece and the second pole piece to form the cell;

10. The battery cell of claim 9, wherein two adhesive-free regions are respectively located at two ends of the battery cell in the width direction, and each adhesive-free region forms a welding surface at a side surface of the adhesive region.

11. The battery cell of claim 10, further comprising connecting pieces, wherein the two connecting pieces are welded to the welding surfaces at two ends of the battery cell respectively.