Electrode plate, and secondary battery comprising same and device

Abstract

The invention provides an electrode plate, a secondary battery comprising the electrode plate and a device. The electrode plate comprises a current collector, and the functional surface of the current collector comprises a tab region and an active layer region located on the periphery of the tab region; the active layer region comprises a first active layer region and a second active layer region which are adjacent, and the first active layer region is close to the tab region; the first active layer area is provided with a first active layer, the second active layer area is provided with a second active layer, and the thickness of the first active layer is smaller than that of the second active layer; the compaction density Q1 of the first active layer and the compaction density Q2 of the second active layer meet the condition that Q1 / Q2 = (0.6-1): 1. The electrode plate has relatively low impedance, and meanwhile, the secondary battery comprising the electrode plate can have good cycle performance.

Description

technical field [0001] The invention relates to an electrode sheet, in particular to an electrode sheet, a secondary battery and a device including the electrode sheet, and belongs to the technical field of batteries. Background technique [0002] With the advent of the 5G era, the status of lithium-ion batteries is becoming more and more important, and lithium-ion batteries are also developing in the direction of high energy density and high rate. In order to reduce the internal impedance of the lithium-ion battery, at this stage, the connection position of the tabs is usually adjusted from the edge of the pole piece to the inside of the pole piece, and the functional layer on the surface of the current collector is restructured by making the tabs contact with the inside of the current collector. Partitioning to achieve impedance reduction. [0003] However, when charging the above-mentioned lithium-ion battery, due to the high current density at the junction of the tabs, ...

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Problems solved by technology

[0003] However, when charging the above-mentioned lithium-ion battery, due to the high current density at the junction of the tabs, the junction of the tabs (that is, the inside of the electrode sheet) will easily decompose lithium at the later stage of the cycle, resulting in the cycle attenuation of the lithium-ion battery. aggravated, poor cycle performance

[0004] Therefore, how to solve the degradation of lithium-ion battery cycle performance caused by the above tab connection method has received more and more attention.

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