Positive electrode and secondary battery

Abstract

The invention provides a positive plate and a secondary battery. The positive plate comprises a positive current collector and a positive diaphragm which is located on the positive current collector and includes a positive active material and a binder, wherein a hydroxyl radical exists on the surface of the positive current collector; the binder comprises an organic polymer binder; the positive plate also comprises a bottom coating which is located between the positive current collector and the positive diaphragm; the bottom coating comprises a conductive polymer material and a dopant; the conductive polymer material contains the nitrogen element and is of a conjugated structure; and the dopant is protonic acid. The positive plate provided by the invention has relatively high binding power and electronic conductivity, and ensures that the secondary battery has lower internal resistance and higher safety performance.

Description

technical field [0001] The invention relates to the technical field of batteries, in particular to a positive electrode sheet and a secondary battery. Background technique [0002] The positive electrode layer of the battery is generally composed of a positive electrode active material, a conductive agent (such as conductive carbon) and a binder (such as PVDF). The way to increase conductivity is usually to increase the amount of conductive agent in the positive electrode formulation, and the way to improve the binding force is usually to increase the amount of binder in the positive electrode formulation. Increasing the amount of conductive agent can improve the electronic conductivity of the positive electrode, but it will lose the ratio of the positive active material, so that the content of the positive active material is relatively reduced, resulting in a decrease in energy density, and the increase of the conductive agent generally consumes less There is too much bind...

AI Technical Summary

Problems solved by technology

Increasing the amount of conductive agent can improve the electronic conductivity of the positive electrode, but it will lose the ratio of the positive active material, so that the content of the positive active material is relatively reduced, resulting in a decrease in energy density, and the increase of the conductive agent generally consumes less There is too much binder, which leads to the disadvantage of insufficient adhesion; although increasing the amount of binder can improve the adhesion of the positive electrode layer to a certain extent, it will increase the impedance of the battery and deteriorate the kinetic performance. A series of problems such as the reduction of effective active substance content, and the improvement of adhesion is very limited

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