CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority to Chinese Patent Application No. 201811337700.4 filed on Nov. 12, 2018, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present application relates to the technical field of batteries, in particular to a negative electrode plate and a lithium-ion secondary battery.

BACKGROUND

Lithium-ion secondary battery can provide stable voltage and current, has a high voltage platform, high energy density and wide temperature range, has no memory effect, and is environmentally friendly and portable, occupying the core position of the power battery.

When a lithium-ion secondary battery uses a manganese-containing positive active material, since the manganese in the positive electrode is prone to disproportionation, the generated manganese ions are dissolved in the electrolyte, migrated and deposited on the negative electrode, and then the manganese ions are ion-exchanged with lithium in the negative electrode, occupying the lithium-intercalation position of the negative electrode. In addition, the ion-exchanged lithium will no longer participate in the electrochemical reaction, causing irreversible capacity loss and deteriorating the cycle performance of the lithium-ion secondary battery.

SUMMARY

The embodiment of this application provides a negative electrode plate and a lithium-ion secondary battery, and aims to solve the technical problem that the manganese dissolution of positive electrode will deteriorate the cycle performance of the lithium-ion secondary battery.

A first aspect of this application provides a negative electrode plate comprising a negative electrode current collector and a negative active material layer disposed on at least one surface of the negative electrode current collector, wherein the negative active material layer comprises a graphite material;

wherein a ratio r between diffraction peak intensity of (004) crystal surface and diffraction peak intensity of (110) crystal surface of the negative electrode plate, a porosity s of the negative electrode plate, and a resistivity t of the negative electrode plate satisfy Formula (1):

0.05≤100×sr×t≤10,Formula⁢⁢(1)
in Formula (1), the unit of t is Ω·m.

A second aspect of this application provides a lithium-ion secondary battery comprising a positive electrode plate, a negative electrode plate according to the first aspect of this application, a separator, and an electrolyte, wherein the positive electrode plate comprises a manganese-containing positive active material.

In the negative electrode plate provided by the embodiment of this application, the negative active material comprises a graphite material, and the ratio r between diffraction peak intensity of (004) crystal surface and diffraction peak intensity of (110) crystal surface of the negative electrode plate, the porosity s of the negative electrode plate, and the resistivity t of the negative electrode plate satisfy the above Formula (1), so that the negative electrode plate can block manganese in the electrolyte outside the negative active material layer, effectively preventing manganese from entering the inside of the negative active material layer, and reducing the deposition of manganese on the negative electrode, thus effectively suppressing the destruction of the negative electrode caused by manganese, improving the stability of the negative electrode, reducing the capacity loss of the negative electrode during the cycle, and further increasing the capacity retention rate of the lithium-ion secondary battery during the cycle, so that the lithium-ion secondary battery has high cycle performance. At the same time, since the negative electrode plate satisfies the above Formula (1), it can also ensure that the negative active material layer has high kinetic performance of delithiation and lithiation, so that the lithium-ion secondary battery has a higher rate performance at the same time.

