Positive pole piece and lithium ion secondary battery comprising same

Abstract

The invention provides a positive pole piece and a lithium ion secondary battery containing the positive pole piece. According to the invention, the polymer electrolyte prepared from a polymer different from that in the prior art is selected as the solid electrolyte in the positive pole piece, and the solid electrolyte has both a bonding function and a lithium conducting function and can replace a binder and the solid electrolyte in the existing pole piece; the transmission performance of lithium ions can be effectively improved, and the internal resistance of the solid-state battery is reduced. Meanwhile, the porosity of the positive pole piece containing the solid electrolyte is low and is about 5% or below, so that pores and holes in the positive pole piece are greatly reduced, the content of a positive active material in unit volume is increased, the transmission of lithium ions and electrons is improved, and the energy density and the cycle performance of the solid-state battery are effectively improved; the positive pole piece containing the solid electrolyte can be applied to a high-energy-density battery system, and the application field of the positive pole piece is widened.

Description

technical field [0001] The invention relates to the technical field of secondary batteries, in particular to a positive pole piece and a lithium ion secondary battery containing the positive pole piece. Background technique [0002] Lithium-ion secondary batteries have the advantages of high energy density, long cycle life, low self-discharge rate, and environmental protection. They have been widely used in energy storage, power vehicles, notebook computers, mobile phones, cameras and other consumer electronics products. However, the main constraints on the development of lithium-ion secondary batteries are energy density and safety. As the next-generation lithium-ion secondary battery closest to practical applications, solid-state batteries have good application potential. [0003] However, the main difficulty of solid-state batteries at present is that the lithium-conducting performance and electrical conductivity between the solid-solid interface are not good, especially...

AI Technical Summary

Problems solved by technology

[0003] However, the main difficulty of solid-state batteries at present is that the lithium-conducting performance and electrical conductivity between the solid-solid interface are not good, especially the solid-solid interface between the positive electrode active material inside the positive electrode sheet of the solid-state battery and the solid-state electrolyte.

The positive electrode sheet of a solid-state battery is mainly composed of positive active material, conductive agent, solid polymer electrolyte, binder and lithium salt; the porosity of the positive electrode sheet of the conventional liquid system is relatively high, refer to the positive electrode of the solid-state battery prepared by the conventional liquid system The pole piece also has a high porosity, which leads to a large internal resistance of the positive pole piece of the solid-state battery; at the same time, with the requirement for high energy density, the positive active material generally adopts a high voltage, high gram capacity positive active material , while the positive pole piece of the conventional solid-state battery is under high voltage conditions, and the solid polymer electrolyte is oxidized and decomposed, which destroys the lithium-conducting conductive network of the positive pole piece of the solid-state battery, resulting in attenuation of battery performance

At the same time, there are still problems such as poor interface contact in the positive electrode of the solid-state battery, which directly affects the cycle performance of the solid-state battery.

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