Binder composition for secondary battery, and electrode for secondary battery and lithium secondary battery comprising same

Abstract

The present invention relates to a binder composition for a secondary battery, the composition comprising: a copolymer comprising a functional group; and an alkali metal ion bound to the functional group of the copolymer or substituted with a constituent element of the functional group. The binder composition for a secondary battery exhibits low resistance due to an alkali metal ion included in the copolymer, together with the improvement of adhesive strength, and thus, can exhibit a more stable electrochemical performance.

Description

technical field [0001] [Cross Reference to Related Application] [0002] This application claims the priority and benefit of Korean Patent Application No. 10-2015-0186395 filed on December 24, 2015 and Korean Patent Application No. 10-2016-0176434 filed on December 22, 2016, both of which The disclosure content of this application is fully incorporated in this specification by reference. [technical field] [0003] The present invention relates to a binder composition for a secondary battery, an electrode for a secondary battery, and a lithium secondary battery including the electrode, and more particularly, to a binder composition that contains alkali metal ions and thus has Binder composition for secondary battery having high adhesive force and low resistance of electrode material, electrode for secondary battery comprising same, and lithium secondary battery including said electrode . Background technique [0004] With the technological development of mobile devices a...

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Problems solved by technology

[0006] The binder is used to ensure the adhesive force or adhesive strength between the active materials and between the active material and the electrode collector, but an excessive amount of the adhesive is required to enhance the adhesive force between the electrode collector and the active material

However, excess binder is problematic in reducing the capacity and conductivity of the electrode

On the contrary, insufficient adhesion will cause electrode peeling phenomenon during the drying and pressing process of the electrode, which is the reason for the high defect rate of the electrode

In addition, electrodes with low adhesion can be separated by external impact, and this electrode peeling will increase the contact resistance between the electrode material and the current collector, causing deterioration of the electrode output performance.

[0007] Especially, in the process of charging and discharging of lithium secondary battery, the negative electrode active material undergoes a volume change due to the reaction with lithium, and, when the charging and discharging process continues, the negative electrode active material is separated from the current collector, and the resistance increases with the active The change of the contact interface between materials increases, so when the cycle of charge and discharge is performed, the capacity of the battery deteriorates rapidly, causing a shortened cycle life

In addition, when materials such as silicon, tin, silicon-tin alloy, etc. are used in combination to increase discharge capacity, a larger volume change is caused by the reaction of silicon, tin, etc. with lithium, and therefore, these problems occur more remarkably

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