DE-102021126672-B4 - ANODE FOR A SECONDARY BATTERY, SECONDARY BATTERY THAT INCLUDES THIS

Abstract

Anode for secondary battery, comprising: an anode current collector; and a first anode active material layer that is formed on the anode current collector and a first silicon-based active material and a first conductive material comprising a single-walled carbon nanotube; and a second anode active material layer formed on top of the first anode active material layer, containing a second silicon-based active material and a second conductive material comprising a multi-walled carbon nanotube, wherein the single-walled carbon nanotube has a Raman R value of 0.01 to 0.1, where the Raman R value represents a ratio of a D-band peak intensity (Id) to a G-band peak intensity (Ig), wherein the content of the first silicon-based active material, based on the total weight of the first anode active material layer, is greater than the content of the second silicon-based active material, based on the total weight of the second anode active material layer, and where the content of the single-walled carbon nanotube is 0.02 to 0.2 wt.%, based on the total weight of the first anode active material layer, and the content of the multi-walled carbon nanotube is 0.2 to 0.5 wt.%, based on the total weight of the second anode active material layer.

Inventors

• Ji Hee Bae
• Jae Ram Kim
• Jung Hwan Kim
• Jae Yun Min
• Sang Won Bae
• Myung Ro LEE
• Yong Seok Lee

Assignees

• SK ON CO., LTD.

Dates

Publication Date

20260513

Application Date

20211014

Priority Date

20201015

Claims (6)

1. Anode for a secondary battery, comprising: an anode current collector; and a first anode active material layer formed on the anode current collector and comprising a first silicon-based active material and a first conductive material comprising a single-walled carbon nanotube; and a second anode active material layer formed on top of the first anode active material layer, comprising a second silicon-based active material and a second conductive material comprising a multi-walled carbon nanotube, where the single-walled carbon nanotube has a Raman R value of 0.01 to 0.1, where the Raman R value is a ratio of a D-band peak intensity (Id) to a G-band peak intensity (Ig), where the content of the first silicon-based active material, based on the total weight of the first anode active material layer, is greater than the content of the second silicon-based active material, based on the total weight of the second anode active material layer, and where the content of the single-walled carbon nanotube is 0.02 to 0.2 wt%, based on the total weight of the first anode active material layer, and the content of the multi-walled carbon nanotube 0.2 to 0.5 wt.%, based on the total weight of the second anode active material layer.
2. Anode for secondary battery after Claim 1 , wherein the content of the first silicon-based active material, based on the total weight of the first anode active material layer, is 5 wt.% or more.
3. Anode for secondary battery after Claim 1 , wherein the single-walled carbon nanotube has a length of 5 µm or more.
4. Anode for secondary battery after Claim 1 , where the single-walled carbon nanotube has a diameter of 1.2 to 2 nm.
5. Anode for secondary battery after Claim 1 , wherein the content of the first silicon-based active material is 5 wt.% or more, based on the total weight of the first anode active material layer, and the content of the second silicon-based active material is less than 5 wt.%, based on the total weight of the second anode active material layer.
6. Secondary battery, comprising: the anode for a secondary battery Claim 1 ; a cathode; and a separating membrane positioned between the anode and the cathode.

Description

[BACKGROUND OF THE INVENTION] 1. Field of the invention The present invention relates to an anode for a secondary battery and a secondary battery comprising the anode, and in particular to an anode for a secondary battery comprising a silicon-based anode active material, and a secondary battery comprising the same. 2. Description of the state of the art A secondary battery is a battery that can be repeatedly charged and discharged and has become widely used in portable electronic communication devices such as camcorders, mobile phones, and laptops with the development of the information, communication, and display industries. Examples of secondary batteries include lithium-ion batteries, nickel-cadmium batteries, nickel-hydrogen batteries, and the like. Among these, lithium-ion batteries offer high operating voltage and high energy density per unit weight, and are advantageous in terms of charging speed and low weight. For these reasons, lithium-ion batteries have been actively developed and used as a power source. The lithium secondary battery can comprise an electrode assembly including a cathode, an anode, and a separator; and an electrolyte in which the electrode assembly is impregnated. The lithium secondary battery can further comprise, for example, a pocket-shaped outer casing in which the electrode assembly and the electrolyte are housed. Since the application area of the lithium secondary battery has recently expanded from a small electronic device to a large device, such as a hybrid vehicle, sufficient capacity and output characteristics cannot be implemented by the existing lithium secondary battery. In the case of an electric vehicle (EV) powered solely by a battery, for example, the high energy consumption rate and quantity imposes a limitation on ensuring sufficient driving time compared to the available secondary battery. Accordingly, the development of a lithium secondary battery capable of ensuring high rate and high capacity characteristics is required. For example, Korean patent disclosure no. 2017-0099748 an electrode arrangement for a lithium secondary battery and a lithium secondary battery containing it, but there is a limitation in ensuring a sufficiently high rate and a sufficient capacity characteristic. US 2015/0280221 A1 discloses a multi-layer anode for a secondary battery in which the silicon-based active material is mainly contained in the upper (outer) composite anode layer and the graphite-based active material is mainly contained in the lower (inner) composite anode layer. CN 107946561 A WO 2020/177624 A1 discloses only an anode with a single-layer structure containing conductive materials including graphene, carbon black, SWCNT, and MWCNT, as well as a silicon-based active material. WO 2020/177624 A1 discloses an anode active material multilayer structure containing a conductive material, in which the content of conductive material in the upper (outer) active material layer is lower than the content of conductive material in the lower (inner) active material layer. [SUMMARY OF THE INVENTION] One object of the present invention is to provide an anode for a secondary battery with stable electrical properties. Another object of the present invention is to provide a secondary battery that includes an anode with stable electrical properties. To solve the above problems, according to one aspect of the present invention, an anode for a secondary battery is provided according to independent claim 1, comprising: an anode current collector; and a first anode active material layer formed on the anode current collector comprising a first silicon-based active material and a first conductive material comprising a single-walled carbon nanotube, wherein the single-walled carbon nanotube has a Raman R value (a D-band peak intensity (Id)/a G-band peak intensity (Ig)) of 0.01 to 0.1. In exemplary embodiments, the content of the first silicon-based active material can be 5 wt.% or more, based on the total weight of the first anode active material layer. In exemplary embodiments, the single-walled carbon nanotube can have a length of 5 µm or more. In exemplary embodiments, the single-walled carbon nanotube can have a diameter of 1.2 to 2 nm. According to the invention, the anode active material layer comprises: a first anode active material layer formed on the anode current collector and containing a first silicon-based active material and a first conductive material comprising the single-walled carbon nanotube; and a second anode active material layer formed on the first anode active material layer and containing a second silicon-based active material and a second conductive material comprising a multi-walled carbon nanotube. According to the invention, the content of the first silicon-based active material, based on the total weight of the first anode active material layer, is greater than the content of the second silicon-based active material, based on the total weight of the second anode