TECHNICAL FIELD
Cross-reference to Related Applications
[0001] This application claims priority from Korean Patent
Application No. 10-2020-0109527, filed on August 28, 2020, the
10 disclosure of which is incorporated by reference herein.
Technical Field
[0002] The present invention relates to a negative electrode
comprising different types of silicon-based particles and
carbon nanotubes and a secondary battery comprising the same.
15 BACKGROUND ART
[0003] Requirements for the use of alternative energy or clean
energy have increased due to the rapid increase in the use of
fossil fuels, and, as a part of this trend, power generation
and electricity storage using an electrochemical reaction are
20 the most actively researched areas.
[0004] Currently, a typical example of an electrochemical
device using the electrochemical energy may be a secondary
battery and there is a trend that its usage area is expanding
more and more. In recent years, demand for secondary batteries
25 as an energy source has been significantly increased as
2
technology development and demand with respect to portable
devices, such as portable computers, mobile phones, and cameras,
have increased, and, among these secondary batteries, lithium
secondary batteries having high energy density, i.e., high
5 capacity, have been subjected to considerable research and
have been commercialized and widely used.
[0005] In general, a secondary battery is composed of a
positive electrode, a negative electrode, an electrolyte, and
a separator. The negative electrode includes a negative
10 electrode active material in which lithium ions from the
positive electrode are intercalated and deintercalated, and
silicon-based particles having high discharge capacity may be
used as the negative electrode active material. However, the
silicon-based particle has low initial efficiency, and its
15 volume changes excessively during a charge and discharge
process. Thus, there is a limitation in that lifetime of the
battery is reduced. Particularly, since cracks occur in the
silicon-based particle as charge and discharge cycles are
repeated, mechanical stability degrades while the lifetime is
20 reduced.
[0006] Typically, in order to address this limitation,
techniques of forming a carbon coating layer on surfaces of
the silicon-based particles have been used. However, even if
the carbon coating layer is formed, the initial efficiency and
25 the reduction in the lifetime of the battery are not
3
significantly improved, and an effect of reducing battery
resistance is not significant. Also, a method of controlling
physical properties of a binder or a thickener so that the
silicon-based particles are not exfoliated from the negative
5 electrode has been used, but its effect is not large.
[0007] Thus, there is a need for a negative electrode which
uses silicon-based active material particles, but may improve
life characteristics.
DISCLOSURE OF THE INVENTION
10 TECHNICAL PROBLEM
[0008] An aspect of the present invention provides a negative
electrode which may improve life characteristics of a battery.
[0009] Another aspect of the present invention provides a
secondary battery comprising the negative electrode.
15 TECHNICAL SOLUTION
[0010] According to an aspect of the present invention, there
is provided a negative electrode which includes a negative
electrode active material layer comprising a negative
electrode active material and a conductive agent, wherein the
20 negative electrode active material includes a first active
material and a second active material, wherein the first active
material includes SiOx particles (0