[Title of the Invention]
LITHIUM SECONDARY BATTERY AND MANUFACTURING METHOD
THEREOF
5 [Technical Field]
The present invention relates to a lithium secondary battery and a method of
manufacturing the same.
This application claims the benefit of priority based on Korean Patent Application No.
10-2021-0100117, filed on July 29, 2021, and the entire contents of the Korean patent
10 application are incorporated herein by reference.
[Background Technology of the Invention]
As development and demand for technology for mobile devices increase, the demand
for secondary batteries serving as energy sources is rapidly increasing. Among these
15 secondary batteries, lithium secondary batteries having a high energy density and operating
potential, a long cycle life, and a low self-discharge rate have been commercialized and widely
used.
Recently, as lithium secondary batteries are used as power sources for medium and
large-sized devices such as electric vehicles, the lithium secondary batteries are further required
20 to have a high capacity, a high energy density, and a low cost. As such a high-performance
secondary battery and/or a secondary battery for a vehicle, a lithium secondary battery is the
most realistic technology. A lithium secondary battery functions as a battery by repeating
intercalation and deintercalation of lithium ions into and from a negative electrode and a
3
positive electrode. Between these electrodes, there is a lithium salt-containing electrolyte in
which lithium ions can move but electrons cannot move.
Although many studies are being conducted on such secondary batteries in terms of
high capacity and high density, improvement of lifetime and safety are also important. For
5 the improvement of lifetime and safety, it is necessary to suppress a decomposition reaction
with an electrolyte on a surface of an electrode and to prevent overcharge/discharge. In
particular, it is necessary to prevent lithium from being deposited on a surface of a negative
electrode, so-called lithium-plating. When lithium metal is deposited, it causes a side reaction
with the electrolyte and a change in kinetic balance of the secondary battery, which can cause
10 the degradation of the secondary battery such as capacity loss or the like, to affect the lifetime
of the secondary battery and cause safety problems such as loss of an overcharge control
function.

[Claims]
[Claim 1]
A lithium secondary battery comprising an electrode assembly including a positive
electrode, a negative electrode, and a separator positioned between the positive electrode and
5 the negative electrode,
wherein the negative electrode includes a negative electrode current collector and a
negative electrode mixture layer, the negative electrode mixture layer being formed between
the negative electrode current collector and the separator, and
wherein a detection probe containing a metal oxide has a potential plateau of 1.3 V to
10 1.8 V is provided on a side surface of the negative electrode mixture layer.
[Claim 2]
The lithium secondary battery of claim 1, wherein the detection probe has a wire
structure including a core wire that includes a conductive metal and a metal oxide layer that
surrounds the core wire.
15 [Claim 3]
The lithium secondary battery of claim 1, wherein the detection probe has an average
diameter of 10 to 200 μm.
[Claim 4]
The lithium secondary battery of claim 1, wherein an average diameter of the detection
20 probe is smaller than an average thickness of the negative electrode mixture layer.
[Claim 5]
The lithium secondary battery of claim 1, wherein the detection probe is disposed to be
spaced 0.1 to 2,000 μm from the side surface of the negative electrode mixture layer.
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[Claim 6]
The lithium secondary battery of claim 1, wherein the metal oxide includes an oxide
containing one or more metals selected from the group consisting of titanium, vanadium, iron,
cobalt, nickel, copper, molybdenum, tungsten, and niobium.
5 [Claim 7]
The lithium secondary battery of claim 1, wherein the metal oxide includes a lithium
titanate compound represented by Chemical Formula 1 below:
[Chemical Formula 1]
LiaTibMcOd
10 wherein M is Sn, Cr, Y, Nb, Mg, Zn, Ni, V, Na, K, Ca, Co, Ta, Mo, Zr, Al, Cu, Mn, or
Bi, a is an integer satisfying 0.4≤a≤5, b is an integer satisfying 0.5≤b≤5.5, c is an integer
satisfying 0≤c≤0.9, and d is an integer satisfying 1.5≤d≤12.5.
[Claim 8]
The lithium secondary battery of claim 1, wherein the detection probe contains a metal
15 oxide charged to a state of charge (SoC) of 40% to 60%.
[Claim 9]
A method of manufacturing a lithium secondary battery, the method comprising:
inserting an electrode assembly including a positive electrode, a negative electrode,
and a separator positioned between the positive electrode and the negative electrode into a case
20 of the lithium secondary battery and placing a detection probe containing a metal oxide having
a potential plateau of 1.3 V to 1.8 V on a side surface of a negative electrode mixture layer of
the negative electrode to assemble the lithium secondary battery;
filling the case of the assembled lithium secondary battery with an electrolyte;
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charging the lithium secondary battery filled with the electrolyte; and
measuring a potential of the detection probe provided in the lithium secondary battery.
[Claim 10]
The method of claim 9, wherein the detection probe is charged to a state of charge (SoC)
5 of 40% to 60%.
[Claim 11]
The method of claim 9, further comprising, after the measuring of the potential of the
detection probe, when the measured potential of the detection probe exceeds 2.0 V, determining
that the lithium secondary battery is defective.