【Technical Field】 5
The present invention relates to a sacrificial positive electrode material with a reduced amount of gas generated during charging by being doped with a zinc ion and having controlled electrical properties, and a lithium secondary battery including the same.
This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0024264, filed on February 23, 2021, and the entire contents of the Korean patent 10 application are incorporated herein by reference.
【Background Art】
Recently, demand for secondary batteries as a power source has rapidly increased. Among secondary batteries, lithium secondary batteries having a high energy density and voltage, a long cycle lifespan, and a low self-discharge rate have been commercialized and 15 widely used.
As a negative electrode material for the lithium secondary batteries, graphite has been mainly used. However, since graphite has a low capacity per unit mass of 372 mAh/g, it is difficult to increase the capacity of lithium secondary batteries. In order to increase the capacity of lithium secondary batteries, as a non-carbon-based negative electrode material 20
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having a higher energy density than graphite, a negative electrode material that forms an intermetallic compound with lithium, such as silicon, tin, an oxide thereof, and the like, has been developed and used. The non-carbon-based negative electrode material has high capacity, but the initial efficiency thereof is low, so a large amount of lithium is consumed during initial charging and discharging, and irreversible capacity loss is large. 5
In this regard, there has been proposed a method of overcoming the irreversible capacity loss of the negative electrode using a material that is able to provide a lithium ion source or reservoir to a positive electrode material and exhibits electrochemical activity after an initial cycle so as not to degrade the overall performance of a battery. Specifically, a method of applying an oxide including an excessive amount of lithium, such as Li6CoO4, as a 10 sacrificial positive electrode material or an irreversible additive (or overdischarge inhibitor) to a positive electrode is known.
However, such a sacrificial positive electrode material or irreversible additive causes oxidation not only during activation of a battery but also during charging and discharging after the activation due to having an unstable structure, and thus oxygen gas may be generated inside 15 a battery. The generated oxygen gas may cause volume expansion and the like and thus acts as one of the main factors leading to degradation of battery performance.
Therefore, there is a demand for the development of a sacrificial positive electrode material having a reduced amount of oxygen gas generated during a charging/discharging process of a battery and a high charge/discharge capacity. 20
[Related-Art Documents]
[Patent Documents]
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Korean Laid-Open Patent Publication No. 10-2019-0059115
【Disclosure】
【Technical Problem】
An object of the present invention is to provide a sacrificial positive electrode material having a higher charge/discharge capacity while having a small amount of oxygen gas 5 generated during a charging/discharging process of a battery, and a positive electrode and lithium secondary battery including the same.
【Technical Solution】
One aspect of the present invention provides a sacrificial positive electrode material which includes a lithium cobalt zinc oxide represented by the following Chemical Formula 1 10 and has a powder electrical conductivity of 1 × 10-4 S/cm to 1 × 10-2 S/cm:
[Chemical Formula 1]
LixCo(1-y)ZnyO4
in Chemical Formula 1, x and y satisfy 5≤x≤7 and 0.05≤y≤0.5.
Specifically, y in Chemical Formula 1 may satisfy 0.2≤y≤0.4. 15
In addition, the sacrificial positive electrode material may have a powder electrical conductivity of 1 × 10-3 S/cm to 9 × 10-3 S/cm.
In addition, the sacrificial positive electrode material may have a tetragonal structure with a space group of P42/nmc.
Another aspect of the present invention provides a positive electrode which includes: a 20 positive electrode current collector; and a positive electrode mixture layer including a positive
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electrode active material, a conductive material, an organic binder polymer, and a sacrificial positive electrode material on the positive electrode current collector, wherein the sacrificial positive electrode material includes a lithium cobalt zinc oxide represented by the following Chemical Formula 1 and has a powder electrical conductivity of 1 × 10-4 S/cm to 1 × 10-2 S/cm:
[Chemical Formula 1] 5
LixCo(1-y)ZnyO4
in Chemical Formula 1, x and y satisfy 5≤x≤7 and 0.05≤y≤0.5.
Here, the sacrificial positive electrode material may be included in an amount of 0.001 to 5.0 parts by weight with respect to 100 parts by weight of the positive electrode active material.

【Claim 1】
A sacrificial positive electrode material comprising a lithium cobalt zinc oxide represented by the following Chemical Formula 1 and having a powder electrical conductivity of 1 × 10-4 S/cm to 1 × 10-2 S/cm: 5
[Chemical Formula 1]
LixCo(1-y)ZnyO4
in Chemical Formula 1, x and y satisfy 5≤x≤7 and 0.05≤y≤0.5.
【Claim 2】 10
The sacrificial positive electrode material of claim 1, wherein y in Chemical Formula 1 satisfies 0.2≤y≤0.4.
【Claim 3】
The sacrificial positive electrode material of claim 1, wherein the sacrificial positive 15 electrode material has a powder electrical conductivity of 1 × 10-3 S/cm to 9 × 10-3 S/cm.
【Claim 4】
The sacrificial positive electrode material of claim 1, wherein the sacrificial positive electrode material has a tetragonal structure with a space group of P42/nmc. 20
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【Claim 5】
A positive electrode comprising:
a positive electrode current collector; and
a positive electrode mixture layer including a positive electrode active material, a 5 conductive material, an organic binder polymer, and a sacrificial positive electrode material on the positive electrode current collector,
wherein the sacrificial positive electrode material includes a lithium cobalt zinc oxide represented by the following Chemical Formula 1 and has a powder electrical conductivity of 1 × 10-4 S/cm to 1 × 10-2 S/cm: 10
[Chemical Formula 1]
LixCo(1-y)ZnyO4
in Chemical Formula 1, x and y satisfy 5≤x≤7 and 0.05≤y≤0.5.
【Claim 6】 15
The positive electrode of claim 5, wherein the sacrificial positive electrode material is included in an amount of 0.001 to 5.0 parts by weight with respect to 100 parts by weight of the positive electrode active material.
【Claim 7】 20
The positive electrode of claim 5, wherein the conductive material is included in an
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amount of 0.5 to 10 parts by weight with respect to a total of 100 parts by weight of the positive electrode mixture layer.
【Claim 8】
The positive electrode of claim 5, wherein the conductive material includes one or more 5 carbon-based materials selected from the group consisting of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, and carbon fibers.
【Claim 9】
The positive electrode of claim 5, wherein the positive electrode active material is a 10 lithium composite transition metal oxide including two or more elements selected from the group consisting of nickel (Ni), cobalt (Co), manganese (Mn), aluminum (Al), zinc (Zn), titanium (Ti), magnesium (Mg), chromium (Cr), and zirconium (Zr).
【Claim 10】 15
The positive electrode of claim 5, wherein the positive electrode mixture layer has an average thickness of 100 μm to 200 μm.
【Claim 11】
The positive electrode of claim 5, wherein the positive electrode has a change rate of 20
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resistance of 10% or less after 30-cycle charging and discharging relative to resistance during initial charging and discharging.
【Claim 12】
An electrode assembly comprising the positive electrode of claim 5. 5
【Claim 13】
A lithium secondary battery comprising the electrode assembly of claim 12.