【TECHNICAL FIELD】
Cross Citation with Related Application(s)
This application claims the benefit of Korean Patent Application No. 10-2020-0168163
10 filed on December 4, 2020 and Korean Patent Application No. 10-2021-0170445 filed on
December 1, 2021 in the Korean Intellectual Property Office, the disclosures of which are
incorporated herein by reference in their entirety.
The present disclosure relates to a negative electrode current collector for a lithium metal
battery, a manufacturing method thereof and a lithium metal battery comprising the same.
15 【BACKGROUND ART】
Graphite has been used as all negative electrodes for lithium secondary batteries which are
currently available from the market, but along with the rise of the development of highperformance secondary batteries with high capacity density and output, there are increasing
attempts to use lithium metal as a negative electrode.
20 Firstly, graphite has a small theoretical capacity of 372 mAh/g and a low lithium ion
conductivity of 10-12 ~ 10-14 cm2
·s-1 when fully charged with Li, and thereby realizes a low capacity
of less than 30% relative to the theoretical capacity at a 2C rate. Graphite is not excellent in its
intrinsic electrochemical properties for using graphite as a negative electrode in high-performance
secondary batteries that require capacity per volume and high output, and thus is unsuitable for
25 use as a next-generation battery negative electrode material.
Secondly, in the case of graphite, the types of electrolytes that can be used stably are limited.
Graphite, which is an interlayer material, forms an interlayer compound with lithium ions as well
as anions and solvent molecules. Typically, when using propylene carbonate (PC) liquid
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electrolyte, the co-intercalation phenomenon in which lithium ions and solvent molecules enter
the inside of graphite at the same time induces the peeling of the graphene layer forming graphite,
and the capacity reduction resulting therefrom is gradually accelerated, which causes a problem
in long-term use.
5 On the other hand, unlike graphite, lithium metal is free from the above problems. Lithium
metal has a theoretical capacity (3862 mAh/g) 10 times or more higher than that of graphite, and
a lithium metal deposition/desorption efficiency of 90% or more even under a current density
condition of 2.0 mA/cm2
or more, and therefore, can be used as a negative electrode of a highperformance secondary battery.
10 However, lithium metal has a porous structure, short circuit, and lithium fine powder called
dead Li due to the growth of lithium metal dendrites appearing on the metal surface during repeated
charge and discharge processes, which causes problems in safety and long-term lifespan
characteristics. The formation of lithium metal dendrites is typically described by a sand time
model, and the rapid decrease in the lithium ion concentration present on the surface of the lithium
15 metal and the charge imbalance of cations and anions resulting therefrom trigger the growth of
lithium metal dendrite. These problems can be alleviated through a ceramic layer or graphene
coating on the lithium metal surface, but it is limited to methods that physically press the growth
of lithium metal dendrites. In order to effectively suppress lithium metal dendrites, it is necessary
to analyze from the nucleation stage to the growth stage of lithium metal dendrites, and there is a
20 need to develop a negative electrode current collector capable of adjusting this.
【DETAILED DESCRIPTION OF THE INVENTION】
【Technical Problem】
It is an object of the present disclosure to provide a negative electrode current collector
for a lithium metal battery that suppresses dendrite formation and exhibits uniform Li growth
25 behavior and improved electrochemical performance by adjusting the lithium ion concentration
and nucleation seed site around the negative electrode current collector, and a manufacturing
method thereof.
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It is another object of the present disclosure to provide a lithium metal battery including
the same.
【Technical Solution】
According to one embodiment of the present disclosure, there is provided a negative electrode
5 current collector for a lithium metal battery, comprising: a metal current collector substrate, and a
coating layer formed on at least one surface of the metal current collector substrate and containing
a ferroelectric, a metallic material capable of alloying with lithium, a conductive material, and a
binder.
Here, the metal current collector substrate may be one selected from the group consisting of
10 copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper that is surface-treated
with dissimilar metal, stainless steel that is surface-treated with dissimilar metal, and an aluminumcadmium alloy, and specifically, it may be a metal including copper.
In one specific embodiment, the coating layer may contain 70 to 89 parts by weight of a
ferroelectric, 3 to 10 parts by weight of a metallic material alloying with lithium, 3 to 10 parts by
15 weight of a conductive material, and 5 to 20 parts by weight of a binder, based on 100 parts by
weight of the coating layer.
In one specific embodiment, the ferroelectric may be at least one selected from the group
consisting of organic ferroelectrics containing BaTiO3, KNbO3, NaTiO3, KTaO3, Pb(Zr, Ti)O3,
SrBiTa2O9, BiTiO12, LiTaO3, LiNbO3, WO3, KH2PO4 or NaKC4H4O6∙4H2O together with a
20 polymer.
In one specific embodiment, the metallic material capable of alloying with lithium may be at
least one selected from the group consisting of Si, Ge, Sn, Pb, Bi, Sb, As, P, Au, Ag, Zn, Al, and
their oxides, and specifically, it may be at least one selected from the group consisting of Si, Ge,
and their oxides.
25 In this case, the metallic material capable of alloying with lithium may have a particle size
(D50) of 10 nm to 10 ㎛.
The binder may be a polyacrylic acid (PAA) aqueous binder.
In one specific embodiment, the coating layer may be formed in a thickness of 1 to 10 ㎛.
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According to another embodiment of the present disclosure, there is provided a method of
manufacturing the negative electrode current collector, the method comprising the step of:
(a) mixing a powdered ferroelectric, a metallic material capable of alloying with lithium, and
a conductive material to prepare a mixture;
5 (b) mixing an aqueous binder with the mixture to prepare a coating layer slurry;
(c) applying the coating layer slurry to the metal current collector substrate; and
(d) primarily drying a metal current collector substrate to which the coating layer slurry is
applied in an air atmosphere, and secondarily drying the same in a vacuum atmosphere.
In one specific embodiment, the ferroelectric may be at least one selected from the group
10 consisting of organic ferroelectrics containing BaTiO3, KNbO3, NaTiO3, KTaO3, Pb(Zr, Ti)O3,
SrBiTa2O9, BiTiO12, LiTaO3, LiNbO3, WO3, KH2PO4 or NaKC4H4O6∙4H2O together with a
polymer.