Field 5 of the Invention
The present disclosure relates to a negative
electrode for a lithium secondary battery comprising a
mesh-type current collector and a lithium thin film, and
10 in particular, to a negative electrode in which a lithium
thin film is inserted to an opening of a current
collector and empty space is formed, a lithium secondary
battery comprising the same, and a manufacturing method
thereof.
15
Background of the Invention
Interests in energy storage technologies have been
increasingly higher recently. As applications are
20 expanded to energy of mobile phones, camcorders and
notebook PCs, and furthermore, to electric vehicles,
efforts on the research and development of
electrochemical devices have been more and more
materialized.
25 Electrochemical devices are fields receiving most
-2-
attentions in such aspects and among these, development
of secondary batteries capable of charge and discharge
have been the focus of attention, and in developing such
batteries, research and development on the design of new
electrodes and batteries for enhancing 5 capacity density
and energy efficiency have been recently progressed.
Among currently used secondary batteries, lithium
secondary batteries developed in early 1990s have
received attentions with advantages of having high
10 operating voltage and significantly higher energy density
compared to conventional batteries such as Ni-MH, Ni-Cd
and sulfuric acid-lead batteries using an aqueous liquid
electrolyte.
A lithium secondary battery is generally formed by
15 an electrode assembly comprising a positive electrode, a
negative electrode and a separator provided between the
positive electrode and the negative electrode being
embedded in a battery case in a laminated or wound
structure, and a non-aqueous liquid electrolyte being
20 injected thereinto.
As for a lithium electrode as the negative
electrode, lithium foil attached on a planar current
collector is used. In this case, lithium formation and
elimination are irregular when charged and discharged
25 producing lithium dendrite, and this leads to continuous
-3-
capacity decline.
In view of the above, studies introducing a polymer
protective layer or inorganic solid protective layer to a
lithium metal layer, increasing a salt concentration of a
liquid electrolyte, or using proper additives 5 have been
progressed. However, effects of suppressing lithium
dendrite resulted from such studies are insignificant.
Accordingly, solving problems through modifying a form of
a lithium metal anode itself or modifying a battery
10 structure may be an effective option.
Prior Art Documents
Patent Documents
Korean Patent No. 10-1621410 “Lithium Electrode and
Lithium Secondary Battery comprising the Same”
15
Summary of the Invention
As described above, lithium dendrite of a lithium
secondary battery is precipitated on a surface of a
20 negative electrode current collector and volume expansion
of a cell is sometimes caused therefrom. In view of the
above, the inventors of the present disclosure have
conducted studies from various angles and, as a result,
have found out a method of solving such a problem caused
25 by dendrite through modifying shape and structure of an
-4-
electrode itself, and have completed the present
disclosure.
Accordingly, the present disclosure is directed to
providing a lithium secondary battery solving a problem
of volume expansion of a cell caused by 5 lithium dendrite
through modifying shape and structure of an electrode,
and having enhanced cell performance.
In view of the above, one embodiment of the present
disclosure provides a negative electrode for a lithium
10 secondary battery comprising a mesh-type anode current
collector formed with a wire rod portion and an opening;
and a lithium thin film formed with an inserted portion
inserted to the opening of the negative electrode current
collector and a non-inserted portion that is not inserted.
15 Another embodiment of the present disclosure
provides a method for manufacturing a negative electrode
for a lithium secondary battery comprising preparing a
mesh-type anode current collector; placing lithium metal
foil on the negative electrode current collector; and
20 rolling the lithium metal foil and the negative electrode
current collector to insert the lithium metal to an
opening of the negative electrode current collector.
Still another embodiment of the present disclosure
provides a lithium secondary battery comprising the
25 negative electrode.
-5-
Brief Description of the Drawings
Fig. 1 is a cross-sectional view of a negative
electrode for a lithium secondary battery 5 comprising a
lithium thin film inserted to an opening of a negative
electrode current collector according to the present
disclosure;
Fig. 2 is a perspective view describing a method
10 for manufacturing a negative electrode for a lithium
secondary battery according to the present disclosure;
Fig. 3 is a step mimetic diagram describing a
method for manufacturing a negative electrode for a
lithium secondary battery according to the present
15 disclosure;
Fig. 4 is an image of a mesh-type anode current
collector used in Example 1 of the present disclosure;
Fig. 5 is a SEM image of a mesh-type anode current
collector used in Example 1 of the present disclosure;
20 Fig. 6 is an image of a negative electrode for a
lithium secondary battery according to Example 1 of the
present disclosure;
Fig. 7 is a SEM image of a negative electrode for a
lithium secondary battery according to Example 1 of the
25 present disclosure;
-6-
Fig. 8 shows initial capacity and efficiency data
of lithium secondary batteries using anodes according to
Example 1 and Comparative Example 1 of the present
disclosure; and
Fig. 9 shows data comparing rate 5 performance of
lithium secondary batteries using anodes according to
Example 1 and Comparative Example 1 of the present
disclosure.
100. Anode Current Collector
10 110. Opening
120. Wire Rod Portion
200. Lithium Thin Film
210. Inserted portion
220. Non-Inserted portion
15 300. Pressure Roller
Detailed Description of the Embodiments
Hereinafter, embodiments of the present disclosure
20 will be described in detail with reference to the
accompanying drawings so that those skilled in the art
may readily implement the present disclosure. However,
the present disclosure may be implemented in various
different forms, and is not limited to the embodiments
25 described herein.
-7-
In the drawings, parts not relevant to the
descriptions are not included in order to clearly
describe the present disclosure, and like reference
numerals are used for like elements throughout the
specification. In addition, sizes and 5 relative sizes of
constituents shown in the drawings are unrelated to
actual scales, and may be reduced or exaggerated for
clarity of the descriptions.
Fig. 1 is a cross-sectional view of a negative
10 electrode for a lithium secondary battery comprising a
lithium thin film inserted to an opening of a negative
electrode current collector according to the present
disclosure. When referring to Fig. 1, the present
disclosure provides a negative electrode for a lithium
15 secondary battery comprising a mesh-type anode current
collector (100) formed with a wire rod portion (120) and
an opening (110); and a lithium thin film (200) formed
with an inserted portion (210) inserted to the opening
(110) of the negative electrode current collector (100)
20 and a non-inserted portion (220) that is not inserted.
The negative electrode for a lithium secondary
battery according to the present disclosure has a
structure in which the lithium thin film (200) is
inserted while one surface thereof adjoins on an upper
25 surface of the mesh-type anode current collector (100),
-8-
and this leaves empty space in the opening (110) as a
part of the lithium thin film (200) is inserted to the
opening (110) of the negative electrode current collector
(100). This space induces lithium dendrite formation
preventing volume expansion 5 of a cell.
In the present disclosure, the electrode material
formed on the negative electrode current collector (100)
is preferably a lithium thin film (200). Lithium thin
film (200) has malleability and ductility, unique
10 properties of a metal film, and changes its form while
spreading thinly when applying a pressure, and therefore,
may be inserted to the mesh-type anode current collector
opening (110) with only a rolling process.
However, among materials used as a negative
15 electrode in a lithium secondary battery, a negative
electrode active material that comprises lithium in a
form that is not a thin film form is normally prepared
into a slurry mixture and a coating process coating the
slurry mixture on a negative electrode current collector
20 is carried out, and unlike lithium in a thin film form,
such a slurry mixture is difficult to be inserted to an
opening of a mesh-type anode current collector through a
coating film-forming process or a rolling process
thereafter, and cracks may also occur due to a pressure
25 applied in the rolling process. Even when the slurry
-9-
mixture inserted to an opening of a negative electrode
current collector by controlling viscosity of the slurry
mixture, there is a problem in that controlling the
viscosity enough to secure empty space to a target level
aimed in the present disclosure 5 is very difficult.
Accordingly, a lithium thin film (200) is
preferably used as a negative electrode material in the
present disclosure, and an inserted portion thickness
(d210) of such a lithium thin film (200) is controlled to
10 be 20% to 60% of the thickness of the whole lithium thin
film. In other words, space filled with the inserted
portion (210) of the lithium thin film is from 20% to 60%
of the thickness of the whole lithium thin film, and
accordingly, empty space is preserved in the opening
15 (110) space. Dendrite is formed in such remaining space
of the opening (110) while gone through charge and
discharge, and as a result, volume expansion of a cell
may be prevented.
Herein, as for a non-inserted portion thickness
20 (d220) of the lithium thin film (200), it is preferred
that 40% to 80% of the total lithium thin film thickness
(d200) is left and only the rest is inserted. When the
lithium thin film (200) is not completely inserted and a
part thereof is left, space remains inside the negative
25 electrode current collector (100), and effects described
-10-
above are secured. In addition, as both surfaces of the
lithium thin film (200) are exposed to a liquid
electrolyte, a stable SEI membrane is formed on the both
surfaces preventing the Li metal surface from being
exposed, and as a result, electrolyte 5 decomposition
caused from charge and discharge may be prevented.
As for a thickness (d200) of the lithium thin film,
those having a thickness of 10 μm to 800 μm are selected,
and selecting those having a larger thickness than the
10 negative electrode current collector is preferred. The
reason is to secure a sufficient non-inserted portion
(220) thickness even after the lithium thin film (200) is
inserted to the opening (110) of the negative electrode
current collector.
15 In addition, as the negative electrode current
collector (100), those having a thickness range of 3 μm
to 500 μm are used. When the negative electrode current
collector has a thickness of less than 3 μm, a current
collecting effect decreases, and an opening (110) having
20 a sufficient size to collect lithium dendrite is not
secured. Meanwhile, the thickness being greater than 500
μm has a problem of reducing processibility when
assembling a cell through folding.
An effect of suppressing lithium dendrite growth is
25 excellent as the size of one opening (110) of the
-11-
negative electrode current collector (100) is smaller and
the percentage of the opening (110) is higher. More
specifically, as the wire rod portion (120) of the
negative electrode current collector (100), those having
a line width of 50 μm to 500 μm and line 5 spacing of 100
μm to 1 mm may be selected, and the size of one opening
(110) that such a wire rod portion (120) forms is
preferably from 10 μm to 300 μm in securing the abovementioned
effects.
10 In addition, as for the percentage of the opening
(110) in the negative electrode current collector (100),
an aperture ratio, the percentage of the area occupied by
the opening (110) region, is preferably from 20% to 80%
based on the total area 100% of the negative electrode
15 current collector (100). When the aperture ratio is less
than 20%, the effect of inducing precipitation and
elimination reactions of lithium dendrite, a goal of the
present disclosure, may not be secured, and when the
aperture ratio is greater than 80%, the area of contact
20 between the negative electrode current collector and the
lithium metal layer relatively decreases, which is not
proper in performing a role as a negative electrode
current collector, and as a result, battery performance
declines.
25 The shape of the opening (110) formed by such a
-12-
wire rod portion (120) of the negative electrode current
collector (100) is not limited, and examples thereof may
comprise a circular, oval or polygonal shape.
The negative electrode current collector (100) is
not particularly limited as long 5 as it has high
conductivity without inducing chemical changes in a
battery, and may be selected from the group consisting of
copper, aluminum, stainless steel, zinc, titanium, silver,
palladium, nickel, iron, chromium, alloys thereof and
10 combinations thereof. The stainless steel may have its
surface treated with carbon, nickel, titanium or silver,
and aluminum-cadmium alloys may be used as the alloy, and
in addition thereto, baked carbon, nonconductive polymers
of which surface is treated with a conductor, conductive
15 polymers or the like may also be used. As the negative
electrode current collector, a copper thin plate is
generally used.
The negative electrode for a lithium secondary
battery in which a part of a lithium thin film is
20 inserted to a negative electrode current collector
according to the present disclosure is capable of
enhancing safety of the lithium secondary battery by
increasing a surface area of contact between the lithium
thin film and the negative electrode current collector,
25 uniformizing electron distribution inside the lithium
-13-
electrode, and inducing lithium dendrite precipitation in
empty space inside the current collector.
Furthermore, the present disclosure provides a
negative electrode for a lithium secondary battery
comprising a mesh-type anode current 5 collector formed
with a wire rod portion and an opening; a lithium thin
film formed with an inserted portion inserted to the
opening of the negative electrode current collector and a
non-inserted portion that is not inserted; and a
10 protection structure formed on a surface opposite to the
lithium thin film that the negative electrode current
collector faces, wherein the protection structure is
formed with an organic polymer portion and an inorganic
material portion, and the organic polymer portion is
15 formed on a surface opposite to the lithium thin film
that the wire rod portion adjoins and the inorganic
material portion is formed on a surface opposite to the
lithium thin film corresponding to the opening.
The protection structure according to the present
20 disclosure may provide an ion path between a negative
electrode and an electrolyte. Such a protection
structure has a form of an inorganic material filling
space between frames that the organic polymer portion
forms, and although an inorganic material cell or layer
25 formed with specific ceramic/glassy may comprise pin-
14-
holes, cracks and/or crystal grain-based defects that may
spread through the whole cell or layer, the presence of a
number of ion paths may minimize the influence of defects
in any one ion path. Accordingly, when defects are
present in the protection structure, 5 this is typically
much less fatal compared to when present inside a
protection structure comprising one or more continuous
ceramic layers. For example, defects may be isolated
(for example, at least partly surrounded by polymer
10 materials), and therefore, the defects spreading to other
ion paths (for example, inorganic material-filled cavity)
may be reduced or avoided.
The organic polymer portion provides advantageous
mechanical properties such as flexibility and strength of
15 the protection structure. Placing a cell filled with an
inorganic material inside a polymer frame may reduce
weakness of the inorganic material-filled cavity for
crack mechanism. The material is not limited, and for
example, may be selected from among polyvinyl alcohol,
20 polyisobutylene, epoxy, polyethylene, polypropylene,
polytetrafluoroethylene and combinations thereof as a
non-ionic conductive polymer.
The inorganic material portion may be a ceramicbased
or glassy-based material as a material ionic
25 communicating with the lithium thin film, and for example,
-15-
may be selected from among Li2O, Li3N, Al2O3, ZrO2, SiO2,
CeO2, Al2TiO5, oxy-sulfide glass and combinations thereof.
The protection structure may be prepared by, for
example, preparing a frame with an organic polymer
portion following a wire rod portion 5 that forms a meshform
of a negative electrode current collector, and then
filling the space therebetween with an inorganic material,
and as the method, methods such as electron beam
deposition, sputtering and thermal deposition may be used.
10 Fig. 2 and Fig. 3 are a perspective view and a step
mimetic diagram describing a method for manufacturing a
negative electrode for a lithium secondary battery
according to the present disclosure. Inserting a lithium
thin film (200) to an opening (110) that a mesh-type
15 anode current collector (100) forms may be accomplished
by placing the lithium thin film (200) on the negative
electrode current collector (100) and performing a
rolling process. More specifically, the present
disclosure provides a method for manufacturing a negative
20 electrode for a lithium secondary battery comprising i)
preparing a mesh-type anode current collector (100); ii)
placing a lithium thin film (200) on the negative
electrode current collector (100); and iii) rolling the
lithium thin film (200) and the negative electrode
25 current collector (100) to insert the lithium thin film
-16-
(200) to an opening (110) of the negative electrode
current collector (100).
The rolling may be carried out using common methods,
and for example, the lithium thin film (200) may be
inserted to an opening (110) of the 5 negative electrode
current collector (100) using a method of compressing
with a pressure roller (300) provided in a roll press and
the like, or compressing over the whole electrode surface
using a plate-like press.
10 Particularly, in such a rolling process, a pressure
of 10 kg/cm2 to 100 ton/cm2 may be applied, and heating
to a temperature of 100ºC to 200ºC may be carried out.
Heat treatment at the above-mentioned temperature
includes either heating while carrying out a rolling
15 process, or carrying out a rolling process while being
heated before carrying out the rolling process. By
controlling temperature and pressure conditions as above,
the degree of lithium thin film insertion may be
controlled, and preferably, the lithium thin film may be
20 rolled so as to satisfy the inserted portion thickness
(d210) range described above.
As for a lithium secondary battery according to the
present disclosure, constitutions other than the
structure and the properties of the negative electrode
25 described above may be prepared through known
-17-
technologies implemented by those skilled in the art, and
will be specifically described below.
A positive electrode according to the present
disclosure may be prepared into a positive electrode form
by forming film on a positive electrode 5 current collector
using a composition comprising a positive electrode
active material, a conductor and a binder.
As the positive electrode active material, any one
selected from the group consisting of LiCoO2, LiNiO2,
10 LiMnO2, LiMn2O4, Li(NiaCobMnc)O2 (0
Lithium foil having a thickness of 40 μm was placed
on a copper mesh having a thickness of 25 μm (illustrated
15 in Fig. 4 and Fig. 5) as a negative electrode current
collector, a pressure was applied so that 50% of the
thicknesses of the lithium foil was inserted, and the
result was roll pressed to prepare a negative electrode
(illustrated in Fig. 6 and Fig. 7).
20 Cathode active material:conductor (carbon
black):binder (KF9700) were formed as a film in a
composition of 95.5:2.0:2.5 on aluminum foil having a
thickness of 12 μm as a positive electrode current
collector to prepare a positive electrode.
25 A separator coating SRS on both surfaces of a 8 μm
-26-
polyethylene (PE) material each to a thickness of 2.5 μm
was used as a separator to prepare a secondary battery.
FEC/DEC was used as an electrolyte, and a liquid
electrolyte containing 1 M of LiPF6 and 0.5 wt% of
additives was used to manufacture a 5 lithium secondary
battery.
A lithium secondary battery was manufactured in the
same manner as in Example 1 except that lithium foil
10 having a thickness of 40 μm was placed on a copper mesh
having a thickness of 25 μm (illustrated in Fig. 4 and
Fig. 5) as the negative electrode current collector, and
the thickness was controlled so that 40% of the
thicknesses of the lithium foil was inserted.
15
A lithium secondary battery was manufactured in the
same manner as in Example 1 except that lithium foil
having a thickness of 40 μm was placed on a copper mesh
having a thickness of 25 μm (illustrated in Fig. 4 and
20 Fig. 5) as the negative electrode current collector, and
the thickness was controlled so that 30% of the
thicknesses of the lithium foil was inserted.
A lithium secondary battery was manufactured in the
25 same manner as in Example 1 except that lithium foil
-27-
having a thickness of 40 μm was placed on a copper mesh
having a thickness of 25 μm (illustrated in Fig. 4 and
Fig. 5) as the negative electrode current collector, and
the thickness was controlled so that 20% of the
thicknesses of the lithium 5 foil was inserted.
A lithium secondary battery was manufactured in the
same manner as in Example 1 except that lithium foil
having a thickness of 40 μm was placed on a copper mesh
10 having a thickness of 25 μm (illustrated in Fig. 4 and
Fig. 5) as the negative electrode current collector, and
the thickness was controlled so that 10% of the
thicknesses of the lithium foil was inserted.
15 A lithium secondary battery was manufactured in the
same manner as in Example 1 except that copper foil
having a thickness of 20 μm was used as the negative
electrode current collector, and the rolling process of
the negative electrode was not carried out.
20
For the lithium secondary batteries of Examples 1
to 5 and Comparative Example 1, a charge and discharge
test was carried out under a condition of 0.1 C
charge/0.1 C discharge, and the results are shown in Fig.
25 8 and summarized in the following Table 1.
-28-
【Table 1】
Charge
Capacity
(mAh/g)
Discharge
Capacity
(mAh/g)
Efficiency (%)
Example 1 225 210 93.22
Example 2 224 209 93.30
Example 3 225 209 92.88
Example 4 226 210 92.92
Example 5 224 209 93.30
Comparative
Example 1
226 210 93.14
As shown in Table 1, initial charge and discharge
capacity and efficiency of the 5 lithium secondary
batteries of Examples 1 to 5 and Comparative Example 1
were similar.
Fig. 9 and table 2 shows data comparing rate
10 performance of the lithium secondary batteries using the
negative electrodes according to Examples 1 to 5 and
Comparative Example 1 of the present disclosure.
【Table 2】
-29-
Capacity Retention (%, Compared to 0.1 C)
Discharge
C-rate
Example
1
Example
2
Example
3
Example
4
Example
5
Comparative
Example 1
0.5 C/0.1 C 92.50 92.30 92.10 91.95 91.80 91.37
1.0 C/0.1 C 85.05 83.55 82.10 80.05 78.05 75.46
2.0 C/0.1 C 66.40 63.35 60.20 55.05 51.05 43.63
3.0 C/0.1 C 44.60 38.66 32.55 27.05 22.10 13.99
The capacity retention rate was identified while
fixing the charge rate and increasing the discharge Crate.
The results described in the table indicates
capacity expression with respect to 0.1 5 C, and the 0.1 C
capacity was identically expressed in the lithium
secondary batteries of Example 1 and Comparative Example
1. However, when increasing the discharge rate, the
lithium secondary batteries of Examples 1 to 5 had a
10 higher capacity retention rate compared to the lithium
secondary battery of Comparative Example 1. The
difference became larger as the C-rate increased. When
discharging with 2.0 C, the lithium secondary battery of
Example 1 exhibited a capacity retention rate of 66%,
15 however, the lithium secondary battery of Comparative
Example 1 had a capacity retention ratio of 44%, and the
difference was approximately 22%. The lithium secondary
batteries of Examples 2 to 5 also exhibited a superior
-30-
capacity retention rate compared to Comparative Example 1.
In other words, when using mesh Cu, the contact
area between Li metal and Cu increases, and resistance
inside a cell is reduced as electrical conductivity
becomes superior. Besides, cell performance 5 is enhanced
while dendrite formation is induced inside empty space of
an opening described above. When using general Cu foil,
interfacial resistance between a separator and Li metal
increases while dendrite is formed on the Li metal
10 surface touching the separator when charged and
discharged, however, when using Mesh Cu, a phenomenon of
increasing interfacial resistance between Li metal and a
separator may be prevented even after charge and
discharge as dendrite formation is induced inside empty
15 space of an opening.
The negative electrode for a lithium secondary
battery in which a part of a lithium thin film is
inserted to a negative electrode current collector
according to the present disclosure is capable of
20 enhancing performance of the lithium secondary battery by
increasing a surface area of contact between the lithium
thin film and the negative electrode current collector,
and is capable of enhancing safety of the lithium
secondary battery by preventing lithium dendrite growth
25 when driving the lithium secondary battery through
-31-
uniformizing electron distribution inside the lithium
electrode.
In addition, volume expansion of a cell can be
prevented as lithium dendrite formation is induced in
empty space left while a part of the lithium 5 thin film is
inserted to an opening of the negative electrode current
collector.
Furthermore, when compared to existing simple joint
structures, an inserted portion of the lithium thin film
10 and an opening of the negative electrode current
collector are connected in a fitted manner and adhesion
efficiency can be enhanced therefrom, and therefore,
stripping of the negative electrode current collector and
the lithium thin film can be prevented while charging and
15 discharging the battery.
What is claimed is:
1. A negative electrode for a lithium secondary
battery comprising:
a mesh-type anode current collector 5 formed with a
wire rod portion and an opening; and
a lithium thin film formed with an inserted portion
inserted to the opening of the negative electrode current
collector and a non-inserted portion that is not inserted.
10
2. The negative electrode for a lithium secondary
battery of Claim 1, wherein a thickness of the inserted
portion of the lithium thin film is 20% to 60% of a
thickness of the whole lithium thin film.
15
3. The negative electrode for a lithium secondary
battery of Claim 1, wherein a thickness of the noninserted
portion of the lithium thin film is 40% to 80%
of a thickness of the whole lithium thin film.
20
4. The negative electrode for a lithium secondary
battery of Claim 1, wherein a thickness of the lithium
thin film is from 10 μm to 800 μm.
25 5. The negative electrode for a lithium secondary
-33-
battery of Claim 1, wherein the wire rod portion of the
negative electrode current collector has a line width of
50 μm to 500 μm and line spacing of 100 μm to 1 mm.
6. The negative electrode for a 5 lithium secondary
battery of Claim 1, wherein a shape of the opening of the
negative electrode current collector is circular, oval or
polygonal.
10 7. The negative electrode for a lithium secondary
battery of Claim 1, wherein an aperture ratio of the
negative electrode current collector is from 20% to 80%.
8. The negative electrode for a lithium secondary
15 battery of Claim 1, wherein a thickness of the negative
electrode current collector is from 3 μm to 500 μm.
9. The negative electrode for a lithium secondary
battery of Claim 1, wherein the negative electrode
20 current collector is one or more types selected from the
group consisting of copper, aluminum, stainless steel,
zinc, titanium, silver, palladium, nickel, iron, chromium,
alloys thereof and combinations thereof.
25 10. A negative electrode for a lithium secondary
-34-
battery comprising:
a mesh-type anode current collector formed with a
wire rod portion and an opening;
a lithium thin film formed with an inserted portion
inserted to the opening of the negative 5 electrode current
collector and a non-inserted portion that is not
inserted; and
a protection structure formed on a surface opposite
to the lithium thin film that the negative electrode
10 current collector faces,
wherein the protection structure is formed with an
organic polymer portion and an inorganic material portion,
and the organic polymer portion is formed on a surface
opposite to the lithium thin film that the wire rod
15 portion adjoins and the inorganic material portion is
formed on a surface opposite to the lithium thin film
corresponding to the opening.
11. The negative electrode for a lithium secondary
20 battery of Claim 10, wherein the organic polymer portion
is selected from among polyvinyl alcohol, polyisobutylene,
epoxy, polyethylene, polypropylene,
polytetrafluoroethylene and combinations thereof.
25 12. The negative electrode for a lithium secondary
-35-
battery of Claim 10, wherein the inorganic material
portion is selected from among Li2O, Li3N, Al2O3, ZrO2,
SiO2, CeO2, Al2TiO5, oxy-sulfide glass and combinations
thereof.
5
13. A method for manufacturing a negative electrode for
a lithium secondary battery comprising:
i) preparing a mesh-type anode current collector;
ii) placing lithium thin film on the negative
electrode current 10 collector; and
iii) rolling the lithium thin film and the negative
electrode current collector to insert the lithium thin
film to an opening of the negative electrode current
collector.
15
14. The method for manufacturing the negative electrode
for a lithium secondary battery of Claim 13, wherein the
rolling in iii) is applying a pressure of 10 kg/cm2 to
100 ton/cm2.
20
15. The method for manufacturing the negative electrode
for a lithium secondary battery of Claim 13, wherein the
rolling in iii) is heating to a temperature of 100ºC to
200 ºC.
25
16. A lithium secondary battery comprising the negative
electrode of any one of Claims 1 to 12.