KR20190030085A - Electrode for all solid battery including solid electrolyte - Google Patents

Abstract

The present invention relates to an electrode for an all-solid-state battery, which comprises: an electrode current collector; and an electrode active material layer having a plurality of predetermined patterns spaced apart from each other on at least one surface of the electrode current collector. The electrode active material layer comprises: a plurality of electrode active material particles; and a solid electrolyte partially coated on surfaces of the plurality of electrode active material particles and connecting the plurality of electrode active material particles to each other. At least a part of the surface of the electrode active material particles is exposed to the outside of the electrode active material layer.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electrode for a solid electrolyte including a solid electrolyte,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electrode for a pre-solid battery including a solid electrolyte, and more particularly to an electrode for a pre-solid battery capable of easily discharging gas generated during charging and discharging to the outside.

A lithium ion battery using a liquid electrolyte is a structure in which a cathode and an anode are partitioned by a separator, so that if the separator is damaged due to deformation or external impact, a short circuit may occur, which may lead to overheating or explosion. Therefore, development of a solid electrolyte capable of ensuring safety in the field of lithium ion secondary batteries is a very important task.

The lithium secondary battery using the solid electrolyte has an advantage that the safety of the battery is enhanced, leakage of the electrolyte is prevented, reliability of the battery is improved, and a thin-type battery is easily manufactured. In addition, since lithium metal can be used as a cathode, the energy density can be improved. Accordingly, a small-sized secondary battery and a high-capacity secondary battery for an electric automobile are expected to be applied to the next generation battery.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram schematically showing an electrode cross section after charging / discharging of a lithium secondary battery including an electrode to which a solid electrolyte is applied. FIG. 1, a gas is generated due to the reaction between the electrode active material particles 21 and the solid electrolyte 22 during charging / discharging of the lithium secondary battery including the solid electrolyte 22. This gas is generated in the liquid electrolyte system The electrode is not discharged to the outside and is trapped inside the electrode. There is a problem that the electrode interface resistance is increased and the life of the battery is lowered.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an electrode for an all solid-state battery capable of easily discharging a gas generated due to a reaction between an electrode active material and a solid electrolyte to the outside of the electrode.

According to an aspect of the present invention, there is provided an electrode for a full-solid-state cell, comprising: an electrode collector; And an electrode active material layer formed on at least one surface of the electrode current collector, the electrode active material layer having a plurality of patterns of a predetermined shape spaced apart from each other, the electrode active material layer comprising a plurality of electrode active material particles, And a solid electrolyte coated on a part of the surface and connecting the plurality of electrode active material particles to each other, wherein at least a part of the surface of the electrode active material particles is exposed to the outside of the electrode active material layer.

Here, the electrode active material layer may further include a conductive material dispersed on a surface of the plurality of electrode active material particles and the inside or the surface of the solid electrolyte.

In addition, a gap channel may be formed between the patterns of the plurality of predetermined shapes.

The patterns of the predetermined shape may be linear, wavy, point, or lattice patterns.

Meanwhile, the solid electrolyte may be any one selected from the group consisting of a polymer solid electrolyte, a polymer gel electrolyte, a sulfide-based solid electrolyte, and an oxide-based solid electrolyte, or a mixture of two or more thereof.

The width of each of the patterns of the predetermined shape may be 1 to 3 times the size of the electrode active material particle.

The size of the electrode active material particles is 1 to 100 mu m, and the spacing between the plurality of patterns may be 0.1 to 30 mu m.

The electrode active material particles may have a size of 5 to 30 탆, and the spacing between the plurality of patterns may be 1 to 20 탆.

According to an embodiment of the present invention, the gas generated due to the reaction between the electrode active material and the solid electrolyte is discharged to the outside of the electrode through the space formed between the patterns of the electrode active material layer, can do.

Thus, it is possible to prevent a problem that the increase in resistance at the electrode interface is suppressed and the life of the battery is lowered.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and together with the description of the invention serve to further the understanding of the technical idea of the invention, It should not be construed as limited.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram schematically showing an electrode cross section after charging / discharging of a battery including an electrode to which a conventional solid electrolyte is applied. FIG.
2 is a diagram schematically showing an electrode cross-section after charging / discharging of a cell including an electrode according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings. The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in the present specification and the constitutions described in the drawings are merely the most preferred embodiments of the present invention, and are not intended to represent all of the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

An electrode for a full solid battery of the present invention comprises: an electrode collector; And an electrode active material layer formed on at least one surface of the electrode current collector, the electrode active material layer having a plurality of patterns of a predetermined shape spaced apart from each other, the electrode active material layer comprising a plurality of electrode active material particles, And a solid electrolyte coated on a part of the surface and connecting the plurality of electrode active material particles to each other, wherein at least a part of the surface of the electrode active material particles is exposed to the outside of the electrode active material layer.

2 is a diagram schematically showing an electrode cross-section after charging / discharging of a cell including an electrode according to an embodiment of the present invention. 2, the gas generated by the reaction between the electrode active material particles 21 and the solid electrolyte 22 is separated from the gap 24 formed between the patterns of the electrode active material particles 21 and the solid electrolyte 22, So that the gas inside the electrode can be easily removed. Thus, it is possible to prevent a problem that the increase in resistance at the electrode interface is suppressed and the life of the battery is lowered.

According to the present invention, at least a part of the surface of the electrode active material particles is exposed to the outside of the electrode active material layer. Exposure to the outside of the electrode active material layer means exposure to the upper surface of the electrode active material layer But also exposes to an interval formed between a plurality of patterns spaced apart from each other.

Particularly, when the structure of the current collector or the solid electrolyte is such that the entire surface of the electrode active material particles is not exposed to the outside, the gas generated by the reaction between the electrode active material particles and the solid electrolyte is present in the electrode active material layer, There arises a problem that the electrode active material particles are floated or the resistance at the electrode interface is increased, and the life of the battery may be degraded.

Therefore, at least a part of the surfaces of all electrode active material particles must be exposed to the outside, which can fundamentally solve the problem of the present invention.

In this case, a gap channel may be formed between the patterns of the plurality of predetermined shapes, so that the gas inside the electrode can be discharged more efficiently.

The pattern of the predetermined shape may include a linear, wavy, point, or lattice pattern. However, the shape of the pattern is not limited to the shape of the patterns. Patterns are possible.

The size of the electrode active material particles is 1 to 100 占 퐉, preferably 5 to 30 占 퐉. The spacing between the plurality of patterns may be 0.1 to 30 탆, preferably 1 to 20 탆. If the spacing between the plurality of patterns is more than 30 탆, preferably more than 20 탆, the electrode density may be decreased. If the spacing is less than 1 탆, preferably less than 0.1 탆, Emissions may not be achieved.

Particularly, when the width of each of the patterns of the predetermined shape is 1 to 3 times the particle size of the electrode active material, it is easier to discharge the gas. When the above condition is satisfied, the electrode active material and the solid electrolyte Since the gas generated at the interface between the electrode active material and the solid electrolyte is easily discharged from the interface between the electrode active material and the solid electrolyte, the interface is maintained even after repeated charging / discharging, and the interface resistance is not increased, .

The electrode active material layer may further include a conductive material dispersed on the surface of the plurality of electrode active material particles and the inside or the surface of the solid electrolyte.

At this time, the conductive material is usually added in an amount of 0.1 to 30% by weight based on the total weight of the mixture including the electrode active material. Such a conductive material is not particularly limited as long as it has electrical conductivity without causing chemical changes in the battery, for example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as carbon fluoride, aluminum, and nickel powder; Conductive whiskers such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Polyphenylene derivatives, and the like, or a mixture of two or more thereof.

In addition, in the present invention, the electrode includes an electrode current collector. The electrode current collector may exhibit electrical conductivity such as a metal plate, and may be suitably used depending on the polarity of the collector electrode known in the secondary battery field .

Meanwhile, in the present invention, the electrode for the pre-solid battery may be any one of a cathode and a cathode. When the electrode is a cathode, the electrode active material may be any material that can be used as a negative electrode active material of a lithium ion secondary battery. For example, the negative electrode active material may be carbon such as non-graphitized carbon or graphite carbon; _{Li x Fe 2 O 3 (0≤x≤1} ), Li x WO 2 (0≤x≤1), Sn x Me 1 - x Me 'y O z (Me: Mn, Fe, Pb, Ge; Me' : Metal complex oxides such as Al, B, P, Si, Group 1, Group 2, Group 3 elements of the periodic table, Halogen, 0 < x < Lithium metal; Lithium alloy; Silicon-based alloys; Tin alloy; _{SnO, SnO 2, PbO, PbO} 2, Pb 2 O 3, Pb 3 O 4, Sb 2 O 3, Sb 2 O 4, Sb 2 O 5, GeO, GeO 2, Bi 2 O 3, Bi 2 O 4, and Bi ₂ O ₅ ; Conductive polymers such as polyacetylene; Li-Co-Ni-based materials; Titanium oxide; Lithium titanium oxide, and the like can be used. In one specific embodiment, the negative electrode active material may include a carbon-based material and / or Si.

When the electrode is an anode, the electrode active material may be used as long as it can be used as a cathode active material of a lithium ion secondary battery. For example, the cathode active material may be a layered compound such as lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), or a compound substituted with one or more transition metals; Lithium manganese oxides such as Li _{1 + x} Mn _{2 - x} O ₄ (where x is 0 to 0.33), LiMnO ₃ , LiMn ₂ O ₃ and LiMnO ₂ ; Lithium copper oxide (Li ₂ CuO ₂ ); Vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ and Cu ₂ V ₂ O ₇ ; A Ni-site type lithium nickel oxide expressed by the formula LiNi _{1 -x} M _x O ₂ (where M = Co, Mn, Al, Cu, Fe, Mg, B or Ga and x = 0.01 to 0.3); Formula _{LiMn 2 - x M x O 2} ( where, M = Co, Ni, Fe , Cr, and Zn, or Ta, x = 0.01 ~ 0.1 Im) or Li ₂ Mn ₃ MO ₈ (where, M = Fe, Co, Ni, Cu, or Zn); A lithium manganese composite oxide having a spinel structure represented by LiNi _x Mn _{2 - x} O ₄ ; LiMn ₂ O _{4 in} which a part of Li in the formula is substituted with an alkaline earth metal ion; Disulfide compounds; Fe ₂ (MoO ₄ ) ₃ , and the like. However, the present invention is not limited to these.

In the present invention, the solid electrolyte is coated on a part of the surface of the electrode active material particles, and is not coated on the entire surface of the electrode active material particles as described above. Particularly, the electrode active material particles are integrated so as to form an electrode active material layer pattern integrated by point bonding and / or surface bonding via the solid electrolyte.

The solid electrolyte of the present invention may be appropriately selected depending on the type of the electrode. For example, in the case of the anode, it is preferable to use a solid electrolyte excellent in oxidation stability, and in the case of the cathode, Is preferably used. Since the solid electrolyte of the present invention mainly plays the role of transferring lithium ions in the electrode, any material having a high ion conductivity, for example, 10 ^-5 s / m or more, preferably 10 ^-4 s / m or more And is not limited to specific components.

Here, the solid electrolyte may be a polymer solid electrolyte formed by adding a polymer resin to a solvated lithium salt, a polymer containing an organic electrolyte containing an organic solvent and a lithium salt, an ionic liquid, a monomer or an oligomer, Gel electrolyte, and may be a sulfide-based solid electrolyte having a high ion conductivity or an oxide-based solid electrolyte having an excellent stability.

Here, the polymer solid electrolyte may be, for example, a polyether polymer, a polycarbonate polymer, an acrylate polymer, a polysiloxane polymer, a phosphazene polymer, a polyethylene derivative, an alkylene oxide derivative, a phosphate ester polymer, Agitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, polymers including ionic dissociation groups, and the like. The polymer solid electrolyte may be a branched polymer in which amorphous polymers such as PMMA, polycarbonate, polysiloxane (pdms) and / or phosphazene are copolymerized with a comonomer in a main chain of PEO (poly ethylene oxide) as a polymer resin, a comb-like polymer, and a crosslinked polymer resin, and may be a mixture of the polymers.

In addition, the polymer gel electrolyte includes an organic electrolyte including a lithium salt and a polymer resin, and the organic electrolyte includes 60 to 400 parts by weight of the polymer resin. The polymer to be applied to the gel electrolyte is not limited to a specific component but may be, for example, a polyether polymer, a PVC polymer, a PMMA polymer, a polyacrylonitrile (PAN), a polyvinylidene fluoride (PVdF) Poly (vinylidene fluoride-hexafluoro propylene: PVdF-HFP, and the like. And may be a mixture of the above polymers.

At this time, the lithium salt can be expressed as Li ⁺ X ^- as an ionizable lithium salt. In this lithium salt anion is not particularly ^{limited, F -, Cl -, Br} -, I -, NO 3 -, N (CN) 2 -, BF 4 -, ClO 4 -, PF 6 -, (CF 3) _{^{2 PF 4 -, (CF 3}} ) 3 PF 3 -, (CF 3) 4 PF 2 -, (CF 3) 5 PF -, (CF 3) 6 P -, CF 3 SO 3 -, CF 3 CF 2 SO _{^{3 -, (CF 3 SO 2}} ) 2 N -, (FSO 2) 2 N -, CF 3 CF 2 (CF 3) 2 CO -, (CF 3 SO 2) 2 CH -, (SF 5) 3 C - _{, (CF 3 SO 2) 3} C -, CF 3 (CF 2) 7 SO 3 -, CF 3 CO 2 -, CH 3 CO 2 -, SCN - or the like ^{_{-, (CF 3 CF 2 SO}} 2) 2 N For example.

Meanwhile, the present invention provides a lithium secondary battery including at least one electrode for the all-solid-state cell. Generally, in a solid-state battery, a solid electrolyte included in an electrode can serve as a separator. However, in the case where the electrode for a solid-state battery is applied to only one of the electrodes, a separate polymer separator film may be required.

Here, the polymer separator film is interposed between the negative electrode and the positive electrode, and functions to electrically insulate the negative electrode from the positive electrode and to pass lithium ions. The polymer separator membrane may be any polymer membrane separator membrane used in a general all solid-state cell field, and is not particularly limited.

The present invention also provides a battery module including the lithium ion secondary battery as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source.

At this time, specific examples of the device include a power tool which is powered by an electric motor and moves; An electric vehicle including an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and the like; An electric motorcycle including an electric bike (E-bike) and an electric scooter (E-scooter); An electric golf cart; And a power storage system, but the present invention is not limited thereto.

Hereinafter, the present invention will be described in further detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

One. Example  One

(1) Manufacture of cathodes

(PEO + LiFSI, 20: 1 (molar ratio)) were mixed at a weight ratio of 70:10:20 to prepare a mixture of 5 g of artificial graphite having an average particle diameter (D ₅₀ ) of 20 μm and carbon black as a conductive material and a polymer solid electrolyte . Acetonitrile (AN) was added to the mixture to adjust the solid content to 30% to prepare an anode slurry.

Subsequently, a linear pattern mask was placed on the copper current collector having a thickness of 20 탆, and then the negative electrode slurry was applied, followed by vacuum drying at 120 캜 for 24 hours. At this time, the width of the linear pattern was 40 占 퐉, and the interval between the patterns was 5 占 퐉.

Subsequently, the pattern mask was removed and the rolling process was performed to form a negative electrode having a thickness of 40 mu m.

(2) Manufacture of batteries

Other emitted by the cathode and a lithium metal thin film 1.7671cm cut into ^two circular as a model for 1.4875cm ² as a counter electrode, to prepare a coin-type half-cell. Specifically, a 50 占 퐉 thick polymer separator film (PEO + LiFSI, 20: 1 (molar ratio)) was placed between the lithium metal and the negative electrode to produce an electrode assembly.

2. Example  2

The electrode assembly was prepared in the same manner as in Example 1 except that the width of the linear pattern was 40 占 퐉, the spacing between the patterns was 5 占 퐉, and the thickness of the negative electrode after rolling was 80 占 퐉.

3. Example  3

The electrode assembly was prepared in the same manner as in Example 1 except that the width of the linear pattern was 60 占 퐉, the spacing between the patterns was 5 占 퐉, and the thickness of the negative electrode after rolling was 80 占 퐉.

4. Example  4

The electrode assembly was prepared in the same manner as in Example 1, except that the width of the linear pattern was 40 占 퐉, the spacing between the patterns was 10 占 퐉, and the thickness of the negative electrode after rolling was 80 占 퐉.

5. Example  5

The electrode assembly was prepared in the same manner as in Example 1, except that the width of the linear pattern was 40 占 퐉, the spacing between the patterns was 20 占 퐉, and the thickness of the negative electrode after rolling was 80 占 퐉.

6. Comparative Example  One

The electrode assembly was prepared in the same manner as in Example 1, except that the pattern was not applied and the thickness of the negative electrode after rolling was 80 占 퐉.

7. Comparative Example  2

The electrode assembly was prepared in the same manner as in Example 1, except that the width of the linear pattern was 100 占 퐉, the spacing between the patterns was 5 占 퐉, and the thickness of the negative electrode after rolling was 80 占 퐉.

8. Experimental Example : Evaluation of life characteristics

The batteries manufactured in Examples 1 to 5 and Comparative Examples 1 and 2 were charged / discharged to evaluate the discharge capacity retention rate, which is shown in Table 1 below. On the other hand, at the time of life characteristics evaluation, charging / discharging was carried out at a temperature of 60 ° C at 0.05 C, and the cycle was terminated in a state of discharging (lithium is not in the negative electrode) for 10 cycles.

Charging conditions: CC (constant current) / CV (constant voltage) (5 mV / 0.005 C current cut-off)

Discharge Condition: CC (Constant Current) Condition 1.5 V

The capacity retention rate was derived by calculating the ratio of the discharge capacity after 10 cycles to the first discharge capacity. This is shown in Table 1 below.

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 The width of the pattern (탆) 40 40 60 40 40 - 100 The spacing of the pattern (탆) 5 5 5 10 20 - 5 Electrode thickness (탆) 40 80 80 80 80 80 80 Life characteristics (%, @ 10 cycles) 94 92 89 92 93 62 74

As can be seen from the above Table 1, it can be confirmed that the life characteristic is remarkably improved by applying the pattern.

In the examples, after the cycle proceeded, the electrode active material and the solid electrolyte were not separated, and therefore, the thickness change due to the gas captured inside the electrode could not be observed. Also, it can be seen from Examples 1 and 2 that the application of the pattern maintains almost the same effect of improving the gas discharge performance and lifetime characteristics even when the electrode thickness, that is, the loading amount is increased.

Furthermore, it can be confirmed from Examples 2, 4 and 5 that the intervals of the patterns are not so large even if the intervals are further increased as long as the intervals are such that the gas can be discharged and moved.

On the other hand, in the case of Comparative Example 2, the width of the pattern is 100 μm, which is about 5 times the particle size of the negative electrode active material. In this case, the trapped gas can not be efficiently discharged. It can be seen from Table 1 that the life characteristics are improved as compared with Comparative Example 1, but the life characteristics are not better than those of Examples having a proper pattern width.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

10: electrode collector
20: electrode active material layer
21: electrode active material particle
22: Solid electrolyte
23: Conductive material
24: Spacing between patterns

Claims (8)

Electrode collector; And
And an electrode active material layer formed on at least one surface of the electrode current collector and having a plurality of patterns of predetermined shapes spaced apart from each other,
Wherein the electrode active material layer includes a plurality of electrode active material particles and a solid electrolyte coated on a part of the surface of the plurality of electrode active material particles and connecting the plurality of electrode active material particles to each other,
Wherein at least a part of the surface of the electrode active material particles is exposed to the outside of the electrode active material layer. The method according to claim 1,
Wherein the electrode active material layer further comprises a conductive material dispersed on a surface of the plurality of electrode active material particles and in or on the surface of the solid electrolyte. The method according to claim 1,
Wherein a gap channel is formed between the patterns of the plurality of predetermined shapes. The method according to claim 1,
Wherein the pattern of the predetermined shape includes a linear, wavy, point or lattice pattern. The method according to claim 1,
Wherein the solid electrolyte is any one selected from the group consisting of a polymer solid electrolyte, a polymer gel electrolyte, a sulfide-based solid electrolyte, and an oxide-based solid electrolyte, or a mixture of two or more thereof. The method according to claim 1,
Wherein the width of each of the patterns of the predetermined shape is 1 to 3 times the particle size of the electrode active material. The method according to claim 1,
The size of the electrode active material particle is 1 to 100 탆,
Wherein an interval between the plurality of patterns is 0.1 to 30 占 퐉. The method according to claim 1,
The size of the electrode active material particles is 5 to 30 탆,
Wherein an interval between the plurality of patterns is 1 to 20 占 퐉.

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