WO2019103311A1 - Positive electrode for all-solid state lithium-polymer secondary battery, method for manufacturing same, and secondary battery comprising same - Google Patents

Abstract

The present invention relates to a positive electrode for an all-solid state lithium-polymer secondary battery, a method for manufacturing the same, and a secondary battery comprising the same, wherein the positive electrode includes a carbon-based conductive material, so that the secondary battery has an enhanced ion conductivity and electrical conductivity and thus has a lower impedance than existing lithium secondary batteries, and has a low rate of capacity reduction according to continuous charging and discharging even when a loading density of a positive electrode active material is increased. Therefore, the secondary battery has an improved lifespan and capacity retention rate.

Description

A cathode for a solid lithium-polymer secondary battery, a method for manufacturing the same, and a secondary battery including the same

The present invention relates to a positive electrode for a full solid lithium-polymer secondary battery, a method for manufacturing the same, and a secondary battery including the same. More particularly, the present invention relates to a positive electrode for a full- To a positive electrode for a full-solid lithium-polymer secondary battery capable of improving discharge characteristics and battery life, a method for manufacturing the same, and a secondary battery including the same.

The secondary battery has been mainly applied to a small battery such as a mobile device, a notebook computer, and a computer, but recently, the research direction has been expanded to a middle or large battery field such as an energy storage device or an electric vehicle.

In the case of such a medium- and large-sized battery, unlike a small-sized battery, operating environment (for example, temperature and impact) is severe. In particular, from the viewpoint of increasing the size of the battery, it is necessary to secure improved lifetime characteristics and safety as compared with the conventional secondary battery.

However, most commercially available lithium secondary batteries are composed of a cathode, a cathode, and an electrolyte, and an organic electrolyte in which an electrolyte is a metal salt dissolved in an organic solvent is widely used. A lithium secondary battery operating in an organic electrolyte has a relatively increased discharge capacity and energy density. However, when organic electrolytes are used, there is a potential risk of electrolyte leakage, ignition, explosion, and the like.

Therefore, replacing organic electrolytes and using a safe and reliable solid electrolyte are attracting attention as an alternative to overcome the stability problem. Specifically, a secondary battery using a solid electrolyte, that is, an all-solid-state battery, refers to a replacement of an organic electrolyte among a battery component including a cathode, an electrolyte, and a cathode by a solid electrolyte.

The solid secondary battery has advantages of stability compared with an organic electrolyte using a conventional combustible organic solvent because there is no risk of explosion or fire of the battery, and it is attracting attention as a next generation secondary battery in view of possibility of high energy density. However, since not only the electrolyte but also all the components are in a solid state, the entire solid secondary battery may have a problem that the performance of the battery is drastically lowered due to the interfacial contact resistance generated at the boundary of the electrolyte during lithium ion movement compared to the organic electrolyte .

Particularly, the bonding force between the solid electrolyte and the current collector corresponding to the electrode of the battery is weakened, and the electrical conductivity tends to deteriorate. Even if the electrical conductivity of the current collector is high, if the electrical conductivity at the interface between the solid electrolyte and the electrode active material is low, the overall conductivity of the battery may be affected. In addition, the contact area of ions and electrons conducted from the solid electrolyte to the current collector is also limited, so that the resistance may increase, and consequently, the conductivity may be lowered.

Therefore, in order to exhibit the performance of the all-solid battery, it is required that the contact property between the solid electrolyte and the active material in the whole solid battery is excellent. Through the improvement of the contact characteristics, it is expected that the theoretical capacity of the active material can be fully expressed. However, it is difficult to meet the demand level as far as it has been studied so far.

On the other hand, the electrode of the lithium secondary battery can be usually obtained by coating an electrode slurry on a metal foil and annealing the electrode slurry. Specifically, the electrode slurry is prepared by mixing an electrode active material for storing energy, a conductive material for imparting electrical conductivity, a binder for adhering it to the electrode foil, and an organic solvent such as NMP (N-methyl pyrrolidone) . As examples of the positive electrode active material, lithium cobalt oxide, lithium manganese oxide, lithium nickel calculated oxide, lithium composite oxide and the like can be considered. Conversely, as an example of the negative electrode active material, an alloy-based active material mainly composed of a carbon-based material or silicon, tin, an oxide or an alloy thereof is considered.

Particularly, from the viewpoint of maximizing the capacity, there is proposed a method in which different cathode active materials are mixed and used, or a method of facilitating the movement of electrons in the electrode by coating a conductive material or the like on the surfaces of the anode and anode active materials.

However, the composition and the approach of the electrode slurry as described above are designed only in terms of the lowering of the resistance, and the mechanical and physical properties of the battery are not sufficiently considered. Therefore, a technology for simultaneously improving not only the capacity and the cell resistance of a battery but also the ion conductivity in the electrode, as well as the mechanical and physical properties, has been attracting attention as a very important task in the art.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a positive electrode for a full solid lithium-polymer secondary battery having low impedance characteristics.

A second object of the present invention is to provide a secondary battery in which the capacity retention ratio and the life of the battery are improved.

A third object of the present invention is to provide a method for producing a positive electrode for a full solid lithium-polymer secondary battery.

In order to achieve the above object, a cathode for a full solid lithium-polymer secondary battery of the present invention includes a cathode active material, a polymer electrolyte, and a carbon-based conductive material.

 In the cathode for a full solid lithium-polymer secondary battery of the present invention, the weight of the carbon-based conductive material is preferably between 0.1 and 2.5 wt% based on the total weight of the anode.

The carbon-based conductive material preferably includes carbon nanotubes, graphene, or a mixture thereof.

In the positive electrode for a full solid lithium-polymer secondary battery of the present invention, it is preferable to further include a conductive carbon.

It is preferable that the conductive carbon includes one kind of amorphous carbon black selected from the group consisting of acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black and Super P.

In the cathode for a full-solid lithium-polymer secondary battery of the present invention, the active material may be LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiCoPO ₄ , LiFePO ₄ and LiNi _x Mn _y Co _z O ₂ = 1). ≪ / RTI >

In the cathode for a full-solid lithium-polymer secondary battery of the present invention, it is preferable that the polymer electrolyte includes a polymer binder, a crosslinking agent, an ionic plasticizer and a lithium salt.

The crosslinking agent is preferably an ethoxylate acrylate having two or more crosslinkable functional groups.

The cross-linking agent preferably includes at least one selected from the group consisting of phosphazene-based, phosphate-based and bisphenol A compounds.

The ion conductive plasticizer is selected from the group consisting of polyethylene glycol dimethyl ether, polyethylene glycol diethyl ether, polyethylene glycol dipropyl ether, polyethylene glycol dibutyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol dimethyl ether, polypropylene glycol diglycidyl Ether, a polypropylene glycol / polyethylene glycol copolymer at the terminal of dibutyl ether, and a polyethylene glycol / polypropylene glycol / polyethylene glycol block copolymer at the terminal of dibutyl ether.

The polymer binder may be at least one selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethylcellulose, starch, hydroxypropylcellulose, A polymer selected from the group consisting of recycled cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene butadiene rubber, It is desirable to include species or more.

The lithium salt may be at least one selected from the group consisting of lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroantimonate (LiSbF ₆ ), lithium hexafluoroacetate (LiAsF ₆ ), lithium difluoromethane sulfoxide (LiC ₄ F ₉ SO ₃ ), lithium perchlorate (LiClO ₄ ), lithium aluminate (LiAlO ₂ ), lithium tetrachloroaluminate (LiAlCl ₄ ), lithium chloride (LiCl), lithium iodide (LiB (C ₂ O ₄ ) ₂ ), lithium trifluoromethanesulfonylimide (LiTFSI), and the like.

In order to achieve the second object of the present invention, there is provided a method for manufacturing a positive electrode for a full-solid lithium-polymer secondary battery, comprising mixing an active material, a polymer electrolyte, a conductive carbon, Producing; Applying the prepared slurry on a substrate; And drying the applied slurry.

In the method for manufacturing a positive electrode for a full solid lithium-polymer secondary battery of the present invention, it is preferable that the thickness of the slurry in the step of applying the slurry on a substrate is 1 to 90 mu m.

In order to achieve the third object of the present invention, a secondary battery including a cathode for a full solid lithium-polymer secondary battery according to the present invention includes a cathode, a cathode, and a first polymer electrolyte disposed between the anode and the cathode.

In addition, the anode includes a cathode active material, a second polymer electrolyte, a conductive carbon, and a carbon-based conductive material.

It is preferable that the loading density of the cathode active material is between 1.0 and 5.0 mg / cm < ² >.

The second polymer electrolyte preferably includes a polymer binder, a crosslinking agent, an ionic plasticizer, and a lithium salt.

Wherein the negative electrode comprises at least one selected from the group consisting of graphite, low temperature sintered carbon, calcined coke, vanadium oxide, lithium vanadium oxide, lithium metal, silicon, silica, conductive polymer, lithium composite and silicon graphite composite .

The positive electrode for a full solid lithium-polymer secondary battery of the present invention includes a carbon-based conductive material and a polymer electrolyte, thereby providing an effect of improving ionic conductivity and electrical conductivity.

In addition, by using the method for producing a positive electrode for a full-solid lithium-polymer secondary battery of the present invention, the charging and discharging characteristics of the secondary battery can be improved even when the loading density of the positive electrode active material is increased by the improved electrical conductivity.

In addition, according to the present invention, by using a positive electrode for a full-solid lithium-polymer secondary battery having a high ion conductivity, the impedance can be lowered and the cycle life of the secondary battery can be improved.

FIG. 1 is a graph showing a change in capacity of a secondary battery including a positive electrode for a full solid lithium-polymer secondary battery manufactured according to Examples 1 to 4 of the present invention and Comparative Example 1 according to the number of cycles.

FIG. 2 is a graph showing a capacity retention rate according to charging and discharging speeds of a secondary battery including a positive electrode for a full solid lithium-polymer secondary battery manufactured according to Example 6 and Comparative Example 1 of the present invention.

3 is a graph showing the impedance of a secondary battery including a positive electrode for a full solid lithium-polymer secondary battery manufactured according to Example 6 and Comparative Example 1 of the present invention.

Hereinafter, the present invention will be described in detail with reference to the embodiments and drawings of the present invention.

The positive electrode for a full solid lithium-polymer secondary battery of the present invention includes an active material, a polymer electrolyte, and a carbon-based conductive material. The carbon-based conductive material preferably includes carbon nanotubes, graphene, or a mixture thereof.

The carbon-based conductive material improves the electrochemical performance of the positive electrode for the all-solid lithium-polymer secondary battery and improves the energy density by forming a flexible conductive network between the positive electrode and the positive electrode active material. In addition, the carbon-based conductive material provides more active sites into which lithium ions can be inserted, thereby ultimately increasing the reversible capacity of the electrode in a very small amount.

In the cathode for a full solid lithium-polymer secondary battery of the present invention, the weight of the carbon-based conductive material is preferably between 0.1 and 2.5 wt% based on the total weight of the anode.

If the weight of the carbon-based conductive material is less than 0.1 wt%, the effect of improving the electrical conductivity can not be exhibited, and the resistance of the electrode increases when the secondary battery is driven, and the capacity is rapidly reduced as the number of cycles increases have. On the contrary, when the weight of the carbon-based conductive material is more than 2.5% by weight, the thickness of the electrode becomes thick and the diffusion path of lithium ions is further extended, so that high polarization may occur at a high rate.

In the positive electrode of the full-solid lithium-polymer secondary battery of the present invention, it is preferable to further include conductive carbon. The conductive carbon preferably includes at least one amorphous carbon black selected from the group consisting of acetylene black, ketjen black, channel black, phenanthrene black, lamp black, and summer black.

Specifically, the conductive carbon preferably includes between 4 and 20% by weight based on the total weight of the cathode for the all-solid lithium-polymer secondary battery. In particular, the conductive carbon preferably includes between 5 and 10% by weight based on the total weight of the anode in view of improving the electric conductivity as well as the carbon-based conductive material.

If the amount of the conductive carbon is less than 4 wt%, the effect of improving electrical conductivity can not be exhibited. If the amount of the conductive carbon is more than 20 wt%, the amount of the cathode active material is decreased, .

By including both the carbon-based conductive material and the conductive carbon in the entire solid lithium-polymer anode of the present invention, the efficiency of short-distance and long-distance electron transfer paths in the anode can be improved. Further, through improvement of the electron transfer path, it is possible to exhibit better performance at a low rate and a high rate discharge capacity than a lithium secondary battery using only a single-component conductive material.

In the cathode for a full solid lithium-polymer secondary battery of the present invention, the cathode active material may include a lithium transition metal oxide. Wherein the cathode active material is at least one selected from the group consisting of LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiCoPO ₄ , LiFePO ₄ and LiNi _x Mn _y Co _z O ₂ (where x + y + z = 1) . LiFePO ₄ is preferable because it can improve the mechanical characteristics of the secondary battery, but the present invention is not limited thereto.

In the cathode for a full-solid lithium-polymer secondary battery of the present invention, the cathode active material is preferably between 50 and 80 wt%, and more preferably between 70 and 80 wt%, based on the total weight of the anode. If the amount of the cathode active material is less than 50% by weight, the capacity of the secondary battery may decrease. On the contrary, when the amount of the cathode active material is more than 80% by weight, physical properties such as interfacial adhesion deteriorate.

In the anode for the all-solid lithium-polymer secondary battery of the present invention, the polymer electrolyte does not use a solvent unlike an organic electrolyte, and is a material composed only of a polymer having a polar group and a salt. Specifically, the polymer electrolyte of the present invention may include a polymer binder, a crosslinking agent, an ionic plasticizer, and a lithium salt.

The polymer binder may be selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxy Propylene-diene monomer, styrene-butadiene rubber, styrene-butadiene rubber, and fluorine rubber, which is a copolymer of ethylene, propylene, propylene, propylene, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene- , And more preferably at least one selected from the group consisting of vinylidene fluoride (PVdF).

The crosslinking agent is preferably an ethoxylate acrylate having two or more crosslinkable functional groups. The crosslinking agent preferably includes at least one selected from the group consisting of phosphazene-based, phosphate-based, and bisphenol-A compounds, but is not limited thereto.

The ion conductive plasticizer is selected from the group consisting of polyethylene glycol dimethyl ether, polyethylene glycol diethyl ether, polyethylene glycol dipropyl ether, polyethylene glycol dibutyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol dimethyl ether, polypropylene glycol diglycidyl Ether, a polypropylene glycol / polyethylene glycol copolymer at the terminal of dibutyl ether, and a polyethylene glycol / polypropylene glycol / polyethylene glycol block copolymer at the terminal of dibutyl ether. Since polyethylene glycol dimethyl ether can form a pentagonal ring, it is preferable from the viewpoint of facilitating dissociation of lithium salt and improving ionic conductivity.

The lithium salt may be at least one selected from the group consisting of lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroantimonate (LiSbF ₆ ), lithium hexafluoroacetate (LiAsF ₆ ), lithium difluoromethane sulfoxide (LiC ₄ F ₉ SO ₃ ), lithium perchlorate (LiClO ₄ ), lithium aluminate (LiAlO ₂ ), lithium tetrachloroaluminate (LiAlCl ₄ ), lithium chloride (LiCl), lithium iodide It is preferable to include at least one selected from the group consisting of lithium tetrafluoroborate (LiB (C ₂ O ₄ ) ₂ ) and lithium trifluoromethanesulfonylimide (LiTFSI), and lithium trifluoromethanesulfonylimide LiTFSI) is more preferable, but is not limited thereto.

A method for producing a positive electrode for a full solid lithium-polymer secondary battery according to the present invention comprises the steps of: preparing a slurry for an anode electrode by mixing an active material, a polymer electrolyte, a conductive carbon, a carbon-based conductive material and a solvent; Applying the prepared slurry on a substrate; And drying the applied slurry.

In the method for producing a positive electrode for a full-solid lithium-polymer secondary battery according to the present invention, the step of preparing the positive electrode slurry may be performed without adding an excessive amount of a dispersion medium or an excessive amount of a solvent. In particular, the carbon-based conductive material may be dispersed in the slurry for the anode electrode. The method for dispersing the carbon-based conductive material may be performed by ultrasonic waves, mechanical shakers, agitation, etc., but is not limited thereto.

In addition, in the method for producing a positive electrode for a full solid lithium-polymer secondary battery of the present invention, the solvent used in the slurry preparation can be easily removed in the step of drying the slurry.

Therefore, only the active material, the electrolyte, the conductive carbon, and the carbon-based conductive material in the state in which unnecessary solvent components are removed remain uniformly distributed on the electrode. This is because even if the weight ratio of the carbon-based conductive material and the conductive carbon contained in the solvent is adjusted in the step of preparing the anode electrode slurry, the weight ratio of the carbon-based conductive material and the conductive carbon distributed in the electrode can be easily adjusted . Accordingly, the carbon-based conductive material and the conductive carbon can be easily applied to the electrodes at a constant weight ratio as compared with the prior art.

Particularly, when the weight ratio of the carbon-based conductive material and the conductive carbon is 1: 9 to 2: 3, not only the carbon-based conductive material and the conductive carbon are uniformly distributed in the electrode but also the loading density of the electrode is increased Can be further confirmed. In addition, in view of further improving the loading density of the electrode, it is more preferable that the weight ratio of the carbon-based conductive material and the conductive carbon is 1: 7.

The solvent may be selected from the group consisting of ethanol, methanol, propanol, butanol, isopropyl alcohol, dimethylformamide (DMF), acetone, tetrahydrofuran (THF), toluene, dimethylacetamide, N, -2-pyrrolidone (NMP), and more preferably N-methyl-2-pyrrolidone (NMP), but not limited thereto.

In the method for manufacturing a positive electrode for a full-solid lithium-polymer secondary battery of the present invention, it is preferable that the thickness of the slurry at the step of applying the slurry is in the range of 1 to 90 탆, and in the aspect of improving the performance of the secondary battery, To 60 [mu] m. If the thickness of the slurry is less than 1 m, the capacity characteristics of the secondary battery may be significantly reduced. On the contrary, if the thickness of the slurry exceeds 90 탆, the performance of the secondary battery may be decreased due to an increase in interfacial resistance in the electrode.

The substrate may be an aluminum substrate, but is not limited thereto.

In the method for producing a positive electrode for a full solid lithium-polymer secondary battery of the present invention, the method for producing the slurry is in accordance with a usual method. In the method for manufacturing a positive electrode for a full-solid lithium-polymer secondary battery according to the present invention, the drying step is performed at a temperature of 100 to 130 ° C. for 0.5 to 24 hours under a vacuum atmosphere. In the above step, Is possible.

In addition, the step of drying may provide high adhesion between the substrate and the carbon-based conductive material, the substrate and the polymer electrolyte or between the substrate and the cathode active material, and the substrate prevents corrosion.

A secondary battery including a cathode for a full solid lithium-polymer secondary battery of the present invention includes a cathode, a cathode, and a first polymer electrolyte disposed between the anode and the cathode. In addition, the anode includes a cathode active material, a second polymer electrolyte, conductive carbon, and a carbon-based conductive material.

The first polymer electrolyte is an electrolyte which is positioned between the anode and the cathode of the secondary battery and provides a path for the movement of ions. Meanwhile, the second polymer electrolyte may be the same as the first polymer electrolyte, but is not limited thereto.

And the loading density of the cathode active material for the secondary battery is preferably 1.0 to 5.0 mg / cm ² . When the loading density of the cathode active material for the secondary battery is less than 1.0 mg / cm ² , the capacity can be expressed, but the electrode material is degraded in a similar pattern to that of the liquid electrolyte, and the performance of the secondary battery is reduced . On the contrary, when the loading density of the cathode active material for the secondary battery is more than 5.0 mg / cm ² , the resistance between the carbon-based conductive material contained in the anode for the secondary battery and the solid polymer electrolyte interface increases to decrease the capacity of the secondary battery Thereby deteriorating the performance of the secondary battery.

The positive electrode included in the secondary battery is the same as the positive electrode for the all-solid lithium-polymer secondary battery described above, and the method for manufacturing the same is described in detail.

The negative electrode includes at least one selected from the group consisting of graphite, low temperature sintered carbon, calcined coke, vanadium oxide, lithium vanadium oxide, lithium metal, silicon, silica, conductive polymer, lithium metal composite and silicon graphite composite .

Hereinafter, the present invention will be described in more detail with reference to the following examples and experimental examples. However, the following examples are intended to illustrate the contents of the present invention, but the scope of the invention is not limited by the following examples.

{Example}

Example 1: Preparation of a positive electrode for a full solid lithium-polymer secondary battery 1

70 wt% of lithium iron phosphate (LFP), 7.85 wt% of conductive carbon (super P), and 0.15 wt% of carbon nanotube as a carbon-based conductive material were dissolved in 2.4 mL of NMP and stirred for 10 minutes to 22 wt% of the polymer electrolyte, Prepared. Next, the slurry was coated on an aluminum foil to a thickness of 60 mu m and dried at a temperature of 120 DEG C for 1 hour to prepare a cathode for a full solid lithium-polymer secondary battery.

Example 2: Preparation of a positive electrode for a full solid lithium-polymer secondary battery 2

A positive electrode for a full solid lithium-polymer secondary battery was prepared in the same manner as in Example 1, except that the content was as shown in Table 1 below.

Example 3: Preparation of positive electrode for all solid lithium-polymer secondary batteries 3

A positive electrode for a full solid lithium-polymer secondary battery was prepared in the same manner as in Example 1, except that the content was as shown in Table 1 below.

Example 4: Preparation of positive electrode for all solid lithium-polymer secondary batteries 4

A positive electrode for a full solid lithium-polymer secondary battery was prepared in the same manner as in Example 1, except that the content was as shown in Table 1 below.

Example 5: Preparation of positive electrode for all solid lithium-polymer secondary batteries 5

A positive electrode for a full solid lithium-polymer secondary battery was prepared in the same manner as in Example 1, except that the content was as shown in Table 1 below.

Example 6: Preparation of a positive electrode for a full solid lithium-polymer secondary battery 6

A positive electrode for a full-solid lithium-polymer secondary battery was prepared in the same manner as in Example 1, except that the content was as shown in Table 1 below.

Comparative Example 1

A positive electrode was prepared in the same manner as in Example 1 except that the carbon-based conductive material was not added, except that the content was as shown in Table 1 below.

The contents of components constituting the positive electrodes of Examples 1 to 6 and Comparative Example 1 are shown in Table 1 below.

In order to evaluate the capacity according to the loading density (1.0 to 5.0 mg / cm ² ) of the battery including the anode for a lithium secondary battery produced according to Examples 1 to 6 and Comparative Example 1, a battery was prepared by the following method.

Preparation Example 1: Preparation of a secondary battery including a positive electrode for a full solid lithium-polymer secondary battery

An electrolyte containing a lithium conductor was coated on the prepared positive electrode for a lithium-polymer secondary battery manufactured according to Examples 1 to 6 and Comparative Example 1, and a lithium metal foil and an SUS spacer were stacked as a negative electrode on the electrolyte, Respectively. Next, the battery was sealed so as not to be exposed to oxygen, and then cured at a temperature of 90 DEG C for 30 minutes to manufacture a battery including a cathode for a full solid lithium-polymer secondary battery.

{Evaluation results}

Experimental Example 1: Capacity evaluation of a secondary battery including a positive electrode for a full solid lithium-polymer secondary battery

In order to evaluate the capacity of the secondary battery including the anode for the all-solid lithium-polymer secondary battery according to the present invention, the capacity change due to charging and discharging of the secondary battery was measured using the constant current measurement method. The results are shown in Fig. 1 and Fig. The graph of FIG. 2 shows the capacity retention rate according to the charge / discharge speed.

Referring to FIG. 1, in the case of a secondary battery including a positive electrode for a full solid lithium-polymer secondary battery manufactured according to Examples 1 to 4, the capacity due to charging and discharging was constantly decreased. However, It was observed that the secondary battery including the positive electrode for the solid lithium-polymer secondary battery sharply decreased from 2C. This is because, in the case of a secondary battery including a positive electrode for a full solid lithium-polymer secondary battery manufactured according to Examples 1 to 4, the electric conductivity is improved by the influence of the carbon-based conductive material contained in the positive electrode, Indicating that the reduction rate is lowered.

In particular, referring to FIG. 2, the capacity retention ratio of the battery including the anode for the all-solid lithium-polymer secondary battery manufactured according to Example 6 containing 1.0% by weight of the carbon-based conductive material according to the charge- Which was much higher than that of the battery manufactured according to the above.

In addition, even if the loading density of the cathode active material is more than 3 mg / cm ² by the inclusion of the carbon-based conductive material, the reversible reaction between the lithium ion transfer and the lithium ion and the cathode active material is not delayed, Maintained and improved. This aspect can be inferred indirectly through FIG. 3, as will be described later.

Experimental Example 2: Impedance Measurement of Secondary Battery

Impedance was measured using an impedance analyzer at a loading density of 1.0 to 5.0 mg / cm ^{2 in} a secondary battery including a positive electrode for a full solid lithium-polymer secondary battery manufactured according to Examples 1 to 6 and Comparative Example 1. In the case of the secondary battery including the positive electrode for a full solid lithium-polymer secondary battery produced according to Examples 1 to 5, the charging density was in the range of 1.0 to 5.0 mg / cm ² , The secondary battery including the positive electrode according to Comparative Example 1 showed a similar pattern to that of the secondary battery.

On the other hand, in the case of the secondary battery including the anode for the all-solid lithium-polymer secondary battery manufactured according to Example 6, the secondary battery including the anode manufactured according to Comparative Example 1 at a loading density of 3.2 mg / cm ² The results are shown in Fig. 3. Fig.

3, the impedance value of a secondary battery including a positive electrode for a full solid lithium-polymer secondary battery manufactured according to Example 6 was measured to be about 145 ohm · cm ² , Was measured at about 190 ohm-cm < ² >. The ionic conductivity and the electrical conductivity of the secondary battery including the positive electrode for the all-solid lithium-polymer secondary battery manufactured according to Example 6 are improved to show that the internal resistance is reduced to have a low impedance result value.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. It will also be appreciated that many modifications and variations will be apparent to those skilled in the art without departing from the scope of the present invention.

Claims (17)

1. Active material;

   Polymer electrolyte; And

   A positive electrode for a full-solid lithium-polymer secondary battery comprising a carbon-based conductive material,

   Wherein the weight of the carbon-based conductive material is 0.1 to 2.5 wt% of the total weight of the positive electrode.
2. The method according to claim 1,

   Wherein the carbon-based conductive material comprises carbon nanotubes, graphene, or a mixture thereof.
3. The method according to claim 1,

   Wherein the positive electrode further comprises conductive carbon on the positive electrode for the secondary battery.
4. The method of claim 3,

   Wherein the conductive carbon comprises one kind of amorphous carbon black selected from the group consisting of acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black.
5. The method according to claim 1,

   Wherein the active material includes at least one selected from the group consisting of LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiCoPO ₄ , LiFePO ₄ and LiNi _x Mn _y Co _z O ₂ (where x + y + z = 1) Wherein the positive electrode is a positive electrode for an all-solid lithium-polymer secondary battery.
6. The method according to claim 1,

   Wherein the polymer electrolyte comprises a polymer binder, a crosslinking agent, an ionic plasticizer, and a lithium salt.
7. The method according to claim 6,

   The polymer binder may be selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, A polymer selected from the group consisting of cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer, sulfonated ethylene-propylene-diene monomer, styrene butadiene rubber, Wherein the positive electrode comprises a positive electrode active material and a negative electrode active material.
8. The method according to claim 6,

   Wherein the crosslinking agent is an ethoxylate acrylate having at least two crosslinkable functional groups.
9. The method according to claim 6,

   Wherein the cross-linking agent comprises at least one member selected from the group consisting of phosphazene-based, phosphate-based, and bisphenol-A compounds.
10. The method according to claim 6,

    The ion conductive plasticizer is selected from the group consisting of polyethylene glycol dimethyl ether, polyethylene glycol diethyl ether, polyethylene glycol dipropyl ether, polyethylene glycol dibutyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol dimethyl ether, polypropylene glycol diglycidyl Ether, a polypropylene glycol / polyethylene glycol copolymer at the terminal of dibutyl ether, and a polyethylene glycol / polypropylene glycol / polyethylene glycol block copolymer at the terminal of dibutyl ether. Anode for lithium-polymer secondary battery.
11. The method according to claim 6,

    The lithium salt may be at least one selected from the group consisting of lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluoroantimonate (LiSbF ₆ ), lithium hexafluoroacetate (LiAsF ₆ ), lithium difluoromethane sulfonate _{(LiC 4 F 9 SO 3)} , lithium perchlorate (LiClO _4), lithium aluminate (LiAlO _2), lithium tetrachloro- aluminate (LiAlCl _4), lithium chloride (LiCl), lithium iodide (LiI), lithium bis oxalate reyito Wherein the positive electrode comprises at least one selected from the group consisting of borate (LiB (C ₂ O ₄ ) ₂ ) and lithium trifluoromethanesulfonylimide (LiTFSI).
12. Preparing a slurry for an anode electrode comprising an active material, a polymer electrolyte, a conductive carbon, a carbon-based conductive material, and a solvent;

    Applying the prepared slurry on a substrate; And

    And drying the applied slurry. The method of manufacturing a positive electrode for a full-solid lithium-polymer secondary battery according to claim 1,
13. 13. The method of claim 12,

    Wherein the step of applying the slurry onto a substrate comprises:

    Wherein the thickness of the slurry is in the range of 1 to 90 占 퐉.
14. anode;

    cathode; And

    And a first polymer electrolyte disposed between the anode and the cathode,

    Wherein the anode comprises a cathode active material, a second polymer electrolyte, a conductive carbon, and a carbon-based conductive material.
15. 15. The method of claim 14,

    And the loading density of the cathode active material is between 1.0 and 5.0 mg / cm < ² >.
16. 15. The method of claim 14,

    Wherein the second polymer electrolyte comprises a polymer binder, a crosslinking agent, an ionic plasticizer, and a lithium salt.
17. 15. The method of claim 14,

    The negative electrode includes at least one selected from the group consisting of graphite, low temperature sintered carbon, calcined coke, vanadium oxide, lithium vanadium oxide, lithium metal, silicon, silica, conductive polymer, lithium metal composite and silicon graphite composite The secondary battery comprising:

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