KR100899549B1 - High Coulomb Efficiency Negative Electrode For Lithium Ion Secondary Battery, Manufacturing Method of Electrode And Lithium Secondary Battery - Google Patents

Abstract

The present invention is a negative electrode for a lithium secondary battery comprising a negative electrode active material, a binder, and a conductive material containing a non-carbon compound, including a negative electrode for a lithium secondary battery having an initial coulombic efficiency of 85% or more, and a non-carbon system exhibiting high capacity characteristics through pretreatment. It provides a method for producing an electrode. In addition, it provides a high efficiency, high energy long life lithium secondary battery having the characteristic electrode.

Lithium secondary battery, negative electrode active material, high efficiency, silicon, tin oxide

Description

High Coulomb Efficiency Negative Electrode For Lithium Ion Secondary Battery, Manufacturing Method of Electrode And Lithium Secondary Battery

The present invention relates to a high efficiency lithium secondary battery negative electrode, an electrode manufacturing method and a lithium secondary battery, and in detail, to prepare a high capacity negative electrode using a compound, alloy material, etc. based on non-carbon-based negative electrode active materials such as silicon-based and tin-based The present invention relates to a method for manufacturing a high capacity high efficiency negative electrode having a high initial coulombic efficiency through pretreatment of an electrode, and a high capacity high energy lithium secondary battery including the high capacity high efficiency negative electrode.

Lithium secondary batteries, which play a role in the development of the mobile electronic information and telecommunications industry, have been commercialized at the high capacity level of 900 mAh based on 18650 batteries in 1992. Developed. Due to such high-performance battery characteristics, demand for medium and large-sized batteries such as electric vehicles and batteries with high output characteristics is steadily increasing.

The lithium secondary battery is mainly composed of a positive electrode, a negative electrode, an electrolyte, a separator, a packaging material, and the like. The positive electrode is formed by binding a mixture of a positive electrode active material, a conductive agent, and a binder to a current collector. Lithium transition metal compounds such as LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , and LiMnO ₂ are mainly used as the positive electrode active material. Surface-modified cathode active materials are also used. These materials are charged / discharged as lithium ions intercalate / deintercalation into the crystal structure and have a high electrochemical reaction potential. Lithium metal, carbon or graphite is mainly used as the negative electrode active material and has a low electrochemical reaction potential as opposed to the positive electrode active material. Lithium metal is inadequate as a secondary battery material due to poor cycle characteristics, and carbon-based materials are currently being used in commercial batteries, and new materials are being developed that surpass the characteristics of carbon-based materials in terms of capacity, initial coulombic efficiency, and cycle life. Electrolyte solution is mainly composed of LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ , LiPF ₆ , LiBF ₄ , LiClO ₄ , LiN ( A salt containing lithium ions such as SO ₂ C ₂ F ₅ ) ₂ and LiBOB is dissolved and used.

Cathode materials are dramatically increasing their specific capacity. Graphite material has a theoretical specific capacity of 372 mAh / g and a density of 2.62 g / ml.However, in the case of silicon-based materials under development, the theoretical specific capacity is 4200 mAh / g, with a high density of 2.33 g / ml and lithium intercalation. Dislocations also have similar characteristics to graphite.

The current lithium secondary battery negative electrode uses a carbon-based material of graphite, and despite the progress of technology development to replace this situation has not been developing a replacement product. The reason for this is that despite the high possibility of silicon-based and tin-based materials, the initial charge-discharge coulombic efficiency is lowered from 40% to 80%, replacing graphite having an initial charge-discharge coulombic efficiency of 90% or more. It is because it is difficult to apply to a battery.

The present invention is to solve the above problems,

It provides a high energy next-generation lithium secondary battery negative electrode using a non-carbon-based material based negative active material exhibits a low initial coulombic efficiency but high specific capacity.

In addition, the initial coulombic efficiency and high capacity characteristics are improved by improving the initial coulombic efficiency through a pretreatment process of a high energy next-generation lithium secondary battery negative electrode using a non-carbon-based material-based negative electrode active material having low initial coulombic efficiency. It provides an electrode manufacturing method that can be applied to the negative electrode, which can be expressed together with the positive electrode,

In addition, by using the negative electrode for the next-generation lithium secondary battery exhibiting the high initial coulombic efficiency and high specific capacity characteristics, the next-generation lithium secondary battery surpasses the carbon-based lithium secondary battery by dramatically improving the energy storage capacity of the existing lithium secondary battery. It aims to provide.

Hereinafter, the present invention will be described in detail.

First, the negative electrode for a lithium secondary battery according to the present invention will be described.

The negative electrode for a lithium secondary battery according to the present invention is a negative electrode for a lithium secondary battery including a negative electrode active material, a binder, and a conductive material containing a non-carbon compound, and has an initial coulombic efficiency of 90% or more.

Non-carbon electrode materials have not been applied to commercial lithium secondary batteries due to problems of initial coulombic efficiency and cycle characteristics despite high specific amounts, but the present invention has solved them.

The negative electrode active material includes the non-carbon compound, but is not limited, but silicon oxide or tin oxide compound is preferable. The silicon oxide has a range of SiO _x to x in the range of 0.1 to 2, preferably in the range of 0.5 to 1.5, and more preferably in the range of 0.9 to 1.1, the characteristics of the active material are excellent.

In particular, the non-carbon-based compound is preferably alloyed with graphite to have the form of a composite. In this case, the weight ratio of non-carbon compound such as silicon oxide and graphite is not limited, but is preferably in the range of 2: 8 to 7: 3 as the weight ratio, and particularly preferably the weight ratio is in the range of 4: 6 to 6: 4. Do. According to the experimental result, it was excellent in the composition ratio of about 5: 5. This is because graphite may serve as a matrix to alleviate the volume expansion of the non-carbon compound.

Although not limited by the alloying method, as an example, a composite is prepared by ball milling a mixture of a non-carbon compound and graphite together with stainless balls using a ball milling machine at a predetermined revolutions per minute in an inert atmosphere such as argon or nitrogen and oxidizing the mixture. The method of heat-processing the composite of silicon and graphite in inert atmosphere, such as argon and nitrogen, is mentioned.

The present invention does not specify the material of the ball with respect to the stainless ball, and can be used as long as it is a ball of a material showing the function of mechanical ball milling. Bowling machine in the present invention is used as a means for imparting the kinetic energy to the ball is not limited to a specific bowling machine. Maintaining an inert atmosphere during ball milling and heat treatment in the present invention is for the purpose of preventing oxidation of the material and can be used according to the oxidation characteristics of the material.

Furthermore, when the carbon material is applied to the non-carbon-based compound alloyed with the graphite, it is possible to reduce the volume expansion of the alloy material while smoothing the electronic conductivity, it can be developed as a high capacity long life electrode material by optimizing the carbon material coating content have.

The coating method of the carbon material is not limited, but a chemical vapor deposition (CVD) method using volatile carbon precursor vapor may also be used, and any method capable of adding and compounding the carbon material is within the scope of the present invention.

In particular, the carbon precursor material may be sufficiently agitated in the composite of silicon oxide and graphite under the same conditions as in the production of the primary composite of silicon oxide and graphite to carbonize the carbon precursor through heat treatment in an inert atmosphere such as argon or nitrogen. .

The carbon precursor is not limited as long as it is a material that can provide carbon so that carbon can be applied to the composite by carbonization, and it is preferable to use pitch, polymer, or organic compound materials. In particular, vinyl resins such as polyvinylidene fluoride (PVDF) and polyvinyl chloride (PVC), conductive polymers such as polyaniline (PAn), polyacetylene, polypyrrole, polythiophene, and the like The conductive polymer may be a conductive polymer doped with hydrochloric acid or the like. Carbon precursors are particularly preferred polyvinylchloride (PVC).

The heat treatment temperature may be used in the range of 500 ° C to 3000 ° C, preferably in the range of 700 ° C to 1200 ° C, and more preferably in the range of 800 ° C to 1000 ° C.

After the heat treatment step, may further comprise the step of grinding and classifying the obtained material.

The binder is not limited, but various adhesive properties such as fluorinated polymer materials such as polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMS, carbonxymethylcellulose), and styrene-butadiene rubber (SBR) It is advisable to use at least one material with

A conductive material may be added and used for the purpose of improving the electron conductivity of the negative electrode active material, and mainly a fine powder carbon-based material may be used and a material of metallic or conductive polymer may be used. As the carbon-based fine powder, at least one of various materials such as carbon black, carbon nanotube, carbon nanofiber and graphite fine powder can be used. Both composite walls can be used.

A solvent may be used for slurrying, and a high dielectric constant organic solvent such as NMP (N-methyl pyrrolidone) or DMF (dimethyl formamide) may be used, and water (H 2 O) may also be used as a solvent. It can be used and there is no limitation on the solvent.

The negative electrode active material is prepared as a slurry together with a binder, a conductive material, and the like to prepare an electrode. Among the negative electrode active materials, conductive materials and bonding materials forming the electrode solids, the weight percent of the negative electrode active materials can be used in the range of 99% to 60% by weight, and the weight percentage of the conductive material can be used in the range of 0% to 30% by weight. And the weight percent of the bonding material can be used in the range of 1 weight percent to 40 weight percent.

In particular, the anode for a lithium secondary battery according to the present invention is manufactured by performing a reduction pretreatment process to be described later, and thus has characteristics that cannot be seen in a non-carbon-based active material, that is, an initial coulombic efficiency is 85% or more, in particular, 90% or more. A more detailed description will be described later in the manufacturing method.

Hereinafter, an electrode manufacturing method according to the present invention will be described. Description is abbreviate | omitted about the matter described in description of said negative electrode for lithium secondary batteries.

Electrode manufacturing method according to the present invention comprises the steps of preparing an electrode slurry by mixing a component including an active material, a binder and a conductive material containing a non-carbon compound, applying the electrode slurry to a current collector, drying to form an electrode, the Characterized in that it comprises the step of pre-treating the formed electrode. Herein, the active material, the binder, and the conductive material are not particularly limited, and the active material, the binder, and the conductive material may be used.

First, an electrode slurry is prepared.

Among the negative electrode active materials, conductive materials and bonding materials forming the electrode solids, the weight percent of the negative electrode active materials can be used in the range of 99% to 60% by weight, and the weight percentage of the conductive material can be used in the range of 0% to 30% by weight. And the weight percent of the bonding material can be used in the range of 1 weight percent to 40 weight percent. A mixture of the above conditions is mixed using a mixer to prepare an electrode slurry.

Next, the prepared electrode sludge is applied onto a thin copper current collector and dried to prepare an electrode plate. The method for producing the electrode plate from the electrode slurry may use a method commonly used in the art and is not limited.

Next, the formed electrode is subjected to reduction pretreatment, followed by oxidation pretreatment as necessary.

2 is a diagram showing an example of a reduction pretreatment and an oxidation pretreatment method. The prepared electrode plate is treated according to one process diagram as shown in FIG. 2 to produce a negative electrode plate having high coulombic efficiency, high specific capacity and long lifetime.

In the process of FIG. 2, the reduction pretreatment process shown in FIG. 2 comprises a lithium counter electrode for reduction pretreatment of ② and a lithium reference electrode for reduction pretreatment of ④ in an electrolytic cell containing an organic electrolyte solution for reduction pretreatment of ③ and according to a continuous process. The electrode plate of ① is supplied to a reduction pretreatment electrolyzer. The lithium reference electrode for reduction pretreatment (4) is used for the purpose of more accurately measuring the potential of the electrode plate, and in some cases, the electrode of the electrode may be used as the potential of the electrode plate. In this case, ② serves as a function of the counter electrode and the reference electrode. Charging of the electrode plate during the reduction pretreatment may be performed on the basis of voltage or electric quantity. The residence time in the electrolyzer is important as a major factor affecting the diffusion of lithium ions into the negative electrode active material. As a method of adding or subtracting the electrolytic cell retention time, a method of adjusting the speed of the electrode plate progression, a method of adjusting the length of the electrolytic cell, a method of installing an additional roller inside the electrolytic cell, and the like can be used. You can add or subtract the plate immersion time.

In the process of FIG. 2, the pre-reduction step may be performed by shorting the electrode plate of ① and the lithium counter electrode for reduction pretreatment of ② to be charged at a constant voltage of 0 V without controlling the voltage or electricity of the reduction pretreatment process of the partial process. .

In the process of FIG. 2, the oxidation pretreatment process of the Z partial process is similar to the reduction pretreatment process of the Z partial process, and is an electrolytic cell process for the pretreatment of the oxidation (discharge) process to increase the potential of the electrode. Various electrochemical conditions such as the potential of the oxidation process and the retention time can be adjusted for the purpose of the electrode manufacturer.

In the process of Figure 2, the partial process is configured for the purpose of washing the electrolyte salt contained in the electrode, and may be composed of an organic solvent constituting the electrolyte or one or more of these organic solvents, within a range that does not damage the electrode Any solvent can be used.

In the process of FIG. 2, the chopped partial process may transition to the chopped partial process without cleaning, depending on the purpose of the electrode manufacturer.

In the process of Figure 2, the partial process is for drying the electrode, the drying temperature and the retention time is configured according to the purpose of the electrode manufacturer.

In the process of FIG. 2, the oxidation pretreatment process shown in FIG. 2 is a part necessary for manufacturing the electrode in a continuous process separately from the reduction pretreatment process. The oxidation pretreatment of ㉡ consists of a lithium counter electrode for oxidation pretreatment ⑤ and a lithium reference electrode for oxidation pretreatment ⑥ in an electrolytic cell containing an organic electrolytic solution for reduction pretreatment of an electrolytic cell ③. It is supplied from the pretreatment electrolyzer to the oxidation pretreatment tank. The lithium reference electrode for oxidation pretreatment of ⑥ is used for the purpose of more accurately measuring the potential of the electrode plate, and in some cases, the electrode of the electrode ⑤ may be used. In this case ⑤ also serves as the counter electrode and reference electrode of the oxidation pretreatment. The discharge of the electrode plate during the oxidation pretreatment is performed on a voltage basis. As a method of adding or subtracting the retention time for the electrolyzer, a method of adjusting the speed of the electrode plate progression, a method of adjusting the length of the electrolyzer, and a method of installing an additional roller inside the electrolyzer may be used. By this, the immersion time of the electrode plate can be reduced.

세정 cleaning tank is for cleaning the electrolyte solution impregnated with the electrode. It uses an organic solvent, consists of a low boiling point organic solvent constituting the organic electrolyte solution, and can be used as a cleaning solution by selecting a solvent in a range that does not dissolve the binder. .

The drying tank of ㉣ is a process of drying the organic solvent impregnated to the electrode.

In the case of producing an electrode in a battery factory and continuously introducing it into a battery manufacturing process, the washing tank process of the tank and the drying tank process of the tank can be omitted.

In addition, when the pretreated electrode plate is stored in a dry space that faithfully manages moisture and is used for battery manufacturing, the cleaning process can be omitted.

FIG. 3 is an example method of eliminating oxidation pretreatment in the process of FIG. 2. The process used in the process of Figure 2 is a process of solving the irreversible specific amount through the electrochemical reduction process and the oxidation process. In Figure 3 is a method of reducing the electrode plate by charging the amount of electricity corresponding to the irreversible specific amount. The result of this method is the same as the result of FIG. In order to produce an electrode plate in a continuous process, after charging the amount of electricity corresponding to the irreversible specific amount, the potential of the electrode plate reaching the potential equilibrium is obtained, and constant voltage charging is performed on the pole plate of continuous transfer to this potential.

This electrode pretreatment process can increase the initial coulombic efficiency of not only the silicon oxide anode, but also all kinds of cathodes, and can express the specific amount at a high value from the beginning. In addition, the pretreatment process of the present invention is not limited to the negative electrode, and can be easily applied to the improvement of one process even for the positive electrode having low initial coulombic efficiency or poor initial specific capacity expression characteristics. Therefore, the electrode manufacturing method of the present invention can be applied not only to the negative electrode but also to the manufacturing method of the positive electrode.

Hereinafter, the lithium secondary battery of the present invention will be described.

The lithium secondary battery of the present invention is a lithium secondary battery having a negative electrode, a positive electrode and an ion conductor, wherein the negative electrode is the above-described negative electrode.

In addition, the lithium secondary battery of the present invention is a lithium secondary battery having a negative electrode, a positive electrode and an ion conductor, at least one of the negative electrode and the positive electrode is manufactured by the electrode manufacturing method described above, the initial coulombic efficiency is 85% or more, In particular, the lithium secondary battery is characterized in that more than 90%.

The lithium secondary battery according to an embodiment of the present invention may further include a negative electrode active material known in the art, in addition to the above-described negative electrode active material. That is, the present invention is not limited thereto, and may further include lithium metal, carbon, graphite, silicon and tin, and alloys and compounds thereof. Since the negative electrode active material and the negative electrode plate have been described above in detail, description thereof will be omitted.

1 shows a lithium secondary battery 1 which is an embodiment of the present invention. The lithium secondary battery 1 includes a negative electrode 2, an electrode 3, a separator 4 disposed between the negative electrode 2 and the positive electrode 3, the negative electrode 2, the positive electrode 3, and the separator 4. ), The ion conductor impregnated in the ()), the battery container (5), and the sealing member (6) for sealing the battery container (5) as a main portion. The shape of the lithium secondary battery illustrated in FIG. 1 may be in a cylindrical shape, but also in various shapes such as a cylindrical shape, a square shape, a coin shape or a sheet shape.

The positive electrode 3 is provided with a positive electrode mixture composed of a positive electrode active material, a conductive material and a binder. As the cathode active material, a compound capable of reversibly intercalating / deintercalating lithium can be used with various materials such as LiMn ₂ O ₄ , LiCoO ₂ , LiFePO ₄ , and LiNiO ₂ . Can be.

As the separator, an olefin porous film such as polyethylene or polypropylene can be used.

The ion conductor is propylene carbonate (hereinafter referred to as PC), ethylene carbonate (hereinafter referred to as EC), butylene carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyl tetrahydrofuran, γ-butyrolactone, and dioxolane as electrolytes. , 4-methyldioxolane, N, N-dimethylformamide, dimethylacetoamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, dimethyl carbonate (hereinafter , DMC), ethyl methyl carbonate (hereinafter EMC), diethyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, ethyl butyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, diethylene glycol, dimethyl ether, etc. To an aprotic solvent or a mixed solvent of two or more of these solvents, LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ , LiPF ₆ , LiBF ₄ , LiClO ₄ , LiBOB, LiN can be used that prepared by dissolving a mixture of the electrolyte alone or in combination of two or more composed of a lithium salt such as a _{(SO 2 C 2 F 5)} 2.

In addition, a polymer solid electrolyte may be used instead of the electrolyte solution. In this case, it is preferable to use a polymer having high ion conductivity with respect to lithium ions, and polyethylene oxide, polypropylene oxide, polyethyleneimine and the like can be used. The solvent and the solute may be added to the polymer of to form a gel.

Non-carbon based base with high coulombic efficiency, high specific capacity, and excellent cycle life characteristics, manufactured by electrode active material and developed material through composite and heat treatment process using silicon oxide based material A new negative electrode was developed, and the results of electrochemical characterization showed that it is excellent as a negative electrode of a lithium secondary battery.

In addition, the lithium secondary battery having the negative electrode active material and the negative electrode plate according to the present invention has a smooth electronic conductivity by the carbon material-based sponge network, and the silicon-based material charge and discharge proceeds in the nano-domain range, thereby buffering the volume expansion to improve the performance of the battery This is significantly improved.

Hereinafter, the present invention will be described in detail through examples. However, the following examples are only preferred embodiments of the present invention and are not intended to limit the scope of rights defined by the claims.

<Example 1>

A composite was prepared by ball milling a mixture of silicon monoxide and graphite in a 5: 5 weight ratio with a stainless steel ball (2 grams / ball) for 24 hours at 350 revolutions per minute in an inert atmosphere of argon using a ball mill. The composite of silicon and graphite was heat-treated at 900 ° C. for 1 hour in an inert atmosphere of argon, and Fig. 4 shows the crystal structure characteristics of silicon oxide and graphite and the material for this example.

Thereafter, an electrode slurry was prepared using a mixture of 85% by weight of the negative electrode active material according to the present invention, 15% by weight of the PVDF binder, and ethylenepyrrolidone as a solvent. The prepared electrode sludge was applied onto a thin copper current collector and dried to prepare an electrode plate.

The prepared electrode plate was treated according to one process diagram as shown in FIG. 2 to finally prepare a negative electrode plate. Here, the reduction pretreatment voltage was 0V, the oxidation pretreatment voltage was 1.5V, and reduction pretreatment was performed at 0V for 10 hours by a constant voltage process.

5 and 6 show the charge-discharge potential change and the specific capacity change according to the cycle for the case of reducing pre-treatment for 10 hours at 0V in the constant voltage process after charging to 0V in the constant current process. The required amount of reduction pretreatment was 1770 mAh / g, and the discharge pretreatment of oxidative pretreatment was 786 mAh / g. The cumulative irreversible cost up to 4 times was 1246 mAh / g and the cumulative irreversible up to 1 time was 1132 mAh / g. The adoption of the constant current and constant voltage process resulted in high discharge (oxidation) cost from the initial pretreatment cycling to 786 mAh / g, and showed a high value of 874 mAh / g in one cycle. The discharge of the first charge-discharge process (two charge-discharge) after pretreatment was 874 mAh / g and the coulomb efficiency was 85%.

<Example 2>

In Example 1, it was carried out in the same manner except that the reduction pretreatment at 0 V for 24 hours in a constant voltage process.

7 and 8 show the charge-discharge potential change and the specific capacity change according to the cycle for the case of reducing pretreatment at 0V for 24 hours in the constant voltage process after charging to 0V in the constant current process. The required amount of reduction pretreatment was 1700 mAh / g, and the discharge pretreatment of oxidation pretreatment was 765 mAh / g. The pretreatment coulombic efficiency was 45% and the initial pretreatment irreversible specific capacity was 935 mAh / g. The cumulative irreversible cost up to four times was 1155 mAh / g and the cumulative irreversible up to one time was 1017 mAh / g. The adoption of the constant current and constant voltage process resulted in high discharge (oxidation) cost of 765 mAh / g from the initial pretreatment cycling, and a high value of 747 mAh / g in one cycle.

<Example 3>

In Example 1, it was carried out in the same manner except that the reduction was pretreated for 48 hours at 0 V in a constant voltage process.

9 and 10 show changes in specific charge and discharge potentials and specific capacities according to cycles when charging to 0V in a constant current process and then reducing pretreatment for 48 hours at 0 V in a constant voltage process. The required amount of reduction pretreatment was 2068 mAh / g, the discharge specificity of oxidation pretreatment was 949 mAh / g, pretreatment coulombic efficiency was 46% and pretreatment irreversible specific capacity was 1119 mAh / g. The cumulative irreversible cost up to four times was 1216 mAh / g and the cumulative irreversible up to one time was 1166 mAh / g. With the adoption of the constant current and constant voltage process, the discharge (oxidation) cost has been high from the initial cycling to 949 mAh / g, and it was possible to immediately show the high value of 786 mAh / g in the single cycling.

As described above, the adoption of the pretreatment process of the constant voltage charging for 10 hours, 24 hours, and 48 hours resulted in high discharge (oxidation) specific capacities from the beginning and most of the irreversible specific capacities were eliminated by the initial pretreatment.

<Example 4>

In Example 1, it was carried out in the same manner except that the reduction pre-treatment to 0V with a constant current without the charging process of the constant voltage.

11 and 12 illustrate changes in charge and discharge potentials and specific amounts of cycles according to cycles for reduction pretreatment up to 0 V with a constant current. Reduction pretreatment required 1139 mAh / g, oxidative pretreatment discharge 568 mAh / g, pretreatment coulombic efficiency 50% and initial irreversible specific capacity 571 mAh / g. The irreversible amount of electricity was shown up to 4 to 5 cycles. The cumulative irreversible cost up to 4 times was 789 mAh / g and the cumulative irreversible up to 10 times was 859 mAh / g. The initial discharge (oxidation) specific capacity was 568 mAh / g, but gradually increased and recovered, indicating 796 mAh / g at 9 times. The irreversible specific capacity was not completely solved at the initial charging and discharging. Rather, the results were poor and there is room for improvement.

The results of the constant voltage pretreatment and the constant current-constant voltage pretreatment for Examples 1 to 4 are summarized in Table 1, and are shown in Tables 13 to 17 by using the results of these Table 1 by category. .

TABLE 1

 Cycle count characteristics Pretreatment process One 2 3 4 5 6 7 8 9 Constant current pretreatment Reduced Electricity (mAh / g) 1139 834 830 819 810 800 801 813 799 809 Oxidation amount (mAh / g) 568 722 777 788 788 783 786 800 787 796 Coulomb Efficiency (%) 50 87 94 96 97 98 98 98 99 98 Irreversible specific capacity (mAh / g) 571 112 53 31 22 17 15 13 12 12 Cumulative Reversible Specific Capacity (mAh / g) 571 683 736 768 789 806 821 835 846 859 Constant current 10 hours constant voltage pretreatment Reduced Electricity (mAh / g) 1769 1023 919 876 843 809 785 771 755 742 Oxidation amount (mAh / g) 786 874 867 841 816 786 772 758 742 729 Coulomb Efficiency (%) 44 85 94 96 97 97 98 98 98 98 Irreversible specific capacity (mAh / g) 983 149 52 35 27 22 13 13 13 13 Cumulative Reversible Specific Capacity (mAh / g) 983 1132 1184 1219 1246 1268 1281 1294 1308 1320 Constant Current 24 Hour Constant Voltage Pretreatment Reduced Electricity (mAh / g) 1700 828 853 809 776 776 777 760 740 734 Oxidation amount (mAh / g) 765 747 764 780 756 760 760 743 727 721 Coulomb Efficiency (%) 45 90 90 96 97 98 98 98 98 98 Irreversible specific capacity (mAh / g) 935 82 89 29 20 16 17 17 13 13 Cumulative Reversible Specific Capacity (mAh / g) 935 1017 1106 1135 1155 1171 1188 1205 1217 1231 Constant Current 48 Hour Constant Voltage Pretreatment Reduced Electricity (mAh / g) 2068 833 767 738 733 719 699 685 681 678 Oxidation amount (mAh / g) 949 786 746 724 719 705 687 676 672 671 Coulomb Efficiency (%) 46 94 97 98 98 98 98 99 99 99 Irreversible specific capacity (mAh / g) 1119 47 21 15 14 14 12 9 9 7 Cumulative Reversible Specific Capacity (mAh / g) 1119 1166 1187 1202 1216 1230 1243 1252 1261 1268 Constant Current 1100 mAh / g Pretreatment Reduced Electricity (mAh / g) 1100 569 932 952 922 Oxidation amount (mAh / g) 0 758 822 873 874 Coulomb Efficiency (%) - 133 92 95 Irreversible specific capacity (mAh / g) 1100 -189 110 79 48 Cumulative Reversible Specific Capacity (mAh / g) 1100 911 1021 1100 1148

Figure 13 shows the change in the reduction (discharge) specific capacity according to the pretreatment conditions, with the same constant current reduction pretreatment conditions, the reduction specific capacity increased with the increase of the constant voltage reduction pretreatment time. This is the result of the electrode is reduced more by the insertion of lithium continuously in the constant voltage process.

14 shows the oxidation (discharge) specific capacity. In the case of using only the constant current process (constant voltage 0 hours), the specific characteristic initially shows a low specific capacity and increases with the increase of the cycle, but by adopting the constant voltage process, a high specific capacity can be exhibited from the beginning. In the case of constant voltage charging for 48 hours, the initial low specific-capacity characteristics could be completely eliminated and adjusted so that the initial specific-capacity value would be the maximum value.

From the result of the constant voltage reduction pretreatment, not only the initial specific capacity characteristic of the electrode material can be controlled, but also the electrode having high coulombic efficiency characteristics can be manufactured by eliminating the irreversible specific amount by the pretreatment process.

15 shows the change according to the number of cycles of the coulombic efficiency, and FIG. 16 shows the irreversible specific capacity according to the number of cycles. In the constant voltage pretreatment, the irreversible specific cost was 571 mAh / g, but with the introduction of the constant voltage pretreatment process, the irreversible cost was increased to 980 ~ 1120 mAh / g.

17 shows the cumulative irreversible specific capacity according to the progress of the charge / discharge cycle.

As shown in FIG. 16 and FIG. 17, the total irreversible specific capacity level of the electrode can be obtained. In the case of the silicon oxide based electrode illustrated in the present invention, the level is 1000 to 1300 mAh / g. FIG. 18 and FIG. 19 show the results of the reduction pretreatment of 1100 mAh / g according to the pretreatment process shown in FIG. 3. Specific capacities for the first reduction and oxidation process were 569 mAh / g and 758 mAh / g, with coulombic efficiency of 133%, irreversible specific capacity of -189 mAh / g, and cumulative irreversible specific capacity up to 1, 911 mAh / g. .

18 and more specifically, after reducing pretreatment at 1100 mAh / g at 48 hours after the reduction pretreatment process shown in FIG. 20, the potential was 60 mV and the potential was continuously maintained for 48 hours. After 48 hours, it showed an increase of 400 mV and a tendency to continuously increase. This indicates that the chemical potential has not reached equilibrium up to the inside of the electrode material.

18 and 19 show that since the electrode is not sufficiently reduced pretreatment up to 0 V, the material property indicating irreversibility is not completely solved, and thus the coulombic efficiency increases gradually with cycling. The coulombic efficiency of the first process at 133%, which is more than 100%, is a consequence of this unresolved irreversible nature.

The irreversible characteristics of the unresolved properties are solved harmoniously by naturally interacting with the positive electrode without artificial manipulation due to charge and discharge cycling after battery construction.

The use of the reduction pretreatment process according to FIGS. 18 and 19 alone can produce electrodes of high initial coulombic efficiency and high initial oxidation (discharge) specific capacity, and further improves electrode productivity by adopting and optimizing the process more concisely. can do.

According to the comparison of the reduction pretreatment process by the constant current and the constant current-constant voltage method as described above, by employing the constant current-constant voltage process together with the detailed description of the process shown in FIG. ) It can be seen that the specific amount can be expressed stably from the beginning.

1 is an example of configuration diagram of a rechargeable lithium battery according to one embodiment of the present invention;

2 is a manufacturing process diagram of a non-carbon-based material-based high-efficiency cathode according to an embodiment of the present invention,

3 is a manufacturing process diagram of a non-carbon-based material-based high-efficiency cathode according to an embodiment of the present invention,

4 is a XRD diffraction analysis of the silicon oxide-based negative active material according to an embodiment of the present invention,

5 is a graph showing a potential and a current with respect to a time of a constant voltage pretreatment process for 10 hours following a constant current pretreatment process of a silicon oxide electrode according to one embodiment of the present invention;

6 is a graph showing specific amounts and coulombic efficiencies of reduction pretreatment and oxidation pretreatment for the number of cycles of the constant voltage pretreatment for 10 hours following the constant current pretreatment of the silicon oxide electrode according to an embodiment of the present invention;

7 is a graph showing a potential and a current with respect to a time of a constant voltage pretreatment process for 24 hours following a constant current pretreatment process of a silicon oxide electrode according to an embodiment of the present invention;

8 is a graph showing specific amounts and coulombic efficiencies of reduction pretreatment and oxidation pretreatment with respect to the number of cycles of the constant voltage pretreatment followed by the constant current pretreatment of the silicon oxide electrode according to the embodiment of the present invention;

9 is a graph showing a potential and a current with respect to a time of a constant voltage pretreatment process for 48 hours following a constant current pretreatment process of a silicon oxide electrode according to one embodiment of the present invention;

10 is a graph showing specific amounts and coulombic efficiencies of reduction pretreatment and oxidation pretreatment for the cycle number of the constant voltage pretreatment for 48 hours following the constant current pretreatment of the silicon oxide electrode according to the embodiment of the present invention;

11 is a graph showing the potential of the specific amount of the constant current pretreatment process of the silicon oxide electrode according to an embodiment of the present invention,

12 is a graph showing specific amounts and coulombic efficiency of reduction pretreatment and oxidation pretreatment for the number of cycles of the constant current pretreatment of a silicon oxide electrode according to an embodiment of the present invention;

13 is a graph showing the change in the reduction (charging) specific capacity with respect to the cycle number with respect to the change in the pretreatment condition of the present invention;

14 is a graph showing the change in oxidation (discharge) specific capacity with respect to the cycle number with respect to the change in pretreatment conditions of the present invention;

15 is a graph showing the coulombic efficiency as a ratio of the reduction (charge) specific capacity and the oxidation (discharge) specific capacity with respect to the change of pretreatment conditions of the present invention with respect to the cycle number;

16 is a graph showing the number of cycles of the irreversible specific amount, which is the difference between the reduction (charge) specific capacity and the oxidation (discharge) specific amount, with respect to the change in the pretreatment condition of the present invention;

FIG. 17 is a graph showing the cumulative irreversible specific amount of the cumulative irreversible specific amount of cycles with respect to the change of pretreatment conditions of the present invention with respect to the number of cycles. FIG.

18 is a graph showing a potential and a current with respect to time when 1100 mAh / g is pretreated in a constant current reduction pretreatment process of a silicon oxide electrode according to an embodiment of the present invention;

19 is a graph showing specific amounts and coulombic efficiency of reduction pretreatment and oxidation pretreatment for the number of cycles when 1100 mAh / g is pretreated in a constant current reduction pretreatment process of a silicon oxide electrode according to an embodiment of the present invention;

20 is an enlarged detailed graph of FIG. 18.

** Description of the main symbols in the drawings *

전 reduction pretreatment electrolyzer

Oxidation pretreatment electrolyzer

㉢ cleaning tank

㉣ Drying tank

① Electrode plate

② Lithium counter electrode for reduction pretreatment

③ Organic electrolytic solution for reduction pretreatment

④ Lithium reference electrode for reduction pretreatment

⑤ Lithium counter electrode for oxidation pretreatment

⑥ Reference electrode for oxidation pretreatment

⑦ Electrode plate cleaning tank

⑧ Electrode Plate Drying Tank

Claims (13)

As a negative electrode for a lithium secondary battery comprising a negative electrode active material, a binder and a conductive material containing a non-carbon compound, The non-carbon-based compound is silicon oxide or tin oxide, the initial coulombic efficiency is more than 85%, the initial coulombic efficiency is characterized in that the characteristics obtained by performing an electrochemical reduction pretreatment process. The negative electrode for a lithium secondary battery of claim 1, wherein the non-carbon-based compound is alloyed with graphite. The negative electrode for a lithium secondary battery according to claim 2, wherein the mixing weight ratio of the non-carbon compound and graphite is in the range of 4: 6 to 6: 4. The negative electrode for a lithium secondary battery of claim 1, wherein the silicon oxide has a range of x to 0.5 to 1.5 in SiOx. delete Preparing an electrode slurry by mixing components including an active material including a non-carbon compound, a binder, and a conductive material; Coating and drying the electrode slurry on a current collector to form an electrode; And Electrochemical reduction pre-treatment of the formed electrode; electrode manufacturing method comprising a. The method of claim 6, further comprising electrochemical oxidation pretreatment of the electrochemical reduction pretreated electrode. The method of claim 6, wherein the non-carbon compound is alloyed with graphite. The method of claim 6, wherein the electrochemical reduction pretreatment is performed by immersing and charging the electrode in a range of 10 to 60 hours in an electrolytic cell equipped with a counter electrode for reduction pretreatment. The method of claim 7, wherein the electrochemical oxidation pretreatment is performed by immersing and discharging the reduced electrode in an electrolytic cell equipped with a counter electrode for oxidation pretreatment. The method of claim 9, wherein in the electrochemical reduction pretreatment step, the electrode for reduction pretreatment and the prepared electrode are short-circuited to reduce pretreatment. The method of claim 6, wherein the electrochemical reduction pretreatment is performed at a constant voltage of 0 V within a range of 10 to 60 hours, after which the voltage is 0 V through a constant current. In a lithium secondary battery having a negative electrode, a positive electrode and an ion conductor, The negative electrode is a lithium secondary battery, characterized in that the negative electrode of any one of claims 1 to 4, or an electrode manufactured by the manufacturing method of any one of claims 6 to 12.

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