KR20230057081A - Secondary battery comprising a anodic active material comprising contorted hexabenzocoronene derivative - Google Patents

Abstract

The present invention relates to a secondary battery comprising: a negative electrode including a negative electrode active material for a secondary battery including a compound represented by Chemical Formula 1; a conductive material including a component having conductivity without inducing chemical changes to the battery; a binder including a component for promoting aggregation between the negative electrode active material and the conductive material or aggregation between the negative electrode active material and a current collector; and a solvent for dispersing the negative electrode active material, the conductive material, and the binder; a positive electrode; a separator disposed between the negative electrode and the positive electrode; and an electrolyte including lithium, sodium, or potassium. According to the present invention, the secondary battery includes the negative electrode active material for a secondary battery including the compound represented by Chemical Formula 1, so that the secondary battery may be used as a universal secondary battery applicable to a sodium secondary battery and a potassium secondary battery as well as a lithium secondary battery.

Description

Secondary battery comprising a negative electrode active material for secondary batteries containing a bent hexabenzocoronene derivative

The present invention relates to a secondary battery including an anode active material for a secondary battery including a bent hexabenzocoronene derivative. Specifically, the present invention relates to a secondary battery including a universal negative electrode that can be applied not only to a lithium ion battery but also to a sodium ion battery and a potassium ion battery by using a chlorine-substituted bent hexabenzocoronene derivative as an anode active material for a secondary battery.

With the rapid development of electronics, communication, and computer industries, camcorders, mobile phones, notebook PCs, etc. are making remarkable progress, and high energy density and stable output of batteries are required as a power source to drive portable electronic devices. At the same time, an inexpensive and simple process in terms of productivity is also required. Among these batteries, lithium secondary batteries are being most actively developed and are widely applied to portable electronic devices.

A lithium secondary battery is a battery that essentially includes a positive electrode, a negative electrode, and an electrolyte, and is characterized in that lithium cations are reversibly intercalated or deintercalated in an electrode to perform charging and discharging. In the process of charging and discharging, lithium cations play a role of forming charge neutrality with electrons entering the electrode through the current collector, and serve as a medium to store electrical energy in the electrode.

A cathode of a lithium secondary battery refers to an electrode into which lithium cations are inserted during a discharge process of the lithium secondary battery. Since electric charges are moved to the anode through an external wire with the insertion of lithium cations, the cathode is characterized in that it is reduced during the discharging process. Typically, a transition metal oxide is included in the positive electrode of a lithium secondary battery. The transition metal oxide included in the cathode is otherwise referred to as a cathode active material, and the cathode active material generally has a repeating and three-dimensional structure.

Conversely, an anode of a lithium secondary battery refers to an electrode from which lithium cations are desorbed during a discharge process of the lithium secondary battery. Since the charge escapes through the external wire along with the desorption of lithium cations, the negative electrode is characterized in that it is oxidized during the discharging process. Typically, the negative electrode of a lithium secondary battery includes lithium metal, carbon material, non-carbon material, etc., and the carbon material included in the negative electrode is otherwise referred to as a negative electrode active material.

In order to maximize the performance of a lithium secondary battery, the key conditions that an anode active material should generally have are as follows. ⅰ) The amount of electricity that can be stored per unit weight should be high, and ii) the density of the negative electrode active material per unit volume should be high. In addition, iii) the structural change due to the intercalation and desorption of lithium ions should be small. This is because when the change in structure is large, strain is accumulated in the structure as charging and discharging proceeds, and as a result, irreversible intercalation and deintercalation of lithium ions may be induced.

However, lithium is a rare metal, and its reserves are limited. As an alternative, secondary batteries using sodium or potassium with large reserves are being developed. Accordingly, there is a need to develop an anode active material for an alkali ion battery to which both sodium and potassium, which are larger in size than lithium ions, can be applied.

Republic of Korea Patent Publication No. 10-2019-0030798

The present application relates to a secondary battery for solving the problems of the prior art, and can be applied to a sodium secondary battery and a potassium secondary battery as well as a lithium secondary battery using chlorine-substituted hexabenzocoronene as an anode active material. The first purpose is to include a universal cathode with

A secondary battery of the present invention for achieving the above technical problem is a negative electrode active material for a secondary battery including a compound represented by Formula 1; A conductive material containing a component having conductivity without causing chemical change in the battery; a binder including a component that promotes aggregation between the anode active material and the conductive material or aggregation between the anode active material and a current collector; and a solvent dispersing the negative electrode active material, the conductive material, and the binder; A cathode comprising a; anode; a separator disposed between the cathode and anode; and an electrolyte solution containing lithium, sodium or potassium; and the compound represented by Chemical Formula 1 is characterized in that it exhibits a crystal phase having symmetry P2 ₁ /n.

[Formula 1]

The positive electrode includes a positive electrode active material capable of intercalating and deintercalating lithium ions, and the positive electrode may be lithium, sodium, or potassium, but is not limited thereto.

The compound represented by Formula 1 may be stacked at intervals of 14.0 Å to 15.5 Å, but is not limited thereto.

The secondary battery may have a reversible capacity of 150 mAh/g to 400 mAh/g when the current density is 0.1 A/g, but is not limited thereto.

The reversible capacity of the secondary battery may be maintained at 80% or more even after 1,000 cycles, but is not limited thereto.

The method of manufacturing a negative electrode for a secondary battery of the present invention includes preparing a negative electrode active material for a secondary battery including the compound represented by Chemical Formula 1; The negative electrode active material for a secondary battery, a conductive material containing a component having conductivity without causing chemical change in a battery, and a component that promotes aggregation between the negative electrode active material and the conductive material or between the negative active material and a current collector preparing a slurry for an anode by dispersing a binder to a solvent; drying the slurry for the negative electrode; and annealing the dried slurry for a negative electrode.

The annealing may be performed at a temperature of 200° C. to 400° C., but is not limited thereto.

The negative electrode active material for a secondary battery of the present invention includes the compound represented by Chemical Formula 1, and the compound represented by Chemical Formula 1 is characterized in that it exhibits a crystalline phase having symmetry P2 ₁ /n.

Compounds represented by Formula 1 may be stacked at intervals of 14.0 Å to 15.5 Å, but are not limited thereto.

The above-described problem solving means are merely exemplary and should not be construed as intended to limit the present disclosure. In addition to the exemplary embodiments described above, additional embodiments may exist in the drawings and detailed description of the invention.

The disclosed technology may have the following effects. However, since a specific embodiment does not mean that all or only the following effects must be included, the scope of rights of the disclosed technology should not be construed as being limited thereby.

According to the above-described problem solving means of the present application, the secondary battery according to the present application includes a negative active material for a secondary battery including a compound represented by Formula 1, and is universal applicable to sodium secondary batteries and potassium secondary batteries as well as lithium secondary batteries. It can be used as a secondary battery.

In particular, chlorine is the most effective among halogen elements to be used as a negative electrode for a universal secondary battery, and a bent hexabenzocoronene derivative substituted with chlorine shows particularly high performance. For example, in the case of bent hexabenzocoronene derivatives substituted with fluorine, they can be used only for lithium and sodium secondary electricity.

In addition, the secondary battery of the present application achieves high rate characteristics with a reversible capacity of 150 mAh/g to 400 mAh/g when the current density is 0.1 A/g, and the reversible capacity is maintained at 80% or more even after 1,000 cycles, resulting in stable characteristics indicate

1 is a diagram of an anode active material according to an embodiment of the present disclosure.
2 is a grazing-incidence wide-angle X-ray diffraction scattering (GIWAXS) graph according to the annealing temperature of the negative electrode manufactured according to the present embodiment.
3 is a graph showing a constant current charge-discharge profile at a current density of 1 A/g to 20 A/g of a lithium secondary battery (Example 1) manufactured according to this embodiment.
4 is a graph showing rate characteristics of a lithium secondary battery (Example 1) manufactured according to this embodiment.
5 is a graph showing charge-discharge cycles at a current density of 8 A/g of a lithium secondary battery (Example 1) manufactured according to this embodiment, and the inset shows the charge and discharge cycles at the first, 100th, and 1,000th cycles. - is the discharge profile.
6 is a CV (cyclic coltammetry) graph measured at a scan rate of 0.1 mV / s to 1.0 mV / s of a lithium secondary battery (Example 1) manufactured according to this embodiment, and the inset shows log (ν) and log It is a graph showing the ratio of (i _p ).
7 is a graph showing a constant current charge-discharge profile at a current density of 0.02 A/g to 4 A/g of a sodium secondary battery (Example 2) manufactured according to this embodiment.
8 is a graph showing rate characteristics of a sodium secondary battery (Example 2) manufactured according to this embodiment.
9 is a graph showing charge-discharge cycles at a current density of 1 A/g of a sodium secondary battery (Example 2) manufactured according to this embodiment.
10 is a CV (cyclic coltammetry) graph measured at a scan rate of 0.1 mV/s to 1.0 mV/s of a sodium secondary battery (Example 2) prepared according to this embodiment, and the inset shows log (ν) and log It is a graph showing the ratio of (i _p ).
11 is a graph showing the capacity contribution according to the scan rate of 0.1 mV/s to 1.0 mV/s of the sodium secondary battery (Example 2) manufactured according to this embodiment.
12 is a graph showing a constant current-charge/discharge profile at a current density of 0.1 A/g to 2.0 A/g of a potassium secondary battery (Example 3) prepared according to this embodiment.
13 is a graph showing rate characteristics of a potassium secondary battery (Example 3) manufactured according to this embodiment.
14 is a graph showing charge-discharge cycles at a current density of 1.0 A/g of a potassium secondary battery (Example 3) manufactured according to this embodiment.
15 is a CV (cyclic coltammetry) graph measured at a scan rate of 0.1 mV/s to 1.0 mV/s of a potassium secondary battery (Example 3) prepared according to this embodiment, and the inset shows log (ν) and log It is a graph showing the ratio of (i _p ).
16 is a graph showing the capacity contribution according to the scan rate of 0.1 mV / s to 1.0 mV / s of the potassium secondary battery (Example 3) manufactured according to this embodiment.

Since the present invention can make various changes and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, or substitutes included in the spirit and technical scope of the present invention.

In describing each figure, like reference numbers are used for like elements. Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are only used for the purpose of distinguishing one component from another.

For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention. The term "and/or" includes any combination of a plurality of related listed items or any of a plurality of related listed items.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

Terms such as those defined in commonly used dictionaries should be interpreted as having meanings consistent with the meanings in the context of the related art, and unless explicitly defined in this application, they should not be interpreted in ideal or excessively formal meanings. Should not be.

Throughout the present specification, when a member is referred to as being “on,” “above,” “on top of,” “below,” “below,” or “below” another member, this means that a member is located in relation to another member. This includes not only the case of contact but also the case of another member between the two members.

Throughout the present specification, when a part "includes" a certain component, it means that it may further include other components without excluding other components unless otherwise stated.

As used herein, the terms "about," "substantially," and the like are used in a sense at or close to that number when manufacturing and material tolerances inherent in the stated meaning are given, and are intended to assist in the understanding of this disclosure. exact or absolute figures are used to prevent unfair use by unscrupulous infringers of the stated disclosure. In addition, throughout the present specification, “steps of” or “steps of” do not mean “steps for”.

Throughout the present specification, the term "combination thereof" included in the expression of the Markush form means one or more mixtures or combinations selected from the group consisting of the components described in the expression of the Markush form, and the components It means including one or more selected from the group consisting of.

Hereinafter, a secondary battery including an anode active material for a secondary battery including a bent hexabenzocoronene derivative of the present application will be described in detail with reference to embodiments and examples and drawings. However, the present application is not limited to these embodiments and examples and drawings.

The present application, a negative electrode active material for a secondary battery including a compound represented by Formula 1; A conductive material containing a component having conductivity without causing chemical change in the battery; a binder including a component that promotes aggregation between the anode active material and the conductive material or aggregation between the anode active material and a current collector; and a solvent dispersing the negative electrode active material, the conductive material, and the binder; A cathode comprising a; anode; a separator disposed between the cathode and anode; and an electrolyte solution containing lithium, sodium or potassium, and the compound represented by Chemical Formula 1 relates to a secondary battery exhibiting a crystal phase having symmetry of P2 ₁ /n.

The secondary battery of the present application can be utilized as a universal secondary battery that can be applied to not only lithium secondary batteries but also sodium secondary batteries and potassium secondary batteries, including a negative electrode active material for secondary batteries including the compound represented by Formula 1. The compound represented by Chemical Formula 1 is a derivative of curved hexabenzocoronene, and chlorine is substituted so that hexabenzocoronene forms a contorted structure. The curved structure includes concave surfaces oriented in both directions. Although the dipole moment increases due to the chlorine, the overall dipole moment is close to zero because of the symmetrical structure.

The positive electrode includes a positive electrode active material capable of intercalating and deintercalating lithium ions, and the positive electrode may be lithium, sodium, or potassium, but is not limited thereto.

Negative electrode active materials for application to lithium secondary batteries as well as sodium secondary batteries and potassium secondary batteries must be tunable enough to accommodate lithium ions, sodium ions and potassium ions, and effectively hold intercalated ions. Irreversible insertion and withdrawal must be possible. In the anode active material of the present application, the spacing can be adjusted according to the type of ion to be inserted, and the partial negative charge of chlorine induces strong electrostatic attraction in the interaction with lithium ion, sodium ion, and potassium ion, thereby intercalating and deintercalating ions. easy to

Specifically, although the gap between the hexabenzocoronene derivatives is larger than that of the graphite negative electrode active material, the partial negative charge of the chlorine induces strong electrostatic attraction in the interaction with lithium ions, sodium ions, and potassium ions, is easy to insert and remove.

The compound represented by Formula 1 has a bent structure, and the matrix includes 13 aromatic rings. In addition, the hexabenzocoronene parent can be divided into 7 internal aromatic rings and 6 external aromatic rings corresponding to benzocoronene. In particular, due to steric hindrance such as syn-pentane interaction, an external aromatic ring cannot be co-located with an adjacent external aromatic ring. Specifically, the curved structure of the compound represented by Formula 1 of the present invention includes concave surfaces oriented in both directions. In addition, the dipole moment caused by substitution of electronegative chlorine is canceled due to the symmetrical structure.

In addition, the compound represented by Formula 1 preferably exhibits a crystalline phase having symmetry P2 ₁ /n. By maintaining the crystalline phase of P2 ₁ /n symmetry, the anode active material of the present invention exhibits strong structural stability even when lithium ions, sodium ions, and potassium ions are repeatedly intercalated and released. In addition, since the compound represented by Chemical Formula 1 has a structure in which electronegative substituents are sufficiently exposed and has a small HOMO-LUMO energy gap, it is not charge-discharge by simple diffusion, but a capacitor method such as surface oxidation-reduction. of charge-discharge is possible.

1 is a diagram of an anode active material according to an embodiment of the present disclosure.

Referring to FIG. 1, the curved structure of the compound represented by Formula 1 includes bidirectionally oriented concave surfaces, so that lithium ions, sodium ions, or potassium ions are inserted at two electrically different positions during charging. . As a result, when the compound represented by Formula 1 of the present invention is included as an anode active material, the capacity characteristics of the secondary battery are improved.

The compound represented by Formula 1 may be stacked at intervals of 14.0 Å to 15.5 Å, but is not limited thereto.

The interval may be adjusted according to the intercalated lithium ion, sodium ion or potassium ion.

In addition, the bending angle of the compound represented by Chemical Formula 1 may be adjusted according to the intercalated lithium ion, sodium ion, or potassium ion. Depending on the type of ion, it may be bent at about 10 ° to 20 °.

The secondary battery may have a reversible capacity of 150 mAh/g to 400 mAh/g when the current density is 0.1 A/g, but is not limited thereto.

In addition, the secondary battery can achieve a reversible capacity of 220 mAh/g when the current density is high at 8 A/g.

The reversible capacity of the secondary battery may be maintained at 80% or more even after 1,000 cycles, but is not limited thereto.

The secondary battery of the present application has excellent safety, and its reversible capacity hardly changes even after 1,000 cycles.

The negative electrode active material may be 20 mass% to 90 mass%, for example 30 mass% to 80 mass%, for example 40 mass% to 70 mass% based on the total mass of the negative electrode.

The conductive material is not particularly limited as long as it has conductivity without causing chemical change in the battery, and examples thereof include graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, ketjen black, channel black, farnes black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; conductive tubes such as carbon nanotubes; metal powders such as fluorocarbon, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; Conductive materials such as polyphenylene derivatives may be used. The amount of the conductive material may be greater than or equal to 0.1% by mass and less than or equal to 10% by mass based on the total mass of the negative electrode, and preferably has a lower limit of 0.5% by mass or greater, more preferably greater than or equal to 1.0% by mass.

The binder is not particularly limited as long as it is a component that promotes aggregation between the anode active material and the conductive material or aggregation between the anode active material and the current collector, and polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF- co-HFP), polyvinylidenefluoride, polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, polyimide, carboxymethylcellulose (CMC), starch, hydroxypropyl Cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluororubber, polyacrylic acid Various types of binder polymers such as polyacrylic acid, polymers in which hydrogen is substituted with Li, Na or Ca, or various copolymers may be used. The amount of the binder may be in the range of about 1 part by mass to about 10 parts by mass, for example, about 2 parts by mass to about 7 parts by mass, based on the total mass of the negative electrode active material. When the content of the binder is in the above range, for example, about 1 part by mass to about 10 parts by mass, the strength of the adhesive strength of the negative electrode to the current collector may reach an appropriate level.

The current collector of the metal material is a metal with high conductivity, which can be easily adhered to the slurry of the positive electrode active material, and has high conductivity without causing chemical change in the battery in the voltage range of the battery. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or surface treatment of aluminum or stainless steel with carbon, nickel, titanium, or silver may be used. In addition, the adhesion of the positive electrode active material may be increased by forming fine irregularities on the surface of the current collector. The current collector may be used in various forms such as a film, sheet, foil, net, porous body, foam body, or non-woven fabric body, and may be used by adjusting the thickness according to the purpose of use.

The negative electrode current collector is generally made to have a thickness of 3 μm to 500 μm. The negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical change to the battery, and for example, the surface of copper, stainless steel, aluminum, nickel, titanium, fired carbon, copper or stainless steel. For the surface treatment with carbon, nickel, titanium, silver, etc., an aluminum-cadmium alloy, etc. may be used. In addition, like the positive electrode current collector, fine irregularities may be formed on the surface to enhance the bonding strength of the negative electrode active material, and may be used in various forms such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics.

Binders and conductive materials used in the negative electrode may be those commonly used in the art like the positive electrode. The negative electrode may be prepared by mixing and stirring the negative electrode active material and the additives to prepare a negative electrode active material slurry, and then applying the slurry to a current collector and compressing the negative electrode active material.

The solvent included in the negative electrode may be selectively used according to the type of binder, and organic solvents such as N-methyl pyrrolidone (NMP), dimethyl formamide (DMF), acetone, dimethyl acetamide, isopropyl alcohol, or the like, or water and the like, and these solvents may be used alone or in combination of two or more. The amount of solvent used is sufficient to dissolve and disperse the positive electrode active material, the binder, and the conductive material in consideration of the coating thickness of the slurry and the manufacturing yield. . For example, the concentration of the solid content including the negative electrode active material and, optionally, the binder and the conductive material may be 50% by mass to 95% by mass, preferably 70% by mass to 90% by mass.

As the dispersant, an aqueous dispersant or an organic dispersant such as N-methyl-2-pyrrolidone may be used.

The anode may be prepared using or using a conventional anode known in the art. For example, a positive electrode may be prepared by preparing a slurry by mixing and stirring a positive electrode active material with a solvent, a binder, a conductive material, and a dispersant, applying (coating) the slurry to a current collector of a metal material, compressing the slurry, and then drying the slurry.

The positive electrode may include one selected from the group consisting of LiFePO ₄ , LiNi _0.5 Mn _1.5 O ₄ , LiNiCoAlO ₂ , LiMn ₂ O ₄ , LiCoO ₂ , LiNiCoMnO ₂ , lithium nickel cobalt manganese aluminum, and combinations thereof, It is not limited thereto.

The cathode active material may be a layered compound such as lithium cobalt oxide [LixCoO ₂ (0.5<x<1.3)] or lithium nickel oxide [Li _x NiO ₂ (0.5<x<1.3)] or a compound substituted with an additional transition metal; 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 , or [Li _x MnO ₂ (0.5<x<1.3)]; lithium copper oxide (Li ₂ CuO ₂ ); vanadium oxides such as LiV ₃ O ₈ , LiFe ₃ O ₄ , V ₂ O ₅ , or Cu ₂ V ₂ O ₇ ; Ni site type lithium nickel oxide represented 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, Zn or Ta and x=0.01 to 0.1 or Li ₂ Mn ₃ MO ₈ where M=Fe, Co, Ni, Cu or Zn) lithium manganese composite oxide; LiMn ₂ O ₄ in which Li part of the formula is substituted with an alkaline earth metal ion; disulfide compounds; Fe ₂ (MoO ₄ ) ₃ and the like. Layered compounds such as lithium cobalt oxide [Li _x CoO ₂ (0.5<x<1.3)] or lithium nickel oxide [Li _x NiO ₂ (0.5<x<1.3)] substituted with the additional transition metal include lithium nickel-manganese. - Cobalt oxide is mentioned.

Preferably, the positive electrode includes a positive electrode active material capable of intercalating and deintercalating sodium ions. In the case of a cathode for a sodium secondary battery, the cathode active material is sodium metal as well as an oxide represented by the chemical formula NaM ¹ _a O ₂ such as NaFeO ₂ , NaMnO ₂ , NaNiO ₂ , NaCoO ₂ (provided that M ¹ is at least one transition metal and , 0≤a<1) or a compound represented by NaMn _1-a M ¹ _a O ₂ (where M ¹ is at least one transition metal and 0≤a < 1), the insertion of sodium ions is reversible It may be a compound that occurs as As examples of representative cathode active materials, sodium metal represented by Na, Na[Ni _1/2 Mn _1/2 ]O ₂ , Na _2/3 [Fe _1/2 Mn _1/2 ]O ₂ , and the like; Oxides represented by Na _0.44 Mn _1-a M ¹ _a O ₂ , Na _0.7 Mn _1-a M ¹ _a O _2.05 (provided that M ¹ is at least one transition metal element, and represented by 0≤a<1) oxide; An oxide represented by Na _b M ² _c Si ₁₂ O ₃₀ (provided that M ² is at least one transition metal element, 2≤b≤6 and 2≤c≤5, for example Na ₆ Fe ₂ Si ₁₂ O ₃₀ or Na ₂ Fe ₅ Si ₁₂ O ₃₀ ); ; An oxide represented by Na _d M ³ _e Si ₆ O ₁₈ (provided that M ³ is at least one transition metal element, 3≤d≤6 and 1≤e≤2, for example Na ₂ Fe ₂ Si ₆ O ₁₈ or Na ₂ MnFeSi ₆ O ₁₈ ); An oxide represented by Na _f M ⁴ _g Si ₂ O ₆ (provided that M ⁴ is at least one element selected from magnesium (Mg) and aluminum (Al), and 1≤f≤2 and 1≤g≤2, eg Na ₂ FeSi ₂ O ₆ ); phosphates such as NaFePO ₄ , Na ₃ Fe ₂ (PO ₄ ) ₃ , Na ₃ V ₂ (PO ₄ ) ₃ , Na ₄ Co ₃ (PO ₄ ) ₂ P ₂ O ₇ ; borates such as NaFeBO ₄ or Na ₃ Fe ₂ (BO ₄ ) ₃ ; A fluoride represented by Na _h M ⁵ F ₆ provided that M ⁵ is at least one transition metal element and 2≤h≤3, for example Na ₃ FeF ₆ or Na ₂ MnF ₆ , Na ₃ V ₂ (PO ₄ ) ₂ F ₃ , Na ₃ V ₂ (PO ₄ ) ₂ FO ₂ and the like can be considered. In addition, the cathode active material of the present invention is not particularly limited by the above, and any suitable cathode active material used in the art may be used.

The positive electrode preferably includes a positive electrode active material capable of intercalating and deintercalating potassium ions. In the case of a cathode for a potassium secondary battery, the cathode active material may be potassium transition metal oxide, specifically, potassium manganese cobalt oxide. Specifically, the cathode active material may have a composition of K _x [Mn _1-y Co _y ] O ₂ (0.445 ≤ x ≤ 0.555, 0.450 ≤ y ≤ 0.550). More specifically, the cathode active material is K _x [Mn _1-y Co _y ] O ₂ (0.450 ≤ x ≤ 0.550, 0. 495 ≤ y ≤ 0.505), more specifically, K _x [Mn _0.5 CO _0.5 ] O ₂ (0.450 ≤ x ≤ 0.550), as an example, it may have a composition of K _0.5 [Mn _0.5 CO _0.5 ] O ₂ , and may have a hexagonal P3 crystal structure (space group: R-3m). The cathode active material may have a layered structure, specifically, a structure in which a layer of K ions and a layer of (Mn _1-y Co _y ) are alternately stacked.

The electrolyte solution may include a lithium salt. The lithium salt is LiCl, LiBr, LiI, LiClO ₄ , LiBF ₄ , LiB ₁₀ Cl ₁₀ , LiPF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiAsF ₆ , LiSbF ₆ , LiAlCl ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, (CF ₃ SO ₂ ) ₂ NLi, lithium chloroborane, lithium lower aliphatic carbonate, lithium 4 phenyl borate, and combinations thereof.

The electrolyte solution may include a sodium salt. Examples include NaClO ₄ , NaPF ₆ , NaBF ₄ , NaCF ₃ SO ₃ , NaN(CF ₃ SO ₂ ) ₂ , NaN(C ₂ F ₅ SO ₂ ) ₂ , NaC(CF ₃ SO ₂ ) _{3 ,} and the like. can The liquid electrolyte may preferably include NaClO ₄ , NaPF ₆ or a combination thereof. The sodium salt is not limited to those mentioned above, and any salt that can be used as a sodium salt in the field may be used. For example, among salts used as lithium salts in lithium batteries, lithium may be substituted with sodium.

The electrolyte solution may include a potassium salt. For example, KNO ₃ , K ₂ CO ₃ , KPF ₆ , KClO ₄ , KBF ₄ , KCF ₃ SO ₃ , KN(CF ₃ SO ₂ ) ₂ , KN(C ₂ F ₅ SO ₂ ) ₂ , KC(CF ₃ SO ₂ ) ₃ and the like. The potassium salt is not limited to those described above, and any salt that can be used as a potassium salt in the field may be used. For example, among salts used as lithium salts in lithium batteries, lithium may be substituted with potassium.

The concentration of the lithium salt, sodium salt or potassium salt contained in the electrolyte solution is not particularly limited. For example, the concentration of the lithium salt, sodium salt, or potassium salt included in the electrolyte may be in the range of 0.1M to 2.0M, respectively, and may be between 0.5M and 1.5M.

The electrolyte solution is sufficient if it can dissolve the lithium salt, sodium salt or potassium salt, and the solvent may be a polar aprotic solvent. Polar aprotic solvents include dimethyl ether, diethyl ether, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate, Methyl acetate, ethyl acetate, n-propyl acetate, dimethylacetate, methyl propionate, ethyl propionate, γ-butyrolactone, decanolide, valerolactone, mevalonolactone, caprolactone, dibutyl ether, Tetraglyme, diglyme, polyethylene glycol dimethyl ether, dimethoxyethane, 2-methyl tetrahydrofuran, 2,2-dimethyl tetrahydrofuran, 2,5-dimethyl tetrahydrofuran, cyclohexanone, triethylamine, tri It may be phenylamine, triether phosphine oxide, acetonitrile, dimethyl formamide, 1,3-dioxolane, and sulfolane, but is not limited thereto, and any solvent that can be used as an organic solvent in the art is used. this is allowed In some embodiments, the solvent preferably includes a carbonate ester, and more preferably includes propylene carbonate.

As the separator, a porous olefin film such as polyethylene or polypropylene and a polymer electrolyte may be used. The separator may have a structure in which two or more porous materials are stacked. The pore diameter of the separator may be in the range of about 0.01 μm to about 10 μm, and the thickness of the separator may be in the range of about 5 μm to about 300 μm.

The method of manufacturing a negative electrode for a secondary battery of the present invention includes preparing a negative electrode active material for a secondary battery including the compound represented by Chemical Formula 1; The negative electrode active material for a secondary battery, a conductive material containing a component having conductivity without causing chemical change in a battery, and a component that promotes aggregation between the negative electrode active material and the conductive material or between the negative active material and a current collector preparing a slurry for an anode by dispersing a binder to a solvent; drying the slurry for the negative electrode; and annealing the dried slurry for a negative electrode.

The annealing may be performed at a temperature of 200° C. to 400° C., but is not limited thereto.

When the annealing temperature is lower than 200° C., the crystallinity of the compound represented by Chemical Formula 1 may not be sufficiently formed.

The negative electrode active material for a secondary battery of the present invention includes the compound represented by Chemical Formula 1, and the compound represented by Chemical Formula 1 is characterized in that it exhibits a crystalline phase having symmetry P2 ₁ /n.

Compounds represented by Formula 1 may be stacked at intervals of 14.0 Å to 15.5 Å, but are not limited thereto.

The secondary battery of the present invention can be manufactured by disposing a separator between the positive electrode and the negative electrode, and supplying an electrolyte. For example, sequentially stacking the negative electrode, the separator and the positive electrode of the present invention; It may be manufactured by winding or folding the stacked structure, sealing the rolled or folded structure in a cylindrical or rectangular battery case or pouch, and then placing a liquid electrolyte in the battery case or pouch. A method of disposing the liquid electrolyte in the case or pouch may be, for example, injecting the liquid electrolyte.

For the purpose of improving charge/discharge characteristics or flame retardancy, the secondary battery may further include additives. For example, pyridine, triethylphosphite, triethanolamine, cyclic ethers, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrroles, 2-methoxy ethanol, aluminum trichloride, and the like may further be added. In some cases, halogen-containing solvents such as carbon tetrachloride and trifluoride ethylene may be further included to impart incombustibility, and carbon dioxide gas may be further included to improve high-temperature storage characteristics, and FEC (Fluoro-Ethylene carbonate), PRS (Propenesultone), FEC (Fluoro-Ethlene carbonate), and the like may be further included.

Since the secondary battery has improved charging characteristics, cycle characteristics, and high rate characteristics, it can be used as a power source for various electronic devices. Examples of electronic devices include air conditioners, washing machines, TVs, refrigerators, freezers, air conditioners, laptops, tablets, smartphones, PC keyboards, PC displays, desktop PCs, CRT monitors, printers, all-in-one PCs, mice, and hard disks. , PC peripherals, iron, clothes dryer, window fan, transceiver, blower, ventilation fan, TV, music recorder, music player, oven, range, toilet with washing function, warm air heater, car component, car navigation , flashlight, humidifier, portable karaoke machine, ventilation fan, dryer, air purifier, mobile phone, emergency light, game machine, blood pressure monitor, coffee grinder, coffee maker, kotatsu, copier, disc changer, radio, razor, juicer, shredder ), water purifiers, lighting fixtures, dehumidifiers, dish dryers, electric rice cookers, stereos, stoves, speakers, trouser presses, vacuum cleaners, body fat scales, scales, bathroom scales, video players, electric blankets, electric rice cookers, electric lamps, Electric kettle, electronic game machine, handheld game machine, electronic dictionary, electronic notebook, microwave oven, electronic cooker, electronic calculator, electric cart, electric wheelchair, electric tools, electric toothbrush, electric foot warmer, hair clipper, telephone, clock, interphone, Air circulator, electric insecticide, hot plate, toaster, hair dryer, electric drill, hot water heater, panel heater, shredder, soldering iron, video camera, VCR, facsimile, food processor, futon dryer, headphones, microphone, massager, mixer, sewing machine , mochi beater, underfloor heating panel, lantern, remote control, hot/cold heater, water cooler, cooling fan, word processor, whisk, electronic musical instrument, motorcycle, toys, lawn mower, fishing float, bicycle, automobile, hybrid car, plug-in Examples include hybrid vehicles, electric vehicles, railways, ships, airplanes, and emergency storage batteries.

The present invention will be described in more detail through the following examples, but the following examples are for illustrative purposes only and are not intended to limit the scope of the present application.

A slurry for an anode was prepared by mixing 60 wt% of the compound represented by Formula 1, 10 wt% of a PVDF poly(vinylidene fluoride) binder, and 30% of carbon black as a conductive material. The slurry for the negative electrode was applied on a copper foil having a thickness of 18 μm according to the doctor blade method. Thereafter, the slurry was dried in a vacuum oven at 120° C., and the solvent and moisture were evaporated and dried. In order to improve crystallinity, annealing was further performed at 330° C. for 40 minutes to prepare a negative electrode.

1.3M LiPF ₆ mixed with 10 wt% FEC as electrolyte (EC:DEC, 3:7 v/v as solvent), 2032 type coin cell using polyethylene membrane as separator and lithium as counter electrode (lithium secondary battery ) was prepared.

The negative electrode of Example 1, 1.0 M NaPF ₆ (EC:DEC 5:5, v/v as solvent) mixed with 10 wt% FEC as electrolyte, 2032 type using polyethylene membrane as separator and sodium as counter electrode of coin cells (sodium secondary batteries) were manufactured.

2032 type coin cell (potassium secondary) using glass microfibers as the negative electrode of Example 1, 0.8 M KPF ₆ as the electrolyte (EC:DEC 5:5, v/v as the solvent), and potassium as the counter electrode as the separator. battery) was prepared.

[evaluation]

One. Cell characterization

The characteristics of the secondary batteries of Examples 1 to 3 were analyzed, and the results are shown as FIGS. 2 to 16 .

2 is a grazing-incidence wide-angle X-ray diffraction scattering (GIWAXS) graph according to the annealing temperature of the negative electrode manufactured according to the present embodiment.

According to the results shown in Figure 2, it can be seen that the crystallinity is improved as the annealing temperature increases.

Referring to FIG. 2 , the annealing temperature of the negative electrode is preferably 200° C. or higher.

3 is a graph showing a constant current charge-discharge profile at a current density of 1 A/g to 20 A/g of a lithium secondary battery (Example 1) manufactured according to this embodiment.

According to the results shown in FIG. 3, it can be seen that charge-discharge occurs in a wide current density range of 1 A/g to 20 A/g.

4 is a graph showing rate characteristics of a lithium secondary battery (Example 1) manufactured according to this embodiment.

According to the results shown in FIG. 4, it can be confirmed that a reversible capacity of up to 393 mAh/g is achieved at a current density of 0.1 A/g. In addition, a high reversible capacity of 75 mAh/g is achieved even at a high current density of 20 A/g.

5 is a graph showing charge-discharge cycles at a current density of 8 A/g of a lithium secondary battery (Example 1) manufactured according to this embodiment, and the inset shows the charge and discharge cycles at the first, 100th, and 1,000th cycles. - is the discharge profile.

Specifically, in FIG. 5, the horizontal axis represents the number of charge-discharge cycles, and the vertical axis represents specific capacity (mAh/g) and coulombic efficiency (%), respectively.

According to the results shown in FIG. 5 , it can be confirmed that the lithium secondary battery of Example 1 maintains a specific capacity of 220 mAh/g even after repeating 1,000 charge-discharge cycles, and the coulombic efficiency is also maintained without a significant difference.

6 is a CV (cyclic coltammetry) graph measured at a scan rate of 0.1 mV / s to 1.0 mV / s of a lithium secondary battery (Example 1) manufactured according to this embodiment, and the inset shows log (ν) and log It is a graph showing the ratio of (i _p ).

According to the results shown in FIG. 6, it can be confirmed that the ratio of log(ν) and log( _ip ) is 0.58 for the positive electrode and 0.51 for the negative electrode. Considering that the closer the ratio of log(ν) to log(i _p ) is to 1, the character of a capacitor increases, and the closer the ratio of log(ν) to log(i _p ) approaches to 0.5, the character of a battery increases. It can be seen that the lithium secondary battery of Example 1 has characteristics as a battery. In addition, it can be confirmed that the insertion of lithium ions is performed by intercalation. Specifically, the intercalation of the lithium ions between the layers of the compound of Formula 1 causes diffusion and intercalation-deintercalation.

7 is a graph showing a constant current charge-discharge profile at a current density of 0.02 A/g to 4 A/g of a sodium secondary battery (Example 2) manufactured according to this embodiment.

According to the results shown in FIG. 7, it can be seen that charge-discharge occurs in a wide current density range of 0.02 A/g to 4 A/g.

8 is a graph showing rate characteristics of a sodium secondary battery (Example 2) manufactured according to this embodiment.

According to the results shown in FIGS. 7 and 8 , it can be confirmed that a reversible capacity of up to 225 mAh/g is achieved at a current density of 0.02 A/g. In addition, it achieves a reversible capacity of 175 mAh/g at 0.1 A/g.

9 is a graph showing charge-discharge cycles at a current density of 1 A/g of a sodium secondary battery (Example 2) manufactured according to this embodiment.

Specifically, in FIG. 9, the horizontal axis represents the number of charge-discharge cycles, and the vertical axis represents specific capacity (mAh/g) and coulombic efficiency (%), respectively.

According to the results shown in FIG. 9 , it can be confirmed that the sodium secondary battery of Example 2 maintained 98.5% of coulombic efficiency and 85.3% of reversible capacity when repeated 800 charge-discharge cycles.

10 is a CV (cyclic coltammetry) graph measured at a scan rate of 0.1 mV/s to 1.0 mV/s of a sodium secondary battery (Example 2) prepared according to this embodiment, and the inset shows log (ν) and log It is a graph showing the ratio of (i _p ).

According to the results shown in FIG. 10, it can be confirmed that the ratio of log(ν) and log( _ip ) is 0.72. Through this, it can be confirmed that when the compound represented by Chemical Formula 1 of the present invention is used as an anode active material, the sodium secondary battery has characteristics as a pseudo-capacitor.

11 is a graph showing the capacity contribution according to the scan rate of 0.1 mV/s to 1.0 mV/s of the sodium secondary battery (Example 2) manufactured according to this embodiment.

According to the results shown in FIG. 11, it can be confirmed that the contribution of capacitive in diffusion-limited increases as the scan speed increases. This is due to the large diameter of the sodium ion.

12 is a graph showing a constant current-charge/discharge profile at a current density of 0.1 A/g to 2.0 A/g of a potassium secondary battery (Example 3) prepared according to this embodiment.

According to the results shown in FIG. 12, it can be seen that charge-discharge occurs in a wide current density range of 0.1 A/g to 2.0 A/g. In particular, it can be confirmed that a reversible capacity of up to 260 mAh/g is achieved at a current density of 0.1 A/g.

13 is a graph showing rate characteristics of a potassium secondary battery (Example 3) manufactured according to this embodiment.

According to the results shown in FIG. 13, it can be confirmed that sufficient reversible capacity is achieved at current densities of 0.1 A/g to 2.0 A/g.

14 is a graph showing charge-discharge cycles at a current density of 1.0 A/g of a potassium secondary battery (Example 3) manufactured according to this embodiment.

According to the results shown in FIG. 14 , it can be confirmed that the potassium secondary battery of Example 3 maintains 99.8% of coulombic efficiency and 86.5% of reversible capacity when repeated 400 charge-discharge cycles.

15 is a CV (cyclic coltammetry) graph measured at a scan rate of 0.1 mV/s to 1.0 mV/s of a potassium secondary battery (Example 3) prepared according to this embodiment, and the inset shows log (ν) and log It is a graph showing the ratio of (i _p ).

According to the results shown in FIG. 15, it can be confirmed that the ratio of log(ν) and log( _ip ) is 0.75. Through this, when the compound represented by Chemical Formula 1 of the present invention is used as an anode active material, it can be confirmed that the potassium secondary battery has the characteristics of a pseudo-capacitor.

16 is a graph showing the capacity contribution according to the scan rate of 0.1 mV / s to 1.0 mV / s of the potassium secondary battery (Example 3) manufactured according to this embodiment.

According to the results shown in FIG. 16, it can be confirmed that the contribution of capacitive in diffusion-limited increases as the scan speed increases. This is due to the large diameter of the potassium ion.

A secondary battery including the compound represented by Chemical Formula 1 of the present application as an anode active material is considered to have stable rate performance, high rate characteristics, and charge-discharge characteristics. In particular, it exhibits high-rate characteristics and stability while being compatible not only with lithium but also with alkali ions with large ion diameters such as sodium and potassium.

The above description of the present application is for illustrative purposes, and those skilled in the art will understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present application. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present application is indicated by the following claims rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts thereof should be construed as being included in the scope of the present application.

Claims (9)

A negative active material for a secondary battery including a compound represented by Formula 1 below;
A conductive material containing a component having conductivity without causing chemical change in the battery;
a binder including a component that promotes aggregation between the anode active material and the conductive material or aggregation between the anode active material and a current collector; and
a solvent dispersing the negative electrode active material, the conductive material, and the binder; A cathode comprising a;
anode;
a separator disposed between the cathode and anode; and
An electrolyte solution containing lithium, sodium or potassium;
The compound represented by Formula 1 represents a crystal phase having symmetry P2 ₁ /n, a secondary battery:
[Formula 1]

.
According to claim 1,
The positive electrode includes a positive electrode active material capable of intercalating and deintercalating lithium ions,
The positive electrode is a secondary battery of lithium, sodium or potassium.
According to claim 1,
A secondary battery in which the compounds represented by Formula 1 are stacked at intervals of 14.0 Å to 15.5 Å.
According to claim 1,
Wherein the secondary battery has a reversible capacity of 150 mAh/g to 400 mAh/g when the current density is 0.1 A/g.
According to claim 1,
The secondary battery of which the reversible capacity of the secondary battery is maintained at 80% or more even after 1,000 cycles.
Preparing an anode active material for a secondary battery containing a compound represented by Formula 1 below;
The negative active material for a secondary battery, a conductive material containing a component having conductivity without causing chemical change in a battery, and a component that promotes aggregation between the negative active material and the conductive material or between the negative active material and a current collector preparing a slurry for an anode by dispersing a binder to a solvent;
drying the slurry for the negative electrode; and
Annealing the dried slurry for a negative electrode; manufacturing method of a negative electrode for a secondary battery comprising:
[Formula 1]

.
According to claim 6,
The annealing is to proceed at a temperature of 200 ℃ to 400 ℃, a method for producing a negative electrode for a secondary battery.
Including a compound represented by the following formula (1),
A negative electrode active material for a secondary battery in which the compound represented by Formula 1 represents a crystal phase having symmetry of P2 ₁ /n:
[Formula 1]
.

.
According to claim 8,
The compound represented by Formula 1 is stacked at intervals of 14.0 Å to 15.5 Å, a negative electrode active material for a secondary battery.

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