Patent Application
20240270600
The present invention relates to a positive electrode active material, its manufacturing method and a lithium secondary battery containing the same. More specifically, it is related to a positive electrode active material for lithium secondary battery, comprising: a lithium metal oxide particle; and a coating layer positioned on at least part of the lithium metal oxide particle surface; wherein, the coating layer includes any one or more of group 5 elements and group 6 elements, B, LiOH, Li2CO3 and Li2SO4, and a method of preparing it, and lithium secondary battery including it.
Recently, there is an explosive increase in demand for IT mobile devices and small electric power devices (e-bikes, small EVs, etc.), and there is a demand for electric vehicles with a driving distance of 400 km or more. Accordingly, the development of secondary batteries having high-capacity and a high energy density to drive them is being actively conducted worldwide.
In order to manufacture such a high-capacity battery, it is necessary to use a high-capacity positive electrode active material. Among the existing layered positive electrode active materials, the highest capacity material is LiNiO2 (275 mAh/g). However, structural collapse occurs easily during charging and discharging, and thermal stability due to oxidation number problem is low, making it difficult to commercially available.
In order to solve this problem, a NCM-based positive electrode active material with improved electrochemical stability was developed by substituting a heterogeneous transition metal (Co, Mn, etc.) at the Ni site.
The present invention relates to a positive electrode active material, its manufacturing method and a lithium secondary battery containing the same. More specifically, it is related to a positive electrode active material for lithium secondary battery, comprising: a lithium metal oxide particle; and a coating layer positioned on at least part of the lithium metal oxide particle surface; wherein, the coating layer includes any one or more of group 5 elements and group 6 elements, B, LiOH, Li2CO3 and Li2SO4, and a method of preparing it, and lithium secondary battery including it.
An exemplary embodiment is related to a positive electrode active material for lithium secondary battery, comprising: a lithium metal oxide particle; and a coating layer positioned on at least part of the lithium metal oxide particle surface; wherein, the coating layer includes any one or more of group 5 elements and group 6 elements, B, LiOH, Li2CO3 and Li2SO4.
The positive electrode active material is in the form of a secondary particle including a plurality of primary particles, and one or more of the Group 5 and Group 6 elements is positioned on at least a portion of the primary particle surface.
The Group 5 element includes Nb.
The Group 6 elements include W.
A content of the group 5 element and group 6 element is 10 ppm to 10,000 ppm based on the total amount of the positive electrode active material.
A content of the LiOH is 100 ppm to 10,000 ppm based on the total amount of the positive electrode active material.
A content of the Li2SO4 is 10 ppm to 3,000 ppm based on the total amount of the positive electrode active material.
The Li2CO3 is not separately injected as a lithium raw material, but is caused by an internal reaction.
The positive electrode active material has a peak around 192.1 eV and a peak around 195.0 eV, and a peak around 35.0 eV and a peak around 38.5 eV when analyzed by XPS.
In the positive electrode active material, during EDS analysis, the ratio of a relative intensities of Ni and W present at the boundary of the primary particle satisfies the following equation 1.
(Here, INi means a relative intensity of Ni present at the boundary of the primary particle, and IW means a relative intensity of W present at the boundary of the primary particle.)
A content of nickel in the metal in the lithium metal oxide particle is 85 mol % or more.
Another exemplary embodiment is related to a manufacturing method of positive electrode active material for lithium secondary battery, comprising:
In the step of washing, a material containing the Group 5 element is a mixture of at least one of:
In the step of washing, a material containing the Group 6 element is a mixture of at least one of:
The secondary heat treatment is performed in the 200 to 450° C. temperature range.
Another exemplary embodiment is related to a lithium secondary battery, comprising: a positive electrode comprising the positive electrode active material of the embodiment; a negative electrode; and a non-aqueous electrolyte.
The positive electrode active material according to an exemplary embodiment may include all group 5 or group 6 elements such as W and Nb and B, LiOH, Li2CO3 and Li2SO4 in the coating layer. Due to this, it is possible to secure the high-capacity of the positive electrode active material. In addition, it has excellent high temperature cycle-life characteristics and can significantly reduce initial resistance and resistance increase rate.
The terms such as first, second, and third are used to describe various portions, components, regions, layers, and/or sections, but various parts, components, regions, layers, and/or sections are not limited to these terms. These terms are only used to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, a first part, component, region, layer, or section described below may be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention.
The term “including/comprising” as used herein concretely indicates specific characteristics, regions, integer numbers, steps, operations, elements, and/or components, and is not to exclude presence or addition of other specific characteristics, regions, integer numbers, steps, operations, elements, and/or components.
Terminologies as used herein are to mention only a specific exemplary embodiment, and are not to limit the present invention. Singular forms used herein include plural forms as long as phrases do not clearly indicate an opposite meaning. The term “including/comprising” as used herein concretely indicates specific characteristics, regions, integer numbers, steps, operations, elements, and/or components, and is not to exclude presence or addition of other specific characteristics, regions, integer numbers, steps, operations, elements, and/or components.
In this specification, the term “combination thereof” included in the expression of the Markush form means one or more mixture or combination selected from the group consisting of the constituent elements described in the expression of the Markush form, and includes one or more selected from the group consisting of the constituent elements.
When any portion is referred to as being “above” or “on” another portion, any portion may be directly above or on another portion or be above or on another portion with the other portion interposed therebetween. In contrast, when any portion is referred to as being “directly on” another portion, the other portion is not interposed between any portion and another portion.
Unless defined otherwise, all terms including technical terms and scientific terms as used herein have the same meaning as the meaning generally understood by a person of an ordinary skill in the art to which the present invention pertains. Terms defined in a generally used dictionary are additionally interpreted as having the meaning matched to the related art document and the currently disclosed contents and are not interpreted as ideal or formal meaning unless defined.
In this specification, unless otherwise noted, % means wt %, and 1 ppm means 0.0001 wt %.
Hereinafter, an exemplary embodiment will be described in detail so that a person of an ordinary skill can easily practice it in the technical field to which the present invention belongs. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.
An exemplary embodiment is related to a positive electrode active material for lithium secondary battery, comprising: a lithium metal oxide particle; and a coating layer positioned on at least part of the lithium metal oxide particle surface; wherein, the coating layer includes any one or more of group 5 elements and group 6 elements, B, LiOH, Li2CO3 and Li2SO4.
More specifically, the lithium metal oxide particle may have a layered structure, and since a coating layer containing at least one of group 5 and group 6 elements, B, LiOH, Li2CO3 and Li2SO4 is positioned on the surface of the particle, the resistance of the surface of the positive electrode active material can be reduced. Accordingly, it is possible to increase capacity and simultaneously improve cycle-life characteristics at high temperature. In addition, there is a merit that can significantly reduce the initial resistance and resistance increase rate at high temperature.
More specifically, any one or more of the group 5 and group 6 elements may be coated with a primary wet coating, and B, LiOH, Li2CO3 and Li2SO4 may be coated with a secondary dry coating.
That is, the positive electrode active material according to an exemplary embodiment is in the form of a secondary particle including a plurality of primary particles, and at least one of the group 5 and group 6 elements may be positioned on at least a part of the surface of the primary particle. In this case, the group 5 element may be Nb. Also, the Group 6 element may be W.
Meanwhile, the positive electrode active material of the present embodiment may exhibit a synergistic effect because the coating layer includes at least five elements or compounds as described above.
In the present embodiment, the content of the group 5 element and the group 6 element may range from 10 ppm to 10,000 ppm, more specifically from 30 ppm to 5,000 ppm, more specifically from 80 ppm to 2,000 ppm, and more specifically from 300 ppm to 800 ppm based on the total amount of the positive electrode active material. If the content of Group 5 and Group 6 elements is too small, there is a drawback that the resistance increase rate increases, and if there are too many, there is a drawback that the cell cycle-life decreases.
In the present embodiment, the content of the B may range from 10 ppm to 3,000 ppm, more specifically from 50 ppm to 2,000 ppm, more specifically from 100 ppm to 1,000 ppm, and more specifically from 300 ppm to 800 ppm based on the total amount of the positive electrode active material. If the content of B satisfies the range, since the average grain size can be reduced during sintering of the positive electrode active material, the initial resistance of the positive electrode active material and the resistance increase rate at high temperature can be significantly reduced.
The content of the LiOH may range from 100 ppm to 10,000 ppm, more specifically from 500 ppm to 7,000 ppm, and more specifically from 1,200 ppm to 3,000 ppm based on the total amount of the positive electrode active material. When the content of LiOH included in the coating layer satisfies the range, it is possible to secure high capacity and simultaneously improve cycle-life characteristics.
The content of the Li2CO3 may range from 1,000 ppm to 5,000 ppm, more specifically from 1,500 ppm to 4,000 ppm, and more specifically from 2,000 ppm to 3,500 ppm based on the total amount of the positive electrode active material. When the content of Li2CO3 satisfies the range, excellent room temperature and high temperature cycle-life characteristics can be improved, and resistance increase rate and average leakage current value can be reduced. At this time, the Li2CO3 is a compound resulting from the reaction between metal raw materials for forming lithium metal oxide and other coating layer forming raw materials without inputting a separate coating layer forming raw material.
The content of the Li2SO4 may range from 10 ppm to 10,000 ppm, more specifically from 80 ppm to 3,000 ppm, more specifically from 100 ppm to 2,000 ppm, more specifically from 100 ppm to 800 ppm, more specifically from 100 ppm to 400 ppm, based on the total amount of the positive electrode active material. When the content of Li2SO4 satisfies the range, it is possible to secure excellent capacity characteristics, simultaneously improve cycle-life characteristics, and reduce initial resistance values.
As such, since the positive electrode active material of the present exemplary embodiment includes at least one of group 5 and group 6 elements, B, LiOH, Li2CO3 and Li2SO4 in the coating layer, the lithium secondary battery to which it is applied exhibits excellent discharge capacity and simultaneously, improved initial temperature, excellent room temperature and high cycle-life characteristics. In addition, the initial resistance and resistance increase rate can be significantly reduced.
This effect is obtained when at least one of the group 5 and group 6 elements, B, LiOH, Li2CO3 and Li2SO4 are included, and if at least one of these elements is not included, desired properties cannot be obtained.
Meanwhile, during XPS analysis of the positive electrode active material of an exemplary embodiment, a peak around 192.1 eV and a peak around 195.0 eV may exist, and a peak around 35.0 eV and a peak around 38.5 eV may exist. Meanwhile, during EDS analysis of the positive electrode active material of an exemplary embodiment, the ratio of relative intensities of Ni and W existing at the boundary of the primary particle may satisfy Equation 1 below.
(Here, INi means a relative intensity of Ni present at the boundary of the primary particle, and IW means a relative intensity of W present at the boundary of the primary particle.)
More specifically, the lower limit of Equation 1 may be 0.2, or 0.4, and the upper limit may be 1.5, 1.0, or 0.8.
Meanwhile, in the present exemplary embodiment, the content of nickel in the metal in the lithium metal oxide may be 85 mol % or more, more specifically 88 mol % or 90 mol % or more.
As in the present embodiment, when the content of nickel among metals in lithium metal oxide is 80% or more, a positive electrode active material having a high power characteristic can be implemented. Since the positive electrode active material of the present exemplary embodiment having such a composition has a high energy density per volume, the capacity of a battery to which it is applied can be improved, and is also suitable for use in an electric vehicle.
Another exemplary embodiment is related to a manufacturing method of positive electrode active material for lithium secondary battery, comprising:
Obtaining a metal precursor by injecting an aqueous metal salt solution into a co-precipitation reactor; preparing a mixture by mixing the metal precursor, a lithium raw material and a doping raw material; cooling after a first heat treatment of the mixture; containing at least one of a group 5 element and a group 6 element; and subjecting the product to a secondary heat treatment, after drying the washed product, and mixing it with a material for forming a coating layer, wherein, the coating layer forming material includes a boron compound, LiOH and Li2SO4.
First, a step of obtaining a metal precursor by injecting an aqueous metal salt solution into a co-precipitation reactor is performed.
More specifically, metal precursors constituting lithium metal oxide, for example, nickel raw material, cobalt raw material, manganese raw material, etc., are mixed with distilled water to prepare a metal salt aqueous solution, and then put into a reactor to perform a co-precipitation process. A metal precursor can be obtained.
Next, a step of preparing a mixture by mixing the metal precursor, lithium raw material and doping raw material is performed.
The lithium metal oxide of the present embodiment may be doped with Al or the like as an element. At this time, lithium metal oxide can be manufactured by introducing a doping material such that the content of the doping element is included in the range of 3,000 ppm to 4,000 ppm for Zr and 200 ppm to 350 ppm for Al based on the total amount of the lithium metal oxide.
Zr serves as a kind of pillar because Zr ions occupy Li sites, and stabilizes the layered structure by alleviating contraction of the lithium ion path during charging and discharging. Also, Al can stabilize the layered structure of the positive electrode active material. Therefore, the cycle-life characteristics of the lithium secondary battery can be further improved. Therefore, by including such a doping element, cycle-life characteristics of a lithium secondary battery to which the positive electrode active material of the present embodiment is applied can be further improved.
Thereafter, the mixture is subjected to a first heat treatment and then a cooling step is performed.
The primary heat treatment may be performed, for example, in the range of 700 degrees to 850 degrees. The duration of the first heat treatment may range from 3 hours to 40 hours. When the first heat treatment condition satisfies the range, the sum of LiOH and Li2CO3, which are residual lithium on the positive electrode surface, is less than 10000 ppm, and the crystal grain size ranges from 80 nm to 210 nm, so a lithium secondary battery with excellent cycle-life and resistance characteristics and excellent thermal stability can be implemented.
After heat treatment as described above, a step of cooling the sintered body is performed. Specifically, the cooling step may be performed by a conventional method.
Next, a step of washing the product generated in the cooling step with water containing at least one of a group 5 element and a group 6 element is performed.
The water washing is for removing residual lithium from the surface, and the reason for washing with a material containing any one or more of group 5 elements and group 6 elements is to wet-coat at least part of the surface of the primary particle or the surface of the secondary particle with any one or more of group 5 elements and group 6 elements. In this case, the group 5 element and the group 6 element may be W or Nb. As the coating layer is formed by the wet coating method, not only the secondary particles but also the primary particles can be uniformly coated, thereby significantly reducing the resistance increase rate.
In the step of washing, a material containing W is a mixture of at least one of:
In the step of washing, a material containing Nb is a mixture of at least one of:
Next, after drying the washed product, a secondary heat treatment step is performed by mixing it with a material for forming a coating layer.
The drying step is to remove moisture from the surface of the positive electrode active material that has been washed with water. This drying may be performed by a conventional method.
The secondary heat treatment can be performed in the temperature range of 200 to 450° C., and the heat treatment time can range from 1 to 12 hr. This is an appropriate temperature and time range that does not compromise the high temperature cycle-life characteristic. If the secondary heat treatment process satisfies these conditions, a coating layer containing all of B, LiOH, Li2CO3 and Li2SO4, any one or more of group 5 elements and group 6 elements is formed.
In the prepared positive electrode active material, each content range of at least one of a group 5 element and a group 6 element, B, LiOH, Li2CO3 and Li2SO4 is the same as described in an exemplary embodiment described above, and will be omitted here.
Meanwhile, in the present exemplary embodiment, the coating layer forming material includes a boron compound, LiOH and Li2SO4. That is, Li2CO3 included in the coating layer of the finally obtained positive electrode active material is formed by the internal reaction of other raw materials introduced in the manufacturing process, and no separate raw material is added.
In the coating layer forming material, a content of the boron compound may be 300 ppm to 2,000 ppm, more specifically 300 ppm to 1,000 ppm based on the entire coating layer forming material. When the content of the boron compound injected into the coating layer forming material satisfies the range, excellent thermal stability is exhibited because the crystal grain size of the positive electrode active material ranges from 80 nm to 210 nm.
At this time, the boron compound includes, for example, H3BO3, boron oxide, a boron compound including Li, BN, B4C, B2H6, B2F4, B2Cl4, B2Br4, B2l4, and the like.
In addition, the content of the LiOH included in the coating layer forming material may range from 10 ppm to 1,000 ppm, more specifically from 50 ppm to 700 ppm, and more specifically from 120 ppm to 300 ppm based on the entire coating layer forming material. When the content of LiOH injected as a coating layer forming material satisfies the range, it is possible to manufacture slurry in a state that can be applied to the electrode when manufacturing a positive electrode by suppressing the gelation phenomenon of the slurry caused by residual lithium.
The content of Li2SO4 included in the coating layer forming material is 10 ppm to 500 ppm, more specifically 10 ppm to 200 ppm, more specifically 10 ppm to 100 ppm, more specifically 20 ppm to 5 ppm based on the entire coating layer forming material. When the content of Li2SO4 injected into the coating layer forming material satisfies the range, a lithium secondary battery with excellent cycle-life characteristics can be implemented by improving the mobility of lithium ions on the surface of the positive electrode active material because a Li—B—C—SO4 based ion conductor is formed on the surface.
That is, in the present embodiment, the input amount of LiOH and Li2SO4 is less than that of LiOH and Li2SO4 present in the coating layer of the finally obtained positive electrode active material. This is expected to be caused by the reaction of lithium and metal raw materials present in lithium metal oxide in the secondary heat treatment process after the coating layer forming material is injected.
Specific characteristics of the positive electrode active material manufactured by the above method are the same as those described in an exemplary embodiment, and will be omitted here.
In addition, process conditions for manufacturing the positive electrode active material of the present exemplary embodiment will be described in more detail in an exemplary embodiment to be described later.
Another exemplary embodiment is related to a lithium secondary battery, comprising: a positive electrode comprising the positive electrode active material of the embodiment; a negative electrode; and a non-aqueous electrolyte.
A description related to the positive electrode active material will be omitted because it is the same as that of an exemplary embodiment described above.
The positive electrode active material layer may include a binder and a conductive material.
The binder serves to attach the positive electrode active material particles well to each other and to attach the positive electrode active material to the current collector well.
The conductive material is used to impart conductivity to the electrode, and any electronic conductive material can be used without causing chemical change in the battery.
The negative electrode includes a current collector and a negative electrode active material layer formed on the current collector, and the negative electrode active material layer includes a negative electrode active material.
The negative electrode active material includes a material capable of intercalating/deintercalating lithium ions reversibly, lithium metal, an alloy of lithium metal, a material capable of doping and undoping lithium, or a transition metal oxide.
A material that can intercalate/deintercalate the lithium ion reversibly is a carbon material. In a lithium ion secondary battery, any generally-used carbon-based negative electrode active material can be used, and typical examples thereof are crystalline carbon and amorphous carbon, or combination thereof.
The alloy of the lithium metal is alloy of lithium and metal selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al and Sn.
Materials capable of doping and undoping the lithium include Si, SiOx (0<x<2), Si—Y alloy (the Y is an element selected from the group consisting of an alkali metal, an alkaline earth metal, a group 13 element, a group 14 element, a transition metal, and a rare earth, and its combination thereof, but not Si), Sn, SnO2, Sn—Y (the Y is an element selected from the group consisting of an alkali metal, an alkaline earth metal, a group 13 element, a group 14 element, a transition metal, a rare earth element and the combination thereof, not Sn), and the like.
Examples of the transition metal oxide include vanadium oxide and lithium vanadium oxide. The negative electrode active material layer also includes a binder and may optionally further include a conductive material.
The binder serves to attach the negative electrode active material particles well to each other and to attach the negative electrode active material to the current collector well.
The conductive material is used to impart conductivity to the electrode, and any electronic conductive material can be used without causing chemical change in the battery.
As the current collector, one selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a conductive metal-coated polymer substrate, and a combination thereof may be used.
The negative electrode and positive electrode are prepared by mixing active material, conductive material and binder in a solvent to prepare an active material composition, and applying this composition to a current collector. Since such an electrode manufacturing method is widely known in the field, detailed description will be omitted in this specification. As the solvent, N-methylpyrrolidone and the like can be used, but is not limited thereto.
The electrolyte contains a non-aqueous organic solvent and a lithium salt.
The non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move.
The lithium salt is a material that dissolves in an organic solvent and acts as a supply source of lithium ion in the battery to enable basic operation of the lithium secondary battery and promotes the movement of lithium ion between the positive electrode and the negative electrode.
Depending on the type of lithium secondary battery, a separator may exist between the positive electrode and the negative electrode. As such a separator, polyethylene, polypropylene, polyvinylidene fluoride or a multilayer of two or more of these may be used, and polyethylene/polypropylene 2-layer separator, a mixed multilayer such as a polyethylene/polypropylene/polyethylene 3-layer separator, polypropylene/polyethylene/polypropylene 3-layer separator, can be used.
Lithium secondary batteries can be classified into lithium ion batteries, lithium ion polymer batteries and lithium polymer batteries according to the type of separator and electrolyte used, and can be classified into cylindrical, prismatic, coin-type, and pouch-type depending on the shape. It can be divided into bulk type and thin film type according to size. Since the structures and manufacturing methods of these batteries are well known in this field, detailed descriptions are omitted.
Hereinafter, an exemplary embodiment will be described in detail. However, this is presented as an example, and the present invention is not limited thereby, and the present invention is only defined by the range of claims to be described later.
A precursor having the composition (Ni0.92Co0.04Mn0.04OH)2 was prepared by a general co-precipitation method.
Specifically, NiSO4·6H2O was used as the nickel raw material, CoSO4·7H2O as the cobalt raw material, and MnSO4·H2O as the manganese raw material. These raw materials were dissolved in distilled water to prepare a metal salt aqueous solution.
Next, after preparing the co-precipitation reactor, N2 was purged to prevent oxidation of metal ions during the co-precipitation reaction, and the temperature of the reactor was maintained at 50° C.
NH4(OH) was added to the co-precipitation reaction as a chelating agent, and NaOH was used for pH control.
The precipitate obtained according to the co-precipitation process was filtered, washed with distilled water, and dried in an oven at 100° C. for 24 hours to prepare a positive electrode active material precursor having an average diameter of 14.8 μm.
Based on 1 mol of the positive electrode active material precursor prepared in Preparation Example 1, a mixture was prepared by uniformly mixing 1.05 mol of LiOH·H2O (Samjeon Chemical, battery grade) and a doping raw material. At this time, as the doping material, ZrO2 (Aldrich, 3N) was used so that Zr was 3,400 ppm, and Al(OH)3 (Aldrich, 4N) was used so that Al was 280 ppm.
The mixture was loaded into a tube furnace and sintered while oxygen was inflowed at 200 mL/min. In this sintering process, the first heat treatment was performed at 480° C. for 5 hours, then the temperature was raised to 760° C. at a heating rate of 5° C./min, maintained at this temperature for 16 hours, and then the product subjected to the sintering process was naturally cooled to 25° C. to prepare a positive electrode active material.
Based on 1 mol of the positive electrode active material precursor prepared in Preparation Example 1, a mixture was prepared by uniformly mixing 1.05 mol of LiOH·H2O (Samjeon Chemical, battery grade) and a doping raw material. At this time, as the doping material, ZrO2 (Aldrich, 3N) was used so that Zr was 3,400 ppm, and Al(OH)3 (Aldrich, 4N) was used so that Al was 280 ppm.
The mixture was loaded into a tube furnace and fired while oxygen was inflowed at 200 mL/min. In this sintering process, the first heat treatment was performed at 480° C. for 5 hours, then the temperature was raised to 760° C. at a heating rate of 5° C./min, maintained at this temperature for 16 hours, and then the product subjected to the sintering process was naturally cooled to 25° C.
Subsequently, the positive electrode powder was washed with distilled water mixed with 0.002 M of ammonium meta-tungstate (AMT) using distilled water, filtered and dried to prepare a positive electrode active material coated with tungsten (W) on the surface.
The cooling product was washed with distilled water, not a mixture of distilled water and AMT, filtered, dried, mixed with 500 ppm of H3BO3 (Aldrich) dry, and then subjected to secondary heat treatment at 280° C. for 5 hours. A positive electrode active material with a coating layer containing 500 ppm of B on the surface was prepared by the same method as in Comparative Example 2, except that.
A positive electrode active material with a coating layer containing 1,700 ppm LiOH and 3,000 ppm Li2CO3 was formed on the surface in the same method as Comparative Example 3, except that the cooling product was dry mixed with 250 ppm of LiOH based on Li and then subjected to secondary heat treatment.
A positive electrode active material with a coating layer containing 1,700 ppm LiOH and 3,000 ppm Li2CO3 and 500 ppm Li2SO4 was prepared on the surface in the same method as Comparative Example 3, except that the cooling product was dry mixed with 250 ppm LiOH and 30 ppm Li2SO4 based on Li and S, and then subjected to secondary heat treatment.
A positive electrode active coating layer containing W 500 ppm, B 500 ppm, LiOH 1700 ppm, Li2CO3 3,000 ppm and Li2SO4 300 ppm was formed on the surface in the same method as in Comparative Example 2, except that the cooling product was dry mixed with H3BO3 500 ppm, LiOH 250 ppm, Li2SO4 30 ppm based on Li and S, and then secondary heat treatment.
The precursor having a composition of (Ni0.92Co0.04Mn0.04)(OH)2 was uniformly mixed with LiOH·H2O (Samjeon Chemical, battery grade) in a 1:1.05 molar ratio, ZrO2 (Aldrich, 4N) to make Zr 3,400 ppm, and Al(OH)3 (Aldrich, 4N) to make Al 280 ppm, and then mixed them uniformly in a tube furnace (interior diameter 50 mm, length 1,000 mm) and sintered while inflowing oxygen at 200 mL/min. The sintering condition was maintained at 480° C. for 5 h and then at 700-750° C. for 16 h, and the heating speed was 5° C./min.
Thereafter, after cooling to room temperature, the sintered body was crushed/classified to produce a positive electrode material. Based on 200 g of positive electrode material, the positive electrode powder was washed with water with a mixture of 0.002M of ammonium meta-tungstate (AMT) in 100 g of distilled water (DI water), filtered, and dehydrated with a filter press. The recovered positive electrode material was dried at 80 degrees for 12 hours, and H3BO3 500 ppm, LiOH 250 ppm, and Li2SO4 30 ppm were quantified and mixed using a mixer, and then secondary heat treatment was performed at 280° C. to prepare a positive electrode material.
A positive electrode material was manufactured by the same method as in Example 2-1, except that 0.0002M of AMT was dissolved and washed with water in the washing process.
A positive electrode material was manufactured by the same method as in Example 2-1, except that 0.0005M of AMT was dissolved and washed with water in the washing process.
A positive electrode material was manufactured by the same method as in Example 2-1, except that 0.01M of AMT was dissolved and washed with water in the washing process.
A positive electrode material was manufactured by the same method as in Example 2-1, except that 0.05M of AMT was dissolved and washed with water in the washing process.
A positive electrode material was manufactured by the same method as in Example 2-1, except that 0.5M of AMT was dissolved and washed with water in the washing process.
The precursor having a composition of (Ni0.92Co0.04Mn0.04)(OH)2 was uniformly mixed with LiOH·H2O (Samjeon Chemical, battery grade) in a 1:1.05 molar ratio, ZrO2 (Aldrich, 4N) so that Zr was 3,400 ppm, and Al(OH)3 (Aldrich, 4N) so that Al was 280 ppm, and then mixed in a tube furnace (interior diameter 50 mm, length 1,000 mm) and sintered while inflowing oxygen at 200 mL/min. The sintering condition was maintained at 480° C. for 5 h and then at 700-750° C. for 16 h, and the heating speed was 5° C./min.
After cooling to room temperature, the sintered body was ground/classified to produce a positive electrode material. Based on 200 g of positive electrode material, the positive electrode powder was washed with water with a mixture of 0.002M of ammonium meta-tungstate (AMT) in 100 g of distilled water (DI water), filtered, and dehydrated with a filter press. The recovered positive electrode material was dried at 80° C. for 12 hours, and after mixing 500 ppm of H3BO3, 250 ppm of LiOH, and 10 ppm of Li2SO4 using a mixer, secondary heat treatment was performed at 280° C. to prepare a positive electrode material.
Except for adding 500 ppm of B, 250 ppm of LiOH, and 20 ppm of Li2SO4, the positive electrode material manufacturing method was the same as exemplary embodiment 3-1, and the positive electrode material was manufactured.
Except for adding 500 ppm of B, 250 ppm of LiOH, and 60 ppm of Li2SO4, the positive electrode material manufacturing method was the same as exemplary embodiment 3-1 to manufacture the positive electrode material.
Except for adding 500 ppm of B, 250 ppm of LiOH, and 120 ppm of Li2SO4, the positive electrode material manufacturing method was the same as exemplary embodiment 3-1 to manufacture the positive electrode material.
Except for adding 500 ppm of B, 250 ppm of LiOH, and 250 ppm of Li2SO4, the positive electrode material manufacturing method was the same as exemplary embodiment 3-1, and the positive electrode material was manufactured.
Except for adding 50 ppm of LiOH, the positive electrode material manufacturing method was the same as Example Embodiment 1 to manufacture the positive electrode material.
Except for the addition of 100 ppm of LiOH, the positive electrode material manufacturing method was the same method as Example Embodiment 1 to manufacture the positive electrode material.
Except for the addition of 500 ppm LiOH, the positive electrode material manufacturing method was the same method as Example Embodiment 1 to manufacture the positive electrode material.
Except for adding 1,000 ppm of LiOH, the positive electrode material manufacturing method was the same as Example 1, and the positive electrode material was manufactured.
Except for carrying out the secondary heat treatment temperature at 200° C., the positive electrode material manufacturing method was the same method as exemplary embodiment 1 to manufacture the positive electrode material.
Except for carrying out the secondary heat treatment temperature at 220° C., the positive electrode material manufacturing method was the same method as exemplary embodiment 1 to manufacture the positive electrode) material.
Except for carrying out the secondary heat treatment temperature at 240° C., the positive electrode material manufacturing method was the same method as exemplary embodiment 1 to manufacture the positive electrode material.
Except for carrying out the secondary heat treatment temperature at 260° C., the rest of the positive electrode material manufacturing method was the same method as exemplary embodiment 1 to manufacture the positive electrode material.
Except for carrying out the secondary heat treatment temperature at 300° C., the rest of the positive electrode material manufacturing method was the same method as exemplary embodiment 1 to manufacture the positive electrode material.
Except for carrying out the secondary heat treatment temperature at 450° C., the rest of the positive electrode material manufacturing method was the same method as exemplary embodiment 1 to manufacture the positive electrode material.
The positive electrode material was manufactured in the same way as exemplary embodiment 1 for the positive electrode material manufacturing method, except that 0.005M ammonium niobium oxalate was dissolved and washed with water as a Nb source instead of ammonium meta tungstate (AMT) in the water washing process.
The positive electrode material was manufactured by the same method as exemplary embodiment 1 for the positive electrode material manufacturing method, except that 0.01M ammonium niobium oxalate was dissolved and washed with water as a Nb source instead of ammonium meta tungstate (AMT) in the water washing process.
The positive electrode material was manufactured by the same method as exemplary embodiment 1 for the positive electrode material manufacturing method, except that 0.02M of ammonium niobium oxalate was dissolved and washed with water as a Nb source instead of ammonium meta tungstate (AMT) in the water washing process.
The positive electrode material was manufactured by the same method as exemplary embodiment 1 for the positive electrode material manufacturing method, except that 0.03M ammonium niobium oxalate was dissolved and washed with water as a Nb source instead of ammonium meta tungstate (AMT) in the water washing process.
The positive electrode material was manufactured by the same method as exemplary embodiment 1 for the positive electrode material manufacturing method, except that 0.05M ammonium niobium oxalate was dissolved and washed with water as a Nb source instead of ammonium meta tungstate (AMT) in the water washing process.
In the water washing process, the positive electrode material was manufactured by the same method as exemplary embodiment 1 for the positive electrode material manufacturing method, except that 0.1M ammonium niobium oxalate was dissolved and washed with Nb source instead of ammonium meta tungstate (AMT).
In the water washing process, the positive electrode material was manufactured by the same method as illustrated embodiment 1 for the positive electrode material manufacturing method, except that 0.3M ammonium niobium oxalate was dissolved and washed with Nb source instead of ammonium meta tungstate (AMT).
A coin-type half-cell was manufactured using the positive electrode active material prepared according to exemplary embodiment 1, exemplary embodiment 2-1 to 2-6, exemplary embodiment 3-1 to 3-5, exemplary embodiment 4-1 to 4-4, exemplary embodiment 5-1 to 5-6, exemplary embodiment 6-1 to 6-7, and Comparative Example 1 to 5.
Positive electrode active material, Denka black conductive material, and polyvinylidene fluoride binder (trade name: KF1100) were mixed at a weight ratio of 92.5:3.5:4, and this mixture was added to N-Methyl-2-pyrrolidone solvent to have a solid content of about 30 wt % to prepare a positive electrode active material slurry.
The slurry was coated on aluminum foil (Al foil, thickness: 15 μm), which is a positive electrode current collector, using a doctor blade (Doctor blade), dried, and rolled to prepare a positive electrode. The loading amount of the positive electrode was 14.6 mg/cm2, and the rolling density was 3.1 g/cm3.
A 2032 coin-type half cell was prepared by a conventional method using the positive electrode, lithium metal negative electrode (200 μm, Honzo metal), electrolyte solution and polypropylene separator. The electrolyte solution is the product obtained by dissolving 1M LiPF6 in a mixed solvent of ethylene carbonate (EC), dimethyl carbonate (DMC) and ethylmethyl carbonate (EMC) (mixing ratio EC:DMC:EMC=3:4:3 volume ratio), and 1.5 wt % of vinylene carbonate was added to 100 wt % of the entire solution.
After aging the prepared coin-type half cell at room temperature 25° C. for 10 hours, charging and discharging were performed.
The capacity evaluation was based on 215 mAh/g, and the charge and discharge conditions were constant current (CC)/constant voltage (CV) 2.5V to 4.25V, and 1/20C cut-off. Initial capacity was performed under 0.1C charge/0.1C discharge condition.
The resistance was calculated by measuring the voltage fluctuation for 60 seconds after applying a 0.2C discharge current at 100% of 4.25V charging at 0.2C. The results are shown in Table 1 below.
The high temperature cycle characteristic was measured 30 times with 0.3C charge/0.3C discharge condition at high temperature 45° C., and then the ratio of the 30th capacity to the first capacity was measured. The resistance was calculated by measuring the voltage fluctuation 60 seconds after the discharge current was applied at 100% of 4.25V charge.
The resistance increase rate was measured by performing the same method as the initial resistance measurement method after 30 cycle compared to the resistance initially measured at high temperature 45° C. (high temperature initial resistance), and the increase rate was converted into percentage (%).
The measurement results are shown in Table 2 below.
Table 1 shows initial efficiency and initial resistance measurement results at room temperature for positive electrode active materials manufactured according to exemplary embodiment 1, exemplary embodiment 2-1 to 2-6, exemplary embodiment 3-1 to 3-5, exemplary embodiment 4-1 to 4-4, exemplary embodiment 5-1 to 5-6, exemplary embodiment 6-1 to 6-7, and Comparative Example 1 to 5.
Table 2 shows measurement results of high temperature cycle-life and resistance increase rate for positive electrode active materials manufactured 10 according to exemplary embodiment 1, exemplary embodiment 2-1 to 2-6, exemplary embodiment 3-1 to 3-5, exemplary embodiment 4-1 to 4-4, exemplary embodiment 5-1 to 5-6, exemplary embodiment 6-1 to 6-7, and Comparative Example 1 to 5.
Referring to Table 1 and Table 2, the positive electrode active material according to embodiment 1, exemplary embodiment 2-1 to 2-6, exemplary embodiment 3-1 to 3-5, exemplary embodiment 4-1 to 4-4, exemplary embodiment 5-1 to 5-6, embodiment 6-1 to 6-7 including W or Nb, B, LiOH, Li2CO3 and Li2SO4 in the coating layer, and Comparative Example 1 to 5, overall initial capacity and high temperature cycle-life characteristics were improved. In addition, it can be seen that both the initial and high temperature resistance and the resistance increase rate are reduced, compared to the positive electrode active material according to Comparative Examples 1 to 5, where no coating layer is formed or a coating layer is formed that does not contain W or Nb, B, LiOH, Li2CO3 and Li2SO4,
The positive electrode active material prepared in exemplary embodiment 1 was subjected to TEM (Transmission Electron Microscope)/EDS (Energy Dispersive X-Ray Spectrometer) analysis and shown in
From the results of
At this time, it was confirmed that the ratio (INi/IW) of the intensity absolute values of the Ni and W peaks was about 0.60 in the EDS line profile result.
XPS (X-ray Photoelectron Spectroscopy) analysis of the positive electrode active material prepared in Example Embodiment 1 was performed and shown in
Referring to
Referring to
Referring to
Referring to
Referring to
The present invention is not limited to the exemplary embodiment, but can be manufactured in a variety of different forms, and a person of an ordinary skill in the technical field to which the present invention belongs does not change the technical idea or essential features of the present invention. It will be understood that it can be implemented in other specific forms. Therefore, the exemplary embodiment described above should be understood as illustrative in all respects and not limiting.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2020-0179806 | Dec 2020 | KR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/KR2021/019443 | 12/20/2021 | WO |
