KR20240065831A - Additive for positive electrodes of lithium secondary batteries, manufacturing method of the same, and lithium secondary batteries including the same - Google Patents

Abstract

The present invention relates to a positive electrode additive for lithium secondary batteries, a method of manufacturing the same, and a lithium secondary battery containing the same. According to the present invention, a positive electrode additive is provided that can improve the safety of lithium secondary batteries by having a stable crystalline phase while enabling improvement of irreversible capacity.

Description

Positive electrode additive for lithium secondary battery, manufacturing method thereof, and lithium secondary battery containing the same

The present invention relates to a positive electrode additive for lithium secondary batteries, a method of manufacturing the same, and a lithium secondary battery containing the same.

As power consumption increases along with the multifunctionalization of electronic devices, there are many attempts to increase the capacity of lithium secondary batteries and improve their charge and discharge efficiency.

As an example, a cathode active material containing 80% or more Ni is applied to the cathode of a lithium secondary battery, and a metal or metal-based anode active material such as SiO, Si, or SiC is applied to the anode, and a carbon-based anode active material such as natural graphite or artificial graphite is applied to the anode. A technology applied together with has been proposed.

Metal and metal oxide-based anode active materials enable higher capacity than carbon-based anode active materials. However, since metal and metal oxide-based negative electrode active materials have a much larger volume change during charging and discharging than graphite, it is difficult to increase the content of metal and metal oxide in the negative electrode to more than 15%. In addition, when metal and metal oxide are added to the negative electrode, an irreversible reaction occurs during initial charging and discharging, and the loss of lithium is greater than when a carbon-based negative electrode active material is used. Therefore, when metal and metal oxide-based negative electrode active materials are applied, the amount of lithium lost increases as the capacity of the battery increases, and the decrease in initial capacity also increases due to this.

Accordingly, various methods have been studied to increase the capacity of lithium secondary batteries or reduce the irreversible capacity. One of them is pre-lithiation, a concept that replenishes the lithium consumed in the formation of the SEI layer (solid electrolyte interphase layer) in the battery in the initial state.

Various methods have been proposed for pre-lithiation in batteries.

For example, a method of preliminary lithiation at the anode includes coating more cathode material in proportion to the amount of lithium consumed at the cathode. However, due to the low capacity of the cathode material itself, the amount of added cathode material increases, and the energy density and capacity per weight of the final battery decrease as the amount of cathode material increases.

Accordingly, a material suitable for preliminary lithiation of a battery at the anode must have irreversible characteristics such that lithium is desorbed at least twice as much as existing anode materials during the first charge and does not react with lithium during subsequent discharge. Additives that satisfy these conditions are called sacrificial positive electrode materials.

Meanwhile, Li ₂ NiO ₂ compounds have been used as a sacrificial positive electrode additive for preliminary lithiation of a negative electrode containing SiO. However, in order to secure irreversible capacity for preliminary lithiation, more than 3% by weight of Li ₂ NiO ₂ compound compared to the cathode material is required. If an excessive amount of Li ₂ NiO ₂ compound, which has relatively low stability, is added, safety issues may arise, such as reduced thermal stability of the lithium secondary battery and increased gas generation.

In order to increase the irreversible capacity, when poly-lithium metal oxides such as Li ₆ CoO ₄ , Li ₅ FeO ₄ and Li ₆ MnO ₄ are used as anode additives, the amount of pre-lithiation is about 1/3 that of the Li ₂ NiO ₂ compound. This effect can be achieved and thermal stability can also be improved. However, the poly-lithium metal oxide generates a higher amount of gas compared to the Li ₂ NiO ₂ compound and exhibits side effects such as an increase in battery resistance due to the elution of metal elements.

The present invention is intended to provide a positive electrode additive that can improve the safety of lithium secondary batteries by having a stable crystalline phase while enabling improvement of irreversible capacity.

The present invention is to provide a method for producing the positive electrode additive.

Additionally, the present invention is intended to provide a lithium secondary battery including the positive electrode additive.

According to one embodiment of the invention,

A positive electrode additive for a lithium secondary battery is provided, comprising a compound represented by the following formula (1):

[Formula 1]

a(Li ₂ Ni _1-x Cu _x O ₂ )-b(Li _y MO _z )

In Formula 1,

M is Co, Mn or Fe,

_a and b are the _molar ratio of the Li _{2 Ni 1-x Cu}

0.1 ≤ x ≤ 0.4, 3 < y < 7, and 3 < z < 5

According to another embodiment of the invention,

Forming a compound represented by Formula 1 by heat-treating a precursor mixture including a lithium precursor, a nickel precursor, a copper precursor, and the precursor M below under an inert gas atmosphere.

A method for producing a positive electrode additive for a lithium secondary battery is provided, including a.

According to another embodiment of the invention, a positive electrode for a lithium secondary battery containing the positive electrode additive is provided.

According to another embodiment of the invention, the anode for the lithium secondary battery; cathode; separation membrane; A lithium secondary battery comprising an electrolyte is provided.

Hereinafter, a positive electrode additive for a lithium secondary battery according to embodiments of the invention, a method of manufacturing the same, and a lithium secondary battery containing the same will be described in more detail.

Terms or words used in this specification and claims should not be construed as limited to their usual or dictionary meanings, and the inventor may appropriately define the concept of terms in order to explain his or her invention in the best way. It must be interpreted with meaning and concept consistent with the technical idea of the invention based on the principle that it exists.

Unless otherwise defined in this specification, all technical and scientific terms have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. The terminology used in the description herein is merely to effectively describe specific embodiments and is not intended to limit the invention.

As used herein, singular forms include plural forms unless phrases clearly indicate the contrary.

As used herein, the meaning of "comprising" is to specify a specific characteristic, area, integer, step, operation, element, and/or component, and to specify another specific property, area, integer, step, operation, element, component, and/or group. It does not exclude the existence or addition of .

Since the present invention can make various changes and take various forms, specific embodiments will be illustrated and described in detail below. However, this is not intended to limit the present invention to a specific disclosed form, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope above.

In this specification, for example, when the positional relationship between two parts is described as 'on top', 'on top', 'on the bottom', 'next to', etc., it is called 'immediately' or 'directly'. One or more other parts may be placed between the two parts unless an expression is used.

In this specification, for example, when a temporal relationship is described as 'after', 'successfully', 'next to', 'before', etc., the expressions 'immediately' or 'directly' are not used. Cases that are not consecutive may also be included.

In this specification, the term 'at least one' should be understood to include all possible combinations from one or more related items.

According to one embodiment of the invention,

A positive electrode additive for a lithium secondary battery is provided, comprising a compound represented by the following formula (1):

[Formula 1]

a(Li ₂ Ni _1-x Cu _x O ₂ )-b(Li _y MO _z )

In Formula 1,

M is Co, Mn or Fe,

_a and b are the _molar ratio of the Li _{2 Ni 1-x Cu}

0.1 ≤ x ≤ 0.4, 3 < y < 7, and 3 < z < 5

The compound of Formula 1 is a complex formed by heat treating a mixture containing a lithium precursor, a nickel precursor, and the precursor of M in the presence of a copper precursor according to a production method described later.

The compound of Formula 1 has a composite crystal phase in which the Li ₂ Ni _1-x Cu _x O ₂ crystal phase and the Li _y MO _z crystal phase coexist. Here, forming the composite crystal phase may mean that the Li ₂ Ni _1-x Cu _x O ₂ crystal phase and the Li _y MO _z crystal phase coexist and exist in a single aggregated particle state. This can be distinguished from a state in which the primary particles of the Li ₂ Ni _1-x Cu _x O ₂ compound and Li _y MO _z compound are simply mixed physically or mechanically.

According to one embodiment, in Formula 1, M is an element capable of forming a crystalline phase of poly-lithium metal oxide. Specifically, M may be Co, Mn, or Fe.

In Formula 1, a and b are the molar ratio (a+b=1) of the Li ₂ Ni _1-x Cu _x O ₂ crystal phase and Li _y MO _z crystal phase included in the compound of Formula 1, where 0.5 ≤ a ≤ 0.9 and 0.1 ≤ b ≤ 0.5. That is, in Formula 1, a:b may be 1:1 to 9:1.

In order for the compound of Formula 1 to exhibit improved irreversible capacity, b is 0.1 or more, or 0.15 or more, or 0.2 or more; It is preferable that a is 0.9 or less, or 0.85 or less, or 0.8 or less. However, if b is excessively large, the amount of gas generated by the compound may increase. Therefore, b is 0.5 or less, or 0.4 or less, or 0.3 or less; And it is preferable that a is 0.5 or more, or 0.6 or more, or 0.7 or more.

Preferably, a may be 0.5 to 0.9, or 0.6 to 0.9, or 0.6 to 0.85, or 0.7 to 0.85, or 0.7 to 0.8. And, b may be 0.1 to 0.5, or 0.15 to 0.5, or 0.15 to 0.4, or 0.2 to 0.4, or 0.2 to 0.3.

In Formula 1, x is the mole fraction of copper (Cu) that replaces a portion of nickel (Ni). Specifically, x is 0.1 or more, or 0.15 or more, or 0.2 or more; And it may be less than 0.4, or less than 0.35, or less than 0.3.

In order to prevent nickel oxide (NiO) secondary phase from being generated during the synthesis of the compound of Formula 1, x is preferably 0.1 or more, 0.15 or more, or 0.2 or more. However, if the compound of Formula 1 contains an excessive amount of copper (Cu), the charging capacity may be relatively reduced. Therefore, it is preferable that x is 0.4 or less, or 0.35 or less, or 0.3 or less.

Preferably, x may be 0.1 to 0.4, or 0.15 to 0.4, or 0.15 to 0.35, or 0.2 to 0.35, or 0.2 to 0.3.

In Formula 1, y may be greater than 3 and less than 7, or 3.5 to 6.5, or 4 to 6.5, or 4.5 to 6.5, or 5 to 6.5. And, in Formula 1, z may be greater than 3 and less than 5, or 3.5 to 4.5.

By meeting the above-mentioned numerical range, the compound of Formula 1 enables improvement of irreversible capacity compared to previously known irreversible anode additives, while improving thermal stability and suppressing gas generation.

The compound of Formula 1 has a composite crystal phase in which the Li ₂ Ni _1-x Cu _x O ₂ crystal phase and the Li _y MO _z crystal phase coexist. Accordingly, characteristic peaks due to the complex crystal phase can be observed during powder X-ray diffraction analysis of the compound of Formula 1.

According to one embodiment, the compound of Formula 1 has 19°±0.5°, 26°±0.5°, 37°±0.5°, and 19°±0.5°, 26°±0.5°, 37°±0.5°, and It may have peaks that appear at 2θ of 43°±0.5°.

In the powder X-ray diffraction analysis, peaks appearing at 2θ of 19°±0.5° and 26°±0.5° are _{characteristic} peaks resulting from the Li ₂ Ni _{1-x Cu} And, the peaks appearing at 2θ of 37°±0.5° and 43°±0.5° are characteristic peaks resulting from unreacted nickel precursors in the precursor mixture used to prepare the compound of Formula 1. For reference, when the primary particles of Li ₂ Ni _1-x Cu _x O ₂ compound and Li _y MO _z compound are simply mixed physically or mechanically, the No peaks are observed.

In addition, the compound of Formula 1 has characteristic peaks resulting from the Li _y MO _z crystal phase during the powder X-ray diffraction analysis. For example, when M is Fe, the compound of Formula 1 may have peaks that appear at 2θ of 21.5°±0.5° and 24°±0.5° resulting from Li _y MO _z .

The compound of Formula 1 is a primary particle having a volume average particle diameter (D50) of 0.5 ㎛ to 45 ㎛, 1 ㎛ to 25 ㎛, or 5 ㎛ to 20 ㎛, or secondary particles in which the primary particles are aggregated. It can have a shape. Within the above particle size range, the positive electrode additive can be uniformly mixed with the positive electrode active material to exhibit appropriate properties within the positive electrode.

In order to have an appropriate particle size distribution and volume average particle size, after synthesizing the compound of Formula 1, the compound particles can be passed through a standard sieve with eye sizes corresponding to the desired particle size distribution. The particle size distribution and volume average particle diameter (D50) of the compound can be measured and calculated using a well-known laser particle size analyzer.

The compound of Formula 1 has the property of irreversibly releasing lithium during charging and discharging of a lithium secondary battery. Therefore, the compound of Formula 1 can be included in a positive electrode for a lithium secondary battery and serve as sacrificial positive electrode materials for pre-lithiation.

According to another embodiment of the invention,

Forming a compound represented by Formula 1 below by heat-treating a precursor mixture including a lithium precursor, a nickel precursor, a copper precursor, and the precursor M below under an inert gas atmosphere.

A method for producing the positive electrode additive for a lithium secondary battery is provided, comprising:

[Formula 1]

a(Li ₂ Ni _1-x Cu _x O ₂ )-b(Li _y MO _z )

In Formula 1,

M is Co, Mn or Fe,

a and b are the molar ratio of Li ₂ Ni _1-x Cu _x O ₂ and Li _y MO _z contained in the compound of Formula 1 and are 0.5 ≤ a ≤ 0.9 and 0.1 ≤ b ≤ 0.5,

0.1 ≤ x ≤ 0.4, 3 < y < 7, and 3 < z < 5.

As previously explained, among the positive electrode additives known as sacrificial positive electrode materials, Li ₂ NiO ₂ compounds require excessive addition to secure irreversible capacity, causing safety issues in lithium secondary batteries. In addition, poly-lithium metal oxides such as Li ₆ CoO ₄ , Li ₅ FeO ₄ and Li ₆ MnO ₄ generate a high amount of gas and cause side effects due to the elution of metal elements.

In order to improve the irreversible capacity of the Li ₂ NiO ₂ compound, a method of adding the precursor of the poly-lithium metal oxide during the synthesis of the Li ₂ NiO ₂ compound can be considered. However, in this synthesis method, due to a problem of mixing nickel (Ni) with other transition metals, the Li ₂ NiO ₂ phase is not formed and tends to precipitate as nickel oxide.

In addition, it has been proposed to use a mixture of Li ₂ NiO ₂ compound and Li ₂ CuO ₂ compound as a positive electrode additive, but it is known that there is little improvement in irreversible capacity due to the addition of Li ₂ CuO ₂ compound.

However, according to the research results of the present inventors, by heat treating a mixture containing a lithium precursor, a nickel precursor, and the precursor of M in the presence of a copper precursor, Li ₂ Ni _1-x Cu _x O ₂ without precipitation of nickel oxide. The compound of Formula 1 can be prepared as a composite crystal phase in which a crystal phase and a crystal phase of Li _y MO _z coexist.

According to one embodiment, a precursor mixture including a lithium precursor, a nickel precursor, a copper precursor, and the M precursor is heat-treated under an inert gas atmosphere to form the compound represented by Formula 1.

The precursor mixture may be prepared by solid-phase mixing the lithium precursor, nickel precursor, copper precursor, and the M precursor to match the stoichiometric ratio according to Formula 1.

As the precursors, compounds known to be usable as precursors of the corresponding elements in the technical field to which the present invention pertains may be applied without particular limitation.

Preferably, the lithium precursor may be lithium oxide, lithium hydroxide, or lithium carbonate.

The nickel precursor is one or more compounds selected from the group consisting of nickel oxide, nickel hydroxide, nickel sulfate, nickel nitrate, nickel acetate, nickel carbonate, nickel oxalate, nickel citrate, nickel halide, nickel phosphate, and hydroxides thereof. It can be.

The copper precursor is one or more compounds selected from the group consisting of copper oxide, copper hydroxide, copper sulfate, copper nitrate, copper acetate, copper carbonate, copper oxalate, copper citrate, copper halide, copper phosphate, and hydroxides thereof. It can be.

In addition, the precursor of M may be one or more compounds selected from the group consisting of oxides, hydroxides, sulfates, nitrates, acetates, carbonates, oxalates, citrates, halides, phosphates, and hydroxides containing the element M. there is.

According to one embodiment, the heat treatment may be performed for 3 hours to 18 hours in an inert gas atmosphere and at a temperature of 600 ℃ to 1000 ℃.

The heat treatment may be performed under an inert gas atmosphere such as Ar, N ₂ , Ne, and He.

In order to enable crystal seeds to be generated at an appropriate rate, the heat treatment is preferably performed at a temperature of 600°C or higher or 700°C or higher. However, if the temperature of the heat treatment is excessively high, a sintering phenomenon in which the grown particles clump together may occur. Therefore, the heat treatment is preferably performed at a temperature of 1000°C or lower or 900°C or lower. Specifically, the heat treatment may be performed at a temperature of 600 ℃ to 1000 ℃, or 700 ℃ to 1000 ℃, or 700 ℃ to 900 ℃.

The heat treatment may be performed for 3 to 18 hours at the heat treatment temperature. The heat treatment time can be adjusted by considering the time required for the precursors to sufficiently react and the time required for the crystal of the compound of Formula 1 to stabilize. Specifically, the heat treatment time is 3 hours or more or 5 hours or more; And it can be 18 hours or less or 15 hours or less. Preferably, the heat treatment time may be 3 hours to 18 hours, or 5 hours to 18 hours, or 5 hours to 15 hours.

If necessary, a step of pulverizing the compound of Formula 1 obtained in the above step may be performed.

If the difference in particle size between the positive electrode active material and the positive electrode additive in the positive electrode material increases, uniform mixing of the positive electrode materials becomes difficult and the internal stress of the electrode increases, making it difficult to achieve stable battery performance.

The particle size of the positive electrode additive obtained through the grinding may be determined at a level similar to that of the positive electrode active material. However, it is not desirable to provide enough energy to excessively generate fine powder during the grinding process.

As a non-limiting example, the grinding includes pre-grinding, which grinds the positive electrode additive obtained in the form of lumps in the above step into chunks of several cm scale, coarse grinding, which grinds the chunks to 1 mm or less, and using a pin mill, etc. Fine grinding may be performed. Afterwards, it can be classified using a standard mesh.

According to another embodiment of the invention, a positive electrode for a lithium secondary battery including the positive electrode additive is provided.

The positive electrode for a lithium secondary battery may include a positive electrode active material, a binder, a conductive material, and the positive electrode additive. Preferably, the positive electrode for a lithium secondary battery includes a positive electrode material including a positive electrode active material, a conductive material, the positive electrode additive, and a binder; And, it includes a current collector that supports the positive electrode material.

According to one embodiment, the positive electrode additive may be included in an amount of more than 0% by weight and less than 15% by weight based on the total weight of the positive electrode material.

In order to compensate for the irreversible lithium consumed in forming the SEI layer, the content of the lithium transition metal oxide is preferably greater than 0% by weight based on the total weight of the cathode material. However, when the positive electrode additive, which is a sacrificial positive electrode material, is included in excess, the content of the positive electrode active material showing reversible charge/discharge capacity is reduced, thereby reducing the capacity of the battery, and the remaining lithium in the battery is plated on the negative electrode, preventing short circuit of the battery. It may cause or impair safety. Therefore, the content of the positive electrode additive is preferably 15% by weight or less based on the total weight of the positive electrode material.

Specifically, the content of the positive electrode additive is more than 0% by weight, or more than 0.5% by weight, or more than 1% by weight, or more than 2% by weight, or more than 3% by weight, based on the total weight of the cathode material; And, it may be 15% by weight or less, or 12% by weight or less, or 10% by weight or less. Preferably, the content of the positive electrode additive is 0.5% to 15% by weight, or 1% to 15% by weight, or 1% to 12% by weight, or 2% to 12% by weight, based on the total weight of the positive electrode material. , or 2% by weight to 10% by weight, or 3% by weight to 10% by weight.

As the positive electrode active material, any material capable of reversible insertion and desorption of lithium ions can be used without particular restrictions. For example, the positive electrode active material may be a complex oxide or phosphate containing cobalt, manganese, nickel, iron, or a combination of these metals and lithium.

As a non-limiting example, the positive electrode active material may be a compound represented by any of the following chemical formulas.

Li _a A _1-b R _b D ₂ (0.90≤a≤1.8, 0≤b≤0.5); Li _a E _1-b R _b O _2-c D _c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); LiE _2-b R _b O _4-c D _c (0≤b≤0.5, 0≤c≤0.05); Li _a Ni _1-bc Co _b R _c D _d (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<d≤2); Li _a Ni _1-bc Co _b R _c O _2-d Z _d (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<d<2); Li _a Ni _1-bc Co _b R _c O _2-d Z ₂ (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<d<2); Li _a Ni _1-bc Mn _b R _c D _d (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<d≤2); Li _a Ni _1-bc Mn _b R _c O _2-d Z _d (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<d<2); Li _a Ni _1-bc Mn _b R _c O _2-d Z ₂ (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<d<2); Li _a Ni _b E _c G _d O ₂ (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1.); Li _a Ni _b Co _c Mn _d G _e O ₂ (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1); Li _a NiG _b O ₂ (0.90≤a≤1.8, 0.001≤b≤0.1); Li _a CoG _b O ₂ (0.90≤a≤1.8, 0.001≤b≤0.1); Li _a MnG _b O ₂ (0.90≤a≤1.8, 0.001≤b≤0.1); Li _a Mn ₂ G _b O ₄ (0.90≤a≤1.8, 0.001≤b≤0.1); QO ₂ ; QS ₂ ; LiQS ₂ ; V ₂ O ₅ ; LiV ₂ O ₅ ; LITO ₂ ; LiNiVO ₄ ; Li _(3-f) J ₂ (PO ₄ ) ₃ (0≤f≤2); Li _(3-f) Fe ₂ (PO ₄ ) ₃ (0≤f≤2); and LiFePO ₄ .

In the above formula, A is Ni, Co, Mn, or a combination thereof; R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P or a combination thereof; E is Co, Mn, or a combination thereof; Z is F, S, P or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; T is Cr, V, Fe, Sc, Y or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

Of course, the positive electrode active material having a coating layer on the surface may be used, or a mixture of the positive electrode active material and the positive electrode active material having a coating layer may be used. Coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof.

According to one embodiment, the positive electrode active material may be included in an amount of 80% to 95% by weight based on the total weight of the positive electrode material.

Specifically, the content of the positive electrode active material is 80% by weight or more, or 82% by weight, or 85% by weight or more, based on the total weight of the positive electrode material; And, it may be 95% by weight or less, or 93% by weight or less, or 90% by weight or less.

Preferably, the content of the positive electrode active material is 82% to 95% by weight, or 82% to 93% by weight, or 85% to 93% by weight, or 85% to 90% by weight, based on the total weight of the positive electrode material. It can be.

The conductive material is used to provide conductivity to the electrode.

The conductive material may be used without particular limitations as long as it has electronic conductivity without causing chemical changes in the battery. As a non-limiting example, the conductive material may include carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, and carbon fiber; Graphites such as natural graphite and artificial graphite; Metal powders or metal fibers such as copper, nickel, aluminum, and silver; Conductive whiskeys such as zinc oxide and potassium titanate; Conductive metal oxides such as titanium oxide; Alternatively, it may be a conductive polymer such as a polyphenylene derivative. As the conductive material, one or a mixture of two or more of the examples described above may be used.

The content of the conductive material can be adjusted within a range that does not cause a decrease in battery capacity while maintaining an appropriate level of conductivity. Preferably, the content of the conductive material may be 1% to 10% by weight or 1% to 5% by weight based on the total weight of the cathode material.

The binder is used to properly attach the positive electrode material to the current collector.

As a non-limiting example, the binder may be a polymer containing polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide, poly It may be vinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc. As the binder, one or a mixture of two or more of the examples described above may be used.

The content of the binder can be adjusted within a range that does not cause a decrease in battery capacity while maintaining an appropriate level of adhesiveness. Preferably, the content of the binder may be 1% to 10% by weight or 1% to 5% by weight based on the total weight of the cathode material.

As the current collector, any material known in the technical field to which the present invention pertains is applicable to the positive electrode of a lithium secondary battery may be used without particular limitation.

As a non-limiting example, the current collector may include stainless steel; aluminum; nickel; titanium; calcined carbon; Alternatively, an aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, etc. can be used.

Preferably, the current collector may have a thickness of 3 ㎛ to 500 ㎛. In order to increase the adhesion of the cathode material, the current collector may have fine irregularities formed on its surface. The current collector may have various forms such as films, sheets, foils, nets, porous materials, foams, and non-woven fabrics.

The cathode for a lithium secondary battery may be formed by applying a cathode material including the cathode active material, the conductive material, the cathode additive, and a binder onto the current collector.

According to another embodiment of the invention, the anode for the lithium secondary battery; cathode; separation membrane; A lithium secondary battery comprising an electrolyte is provided.

The lithium secondary battery includes a positive electrode containing the positive electrode additive. Accordingly, the lithium secondary battery can exhibit improved irreversible capacity and improved safety. In addition, the lithium secondary battery can exhibit high discharge capacity, excellent output characteristics, and capacity maintenance rate.

The lithium secondary battery is used in the field of portable electronic devices such as mobile phones, laptop computers, tablet computers, mobile batteries, and digital cameras; And it can be used as an energy source with improved performance and safety in the field of transportation such as electric vehicles, electric motorcycles, and personal mobility devices.

The lithium secondary battery may include an electrode assembly wound with a separator between the positive electrode and the negative electrode, and a case in which the electrode assembly is built. In addition, the anode, the cathode, and the separator may be impregnated with an electrolyte.

The lithium secondary battery may have various shapes, such as prismatic, cylindrical, or pouch-shaped.

Details regarding the positive electrode are replaced with those described in the section on the positive electrode for lithium secondary batteries.

The negative electrode includes a negative electrode material including a negative electrode active material, a conductive material, and a binder; And it may include a current collector supporting the negative electrode material.

The negative electrode active material includes a material capable of reversibly intercalating and deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, and a transition metal oxide. It can be included.

Examples of materials that can reversibly intercalate and deintercalate lithium ions include crystalline carbon, amorphous carbon, or mixtures thereof as carbonaceous materials. Specifically, the carbonaceous material includes natural graphite, artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitches, mesophase pitch based carbon fiber, These may be meso-carbon microbeads, petroleum or coal tar pitch derived cokes, soft carbon, and hard carbon.

The alloy of the lithium metal is Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, Sn, Bi, Ga, and Cd. It may be an alloy of lithium and a metal selected from the group consisting of.

Materials capable of doping and dedoping lithium include Si, Si-C composite, SiOx (0<x<2), Si-Q alloy (where Q is an alkali metal, an alkaline earth metal, a group 13 element, a group 14 element, and a group 15 elements selected from the group consisting of group 16 elements, transition metals, rare earth elements, and combinations thereof; however, Si is excluded), Sn, SnO ₂ , and Sn-R alloy (where R is an alkali metal, alkali). It may be an element selected from the group consisting of earth metals, group 13 elements, group 14 elements, group 15 elements, transition metals, rare earth elements, and combinations thereof; however, Sn is excluded). And, as a material capable of doping and dedoping lithium, at least one of the above examples and SiO ₂ can be used in combination. Q and R are Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe , Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S , Se, Te, Po, etc.

And, the transition metal oxide may be vanadium oxide, lithium vanadium oxide, lithium titanium oxide, etc.

Preferably, the negative electrode may include one or more negative electrode active materials selected from the group consisting of carbonaceous materials and silicon compounds.

That is, according to another embodiment of the invention, the anode for the lithium secondary battery; A negative electrode containing at least one negative electrode active material selected from the group consisting of carbonaceous materials and silicon compounds; separation membrane; A lithium secondary battery comprising an electrolyte is provided.

Here, the carbonaceous material is, as previously exemplified, natural graphite, artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch, mesophase pitch-based carbon fiber, carbon microspheres, petroleum or coal-based coke, softened carbon, and hardened carbon. It is one or more substances selected from the group consisting of. And, the silicon compound is a compound containing Si as previously exemplified, that is, Si, Si-C composite, SiOx (0<x<2), the Si-Q alloy, a mixture thereof, or at least one of these and SiO It may be a mixture of ₂ .

According to one embodiment, the negative electrode active material may be included in an amount of 85% to 98% by weight based on the total weight of the negative electrode material.

Specifically, the content of the negative electrode active material is 85% by weight or more, or 87% by weight, or 90% by weight or more, based on the total weight of the negative electrode material; And, it may be 98% by weight or less, or 97% by weight or less, or 95% by weight or less.

Preferably, the content of the negative electrode active material is 85% to 97% by weight, or 87% to 97% by weight, or 87% to 95% by weight, or 90% to 95% by weight, relative to the total weight of the negative electrode material. It can be.

The conductive material, the binder, and the current collector included in the negative electrode material are replaced with the information described in the section on the positive electrode for a lithium secondary battery.

The separator separates the anode and cathode and provides a passage for lithium ions. As the separator, any membrane known in the technical field to which the present invention pertains is applicable to a separator of a lithium secondary battery may be used without particular limitation. The separator preferably has low resistance to ion movement in the electrolyte and has excellent wettability to the electrolyte.

Specifically, the separator may be a porous polymer film made of polyolefin-based polymers such as polyethylene, polypropylene, ethylene-butene copolymer, ethylene-hexene copolymer, and ethylene-methacrylate copolymer. The separator may be a multilayer membrane in which two or more layers of the porous polymer film are stacked. The separator may be a non-woven fabric containing glass fiber, polyethylene terephthalate fiber, etc. Additionally, the separator may be coated with a ceramic component or polymer material to ensure heat resistance or mechanical strength.

Meanwhile, the electrolyte may be used without particular limitation as long as it is known to be applicable to lithium secondary batteries in the technical field to which the present invention pertains. For example, the electrolyte may be an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, etc.

Specifically, the electrolyte may include a non-aqueous organic solvent and a lithium salt.

The non-aqueous organic solvent may be used without particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move.

Specifically, the non-aqueous organic solvent includes ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether-based solvents such as dibutyl ether and tetrahydrofuran; Ketone-based solvents such as cyclohexanone; Aromatic hydrocarbon solvents such as benzene and fluorobenzene; Dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and carbonate-based solvents such as propylene carbonate (PC); alcohol-based solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (R is a C2 to C20 straight-chain, branched or ring-structured hydrocarbon group, and may include a double bond aromatic ring or ether bond); Amides such as dimethylformamide; Dioxolanes such as 1,3-dioxolane; and sulfolane.

Among the above examples, a carbonate-based solvent may be preferably used as the non-aqueous organic solvent.

In particular, considering the charge/discharge performance of the battery and compatibility with the sacrificial cathode material, the non-aqueous organic solvent may be a cyclic carbonate (e.g., ethylene carbonate, propylene carbonate) with high ionic conductivity and high dielectric constant and a low viscosity. Mixtures of linear carbonates (e.g., ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate) may be preferably used. In this case, it may be advantageous to achieve the above-mentioned performance by mixing the cyclic carbonate and the linear carbonate at a volume ratio of 1:1 to 1:9.

In addition, the non-aqueous organic solvent includes ethylene carbonate (EC) and ethyl methyl carbonate (EMC) mixed at a volume ratio of 1:2 to 1:10; Alternatively, a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 1 to 3:1 to 9:1 may be preferably used.

The lithium salt contained in the electrolyte is dissolved in the non-aqueous organic solvent and acts as a source of lithium ions in the battery, enabling the operation of a basic lithium secondary battery and promoting the movement of lithium ions between the positive electrode and the negative electrode. It plays a role.

Specifically, the lithium salt is LiPF ₆ , LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAl0 ₄ , LiAlCl ₄ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN(C ₂ F ₅ SO ₃ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN(CF ₃ SO ₂ ) ₂ , LiN(SO ₂ F) ₂ (LiFSI, lithium bis(fluorosulfonyl)imide), LiCl, LiI, and LiB(C ₂ O4) It could be _2nd place. Preferably, the lithium salt may be LiPF ₆ , LiFSI, or a mixture thereof.

The lithium salt may be included in the electrolyte at a concentration of 0.1 M to 2.0 M. The lithium salt contained in the above concentration range enables excellent electrolyte performance by providing appropriate conductivity and viscosity to the electrolyte.

Optionally, the electrolyte may contain additives for the purpose of improving battery life characteristics, suppressing battery capacity reduction, and improving battery discharge capacity.

For example, the additives include haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, and tria hexaphosphate. It may be mead, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxy ethanol, aluminum trichloride, etc. . The additive may be included in an amount of 0.1% to 5% by weight based on the total weight of the electrolyte.

According to the present invention, a positive electrode additive is provided that can improve the safety of lithium secondary batteries by having a stable crystalline phase while enabling improvement of irreversible capacity.

Figures 1 to 4 show the results of X-ray diffraction (XRD) analysis of the positive electrode additives prepared in Examples and Comparative Examples of the invention.

Hereinafter, the operation and effect of the invention will be described in more detail through specific examples of the invention. However, this is presented as an example to aid understanding of the invention. It is not intended that the scope of the invention is limited in any way through the following examples, and it will be clear to those skilled in the art that various changes and modifications are possible within the scope and technical idea of the present invention.

Example 1

(1) Preparation of anode additives

Compound 0.8(Li ₂ Ni _0.75 Cu _0.25 O ₂ )-0.2(Li ₅ FeO ₄ ) was synthesized by the following method.

Prepare a total of 50 g of precursor mixture by mixing Li ₂ O (Ganfeng Lithium), NiO (Sigma-Aldrich), CuO (Sigma-Aldrich), and Fe ₂ O ₃ (Sigma-Aldrich) in the above equivalence ratio. did. The precursor mixture was placed in a blender (BL142-AKR, Tefal) and mixed for more than 5 minutes. The precursor mixture was placed in an alumina crucible and the crucible lid was closed. The crucible was placed in a gas pressure sintering furnace, heat treated for 12 hours at 700° C. in an N ₂ gas atmosphere, and then cooled. The compound particles thus obtained were placed in a jaw crusher (Retsch BB50), coarsely crushed with a blade gap of 2 mm, and then ground in a pin mill (Retsch ZM200) at 18,000 rpm. The pulverized compound particles were classified into particle sizes of 38 ㎛ or less using a sieve shaker.

(2) Manufacturing of lithium secondary batteries

The above 0.8(Li ₂ Ni _0.75 Cu _0.25 O ₂ )-0.2(Li ₅ FeO ₄ ) compound, carbon black as a conductive material, and polyvinylidene fluoride (PVdF) as a binder were mixed in an organic solvent at a weight ratio of 95:3:2. A cathode material slurry was prepared by mixing with (N-methyl-2-pyrrolidone). The positive electrode material slurry was applied to one side of a current collector, which was an aluminum foil with a thickness of 15 ㎛, and was rolled and dried to produce a positive electrode (punch size Φ14 mm).

A coin-shaped half-cell was manufactured by preparing the anode, cathode, separator, and electrolyte solution. At this time, Li-metal (punch size Φ15mm) with a thickness of 300 ㎛ was used as the cathode. The electrolyte solution is a non-aqueous organic solvent mixed with ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) in a volume ratio of 1:2:1, 1.0 M of LiPF ₆ , and 2% by weight of vinylene. Dissolved carbonate (VC) was used. And, as the separator, a PE resin separator (manufactured by W-scope, WL20C, 20 ㎛) was used.

Example 2

(1) Preparation of anode additives

0.7(Li ₂ Ni _0.75 Cu _0.25 O ₂ )-0.3(Li ₅ FeO ₄ ) compound was synthesized in the same manner as in Example 1, except that the equivalence ratio of the precursors was changed.

(2) Manufacturing of lithium secondary batteries

A lithium secondary battery was manufactured in the same manner as Example 1, except that the 0.7(Li ₂ Ni _0.75 Cu _0.25 O ₂ )-0.3(Li ₅ FeO ₄ ) compound was used as a positive electrode additive.

Comparative Example 1

(1) Preparation of anode additives

Li ₂ O (Ganfeng Lithium), NiO (Sigma-Aldrich), and Fe ₂ O ₃ (Sigma-Aldrich) were mixed so that the molar ratio of Li: Fe: Ni was 2.6: 0.2: 0.8, and a total of 50 g was added. A precursor mixture was prepared. A positive electrode additive was prepared in the same manner as Example 1, except that the precursor mixture was used. According to the following XRD analysis results, the positive electrode additive according to Comparative Example 1 was confirmed to be a mixture of Li ₅ FeO ₄ and NiO.

(2) Manufacturing of lithium secondary batteries

A lithium secondary battery was manufactured in the same manner as Example 1, except that the positive electrode additive was used.

Comparative Example 2

(1) Preparation of anode additives

A total of 50 g of precursor mixture was prepared by mixing Li ₂ O (Ganfeng Lithium), NiO (Sigma-Aldrich), and CoO (Sigma-Aldrich) at a Li:Co:Ni molar ratio of 3.2:0.3:0.7. Ready. A positive electrode additive was prepared in the same manner as Example 1, except that the precursor mixture was used. According to the following XRD analysis results, the positive electrode additive according to Comparative Example 2 was confirmed to be a mixture of Li ₂ NiO ₂ and Li ₆ CoO ₄ .

(2) Manufacturing of lithium secondary batteries

A lithium secondary battery was manufactured in the same manner as Example 1, except that the positive electrode additive was used.

Comparative Example 3

(1) Preparation of anode additives

Li ₂ O (Ganfeng Lithium), NiO (Sigma-Aldrich), and MnO ₂ (Sigma-Aldrich) were mixed at a Li:Mn:Ni molar ratio of 2.8:0.2:0.8 to produce a total of 50 g of precursor mixture. prepared. A positive electrode additive was prepared in the same manner as Example 1, except that the precursor mixture was used. According to the following XRD analysis results, the positive electrode additive according to Comparative Example 3 was confirmed to be a mixture of Li ₂ NiO ₂ and NiO.

(2) Manufacturing of lithium secondary batteries

A lithium secondary battery was manufactured in the same manner as Example 1, except that the positive electrode additive was used.

Comparative Example 4

(1) Preparation of anode additives

Li ₂ O (Ganfeng Lithium), NiO (Sigma-Aldrich), and CuO (Sigma-Aldrich) were mixed so that the molar ratio of Li:Ni:Cu was 2:0.75:0.25. The mixture was prepared in the form of pellets using a press, and fired at 750° C. in an Ar atmosphere to obtain Li ₂ Ni _0.75 Cu _0.25 O ₂ particles. The Li ₂ Ni _0.75 Cu _0.25 O ₂ particles were pulverized and classified in the same manner as in Example 1.

Li ₂ O (Ganfeng Lithium) and Fe ₂ O ₃ (Sigma-Aldrich) were mixed so that the Li:Fe molar ratio was 5:1. The mixture was prepared in the form of pellets using a press and calcined at 750°C in an Ar atmosphere to obtain Li ₅ FeO ₄ particles. The Li ₅ FeO ₄ particles were pulverized and classified in the same manner as in Example 1.

A positive electrode additive was prepared by adding the Li ₂ Ni _0.75 Cu _0.25 O ₂ particles and the Li ₅ FeO ₄ particles in a mixer (BL142-AKR, Tefal) at a weight ratio of 8:2 and mixing for at least 5 minutes.

(2) Manufacturing of lithium secondary batteries

A lithium secondary battery was manufactured in the same manner as Example 1, except that the positive electrode additive was used.

Test example

(1) X-ray diffraction analysis

Powder X-ray diffraction analysis was performed on the positive electrode additives prepared in the above examples and comparative examples using XRD analysis equipment (Bruker D4 Endeavor, Cu Kα X-ray (X-rα)). The results are shown in Figure 1 (Example 1), Figure 2 (Comparative Example 1), Figure 3 (Comparative Example 2), and Figure 4 (Comparative Example 3).

Referring to Figure 1, in the 0.8(Li ₂ Ni _0.75 Cu _0.25 O ₂ )-0.2(Li ₅ FeO ₄ ) compound of Example 1, 19°±0.5° resulting from the Li ₂ Ni _0.75 Cu _0.25 O ₂ crystal phase and Peaks appearing at 2θ of 26°±0.5°, peaks appearing at 21.5°±0.5° and 24°±0.5° resulting from the Li ₅ FeO ₄ crystalline phase, and 37 originating from unreacted nickel precursor (NiO). Peaks appearing at 2θ of °±0.5° and 43°±0.5° were observed.

Referring to FIG. 2, in Comparative Example 1, almost no characteristic peaks due to the Li ₂ NiO ₂ crystal phase were observed, no characteristic peaks due to the Li ₂ NiO ₂ -Li ₅ FeO ₄ composite crystal phase were observed, and in NiO The resulting characteristic peak appeared strongly.

Referring to FIG. 3, in Comparative Example 2, a weak characteristic peak resulting from the composite crystal phase of the Li ₂ NiO ₂ crystal phase and Li ₆ CoO ₄ crystal phase was observed, but it was confirmed that a large amount of unreacted Li ₂ O and NiO remained.

Referring to FIG. 4, in Comparative Example 3, only a weak characteristic peak due to the Li ₂ NiO ₂ crystal phase was observed, and no characteristic peak due to the Li ₂ NiO ₂ -Li ₆ MnO ₄ composite crystal phase was observed, and Li ₂ O And it was confirmed that a large amount of NiO remained.

(2) Charge/discharge capacity and gas generation amount

The lithium secondary batteries prepared in Example 1, Example 2, and Comparative Example 4 were charged until 4.25 V at a constant current of 60 mA/g and a constant voltage of 30 mA/g at 45°C, and the constant current was 10 mA. A charge/discharge experiment was conducted by discharging to 2.5 V under /g. Through the above charging and discharging experiment, the primary charging capacity and primary discharging capacity were calculated, respectively.

Then, the amount of gas generated in the charge and discharge experiment was measured using a hydrometer (MATSUHAKU, TWD-150DM). The difference between the original weight of the lithium secondary battery and the weight in water was measured, the change in volume within the battery was calculated, and the amount of gas generated per weight was calculated by dividing the change in volume by the weight of the positive electrode additive.

Primary charging capacity
(mAh/g) Primary discharge capacity
(mAh/g) irreversible capacity
(mAh/g) Formation
amount of gas generated
(mL/g) Example 1 462 111 350 0.275 Example 2 489 99 390 - Comparative Example 4 463 115 348 0.325

Referring to the results of the above test example, in this example, a complex crystalline compound containing a Li ₂ Ni _0.75 Cu _0.25 O ₂ crystal phase and a Li ₅ FeO ₄ crystal phase was obtained, and the lithium secondary battery containing the compound was obtained in the comparative example. Compared to 4, it is confirmed that gas generation can be suppressed while exhibiting an irreversible capacity equal to or greater than that of 4.

Although the present invention has been described above with limited examples, the present invention is not limited thereto, and the technical idea of the present invention and the patents described below will be understood by those skilled in the art. Of course, various modifications and variations are possible within the scope of equivalence of the claims.

Claims (12)

A positive electrode additive for a lithium secondary battery comprising a compound represented by the following formula (1):
[Formula 1]
a(Li ₂ Ni _1-x Cu _x O ₂ )-b(Li _y MO _z )
In Formula 1,
M is Co, Mn or Fe,
_a and b are the _molar ratio of the Li _{2 Ni 1-x Cu}
0.1 ≤ x ≤ 0.4, 3 < y < 7, and 3 < z < 5.
According to claim 1,
The compound of Formula 1 has a composite crystal phase in which the Li ₂ Ni _1-x Cu _x O ₂ crystal phase and the Li _y MO _z crystal phase coexist, a positive electrode additive for a lithium secondary battery.
According to claim 1,
The compound of Formula 1 has 19°±0.5°, 26°±0.5°, 37°±0.5°, and 43°±0.5° when analyzed by powder X-ray diffraction by Cu Kα X-ray (X-rα). A positive electrode additive for lithium secondary batteries, which has peaks that appear at 2θ.
Forming a compound represented by Formula 1 below by heat-treating a precursor mixture including a lithium precursor, a nickel precursor, a copper precursor, and the precursor M below under an inert gas atmosphere.
Method for producing a positive electrode additive for a lithium secondary battery according to claim 1, comprising:
[Formula 1]
a(Li ₂ Ni _1-x Cu _x O ₂ )-b(Li _y MO _z )
In Formula 1,
M is Co, Mn or Fe,
a and b are the _molar ratio _of Li _{2 Ni 1-x Cu}
0.1 ≤ x ≤ 0.4, 3 < y < 7, and 3 < z < 5.
According to claim 4,
The heat treatment is performed for 3 hours to 18 hours in an inert gas atmosphere and at a temperature of 600 ℃ to 1000 ℃.
According to claim 4,
A method of producing a positive electrode additive for a lithium secondary battery, wherein the lithium precursor is lithium oxide, lithium hydroxide, or lithium carbonate.
According to claim 4,
The nickel precursor is one or more compounds selected from the group consisting of nickel oxide, nickel hydroxide, nickel sulfate, nickel nitrate, nickel acetate, nickel carbonate, nickel oxalate, nickel citrate, nickel halide, nickel phosphate, and hydroxides thereof. Method for producing cathode additives for phosphorus and lithium secondary batteries.
According to claim 4,
The copper precursor is one or more compounds selected from the group consisting of copper oxide, copper hydroxide, copper sulfate, copper nitrate, copper acetate, copper carbonate, copper oxalate, copper citrate, copper halide, copper phosphate, and hydroxides thereof. Method for producing cathode additives for phosphorus and lithium secondary batteries.
According to claim 4,
The precursor of M is lithium secondary, which is one or more compounds selected from the group consisting of oxides, hydroxides, sulfates, nitrates, acetates, carbonates, oxalates, citrates, halides, phosphates, and hydroxides thereof containing the M. Method for producing a positive electrode additive for batteries.
A positive electrode for a lithium secondary battery comprising the positive electrode additive according to claim 1.
A positive electrode for a lithium secondary battery according to claim 10; cathode; separation membrane; and a lithium secondary battery comprising an electrolyte.
According to claim 11,
A lithium secondary battery, wherein the negative electrode includes at least one negative electrode active material selected from the group consisting of carbonaceous materials and silicon compounds.