CN1897336A - Cathode active material, method of manufacturing it, cathode, and battery - Google Patents

Cathode active material, method of manufacturing it, cathode, and battery Download PDF

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CN1897336A
CN1897336A CNA2006101212559A CN200610121255A CN1897336A CN 1897336 A CN1897336 A CN 1897336A CN A2006101212559 A CNA2006101212559 A CN A2006101212559A CN 200610121255 A CN200610121255 A CN 200610121255A CN 1897336 A CN1897336 A CN 1897336A
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manganese
nickel
composite oxide
coating layer
oxide particle
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CN100527489C (en
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渡辺春夫
荻须谦二
森田耕诗
相马正典
细谷洋介
东秀人
大山有代
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Murata Northeast China
Murata Manufacturing Co Ltd
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Sony Corp
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Abstract

A cathode active material capable of increasing a capacity and improving high temperature characteristics or cycle characteristics, a method of manufacturing it, a cathode using the cathode active material, and a battery using the cathode active material are provided. In a cathode active material contained in a cathode, a coating layer is provided on at least part of a complex oxide particle containing at least lithium (Li) and cobalt (Co). The coating layer is an oxide which contains lithium (Li) and at least one of nickel (Ni) and manganese (Mn).

Description

Positive electrode active materials and production method thereof, positive pole and battery
The cross reference of related application
The present invention includes the theme of the Japanese patent application JP2005-156033 that submits in Japan Patent office in Japanese patent application JP2005-156031 that the Japanese patent application JP 2005-156030 that submits in Japan Patent office that relates on May 27th, 2005, on May 27th, 2005 submit in Japan Patent office and on May 27th, 2005, the full content of these applications here is incorporated herein by reference.
Technical field
The present invention relates to a kind of positive electrode active materials that contains the composite oxides that comprise lithium (Li) and cobalt (Co), a kind of method of making this positive electrode active materials, the battery that uses the anodal of this positive electrode active materials and use this positive electrode active materials.
Background technology
In recent years, as making up the portable unit extensive use of camera and notebook personal computer.Therefore, the needs for the small-sized secondary batteries with high power capacity increase day by day.Applied now secondary cell comprises the nickel-cadmium cell that uses alkaline electrolyte.Yet its cell voltage is 1.2V, and this voltage is low, therefore is difficult to improve energy density.Therefore, considered to develop the so-called lithium metal secondary batteries of utilizing the lithium metal.This lithium metal has 0.534 proportion, and it is the lightest simple substance in solid-state simple substance the inside.In addition, in the metal negative material, the lithium metal has the voltage of remarkable deficiency and has the highest current capacity of per unit weight.Yet, in the lithium metal secondary batteries, have following shortcoming.Just, along with discharging and recharging, lithium is dendritic growth on negative pole, causes the cycle characteristics that reduces.In addition, the lithium of growth destroys barrier film like this, causes internal short-circuit.Therefore, developed wherein material with carbon element such as coke as negative pole, the secondary cell that embeds and take off the embedding alkali metal ion and repeat thus to discharge and recharge.As a result, reduced because the negative pole deterioration that discharges and recharges (for example, referring to the open No.H10-333573 of Japanese Unexamined Patent Application).
In present common employed lithium rechargeable battery, use cobalt acid lithium as positive pole, use material with carbon element as negative pole, and operating voltage arrive within the scope of 2.5V at 4.2V.As for being used as anodal positive electrode active materials such as cobalt acid lithium in the lithium secondary battery of under 4.2V, working, only utilize about 60% capacity with respect to theoretical capacity in this maximum.Therefore, can utilize remaining capacity by further raising charging voltage in theory.In fact, known to improving charging voltage to 4.25V or higher realization high-energy-density (referring to the open No.WO03/197131 in the world).Especially, as positive electrode active materials, except cobalt acid lithium, also have lithium nickelate, have the LiMn2O4 of spinel structure etc.Especially, because cobalt acid lithium can improve voltage the biglyyest, preferably use cobalt acid lithium.
Yet, when improving charging voltage, have following shortcoming.Near oxidizing atmosphere grow promptly anodal.As a result, electrolyte passes through oxidation Decomposition and deterioration easily, and perhaps cobalt comes out from anodal elution easily.Therefore, efficiency for charge-discharge reduces, and cycle characteristics reduces, and therefore is difficult to improve charging voltage.
In the past,, reported method as described below etc. as the method for the stability of improving positive electrode active materials.A kind of method is exactly the different element of dissolving such as aluminium (Al), magnesium (Mg), zirconium (Zr) and titanium (Ti) (referring to the open No.2004-303459 of Japanese Unexamined Patent Application).Another kind method is (referring to the open No.2002-100357 of Japanese Unexamined Patent Application) such as a spot of lithium-nickel-manganese composite oxides of mixing.Also having a kind of method is to coat cobalt acid lithium surface (referring to open No.H10-333573 of Japanese Unexamined Patent Application and H10-372470) with the LiMn2O4 with spinel structure or nickel-cobalt composite oxide.
Summary of the invention
Yet, in the method for the different elements of dissolving, have following shortcoming.That is,, can not substantially improve hot properties or cycle characteristics, and when meltage was big, capacity reduced when meltage hour.When mixing lithium-nickel-manganese composite oxide etc., the shortcoming of existence is to substantially improve characteristic.Coating with LiMn2O4 or lithium titanate in the method on cobalt acid lithium surface, the shortcoming of existence is that capacity reduces.In addition, under the situation of using LiMn2O4, such shortcoming is arranged: so because the wash-out characteristic of manganese reduces (referring to open No.2987358 of Japan Patent and the open No.2004-227869 of Japanese Unexamined Patent Application).In addition, in the method that coats cobalt acid lithium surface with nickel-cobalt composite oxide, there is following shortcoming.A shortcoming is that thermal stability reduces (referring to the open No.H10-236826 of Japanese Unexamined Patent Application).Another shortcoming is that its discharge potential is low owing to compare with cobalt acid lithium, is disadvantageous for increasing energy density therefore.
Consider foregoing, in the present invention, be desirable to provide and a kind ofly can improve capacity and improve hot properties and the positive electrode active materials of cycle characteristics that its production method is used the positive pole of this positive electrode active materials and used the battery of this positive electrode active materials.
According to the embodiment of the present invention, provide a kind of positive electrode active materials, having comprised: the composite oxide particle that makes by the oxide that contains lithium (Li) and cobalt (Co) at least; And be arranged on this composite oxide particle to small part and by containing the coating layer that oxide at least a in lithium and nickel and the manganese makes.
More specifically, the average composition of composite oxide particle is represented with Chemical formula 1.
In addition, the available Chemical formula 2 of average composition of composite oxide particle is represented, and the concentration ratio of the manganese in the layer segment is high in the interior layer segment of coating layer outside coating layer.
In addition, the also available chemical formula 3 of the average composition of composite oxide particle is represented, and in the diffraction maximum that obtains by CuK α powder x-ray diffraction, on spending a side of the angle in the 1.0 degree scopes, the angle of diffraction 2 θ low 0.2 than the diffraction maximum of the face that belongs to composite oxide particle [101] have the diffraction maximum of coating layer.
(Chemical formula 1)
Li (1+w)Co (1-x-y)M1 xM2 yO (2-z)
In Chemical formula 1, M1 represents to be selected from least a element of magnesium (Mg), aluminium (Al), titanium (Ti) and zirconium (Zr).M2 represents to be selected from least a element of boron (B), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), tungsten (W), yttrium (Y), niobium (Nb), calcium (Ca) and strontium (Sr).The value of w, x, y and z respectively-0.10≤w≤0.10,0.001＜x＜0.10,0≤y＜0.40 and-scope of 0.10≤z≤0.20 in.
(Chemical formula 2)
Li (1+x)Co (1-y)M yO (2-z)
In Chemical formula 2, M represents to be selected from least a element of magnesium (Mg), aluminium (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), tungsten (W), zirconium (Zr), yttrium (Y), niobium (Nb), calcium (Ca) and strontium (Sr).The value of x, y and z respectively-0.10≤x≤0.10,0≤y＜0.50 and-scope of 0.10≤z≤0.20 in.
(chemical formula 3)
Li (1+x)Co (1-y)M yO (2-z)
In chemical formula 3, M represents to be selected from least a element of magnesium (Mg), aluminium (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), tungsten (W), zirconium (Zr), yttrium (Y), niobium (Nb), calcium (Ca) and strontium (Sr).The value of x, y and z respectively-0.10≤x≤0.10,0≤y＜0.50 and-scope of 0.10≤z≤0.20 in.
According to the embodiment of the present invention, a kind of method of making positive electrode active materials is provided, may further comprise the steps: have 12 or the aqueous solution of bigger hydrogen ion exponent pH in, at the inside precursor layer that forms the hydroxide that contains nickel (Ni) and manganese (Mn) to the small part of composite oxide particle with average composition of representing with Chemical formula 1 or Chemical formula 2; After forming inner precursor layer, by changing the chemical valence of the manganese ion that in the aqueous solution, is comprised, has outside precursor layer than the hydroxide of the manganese concentration of inner precursor floor height in the formation to the small part of composite oxide particle; And form the coating layer that makes by the oxide that contains lithium, nickel and manganese, by inner precursor layer and outside precursor layer are heat-treated, make at composite oxide particle to small part that wherein the manganese concentration of outer layer segment is greater than the manganese concentration of interior layer segment.
(Chemical formula 1)
Li (1+w)Co (1-x-y)M1 xM2 yO (2-z)
In Chemical formula 1, M1 represents to be selected from least a element of magnesium (Mg), aluminium (Al), titanium (Ti) and zirconium (Zr).M2 represents to be selected from least a element of boron (B), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), tungsten (W), yttrium (Y), niobium (Nb), calcium (Ca) and strontium (Sr).The value of w, x, y and z respectively-0.10≤w≤0.10,0.001＜x＜0.10,0≤y＜0.40 and-scope of 0.10≤z≤0.20 in.
(Chemical formula 2)
Li (1+x)Co (1-y)M yO (2-z)
In Chemical formula 2, M represents to be selected from least a element of magnesium (Mg), aluminium (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), tungsten (W), zirconium (Zr), yttrium (Y), niobium (Nb), calcium (Ca) and strontium (Sr).The value of x, y and z respectively-0.10≤x≤0.10,0≤y＜0.50 and-scope of 0.10≤z≤0.20 in.
According to the embodiment of the present invention, provide a kind of positive pole that comprises the positive electrode active materials of above-mentioned embodiments of the present invention.
According to the embodiment of the present invention, provide a kind of positive pole, negative pole and electrolytical battery of comprising, the wherein anodal positive electrode active materials that contains above-mentioned embodiment of the present invention.
According to the positive electrode active materials of embodiment of the present invention, in the high power capacity and high-tension characteristic that keep composite oxide particle, also can improve the chemical stability of positive electrode active materials.In addition, even break or destroy owing to external force, the activity on the surface of Bao Luing is also low thus.Therefore, the battery according to the embodiments of the present invention of using this positive electrode active materials can obtain high power capacity and high voltage, can improve hot properties or cycle characteristics, and can improve chemical stability.
The present invention other and further purpose, feature and advantage will embody from following description more fully.
Description of drawings
Fig. 1 is the flow chart that shows the manufacture method of positive electrode active materials according to the embodiment of the present invention;
Fig. 2 is the cross section that shows the first kind of secondary battery construction that uses positive electrode active materials according to the embodiment of the present invention;
Fig. 3 is the decomposition cross section that shows the part of the spiral winding electrode in the secondary cell shown in figure 2;
Fig. 4 is the decomposition diagram that shows the structure of the second kind of secondary cell that uses positive electrode active materials according to the embodiment of the present invention;
Fig. 5 is the cross section along the line I-I of the spiral winding electrode shown in Fig. 4;
Fig. 6 measures distribution map according to the powder x-ray diffraction of the positive electrode active materials of embodiment 1-1;
Fig. 7 measures distribution map according to the powder x-ray diffraction of the positive electrode active materials of embodiment 1-3; And
Fig. 8 measures distribution map according to the powder x-ray diffraction of the positive electrode active materials of comparative example 1-2.
Embodiment
Describe embodiments of the present invention below with reference to accompanying drawings in detail.
According to the positive electrode active materials of embodiment of the present invention comprise the composite oxide particle that makes by the oxide that contains lithium (Li) and cobalt (Co) at least and be arranged on composite oxide particle to small part and by containing the coating layer that oxide at least a in lithium and nickel and the manganese makes.More specifically, positive electrode active materials can be implemented as follows.
(first kind of positive electrode active materials)
In positive electrode active materials according to first execution mode of the present invention, its average form the composite oxide particle represented by Chemical formula 1 to small part, coating layer is set.In positive electrode active materials,, can obtain high power capacity and high discharge potential, and can improve chemical stability by constituting as average composition at the composite oxide particle shown in the Chemical formula 1.
(Chemical formula 1)
Li (1+w)Co (1-x-y)M1 xM2 yO (2-z)
In Chemical formula 1, M1 represents to be selected from least a element of magnesium, aluminium, titanium and zirconium.M2 represents to be selected from least a element of boron, vanadium, chromium, manganese, iron, nickel, copper, zinc, molybdenum, tin, tungsten, yttrium, niobium, calcium and strontium.
The value of w is in the scope of-0.10≤w≤0.10, preferably in the scope of-0.08≤w≤0.08, and more preferably in the scope of-0.06≤w≤0.06.When the value of w during less than aforementioned range, discharge capacity reduces.Simultaneously, when the value of w during, lithium diffusion in forming coating layer, and control this step difficulty greater than aforementioned range.
The value of x is in the scope of 0.001＜x＜0.10, preferably in the scope of 0.002＜x＜0.08, and more preferably in the scope of 0.003＜x＜0.06.When M1 content during less than aforementioned range, the chemical stability of composite oxide particle reduces.Simultaneously, when M1 content during greater than aforementioned range, capacity reduces.The concentration of M1 in composite oxide particle needn't homogeneous, but for example its concentration can be between face side and central side distribution gradient.Yet, on its concentration preferred general approximate evenly wait the surface activity of exposure by breaking because can reduce.
The value of y is in the scope of 0≤y＜0.40, preferably in the scope of 0≤y＜0.30, and more preferably in the scope of 0≤y＜0.20.That is, M2 is not necessity formation element in the Chemical formula 1.Sometimes, because chemical stability can be improved more, except M1, also preferably include M2.Yet, when M2 content is big, the characteristic forfeiture of cobalt acid lithium, and reduction capacity and discharge potential.
The value of z is in the scope of-0.10≤z≤0.20, preferably in the scope of-0.08≤z≤0.18, and more preferably in the scope of-0.06≤z≤0.16.In aforementioned range, discharge capacity can be improved more.
Coating layer plays the effect of reaction inhibiting layer.Coating layer is made up of the oxide that contains lithium, nickel and manganese.Nickel and the manganese concentration in coating layer changes on depth direction.High in the inside part of the coating layer of concentration ratio on the composite oxide particle side of manganese in the layer segment outside its relative with the interior layer segment of coating layer.Be set to be higher than the average composition of coating layer by the concentration of the manganese in the outer layer segment, can improve efficiency for charge-discharge more.
Coating layer plays the effect of reaction inhibiting layer.Coating layer is formed by containing oxide at least a in lithium and nickel and the manganese.Nickel and manganese at the ratio of components of coating layer with nickel: the mol ratio of manganese is expressed as preferably in the scope at 100: 0 to 20: 80, and more preferably in 100: 0 to 40: 60 scope.When the amount of manganese was big, the embedded quantity of lithium in coating layer reduced, and the capacity of positive electrode active materials reduces.
In addition, as constituting element, in the oxide of coating layer, can further comprise at least a element that is selected from magnesium, aluminium, boron, titanium, vanadium, chromium, iron, cobalt, copper, zinc, molybdenum, tin, tungsten, zirconium, yttrium, niobium, calcium and strontium.Thus, the stability of positive electrode active materials can be improved more, and the diffusion property of lithium ion can be improved more.In this case, the total content of these additional elements is preferably 40 moles of % or still less with respect to the total content of nickel, manganese and these additional elements in the coating layer, 30 moles of % or still less more preferably, and more preferably 20 moles of % or still less.When the content of these additional elements was big, the embedded quantity of lithium reduced, and the capacity of positive electrode active materials reduces.These additional elements are solvable or can be insoluble in oxide.
Coating layer with respect to the amount of composite oxide particle preferably at 0.5 weight % in the scope of 50 weight %, more preferably at 1.0 weight % in the scope of 40 weight %, and also more preferably at 2.0 weight % in the scope of 35 weight %.When the amount of coating layer was big, capacity reduced.Equally, when the amount of coating layer hour, can not substantially improve stability.
Coating layer refers to from the surface of positive electrode active materials to the zone of its inside, and wherein when the concentration that detects nickel and manganese from the surface of positive electrode active materials to inside changed, concentration that all can't see nickel and manganese basically changed.Can following acquisition nickel and the concentration of manganese from the surface of positive electrode active materials to inside change.For example, in by (scrape) positive electrode active materials of pruning such as sputters, can measure the composition of positive electrode active materials by Auger electron spectroscopy (AES) or secondary ion mass spectrometry (SIMS).In addition, positive electrode active materials can slowly be dissolved in the acid solution etc., and changes by the time that inductively coupled plasma (ICP) spectrometry etc. is measured the wash-out part.
The average grain diameter of positive electrode active materials preferably at 2.0 μ m in the scope of 50 μ m.When average grain diameter during less than 2.0 μ m, positive electrode active materials separates from positive electrode collector easily in pressing step in forming positive pole.In addition, it is big that the surface area of positive electrode active materials becomes, and therefore the amount of additive such as electric conductor and binding agent should increase, and therefore the energy density of per unit weight reduces.On the contrary, when average grain diameter during greater than 50 μ m, positive electrode active materials passes barrier film, the possibility that this increase is short-circuited.
Fig. 1 shows the step of manufacturing of positive electrode active materials.At first, for example have 12 or the aqueous solution of bigger hydrogen ion exponent pH in, at the inside precursor layer (step S101) that forms the hydroxide that contains nickel and manganese to the small part of composite oxide particle with average composition of representing with Chemical formula 1.By as above have 12 or the aqueous solution of bigger hydrogen ion exponent pH in coprecipitated hydroxide, the settling rate of hydroxide can be slack-off, and can form fine and close more and uniform more inner precursor layer.
When forming inner precursor layer, as shown in Figure 1, can have 12 or the aqueous solution of bigger hydrogen ion exponent pH in disperse composite oxide particle (step S111), and in the aqueous solution, add nickel compound and manganese compound subsequently and be settled out its hydroxide (step S112).In addition, can in the aqueous solution that is dissolved with nickel compound and manganese compound, disperse composite oxide particle (step S121), and subsequently the hydrogen ion exponent pH of the aqueous solution be adjusted to 12 or bigger to precipitate its hydroxide (step S122).
As the raw-material nickel compound of nickel, can enumerate inorganic compound such as nickel hydroxide, nickelous carbonate, nickel nitrate, nickel fluoride, nickel chloride, nickelous bromide, nickel iodide, nickelous perchlorate, bromic acid nickel, nickelous iodate, nickel oxide, nickel peroxide, nickel sulfide, nickelous sulfate, hydrogen sulfate nickel, nickel oxide, nickelous nitrite, nickel phosphate and nickel thiocyanide; Perhaps organic compound such as nickel oxalate and nickel acetate.Can use a kind of in the above-mentioned nickel compound separately, perhaps also can use them two kinds or more of by mixing.
As the raw-material manganese compound of manganese, can enumerate inorganic compound such as manganous hydroxide, manganese carbonate, manganese nitrate, manganous fluoride, manganese chloride, manganous bromide, manganese iodide, chloric acid manganese, perchloric acid manganese, bromic acid manganese, Manganese diiodate, manganese oxide, phosphonous acid manganese, manganese sulfide, hydrogen manganese sulfide, manganese sulfate, hydrogen sulfate manganese, thiocyanic acid manganese, nitrous acid manganese, manganese phosphate, phosphate dihydrogen manganese and bicarbonate manganese; Perhaps organic compound such as manganese oxalate and manganese acetate.Especially, the compound of preferred manganese (II) is because can obtain sufficient solubility for the aqueous solution.Can use a kind of in the above-mentioned manganese compound separately, perhaps also can use them two kinds or more of by mixing.
Next, for example, in the aqueous solution, be blown into oxidizing gas such as air and oxygen, and have 12 or the aqueous solution of bigger hydrogen ion exponent pH in change the chemical valence of manganese ion.For example, thereby manganese oxide (II) ion becomes manganese (IV) ion, and manganous hydroxide is to the solubility reduction of the aqueous solution.Therefore, has outside precursor layer (step S102) forming to the small part of composite oxide particle than the hydroxide of the manganese concentration of inner precursor floor height.
For example, regulate and form inner precursor layer and the outside precursor layer hydrogen ion exponent pH in forming by in the aqueous solution, adding alkali.For example, as alkali, can enumerate lithium hydroxide, NaOH or potassium hydroxide.Can use it a kind of separately, perhaps also can use them two kinds or more of by mixing.Yet, more preferably use lithium hydroxide.Therefore, can improve the purity of positive electrode active materials.In addition, in this case, by when the composite oxide particle that is formed with inner precursor layer and outside precursor layer separates, regulate the adhesion amount (adhesive amount) of the aqueous solution, the lithium content in the may command coating layer from the aqueous solution.
The hydrogen ion exponent pH height of preferred aqueous solutions, more preferably 13 or higher, and also be preferably 14 or higher.Hydrogen ion exponent pH is high more, can form uniform more inner precursor layer and outside precursor layer.In addition, the temperature of the aqueous solution is preferably 40 degrees centigrade or higher when forming inner precursor layer and outside precursor layer, and more preferably 60 degrees centigrade or higher, also more preferably 80 degrees centigrade or higher, and can be 100 degrees centigrade or higher.Temperature is high more, can form uniform more precursor layer.
Subsequently, separation is formed with the composite oxide particle of inner precursor layer and outside precursor layer from the aqueous solution, and heat-treats.Make the hydroxide dehydration of inner precursor layer and outside precursor layer thus, and form the coating layer (step S103) of the oxide that contains lithium, nickel and manganese.Preferably in oxidizing atmosphere such as air and pure oxygen, under about 300 degrees centigrade to 1000 degrees centigrade temperature, implement heat treatment.
By this heat treatment, lithium is diffused into coating layer from composite oxide particle.Before heat treatment is provided,, in inner precursor layer and outside precursor layer, can inject (impregnate) lithium compound in order to regulate the content of the lithium in the coating layer.As lithium compound, for example, can enumerate inorganic compound such as lithium hydroxide, lithium carbonate, lithium nitrate, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, lithium chlorate, lithium perchlorate, lithium bromate, lithium iodate, lithia, lithium peroxide, lithium sulfide, hydrogen lithium sulfide, lithium sulfate, lithium hydrogen sulfate, lithium nitride, Lithium Azide, lithium nitrite, lithium phosphate, lithium dihydrogen phosphate and lithium bicarbonate; Perhaps organic compound such as lithium methide, vinyl lithium, isopropyl lithium, butyl lithium, phenyl lithium, lithium oxalate and lithium acetate.
Before forming precursor layer, can pass through ball mill, disintegrating machine etc. if necessary the offspring of composite oxides is pulverized.In addition, after forming coating layer, can slightly pulverize if necessary, progressive operation etc., thereby and can adjust the particle diameter of positive electrode active materials.
For example pass through on aforementioned composite oxide particle, to form the precursor layer of coating layer, and in oxidizing atmosphere such as air and pure oxygen, under 300 degrees centigrade to 1000 degrees centigrade temperature, the product that obtains is heat-treated subsequently, can obtain positive electrode active materials.As the material of precursor layer, can use the material that can form oxide by the hydroxide, carbonate, nitrate etc. that roasting comprises the element that constitutes coating layer.In addition, as the material of precursor layer, can use oxide that constitutes coating layer or the multiple oxide that contains the element that constitutes coating layer.In addition, can pulverize and mix the material of composite oxides and precursor layer, come the attached precursors layer by using for example ball mill, aeropulverizer or flour mill.Then, can use decentralized medium or ratio of solvent such as water.In addition, also can handle such as mechanochemistry fusion or vapour deposition such as sputtering method and chemical vapor deposition (CVD) method attached precursors layer by mechanochemistry.
(second kind of positive electrode active materials)
In positive electrode active materials according to second execution mode of the present invention, its average form the composite oxide particle represented with Chemical formula 2 to small part, coating layer is set.In positive electrode active materials,, can obtain high power capacity and high discharge potential by constituting the average composition of the composite oxide particle shown in Chemical formula 2.
(Chemical formula 2)
Li (1+x)Co (1-y)M yO (2-z)
In Chemical formula 2, M represents to be selected from least a element of magnesium, aluminium, boron, titanium, vanadium, chromium, manganese, iron, nickel, copper, zinc, molybdenum, tin, tungsten, zirconium, yttrium, niobium, calcium and strontium.
The value of x is in the scope of-0.10≤w≤0.10, preferably in the scope of-0.08≤w≤0.08, and more preferably in the scope of-0.06≤w≤0.06.When the value of x during less than aforementioned range, discharge capacity reduces.Simultaneously, when the value of x during, lithium diffusion when forming coating layer, and control this step difficulty greater than aforementioned range.
The value of y is in the scope of 0≤y＜0.50, preferably in the scope of 0≤y＜0.40, and more preferably in the scope of 0≤y＜0.30.That is, the M in the Chemical formula 2 is not necessary formation element.Owing to can obtain high power capacity and discharge potential height, preferred cobalt acid lithium.In addition, owing to can improve stability thus, preferably comprise M.Yet, when M content is big, the characteristic forfeiture of cobalt acid lithium, and capacity and discharge potential reduction.
The value of z is in the scope of-0.10≤z≤0.20, preferably in the scope of-0.08≤z≤0.18, and more preferably in the scope of-0.06≤z≤0.16.In aforementioned range, can improve discharge capacity more.
Coating layer plays the effect of reaction inhibiting layer.Coating layer is made up of the oxide that contains lithium, nickel and manganese.By means of this composition, suppressed the capacity reduction, and can improve chemical stability.
In the diffraction maximum that obtains by CuK α powder x-ray diffraction, coating layer has than the diffraction maximum on the side of low 0.2 degree (deg) of the angle of diffraction 2 θ of the diffraction maximum of the face that belongs to composite oxide particle [101] angle in the 1.0 degree scopes.When the diffraction maximum of coating layer on a side of the angle lower than the diffraction maximum of the face that belongs to composite oxide particle [101] do not fall in the aforementioned range and its difference drop on less than the scope of 0.2 degree in the time, the dissolving of composite oxide particle and coating layer is carried out when forming coating layer, and reduces as the effect of reaction inhibiting layer.In the time of in its difference drops on about 1.0 scopes of spending, the contact performance of coating layer reduces, and can not obtain favourable coated state.Especially, the diffraction maximum of preferred coating layer is present in than the diffraction maximum low 0.3 of the face that belongs to composite oxide particle [101] and spends on angle one side in the 0.55 degree scope.Thus, can obtain higher effect.
In X-ray diffraction is measured, use Cu-K α 1 (wavelength: 0.15405nm) as X-ray source.The angle of diffraction 2 θ of the diffraction maximum of coating layer and composite oxide particle can read in the position, peak maximum that is derived from Cu-K α 1.
Ratio of components in the coating layer between nickel and the manganese, with nickel: the mol ratio of manganese is expressed as preferably in 90: 10 to 30: 70 scope, and more preferably in 70: 30 to 40: 60 scope.When the amount of manganese during greater than aforementioned range, the embedded quantity of lithium reduces in the coating layer, and the capacity of positive electrode active materials also reduces, and resistance increases.When the amount of nickel during greater than above-mentioned scope, the thermal stability of coating layer reduces, and hot properties reduces.That is, by the ratio of component between nickel and the manganese is set in the aforementioned range, the stability in the time of can improving high temperature more, and can improve capacity more.
In addition, as constituting element, in the oxide of coating layer, may further include at least a element that is selected from magnesium, aluminium, boron, titanium, vanadium, chromium, iron, cobalt, copper, zinc, molybdenum, tin, tungsten, zirconium, yttrium, niobium, calcium and strontium.Thus, the stability of positive electrode active materials can be improved more, and the diffusion property of lithium ion can be improved more.In this case, the total content of these additional elements is preferably 40 moles of % or still less to nickel in the coating layer, manganese and these ratios that adds the total content of elements, more preferably 35 moles of % or still less.When the content of these additional elements was big, the embedded quantity of lithium reduced, and the capacity of positive electrode active materials reduces.These additional elements are solvable or soluble in oxide.
Coating layer with respect to the amount of composite oxide particle preferably at 2 weight % in the scope of 30 weight %, more preferably at 5 weight % in the scope of 20 weight %.When the amount of coating layer was big, capacity reduced.Equally, when the amount of coating layer hour, can't substantially improve stability.In addition, the total content of nickel and manganese in the positive electrode active materials, just in composite oxide particle and the coating layer total amount of nickel and manganese with respect to the ratio of the total amount of metallic element except that lithium and nonmetalloid preferably in 30 moles of % or lower scope.When the content of the content of nickel and manganese was big, capacity reduced.
The average grain diameter of positive electrode active materials preferably at 2.0 μ m in the scope of 50 μ m.When average grain diameter during less than 2.0 μ m, positive electrode active materials separates from positive electrode collector easily in forming anodal pressing step, and the surface area of positive electrode active materials becomes big.As a result, the amount of additive such as electric conductor and binding agent should increase, and therefore the energy density of per unit weight reduces.On the contrary, when average grain diameter during greater than 50 μ m, positive electrode active materials passes barrier film, and this has increased the possibility that is short-circuited.
The method of making this positive electrode active materials is similar with the method for making first kind of positive electrode active materials.
For example first kind and second kind of positive electrode active materials are used for following secondary cell.
(first kind of secondary cell)
Fig. 2 shows the cross-sectional structure of the first kind of secondary cell that uses aforesaid positive electrode active materials.This secondary cell is so-called lithium rechargeable battery, wherein uses lithium as the electrode reaction thing, and capacity of negative plates is by being represented by the embedding of lithium and the capacity component of taking off embedding.This secondary cell still is so-called cylindrical battery, and has spirally the electrode body 20 of reeling, wherein a pair of bar shaped anodal 21 and bar shaped negative pole 22 and the barrier film between them 23 battery case 11 interior roll that are similar to the hollow cylinder shape around.Electrolytic solution (it is a liquid electrolyte) is injected in the battery case 11.Electrolytic solution is immersed in the barrier film 23.For example, battery case 11 is got by the iron of nickel plating.The one end sealing of battery case 11, and its other end is opened.In battery case 11 inside, a pair of insulation board 12 and 13 is arranged perpendicular to the screw winding peripheral surface respectively, makes spiral winding electrode 20 be clipped between insulation board 12 and 13.
At the openend of battery case 11, by battery cover 14 and the relief valve mechanism 15 and PTC (positive temperature coefficient) devices 16 that are arranged in the battery cover 14 being enclosed with packing ring 17 joint fillings.Thereby the inside of sealed cell shell 11 airtightly.For example, battery cover 14 is by making with battery case 11 materials similar.By PTC device 16 relief valve mechanism 15 is electrically connected to battery cover 14.When because internal short-circuit, external heat etc. make the interior pressure of battery acquire a certain degree or when bigger, disc plate is scratched (flip) for 15 times to cut off the electrical connection between battery cover 14 and the spiral winding electrode 20.When temperature raise, PTC device 16 limited electric current to avoid owing to big electric current causes unusual heat generation by increasing resistance.For example, packing ring 17 is made by insulating material, and its surface-coated has pitch.
For example, spiral winding electrode 20 is to reel in the center with centrepin 24.To be connected to the positive pole 21 of spiral winding electrode 20 by the positive wire 25 that aluminium etc. makes.To be connected to negative pole 22 by the negative wire 26 that nickel etc. makes.Positive wire 25 is electrically connected to battery cover 14 by being welded on the relief valve mechanism 15.Negative wire 26 is soldered and be electrically connected on the battery case 11.
Fig. 3 shows the amplifier section of the spiral winding electrode 20 shown in Fig. 2.For example, anodal 21 have such structure, and wherein anode active material layer 21B is arranged on the two sides of the positive electrode collector 21A with a pair of opposed surface.Although do not illustrate, anode active material layer 21B also can only be arranged on the one side of positive electrode collector 21A.Positive electrode collector 21A is made by metal forming such as aluminium foil, nickel foil and stainless steel foil.For example, anode active material layer 21B include according to the graininess positive electrode active materials of present embodiment and if necessary electric conductor such as stone mill and binding agent such as polyvinylidene fluoride.Anode active material layer 21B can further include one or more other positive electrode active materials.
Negative pole 22 has such structure, and wherein anode active material layer 22B is arranged on the two sides of the negative electrode collector 22A with a pair of opposed surface.Although do not illustrate, anode active material layer 22B also can only be arranged on the one side of negative electrode collector 22A.For example, negative electrode collector 22A is made by the metal forming with favourable electrochemical stability, conductivity and mechanical strength such as Copper Foil, nickel foil and stainless steel foil.
Anode active material layer 22B contain one or more can embed and the material of removal lithium embedded as negative active core-shell material.If necessary, anode active material layer 22B also comprises the similar binding agent with anode active material layer 21B.
In this secondary cell, can embed and the charging capacity of the negative material of removal lithium embedded greater than anodal 21 charging capacity.Therefore, the lithium metal is not deposited on the negative pole 22 in charging process.
For example, as can embedding and the negative material of removal lithium embedded, but can enumerate material with carbon element such as ungraphitised carbon graphitized carbon, graphite, RESEARCH OF PYROCARBON, coke, vitreous carbon, organic polymer quantizes compound sintered body, carbon fiber and active carbon.In the previous materials, coke comprises pitch coke, needle coke, petroleum coke etc.Quantize the compound sintered body by obtaining organic polymer at proper temperature sintering and carbonized polymeric amount material such as phenolic resins and furane resins, but and in them some be classified as ungraphitised carbon or graphitized carbon.Because the crystal structure that produces during discharging and recharging change is little, and can obtain high charge/discharge capacity, and can obtain good cycle characteristics, so preferred these material with carbon elements.Especially, because electrochemical equivalent is big, and can obtain high-energy-density, therefore preferred graphite.In addition, owing to can obtain excellent cycle characteristics, therefore preferred ungraphitised carbon.And, preferably have the material of low charging and discharge potential, particularly have and the approaching charging of lithium metal and the material of discharge potential, because can realize the high-energy-density of battery thus easily.
As the negative material that can embed with removal lithium embedded, also can enumerate can embedding and removal lithium embedded and comprise metallic element and metalloid element at least a as the material that constitutes element.When using this material, can obtain high-energy-density.Especially, preferably this material and material with carbon element are used together,, and can obtain excellent cycle characteristics because can obtain high-energy-density.This negative material can be simple substance, alloy or the compound of metallic element or metalloid element, perhaps can have one or more phases to small part.Among the present invention, except the alloy that comprises two kinds or more of metallic elements, alloy also comprises the alloy that contains one or more metallic elements and one or more metalloid elements.In addition, alloy can comprise nonmetalloid.Its structure comprises solid solution, eutectic crystal (eutectic mixture), intermetallic compound and the structure of its two kinds or more of coexistences wherein.
As metal or the metalloid element of forming negative material, can enumerate magnesium, boron, aluminium, gallium (Ga), indium (In), silicon (Si), germanium (Ge), tin, lead (Pb), bismuth (Bi), cadmium (Cd), silver (Ag), zinc, hafnium (Hf), zirconium, yttrium, palladium (Pd) or platinum (Pt).They can be crystal or noncrystal.
Especially, as this negative material, preferably contain the metallic element of the 4B family in the short period periodic table of elements or metalloid element as the material that constitutes element.Especially preferably contain at least a material in silicon and the tin as the formation element.Silicon and tin have the high embedding and the ability of removal lithium embedded, and high-energy-density can be provided.
As the negative material that can embed with removal lithium embedded, also can further enumerate other metallic compound or high molecular weight material.As other metallic compound, can enumerate oxide such as iron oxide, ruthenium-oxide, molybdenum oxide, tungsten oxide, titanium oxide and tin oxide; Sulfide such as nickel sulfide and molybdenum sulfide; Perhaps nitride such as lithium nitride.As high molecular weight material, can enumerate polyacetylene, polypyrrole etc.
Barrier film 23 is by for example, and by the perforated membrane that synthetic resin such as polytetrafluoroethylene, polypropylene and polyethylene make, perhaps ceramic porous membrane is made.Barrier film 23 can have wherein with the two-layer or aforementioned porous membrane laminated structure of multilayer.Especially, preferably the perforated membrane of being made by polyolefin because prevent that the short circuit effect is superior, and can improve battery security by closing function.
For example, electrolytic solution contains nonaqueous solvents such as organic solvent and the electrolytic salt that is dissolved in the nonaqueous solvents.For example, as nonaqueous solvents, can enumerate ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, 1,2-dimethoxy-ethane, 1,2-diethoxyethane, gamma-butyrolacton, N-methyl pyrrolidone, acetonitrile, N, dinethylformamide, dimethyl sulfoxide (DMSO), oxolane, 2-methyltetrahydrofuran, 1,3-dioxolanes, 4-methyl isophthalic acid, 3-dioxolanes, Anaesthetie Ether, sulfolane, methyl sulfolane, propionitrile, methyl phenyl ethers anisole, acetate, butyrate or propionic ester.Can be used alone nonaqueous solvents, perhaps also can use two kinds or more of nonaqueous solventss by mixing.
For example, can enumerate lithium salts as electrolytic salt.Can be used alone lithium salts, perhaps also can use two kinds or more of lithium salts by mixing.As lithium salts, can enumerate LiPF 6, LiBF 4, LiAsF 6, LiClO 4, LiB (C 6H 5) 4, LiCH 3SO 3, LiCF 3SO 3, LiN (SO 2CF 3) 2, LiC (SO 2CF 3) 3, LiAlCl 4, LiSiF 6, LiCl, difluoro [oxalic acid closes-O, O '] lithium borate, two oxalate lithium borate (lithiumbis oxalate borate), LiBr etc.
In this secondary cell, the open circuit voltage when charging fully (cell voltage) can be 4.20V, but is preferably designed to greater than 4.20V, and falls into 4.25V in the scope of 4.80V.By improving cell voltage, energy density can be high.In addition, according to present embodiment, even cell voltage increases, because the improved chemical stability of positive electrode active materials also can obtain excellent cycle characteristics.In this case, even use identical positive electrode active materials, it is that the situation of 4.20V is big than cell voltage also that the lithium of per unit weight takes off the embedding amount.Therefore, adjust the amount of positive electrode active materials and negative active core-shell material.
For example, can following manufacturing secondary cell.
For example, at first, form anodal 21 by on positive electrode collector 21A, forming anode active material layer 21B.Following formation anode active material layer 21B.For example, positive electrode active materials, electric conductor and binding agent are mixed prepare cathode mix.Afterwards, cathode mix is distributed to acquisition pasty state cathode mix slurry in solvent such as the N-N-methyl-2-2-pyrrolidone N-.Apply positive electrode collector 21A with this cathode mix slurry, dry solvent, and by mold pressing products therefroms such as roll squeezers to form anode active material layer 21B.
In addition, for example, form negative pole 22 by on negative electrode collector 22A, forming anode active material layer 22B.For example, anode active material layer 22B can pass through any formation in vapour deposition, liquid phase deposition method, sintering process and the rubbing method, perhaps can be by the two kinds or more of combinations in these methods are formed.For example, as vapour deposition, can use physical deposition method or chemical deposition method.Especially, can use vacuum vapour deposition, sputtering method, ion plating, laser ablation method, hot CVD (chemical vapor deposition) method, plasma CVD method etc.As the liquid phase deposition method, can use known technology such as metallide and chemical plating.About sintering process, can use known technology.For example, can use atmosphere sintering method, reactive sintering process or hot pressing sintering method.Under the situation of using rubbing method, can form anode active material layer 22B with anodal 21 identical modes.
Subsequently, wait by welding positive wire 25 is attached on the positive electrode collector 21A, and negative wire 26 is attached on the negative electrode collector 22A by welding etc.Afterwards, positive pole 21 and negative pole 22 are reeled with the barrier film between them 23.The end of positive wire 25 is welded on the relief valve mechanism 15, and the end of negative wire 26 is welded on the battery case 11.Positive pole 21 of reeling and the negative pole 22 of coiling are clipped between a pair of insulation board 12 and 13, and are contained in the inside of battery case 11.After being included in positive pole 21 and negative pole 22 in the battery case 11, it is inner and be immersed in the barrier film 23 that electrolytic solution is injected into battery case 11.Afterwards, at the openend of battery case 11, by fixing battery cover 14, relief valve mechanism 15 and PTC device 16 with packing ring 17 joint fillings.Thereby form the secondary cell shown in Fig. 2 and 3.
In this secondary cell, during charging, lithium ion from anode active material layer 21B, take off embedding and by electrolytic solution be embedded into be included among the anode active material layer 22B can embed and the negative material of removal lithium embedded in.Then, during discharge, the lithium ion that is embedded in the negative material that can embed among the anode active material layer 22B with removal lithium embedded takes off embedding, and is embedded among the anode active material layer 21B by electrolytic solution.In the present embodiment, owing to use above-mentioned positive electrode active materials, anodal 21 chemical stability height.Therefore, even increase open circuit voltage when charging fully, also suppress anodal 21 and the deterioration reaction of electrolytic solution.
(second kind of secondary cell)
Fig. 4 shows the structure of the second kind of secondary cell that uses aforesaid positive electrode active materials.In this secondary cell, the spiral winding electrode 30 that is attached with positive wire 31 and negative wire 32 on it is included in the film package member 40.Thus, can obtain little, light and thin secondary cell.
For example, positive wire 31 and negative wire 32 are guided to its outside from the inside of package member 40 respectively with equidirectional.For example, positive wire 31 and negative wire 32 are made by metal material such as aluminium, copper, nickel and stainless steel respectively, and are respectively lamellar or netted.
Package member 40 is made by the rectangular aluminum laminated film, in described aluminium lamination press mold for example nylon membrane, aluminium foil and polyethylene film according to this order combination.For example, arrange package member 40, make the polyethylene film side relative with spiral winding electrode 30.By melting welding or binding agent its each outer rim is contacted with each other.Between package member 40 and positive wire 31, negative wire 32, insert the adhesive film 41 that prevents that extraneous gas from invading.This adhesive film 41 is made by the material that has contact performance for positive wire 31 and negative wire 32, for example vistanex such as polyethylene, polypropylene, modified poly ethylene and modified polypropene.
Package member 40 can replace the aluminium lamination press mold of front to make by the laminated film with other structure, high molecular weight membrane such as polypropylene or metal film.
Fig. 5 shows along the cross-sectional structure of the line I-I of the spiral winding electrode shown in Fig. 4 30.In spiral winding electrode 30, positive pole 33 and negative pole 34 and the barrier film between them 35 and dielectric substrate 36 stacked and coilings.Utilize boundary belt 37 its outermost of protection.
Anodal 33 have such structure, and wherein anode active material layer 33B is arranged on the two sides of positive electrode collector 33A.Negative pole 34 has such structure, and wherein anode active material layer 34B is arranged on the two sides of negative electrode collector 34A.The structure of positive electrode collector 33A, anode active material layer 33B, negative electrode collector 34A, anode active material layer 34B and barrier film 35 respectively with the similar of above-mentioned positive electrode collector 21A, anode active material layer 21B, negative electrode collector 22A, anode active material layer 22B and barrier film 23.
Dielectric substrate 36 by contain electrolytic solution and can become keep electrolytic solution the so-called gel-like electrolyte of high-molecular weight compounds of maintenance body make.Preferred gel-like electrolyte layer 36 because can obtain high ionic conductivity thus, and can be avoided leakage thus.The structure of electrolytic solution and first kind of secondary cell similar.For example, as high-molecular weight compounds, can enumerate copolymer, polytetrafluoroethylene, polyhexafluoropropylene, poly(ethylene oxide), PPOX, polyphosphazene, polysiloxanes, polyvinyl acetate, polyvinyl alcohol, polymethyl methacrylate (polymethacrylic methyl), polyacrylic acid, polymethylacrylic acid, butadiene-styrene rubber, acrylonitrile-butadiene rubber, polystyrene, Merlon of polyacrylonitrile, polyvinylidene fluoride, vinylidene fluoride and hexafluoropropylene etc.Especially, consider electrochemical stability, optimization polypropylene nitrile, polyvinylidene fluoride, polyhexafluoropropylene or poly(ethylene oxide).
For example, can this secondary cell of following manufacturing.
At first, with first kind of secondary cell in identical mode make anodal 33 and negative pole 34.Afterwards, apply positive pole 33 and negative pole 34 respectively with the precursor solution that contains electrolytic solution, high-molecular weight compounds and mixed solvent.With the mixed solvent volatilization, to form dielectric substrate 36.Afterwards, positive wire 31 is attached on the positive electrode collector 33A, and negative wire 32 is attached on the negative electrode collector 34A.Next, will be formed with the positive pole 33 and the negative pole 34 of dielectric substrate 36 and the barrier film 35 that is clipped between them stacked to obtain laminate.The laminate of reeling in the vertical adheres to its outermost to form spiral winding electrode 30 with boundary belt 37.At last, for example, spiral winding electrode 30 is clipped between the package member 40, thereby and makes the outer rim contact sealing screw rolled electrode body 30 of package member 40 by thermofussion welding etc.At this moment, adhesive film 41 is inserted between positive wire 31, negative wire 32 and the package member 40.Thereby, finish the secondary cell shown in the Figure 4 and 5.
In addition, can this secondary cell of following production.At first, as mentioned above, form positive pole 33 and negative pole 34, and positive wire 31 and negative wire 32 are attached on positive pole 33 and the negative pole 34.Afterwards, with positive pole 33 and negative pole 34 and the 35 stacked and coilings of the barrier film between them.Boundary belt 37 is adhered to its outermost, form the screw winding body, it is the precursor of spiral winding electrode 30.Next, the screw winding body is clipped between the package member 40, and will be, obtaining a bag shape, and the screw winding body is contained within the package member 40 except that the outer most edge thermofussion welding the side.Subsequently, will contain electrolytic solution, monomer, polymerization initiator as the high-molecular weight compounds raw material and if necessary other material such as the electrolyte composition of polymerization inhibitor be injected into the inside of package member 40, and pack the opening of parts 40.Afterwards, thus gains heating is obtained high-molecular weight compounds with polymerization single polymerization monomer.Therefore, form gel-like electrolyte layer 36, and the secondary cell shown in the assembling Figure 4 and 5.
This secondary cell and first kind of secondary cell are worked similarly.
According to above-mentioned embodiment of the present invention, use such positive electrode active materials, wherein use Li in its average composition (1+w)Co (1-x-y)M1 xM2 yO (2-z)On the composite oxide particle of expression coating layer is set.Thus, even because external force causes breaks or destroy, the activity on the surface of Bao Luing also can be very low thus.
In addition,, use such positive electrode active materials, wherein use Li in its average composition according to above-mentioned embodiment of the present invention (1+x)Co (1-y)M yO (2-z)On the composite oxide particle of expression coating layer is set, this coating layer is made of the oxide that contains lithium, nickel and manganese, the height in the concentration ratio of the manganese in its ectomesoderm part in the layer segment.Thus, when keeping composite oxide particle to have the characteristic of high power capacity and high potential, can improve the chemical stability of positive electrode active materials.
In addition,, use such positive electrode active materials, wherein use Li in its average composition according to above-mentioned embodiment of the present invention (1+x)Co (1-y)M yO (2-z)On the composite oxide particle of expression coating layer is set, this coating layer contains lithium, nickel and manganese, and has diffraction maximum on angle of diffraction 2 θ low 0.2 than the diffraction maximum of the face that belongs to composite oxide particle [101] spend a side of angle in the 1.0 degree scopes.Thus, when keeping composite oxide particle to have the characteristic of high power capacity and high potential, can improve the chemical stability of positive electrode active materials.
Therefore, the battery according to the embodiment of the present invention of using these positive electrode active materials can obtain high power capacity and high potential, in addition, can improve hot properties or cycle characteristics, and can improve chemical stability.
In addition, have 12 or the aqueous solution of bigger hydrogen ion exponent pH in form the inside precursor layer of the hydroxide that contains nickel and manganese after, change the chemical valence of manganese ion, and form the high outside precursor layer in the inner precursor layer of manganese concentration ratio wherein subsequently.Therefore, can easily form positive electrode active materials according to present embodiment.
(embodiment)
Hereinafter will further describe specific embodiments of the invention.
(embodiment 1-1 and 1-2)
Following formation positive electrode active materials.At first, the lithium carbonate (Li that mixes 38.1 weight portions 2CO 3), the cobalt carbonate (CoCO of 113.0 weight portions 3), the aluminium hydroxide (Al (OH) of 23.4 weight portions 3) and the magnesium carbonate (MgCO of 16.9 weight portions 3), use ball mill grinding simultaneously.In air under 650 degrees centigrade with after the gains calcining 5 hours, with product in air 950 degrees centigrade of following sintering 20 hours, form composite oxide particle.Check the average composition of formed composite oxide particle by the ICP spectrometry.The result is Li 1.03Co 0.95Al 0.03Mg 0.02O 2.02Next, pulverize composite oxide particle, and adjust particle diameter.The average grain diameter of utilizing laser scattering method to record is 11 μ m.
Next, under 80 degrees centigrade the composite oxide particle of 20 weight portions is being stirred in the lithium hydroxide aqueous solution of the 2N of 300 weight portions and disperseing 2 hours.Subsequently, the nickel nitrate (Ni (NO that mixes 1.60 weight portions 3) 26H 2O) and the manganese nitrate of 1.65 weight portions (Mn (NO 3) 26H 2O).In gains, add pure water, obtain the aqueous solution of 10 weight portions.The aqueous solution with whole 10 weight portions in 30 minutes adds in the lithium hydroxide aqueous solution that is dispersed with composite oxide particle.The hydrogen ion exponent pH of lithium hydroxide aqueous solution is 14.2 after the aqueous solution that adds nickel nitrate and manganese nitrate.In addition, gains are stirred and disperse to contain with precipitation on composite oxide particle in 3 hours the hydroxide of nickel and manganese under 80 degrees centigrade.With after the gains coolings, filter gains and be dried at 120 degrees centigrade.
Afterwards, utilize electric furnace to the speed heating with 5 degrees celsius/minute of the composite oxide particle that is formed with precursor layer, kept 5 hours down at 950 degrees centigrade, the speed with 7 degrees celsius/minute is cooled to 150 degrees centigrade afterwards.Thereby, form coating layer and obtain positive electrode active materials.For the positive electrode active materials that obtains, detect the change in concentration of nickel and manganese.Nickel content and manganese content are reduced to zero rapidly from the surface to inside.That is, confirm on the surface of composite oxide particle, to form the coating layer that contains nickel and manganese.
Next, utilize the secondary cell shown in positive electrode active materials shop drawings 2 and 3.At first the positive electrode active material powder of the formation of 86 weight %, 10 weight % are mixed as the polyvinylidene fluoride of binding agent as the graphite of electric conductor and 4 weight %, and be distributed in the N-N-methyl-2-2-pyrrolidone N-as solvent.Afterwards, apply the two sides of the positive electrode collector 21A that makes by the thick bar shaped aluminium foil of 20 μ m with this gains, thus be dried and with the roll squeezer mold pressing to form anode active material layer 21B and to form positive pole 21.Afterwards, in embodiment 1-1, undertaken once by the mold pressing of roll squeezer.In embodiment 1-2, under the condition identical, undertaken three times by the mold pressing of roll squeezer with embodiment 1-1.Next, will be attached on the positive electrode collector 21A by the positive wire 25 that aluminum gets.
In addition, 90 weight % are mixed as the polyvinylidene fluoride of binding agent as the Delanium powder of negative active core-shell material and 10 weight %, and be distributed in the N-N-methyl-2-2-pyrrolidone N-as solvent.Afterwards, apply the two sides of the negative electrode collector 22A that makes by the thick bar shaped Copper Foil of 10 μ m with this gains, thus be dried and with the roll squeezer mold pressing to form anode active material layer 22B and formation negative pole 22.Next, will be attached on the negative electrode collector 22A by the negative wire 26 that nickel makes.Afterwards, design, feasible amount of regulating positive electrode active materials and negative active core-shell material, open circuit voltage is 4.40V when charging fully, and the capacity of negative pole 22 is by being expressed by the capacity component of embedding and removal lithium embedded.
Next, the positive pole 21 that forms and the negative pole 22 of formation are reeled repeatedly to form spiral winding electrode 20 with the barrier film 23 that is made by porous polyolefin membrane that is clipped between them.Subsequently, spiral winding electrode 20 is clipped between a pair of insulation board 12 and 13, negative wire 26 is welded on the battery case 11, and positive wire 25 is welded on the relief valve mechanism 15, and gains are contained within the battery case 11.Afterwards, electrolytic solution is injected within the battery case 11, and with 17 pairs of battery case 11 calkings of packing ring.Thereby fixedly relief valve mechanism 15, PTC device 16 and battery cover 14 are to obtain 18mm external diameter and the high column secondary battery of 65mm.About electrolytic solution, use wherein ethylene carbonate and diethyl carbonate volume ratio be in 1: 1 the mixed solvent dissolving as the LiPF of electrolytic salt 6, make LiPF 6Concentration become the solution of 1.0mol/l.
In addition, as comparative example 1-1 and 1-2, become Li except using average group with respect to embodiment 1-1 and 1-2 1.03CoO 2.02Composite oxide particle outside, positive electrode active materials all is to make with the embodiment 1-1 mode identical with 1-2 with secondary cell.The lithium carbonate by mixing 38.1 weight portions and the cobalt carbonate of 118.9 weight portions, in air under 650 degrees centigrade with gains calcining 5 hours, will produce afterwards thing in air 950 degrees centigrade of following sintering 20 hours, the formation composite oxide particle.In addition, forming when anodal, in comparative example 1-1 and similar among the embodiment 1-1, undertaken once by the mold pressing of roll squeezer, and in comparative example 1-2 and embodiment 1-2 similar, undertaken three times by the mold pressing of roll squeezer.
Secondary cell for embodiment 1-1 and 1-2 and comparative example 1-1 and 1-2 manufacturing, under 45 degrees centigrade, charge and discharge, and the discharge capacity that obtains the circulation time first time detects the 200th circulation with respect to the discharge capacitance that circulates for the first time as initial capacity.For charging, carry out constant current charge with the constant current of 1000mA and reach 4.40V, and carry out constant voltage charge with the constant voltage of 4.40V subsequently and reach 2.5 hours up to total charging time up to cell voltage.For discharge, carry out constant-current discharge with the constant current of 800mA and reach 2.75V up to cell voltage.The gained result has been shown in table 1.
Table 1
Composite oxide particle Anodal mold pressing number of times Initial capacity (mAh) Discharge capacitance (%)
Embodiment 1-1 Li 1.03Co 0.95Al 0.03 Mg 0.02O 2.02 1 2400 88
Embodiment 1-2 3 2400 84
Comparative example 1-1 Li 1.03CoO 2.02 1 2480 80
Comparative example 1-2 3 2470 75
As shown in table 1, according to embodiment 1-1 and 1-2, initial capacity is compared with 1-2 a little with the comparative example 1-1 that uses cobalt acid lithium as composite oxide particle and is reduced.Yet according to embodiment 1-1 and 1-2, discharge capacitance can improve.Especially, when the compressed coefficient increased, in comparative example 1-1 and 1-2, discharge capacitance reduced by 6.3%, and initial capacity also reduces.Yet in embodiment 1-1 and 1-2, even when the compressed coefficient increases, the reduction ratio of discharge capacitance is 4.5%, and this is less than comparative example 1-2, and initial capacity does not reduce.
That is, find when use contains the composite oxide particle of other element except cobalt such as aluminium and manganese,, and can to improve cycle characteristics even if the external force of applying also can obtain high chemical stability.
(embodiment 2-1 is to 2-4)
Except the average composition change of composite oxide particle, make positive electrode active materials and secondary cell in the mode identical with embodiment 1-1.In embodiment 2-1, except the magnesium carbonate of the aluminium hydroxide of the cobalt carbonate of the lithium carbonate that mixes 38.1 weight portions, 116.5 weight portions, 7.8 weight portions and 8.4 weight portions, with embodiment 1-1 in identical mode form composite oxide particle.When detecting its average composition in the mode identical with embodiment 1-1, the result is Li 1.03Co 0.98Al 0.01Mg 0.01O 2.02
In embodiment 2-2,, and gains are added and be mixed into by titanium ethanolate ((C with 45.6 weight portions except the lithium carbonate that mixes 38.1 weight portions and the cobalt carbonate of 116.5 weight portions 2H 5O) 4Ti) outside being dissolved in the solution that obtains in the absolute ethyl alcohol, with embodiment 1-1 in identical mode form composite oxide particle.When detecting its average composition in the mode identical with embodiment 1-1, the result is Li 1.03Co 0.98Ti 0.02O 2.02
In embodiment 2-3,, and gains are added and be mixed into by ethanol zirconium ((C with 54.3 weight portions except the lithium carbonate that mixes 38.1 weight portions and the cobalt carbonate of 116.5 weight portions 2H 5O) 4Zr) outside being dissolved in the solution that obtains in the absolute ethyl alcohol, with embodiment 1-1 in identical mode form composite oxide particle.When detecting its average composition in the mode identical with embodiment 1-1, the result is Li 1.03Co 0.98Zr 0.02O 2.02
In embodiment 2-4, except the aluminium hydroxide of the cobalt carbonate of the lithium carbonate that mixes 38.1 weight portions, 117.7 weight portions and 7.8 weight portions, with embodiment 1-1 in identical mode form composite oxide particle.When detecting its average composition in the mode identical with embodiment 1-1, the result is Li 1.03Co 0.99Al 0.01O 2.02
The secondary cell of making to 2-4 for embodiment 2-1, with embodiment 1-1 in identical mode obtain initial capacity and discharge capacitance.With the result of gained result and embodiment 1-1 and comparative example 1-1 together shown in the table 2.
Table 2
Composite oxide particle Initial capacity (mAh) Discharge capacitance (%)
Embodiment 1-1 Li 1.03Co 0.95Al 0.03Mg 0.02O 2.02 2400 88
Embodiment 2-1 Li 1.03Co 0.98Al 0.01Mg 0.01O 2.02 2460 86
Embodiment 2-2 Li 1.03Co 0.98Ti 0.02O 2.02 2410 84
Embodiment 2-3 Li 1.03Co 0.98Zr 0.02O 2.02 2460 83
Embodiment 2-4 Li 1.03Co 0.99Al 0.01O 2.02 2460 83
Comparative example 1-1 Li 1.03CoO 2.02 2480 80
As confirming in the table 2 that 1-1 compares with comparative example, according to embodiment 2-1 to 2-4 and embodiment 1-1 similarly, discharge capacitance can improve.Just, find when use also contains at least a composite oxide particle that is selected from magnesium, aluminium, titanium and zirconium except that cobalt,, and can to improve cycle characteristics even the external force of applying also can obtain high chemical stability.
(embodiment 3-1 is to 3-3)
Except the method that forms coating layer changes, make positive electrode active materials and secondary cell in the mode identical with embodiment 2-1.In embodiment 3-1, except the nickel nitrate that mixes 3.20 weight portions and the manganese nitrate of 3.30 weight portions, and gains are added in the pure water to obtain the aqueous solution of 20 weight portions, and outside in one hour, adding to the aqueous solution of whole 20 weight portions in the lithium hydroxide aqueous solution that wherein is dispersed with composite oxide particle, with embodiment 2-1 in identical mode form positive electrode active materials.Just, the addition of nickel nitrate and manganese nitrate is the twice of embodiment 2-1.
In embodiment 3-2, except being aluminum nitrate (Al (NO with 0.86 weight portion 3) 39H 2O) commercial reagent adds in the manganese nitrate of the nickel nitrate of 3.20 weight portions and 3.30 weight portions, and further pure water is added in the gains to obtain the aqueous solution of 20 weight portions, and outside in one hour, adding to the aqueous solution of whole 20 weight portions in the lithium hydroxide aqueous solution that wherein is dispersed with composite oxide particle, with embodiment 2-1 in identical mode form positive electrode active materials.Just, except nickel nitrate and manganese nitrate, also form precursor layer by adding aluminum nitrate.
In embodiment 3-3, at first, the composite oxide particle of 20 weight portions that will be identical with embodiment 2-1 under 80 degrees centigrade stirs in the pure water of 300 weight portions and disperseed 1 hour, wherein adds the nickel nitrate of 1.60 weight portions and the manganese nitrate of 1.65 weight portions.Next, added the lithium hydroxide aqueous solution of 2N in 30 minutes in aforementioned gains, pH becomes 13 up to hydrogen ion exponent.With gains further stir under 80 degrees centigrade and disperse 3 hours with surface at composite oxide particle on precipitation contain the hydroxide of nickel and manganese.After the gains cooling, the filtration gains also are dried under 120 degrees centigrade.Subsequently, the lithium hydroxide aqueous solution of 2 weight portion 2N is infiltrated up in the composite oxide particle that is formed with precursor layer of 10 weight portions, to regulate the amount of lithium.evenly mix and dry gains after, carry out with the similar heat treatment of embodiment 2-1 to form coating layer.
At embodiment 2-1 and 3-1 in 3-3, for the composite oxide particle that is formed with precursor layer, the mol ratio Li of analyzing metal elements: Co: Ni: Mn: Al: Mg.Among the embodiment 2-1, the result is 1.04: 0.94: 0.02: 0.02: 0.01: 0.01.Among the embodiment 3-1, the result is 1.03: 0.88: 0.05: 0.05: 0.01: 0.01.Among the embodiment 3-2, the result is 1.03: 0.88: 0.05: 0.05: 0.02: 0.01.Among the embodiment 3-3, the result is 1.00: 0.94: 0.02: 0.02: 0.01: 0.01.
The secondary cell of making to 3-3 for embodiment 3-1, with embodiment 2-1 in identical mode obtain initial capacity and discharge capacitance.With the result of gained result and embodiment 2-1 and comparative example 1-1 together shown in the table 3.
Table 3
Composite oxide particle Form the precursor layer mol ratio Li of metallic element afterwards: Co: Ni: Mn: Al: Mg Initial capacity (mAh) Discharge capacitance (%)
Embodiment 2-1 Li 1.03Co 0.98Al 0.01 Mg 0.01O 2.02 1.04∶0.94∶0.02∶0.02∶0.01∶0.01 2460 86
Embodiment 3-1 1.03∶0.88∶0.05∶0.05∶0.01∶0.01 2420 87
Embodiment 3-2 1.03∶0.88∶0.05∶0.05∶0.02∶0.01 2400 89
Embodiment 3-3 1.00∶0.94∶0.02∶0.02∶0.01∶0.01 2440 81
Comparative example 1-1 Li 1.03CoO 2.02 - 2480 80
As confirming in the table 3 that similar to 3-3 and embodiment 2-1 according to embodiment 3-1,1-1 compares with comparative example, discharge capacitance can improve.In addition, as between embodiment 2-1 and the embodiment 3-1 comparison confirmed, according to the embodiment 3-1 with big coating layer amount, although initial capacity reduces, discharge capacitance can improve more.In addition, as between embodiment 3-1 and embodiment 3-2 comparison confirmed, according to the embodiment 3-2 that is formed coating layer by the oxide that also contains aluminium except lithium, nickel and magnesium, although initial capacity reduces, discharge capacitance can improve more.Just, find when the coating layer amount is big, perhaps when coating layer is formed by the oxide that further contains other element such as aluminium, can improve the chemical stability of positive electrode active materials more.
In addition, as between comparative example 2-1 and the embodiment 3-3 comparison confirmed, be dispersed in according to composite oxide particle wherein in the aqueous solution of the hydrogen ion exponent pH with adjustment and add the raw material of precursor layer to wherein comparative example 2-1, with wherein be dispersed in the aqueous solution that is dissolved with the precursor layer raw material back and regulate among the embodiment 3-3 of hydrogen ion exponent pH and compare at composite oxide particle, for initial capacity and discharge capacitance, all obtain higher value.Just, find when be dispersed at composite oxide particle have 12 or the aqueous solution of higher hydrogen ion exponent pH in during the raw material of back interpolation precursor layer, can improve the chemical stability of positive electrode active materials more.
(embodiment 4-1)
At first, the average group that has with 20 weight portions becomes Li 1.03Co 0.98Al 0.01Mg 0.01O 2.02And be that the composite oxide particle of 13 μ m stirred 2 hours in the lithium hydroxide aqueous solution (hydrogen ion exponent pH is 14.3) at the 2N of 300 weight portions under 80 degrees centigrade and disperses by the average grain diameter that laser scattering method records, while circulating nitrogen gas (step S111 is referring to Fig. 1).Next, the nickel nitrate (Ni (NO that mixes 1.60 weight portions 3) 26H 2O) manganese nitrate (Mn (NO of commercial reagent and 1.65 weight portions 3) 26H 2O) commercial reagent, and pure water added in the gains obtaining the aqueous solution of 10 weight portions, and the aqueous solution of whole 10 weight portions was added in 30 minutes in the lithium hydroxide aqueous solution that wherein is dispersed with composite oxide particle, circulating nitrogen gas simultaneously.Thus, on the surface of composite oxide particle, form the inside precursor layer (step S112 is referring to Fig. 1) of the hydroxide that contains nickel and manganese.After the aqueous solution that adds nickel nitrate and manganese nitrate, the hydrogen ion exponent pH of lithium hydroxide aqueous solution is 14.2.
Subsequently, when in the aqueous solution, circulating, but continue down to stir and disperseed 3 hours at 80 degrees centigrade with air replacement nitrogen.Thus, on the surface of the composite oxide particle that cools off, form the outside precursor layer (step S102 is referring to Fig. 1) of the hydroxide that contains nickel and manganese.Afterwards, filtration product, and 120 degrees centigrade of dryings, and do not wash.For the composite oxide particle of inner precursor layer of being formed with of such acquisition and outside precursor layer, the mol ratio of analyzing metal elements.The result is Li: Co: Ni: Mn: Al: Mg=1.04: 0.94: 0.02: 0.02: 0.01: 0.01.
Next, utilize electric furnace to the speed heating with 5 degrees celsius/minute of the composite oxide particle that is formed with inner precursor layer and outside precursor layer, kept 5 hours down at 950 degrees centigrade, the speed with 7 degrees celsius/minute is cooled to 150 degrees centigrade afterwards.Thereby, form coating layer and obtain positive electrode active materials (step S103 is referring to Fig. 1).
(embodiment 4-2)
Except the nickel nitrate that mixes 3.20 weight portions and the manganese nitrate of 3.30 weight portions, and pure water added in the gains to obtain the aqueous solution of 20 weight portions, and in 1 hour, add to the aqueous solution of whole 20 weight portions in the lithium hydroxide aqueous solution that wherein is dispersed with composite oxide particle, simultaneously outside the circulating nitrogen gas, to form positive electrode active materials with the embodiment 1-1 condition identical with 1-2.Just, the addition of nickel nitrate and manganese nitrate is the twice of embodiment 1-1 and 1-2.After the aqueous solution that adds nickel nitrate and manganese nitrate, the hydrogen ion exponent pH of lithium hydroxide aqueous solution is 14.2.For the composite oxide particle that is formed with inner precursor layer and outside precursor layer, the mol ratio of analyzing metal elements.The result is Li: Co: Ni: Mn: Al: Mg=1.03: 0.88: 0.05: 0.05: 0.01: 0.01.
(embodiment 4-3)
Except with 0.86 weight portion aluminum nitrate (Al (NO 3) 39H 2O) commercial reagent adds in the manganese nitrate of the nickel nitrate of 3.20 weight portions and 3.30 weight portions, and pure water further added in the gains to obtain the aqueous solution of 20 weight portions, and in 1 hour, add to the aqueous solution of whole 20 weight portions in the lithium hydroxide aqueous solution that wherein is dispersed with composite oxide particle, simultaneously outside the circulating nitrogen gas, to form positive electrode active materials with the embodiment 1-1 condition identical with 1-2.Just, form inner precursor layer and outside precursor layer by except nickel nitrate and manganese nitrate, also adding aluminum nitrate.For the composite oxide particle that is formed with inner precursor layer and outside precursor layer, the mol ratio of analyzing metal elements.The result is Li: Co: Ni: Mn: Al: Mg=1.03: 0.88: 0.05: 0.05: 0.02: 0.01.
(comparative example 4-1)
Directly use and embodiment 4-1 to the composite oxide particle of 4-3 same batch (same lot) as positive electrode active materials.
(comparative example 4-2 is to 4-4)
Except not circulating nitrogen gas and air in the aqueous solution, outside coprecipitated hydroxide on the composite oxide particle, to form positive electrode active materials to the identical condition of 3-3 with embodiment 1-1.For precipitation the composite oxide particle of hydroxide, the mol ratio of analyzing metal elements (Li: Co: Ni: Mn: Al: Mg) are arranged.In comparative example 4-2, the result is Li: Co: Ni: Mn: Al: Mg=1.04: 0.94: 0.02: 0.02: 0.01: 0.01.In comparative example 4-3, the result is Li: Co: Ni: Mn: Al: Mg=1.03: 0.88: 0.05: 0.05: 0.01: 0.01.In comparative example 4-4, the result is Li: Co: Ni: Mn: Al: Mg=1.03: 0.88: 0.05: 0.05: 0.02: 0.01.
For embodiment 4-1 to 4-3 and comparative example 4-2 to the formed positive electrode active materials of 4-4, detect the distribution that metallic element is gone up on the surface by XPS (x-ray photoelectron spectroscopy method).As a result, confirm in 4-3, to be arranged in the height of the concentration ratio comparative example 4-2 of lip-deep manganese to 4-4 at embodiment 4-1.
Next, by use embodiment 4-1 to 4-3 and comparative example 4-1 to the formed positive electrode active materials of 4-4, produce the secondary cell shown in Fig. 2 and 3 in the mode identical with embodiment 1-1.
About the secondary cell of being produced, under 45 degrees centigrade, charge and discharge, and the discharge capacity that obtains circulation time for the first time is as initial capacity, detect the 200th circulation with respect to the discharge capacitance of circulation for the first time.For charging, carry out constant current charge with the constant current of 1000mA and reach 4.40V, and carry out constant voltage charge with the constant voltage of 4.40V subsequently and reach 2.5 hours up to total charging time up to cell voltage.For discharge, carry out constant-current discharge with the constant current of 800mA and reach 2.75V up to cell voltage.The gained result has been shown in table 4.
Table 4
Outside precursor layer Form inner precursor layer and the outside precursor layer mol ratio Li of metallic element afterwards: Co: Ni: Mn: Al: Mg Initial capacity (mAh) Discharge capacitance (%)
Embodiment 4-1 Form 1.04∶0.94∶0.02∶0.02∶0.01∶0.01 2460 87
Embodiment 4-2 1.03∶0.88∶0.05∶0.05∶0.01∶0.01 2430 88
Embodiment 4-3 1.03∶0.88∶0.05∶0.05∶0.02∶0.01 2410 90
Comparative example 4-1 - - 2200 35
Comparative example 4-2 Do not form 1.04∶0.94∶0.02∶0.02∶0.01∶0.01 2460 86
Comparative example 4-3 1.03∶0.88∶0.05∶0.05∶0.01∶0.01 2420 87
Comparative example 4-4 1.03∶0.88∶0.05∶0.05∶0.02∶0.01 2400 89
As confirming in the table 4 that, compare with the comparative example 4-1 that does not form coating layer to 4-3 according to embodiment 4-1, initial capacity and discharge capacitance can significantly improve.In addition,, compare to 4-4 with the comparative example 4-2 that does not form outside precursor layer to 4-3 according to embodiment 4-1, discharge capacitance can further improve.That is, find when big in its inside of concentration ratio of the manganese in the outside in the coating layer, can improve the chemical stability of positive electrode active materials more, and can improve capacity and cycle characteristics.
(embodiment 5-1 is to 5-9)
Following formation positive electrode active materials.In embodiment 5-1, at first, as composite oxide particle, preparation has average group becomes Li 1.03CoO 2And be the cobalt acid lithium powder of 13 μ m by the average grain diameter that laser scattering method records, and as the coating layer raw material, preparation is by with lithium carbonate (Li 2CO 3) powder, nickel hydroxide (Ni (OH) 2) powder and manganese carbonate (MnCO 3) powder is with mol ratio Li 2CO 3: Ni (OH) 2: MnCO 3=1.08: the precursor powder that mixing in 1: 1 obtains.Next, this precursor powder is added in the cobalt acid lithium powder of 100 weight portions, make when being converted into Li 1.08Ni 0.5Mn 0.5O 2, obtain 10 weight portions.Under 25 degrees centigrade by using 100 parts by weight of purified water that gains are stirred and disperseing 1 hour.Afterwards, make the gains decompression, and under 70 degrees centigrade, carry out drying, on the surface of composite oxide particle, form precursor layer.Subsequently, the speed heating gains with 3 degrees celsius/minute kept 3 hours down at 800 degrees centigrade, afterwards cooling.Thus, form coating layer and obtain positive electrode active materials.
In embodiment 5-2; except becoming 1 μ m or littler up to average grain diameter with ball mill pulverizing and the similar precursor powder of embodiment 5-1; and, form positive electrode active materials in the mode identical with embodiment 5-1 with outside gains and the composite oxide particle mixing.
In embodiment 5-3, following formation positive electrode active materials.With pulverized become up to its average grain diameter that 1 μ m or littler and the similar precursor powder of embodiment 1-1 add 100 weight portions to the similar composite oxide particle of embodiment 5-1 in, make when being converted into Li 1.08Ni 0.5Mn 0.5O 2The time, obtain 10 weight portions.Utilize machinery fusing (mechanofusion) device to handle product to form precursor layer.Afterwards, carry out similar heat treatment, thereby form coating layer with embodiment 5-1.As a result, form positive electrode active materials.
In embodiment 5-4,, form positive electrode active materials in the mode identical with embodiment 5-1 except heat treatment temperature is 750 degrees centigrade.
In embodiment 5-5, the heating rate of removing in the heat treatment is 10 degrees celsius/minute, and is outside 2 hours 800 degrees centigrade of following retention times, forms positive electrode active materials in the mode identical with embodiment 5-1.
In embodiment 5-6, remove and use average group to become Li 1.03Co 0.98Al 0.01Mg 0.01O 2Composite oxide power as composite oxide particle; become 1 μ m or littler with ball mill pulverizing and the similar precursor powder of embodiment 5-1 up to average grain diameter; and, form positive electrode active materials in the mode identical with embodiment 5-1 with outside gains and the composite oxide particle mixing.
In embodiment 5-7, following formation positive electrode active materials.That handles 100 weight portions with mechanical melting appartus becomes Li with the similar composite oxide particle of embodiment 5-1 and its average group of 10 weight portions 1.03Ni 0.5Mn 0.5O 2And average grain diameter is the nickel LiMn2O4 powder of 3 μ m, to form precursor layer.Afterwards, carry out under the programming rate of 3 degrees celsius/minute, the heat treatment of retention time of 650 degrees centigrade heat treatment temperature and 3 hours, thereby form coating layer.As a result, form positive electrode active materials.
In embodiment 5-8, following formation positive electrode active materials.That handles 100 weight portions with mechanical melting appartus becomes Li with the similar composite oxide particle of embodiment 5-1 and its average group of 10 weight portions 1.03Ni 0.33Co 0.33Mn 0.33O 2And average grain diameter is the nickle cobalt lithium manganate powder of 3 μ m, to form precursor layer.Afterwards, carry out under the programming rate of 3 degrees celsius/minute, the heat treatment of retention time of 650 degrees centigrade heat treatment temperature and 3 hours, thereby form coating layer.As a result, form positive electrode active materials.
In embodiment 5-9, following formation positive electrode active materials.At first, as the coating layer raw material, with lithium carbonate powder, nickel hydroxide powder and manganese carbonate powder with mol ratio Li 2CO 3: Ni (OH) 2: MnCO 3=1.08: mix at 1.6: 0.4, pulverizing gains becomes 1 μ m or littler up to average grain diameter, thereby obtains precursor powder.Next, add this precursor powder to 100 weight portions with the similar composite oxide particle of embodiment 5-1 in, make to obtain when being converted into Li 1.08Ni 0.8Mn 0.2O 2The precursor powder of Shi Bianwei 10 weight portions is handled gains to form precursor layer with mechanical melting appartus.Afterwards, carry out similar heat treatment, thereby form coating layer with embodiment 5-1.As a result, form positive electrode active materials.
In addition, as with respect to the comparative example 5-1 of embodiment 5-1, directly use the cobalt acid lithium powder that in embodiment 5-1, is used as composite oxide power as positive electrode active materials to 5-9.5-2 as a comparative example, following formation positive electrode active materials.With lithium carbonate (Li 2CO 3) powder, cobalt hydroxide (Co (OH) 2) powder, nickel hydroxide (Ni (OH) 2) powder and manganese carbonate (MnCO 3) powder is with mol ratio Li 2CO 3: Co (OH) 2: Ni (OH) 2: MnCO 3=0.52: mix at 0.91: 0.045: 0.045, pulverizing gains with ball mill becomes 1 μ m or littler up to average grain diameter.Afterwards, carry out under the programming rate of 3 degrees celsius/minute, the heat treatment of retention time of 900 degrees centigrade heat treatment temperature and 3 hours.Thereby formation positive electrode active materials.
5-3 except heat treatment temperature is 1000 degrees centigrade, forms positive electrode active materials in the mode identical with embodiment 5-1 as a comparative example.5-4 passes through with Li except using as a comparative example 2CO 3: Ni (OH) 2=0.54: 1 mixed in molar ratio lithium carbonate (Li 2CO 3) powder and nickel hydroxide (Ni (OH) 2) powder and the precursor powder that obtains be as the raw material of coating layer, and heat treatment temperature is outside 700 degrees centigrade, forms positive electrode active materials in the mode identical with embodiment 5-1.5-5 passes through with Li except using as a comparative example 2CO 3: MnCO 3=1: 4 mixed in molar ratio lithium carbonate (Li 2CO 3) powder and manganese carbonate (MnCO 3) powder and the precursor powder that obtains be as the raw material of coating layer, and heat treatment temperature is outside 900 degrees centigrade, forms positive electrode active materials in the mode identical with embodiment 5-1.
For embodiment 5-1 to 5-9 and comparative example 5-1 to the formed positive electrode active materials of 5-5, carry out by utilizing Cu-K α 1 to measure as the powder x-ray diffraction of X-ray source.About the X-ray diffraction device, use the RINT 2000 of Rigakudenki Co..The X-ray tube voltage is 40kV, and electric current is 200mA, and divergent slit is 0.5 degree, and scatter slit is 0.5 degree, and light-receiving (photo acceptance) gap width is 0.15mm, and uses monochromator.Sweep speed be 2 degree/minute, the scanning stride is that 0.02 degree and scan axis are to measure under the condition of 2 θ/θ.Wherein, as representative instance, the measurement distribution map that is obtained for embodiment 5-1, embodiment 5-3 and comparative example 5-2 has been shown in Fig. 6,7 and 8.
As a result, as shown in Fig. 6 and 7, to 5-9, observe the diffraction maximum of composite oxide particle and as if corresponding to the diffraction maximum of the coating layer of the lithium oxide that contains nickel and manganese with bedded salt structure for all embodiment 5-1.In near the diffraction maximum that illustrates 37 degree that belongs to the face of composite oxide particle [101] and the difference that is located at than peak-to-peak angle of diffraction 2 θ of diffraction of the coating layer of low angle side is 0.44 degree in embodiment 5-1, it in embodiment 5-2 0.40 degree, it in embodiment 5-3 0.24 degree, it in embodiment 5-4 0.52 degree, it in embodiment 5-5 0.44 degree, it in embodiment 5-6 0.35 degree, it in embodiment 5-7 0.80 degree, be 0.58 degree in embodiment 5-8, and be 0.37 degree in embodiment 5-9.The results are shown in the table 5.As described in this embodiment, read the angle of diffraction of each diffraction maximum in the position, peak maximum of the measurement distribution map that obtains.
Equally, as shown in Figure 8, in 5-2, observe the diffraction maximum of composite oxides with bedded salt structure at comparative example 5-1.Near 37 degree, there is a diffraction maximum that belongs to face [101].In 5-5 and at embodiment 5-1, in 5-9, observe the diffraction maximum of composite oxide particle and the diffraction maximum of coating layer at comparative example 5-3 similarly.In diffraction maximum that belongs to the face of composite oxide particle [101] and the difference that is located at than peak-to-peak angle of diffraction 2 θ of diffraction of the coating layer of low angle side is 0.1 degree or littler in comparative example 5-3 and comparative example 5-4, and is 1.10 degree in comparative example 5-5.Its result is together shown in the table 5.
In addition, by utilizing scanning electron microscopy (SEM) and energy to disperse x-ray fluorescence spectrometer (EDX) to observe embodiment 5-1 to the formed positive electrode active materials of 5-9.Demonstrate, have on the surface of the oxide particle that contains nickel and manganese from 0.1 μ m to 5 μ m particle diameters attached to composite oxide particle, and nickel and the approximate existence equably of manganese on the surface of composite oxide particle.The average grain diameter of positive electrode active materials at 2 μ m in the scope of 50 μ m.
Next, by using the positive electrode active materials of such formation, with the secondary cell shown in the mode shop drawings 2 and 3 identical with embodiment 1-1.
For the secondary cell that embodiment 5-1 makes to 5-9 and comparative example 5-1 to 5-5, under 45 degrees centigrade, charge and discharge, and detection initial capacity and cycle characteristics.For charging, carry out constant current charge with the constant current of 1000mA and reach 4.4V, and carry out constant voltage charge with constant voltage subsequently and reach 2.5 hours to obtain complete charged state up to total charging time up to cell voltage.For discharge, carry out constant-current discharge with the constant current of 800mA and reach 3.0V to obtain complete discharge condition up to cell voltage.Initial capacity refers to the discharge capacity of circulation time for the first time.The discharge capacity of cycle characteristics by the 200th circulation time obtains cycle characteristics with respect to the discharge capacitance of initial capacity as (discharge capacity/initial capacity of the 200th circulation time) * 100.Resulting result is shown in the table 5.
Table 5
Charging voltage: 4.4V
Composite oxide particle Coating layer 2 θ differences (degree) of diffraction maximum Initial capacity (Wh) Capability retention (%)
Embodiment 5-1 Li 1.03CoO 2 Li 1.08Ni 0.5Mn 0.5O 2 *1 0.44 9.1 80
Embodiment 5-2 0.40 9.1 81
Embodiment 5-3 0.24 9.1 79
Embodiment 5-4 0.52 9.1 81
Embodiment 5-5 0.44 9.1 82
Embodiment 5-6 Li 1.03Co 0.98 Al 0.01O 2 0.35 9.1 86
Embodiment 5-7 Li 1.03CoO 2 Li 1.03Ni 0.5Mn 0.5O 2 0.80 9.0 74
Embodiment 5-8 Li 1.03Ni 0.33Co 0.33Mn 0.33 O 2 0.58 9.1 72
Embodiment 5-9 Li 1.08Ni 0.8Mn 0.2O 2 *2 0.37 9.2 83
Comparative example 5-1 Li 1.03CoO 2 - 9.2 48
Comparative example 5-2 Li 1.04Ni 0.045Co 0.91Mg 0.045O 2 *3 - 9.0 55
Comparative example 5-3 Li 1.03CoO 2 Li 1.08Ni 0.5Mn 0.5O 2 *1 0.1 it is or lower 9.1 57
Comparative example 5-4 Li 1.08NiO 2 *4 0.1 it is or lower 8.9 61
Comparative example 5-5 LiMn 2O 4 *5 1.10 8.7 64
*1: sintering Li 2CO 3: Ni (OH) 2: MnCO 3=1.08: the mixture of 1: 1 (mol ratio).
*2: sintering Li 2CO 3: Ni (OH) 2: MnCO 3=1.08: the mixture of 1.6: 0.4 (mol ratio).
*3: sintering Li 2CO 3: Co (OH) 2: Ni (OH) 2: MnCO 3=0.52: the mixture of 0.91: 0.045: 0.045 (mol ratio).
*4: sintering Li 2CO 3: Ni (OH) 2The mixture of=0.54: 1 (mol ratio).
*5: sintering Li 2CO 3: MnCO 3The mixture of=1: 4 (mol ratios).
As shown in table 5, according to the embodiment 5-1 of the diffraction maximum that on a side of spending angle in the 1.0 degree scopes than the diffraction maximum of the face that belongs to composite oxide particle [101] low 0.2, has coating layer to 5-9, initial capacity and not to be provided with the comparative example 5-1 and the 5-2 of coating layer almost equal, but capability retention can significantly improve.Equally, on a side, have among the comparative example 5-3 and 5-4 of diffraction maximum of coating layer than the angle in the scope below low 0.2 degree of the diffraction maximum of the face that belongs to composite oxide particle [101], and have on the side of the angle in the diffraction maximum than the face that belongs to composite oxide particle [101] is lower than the scopes that surpass 1.0 degree among the comparative example 5-5 of diffraction maximum of coating layer, although compare with 5-2 with comparative example 5-1 and can improve capability retention, the improvement degree is small.In addition, in comparative example 5-4 and 5-5, initial capacity reduces.
Just, find when on a side of spending the angle in 1.0 degree scopes than the diffraction maximum low 0.2 of the face that belongs to composite oxide particle [101], having the diffraction maximum of coating layer, can improve capacity, and can improve hot properties and cycle characteristics.
(embodiment 6-1 is to 6-4)
Except the covering amount of change coating layer with respect to composite oxide particle as shown in table 6, make positive electrode active materials and secondary cell in the mode identical with embodiment 5-2., carry out by utilizing Cu-K α 1 to measure to the formed positive electrode active materials of 6-4 for embodiment 6-1 in the mode identical with embodiment 5-2 as the powder x-ray diffraction of X-ray source.As a result and embodiment 5-2 similar, observe the diffraction maximum of composite oxide particle and the diffraction maximum of coating layer.Is 0.28 degree in the diffraction maximum that belongs to the face of composite oxide particle [101] in embodiment 6-1 with the difference that is located at than peak-to-peak angle of diffraction 2 θ of the diffraction of the coating layer on the low angle side, it in embodiment 6-2 0.36 degree, be 0.42 degree in embodiment 6-3, and be 0.45 degree in embodiment 6-4.Just, aforementioned value is all spent in the scope of 1.0 degree 0.2.In addition, to the secondary cell that 6-4 makes, detect initial capacity and cycle characteristics for embodiment 6-1 in the mode identical with embodiment 5-2.With the result shown in the table 6.
Table 6
Charging voltage: 4.4V
Composite oxide particle Coating layer 2 θ differences (degree) of diffraction peak Initial capacity (Wh) Capability retention (%)
Form Covering amount (weight %)
Embodiment 6-1 Li 1.03CoO 2 Li 1.08Ni 0.5 Mn 0.5O 2 * 2.5 0.28 9.2 70
Embodiment 6-2 5 0.36 9.2 73
Embodiment 5-2 10 0.40 9.1 81
Embodiment 6-3 20 0.42 8.9 84
Embodiment 6-4 50 0.45 8.2 84
*: sintering Li 2CO 3: Ni (OH) 2: MnCO 3=1.08: the mixture of 1: 1 (mol ratio).
As shown in Figure 6, similar in 6-4 and the embodiment 5-2 according to embodiment 6-1, can significantly improve capability retention.In addition, such trend is arranged, when the coating layer amount increased, capability retention improved but initial capacity reduces.Just, find preferred coating layer amount at 2 weight % of composite oxide particle in the scope of 30 weight %, and more preferably at 5 weight % in the scope of 20 weight %.
(embodiment 7-1 is to 7-3)
Except use with embodiment 5-1 in identical positive electrode active materials, and the amount of adjusting positive electrode active materials and negative active core-shell material makes that the open circuit voltage when charging fully is outside 4.2V, 4.3V or the 4.5V, makes secondary cell in the mode identical with embodiment 5-1.In addition, as with respect to embodiment 7-1 to the comparative example 7-1 of 7-3 to 7-3, except use with comparative example 5-1 in identical positive electrode active materials, even be used in the sour lithium of the cobalt that is used as composite oxide particle among the comparative example 5-1 as positive electrode active materials, and the amount of adjusting positive electrode active materials and negative active core-shell material makes that the open circuit voltage when charging fully is outside 4.2V, 4.3V or the 4.5V, makes secondary cell in the mode identical with embodiment 1-1.
The secondary cell of making to 7-3 and comparative example 7-1 to 7-3 for embodiment 7-1 charges and discharge in the mode identical with embodiment 5-1, and detection initial capacity and cycle characteristics.Subsequently, charging voltage is carried out conversion from 4.2V, 4.3V to 4.5V.In result shown in the table 7.
Table 7
Composite oxide particle Coating layer 2 θ differences (degree) of diffraction peak Charging voltage (V) Initial capacity (Wh) Capability retention (%)
Embodiment 7-1 Li 1.03CoO 2 Li 1.08Ni 0.5 Mn 0.5O 2 * 0.44 4.2 8.1 90
Embodiment 7-2 4.3 8.5 88
Embodiment 5-1 4.4 9.1 80
Embodiment 7-3 4.5 9.6 73
Comparative example 7-1 Li 1.03CoO 2 4.2 8.1 82
Comparative example 7-2 4.3 8.5 78
Comparative example 5-1 4.4 9.2 48
Comparative example 7-3 4.5 9.5 36
*: sintering Li 2CO 3: Ni (OH) 2: MnCO 3=1.08: the mixture of 1: 1 (mol ratio).
As shown in table 7, to 7-3, when improving charging voltage, initial capacity is improved according to the comparative example 5-1 that coating layer is not set and 7-1, but capability retention significantly reduces.Equally, to 7-3, the reduction degree of capability retention is little, and compares and can significantly improve to 7-3 with 7-1 with comparative example 5-1 according to the embodiment 5-1 that is provided with above-mentioned coating layer and 7-1.In addition, the charging voltage increase is many more, and effect is big more.Just, find when cell voltage is higher than 4.2V, can obtain higher effect.
With reference to execution mode and embodiment the present invention has been described.Yet the present invention is not limited to the execution mode and the embodiment of front, and can make various modifications.For example, in front the execution mode or embodiment, to using electrolytic solution (it is liquid electrolyte) or wherein keeping the situation of the gel-like electrolyte of electrolytic solution to provide description by high-molecular weight compounds.Yet, can use other electrolyte.For example, as other electrolyte, can enumerate inorganic solid electrolyte, molten salt electrolyte or its mixture that electrolytic salt wherein is dispersed in high molecular weight electrolyte in the high-molecular weight compounds with ionic conductivity, is made up of ionic conductivity ceramics, ionic conducting glass, ionic crystals etc.
In addition, in front the execution mode and embodiment, to capacity of negative plates wherein with owing to embed and so-called lithium rechargeable battery that the capacity component of removal lithium embedded is expressed has provided description.Yet, the present invention can be applied to so-called lithium metal secondary batteries similarly, wherein use the lithium metal as negative active core-shell material, and capacity of negative plates with since the precipitation and the capacity component of decomposing lithium express, perhaps can be applied in such secondary cell, wherein set charging capacity for less than positive pole by embedding with the charging capacity of the negative material of removal lithium embedded, capacity of negative plates comprises owing to the capacity component of embedding and removal lithium embedded with owing to the capacity component that precipitates and decompose lithium, and capacity of negative plates is represented with their summation.
In addition, in front the execution mode and embodiment, the secondary cell with screw winding structure has been provided description.Yet the present invention can be applied to have the secondary cell of other structure similarly, and described structure is as wherein with anodal and structure that negative pole is folding and with positive pole and the stacked structure of negative pole.In addition, the present invention also can be applied to have secondary cell such as Coin-shaped battery, button cell and the square battery of other shape.In addition, the present invention also can be applied in the primary cell except secondary cell.
Should be appreciated that for a person skilled in the art, in the scope of claims or its equivalent,, can carry out various modifications, combination, recombinant and alternately according to design requirement and other factors.

Claims (32)

1, a kind of positive electrode active materials comprises:
The composite oxide particle that makes by the oxide that contains lithium (Li) and cobalt (Co) at least; And
Be arranged on composite oxide particle to small part and by containing the coating layer that oxide at least a in lithium and nickel and the manganese makes.
2, positive electrode active materials according to claim 1, wherein the average composition of this composite oxide particle is represented with Chemical formula 1,
(Chemical formula 1)
Li (1+w)Co (1-x-y)M1 xM2 yO (2-z)
Wherein M1 represents to be selected from least a of magnesium (Mg), aluminium (Al), titanium (Ti) and zirconium (Zr), and M2 represents to be selected from least a of boron (B), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), tungsten (W), yttrium (Y), niobium (Nb), calcium (Ca) and strontium (Sr); And the value of w, x, y and z respectively-0.10≤w≤0.10,0.001＜x＜0.10,0≤y＜0.40 and-scope of 0.10≤z≤0.20 in.
3, positive electrode active materials according to claim 1, wherein the average composition of this composite oxide particle is represented with Chemical formula 2, and
The height of the concentration ratio of the manganese outside this coating layer in the layer segment in the interior layer segment of this coating layer,
(Chemical formula 2)
Li (1+x)Co (1-y)M yO (2-z)
Wherein M represents to be selected from least a of magnesium (Mg), aluminium (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), tungsten (W), zirconium (Zr), yttrium (Y), niobium (Nb), calcium (Ca) and strontium (Sr); And the value of x, y and z-0.10≤x≤0.10,0≤y＜0.50 and-scope of 0.10≤z≤0.20 in.
4, positive electrode active materials according to claim 3, wherein nickel in this coating layer and the ratio of components between the manganese are with nickel: the mol ratio of manganese is illustrated in 100: 0 to 20: 80 the scope.
5, positive electrode active materials according to claim 1, wherein the average composition of this composite oxide particle is represented with chemical formula 3, and
In the diffraction maximum that obtains by CuK α powder x-ray diffraction, on spending a side of angle in the 1.0 degree scopes, angle of diffraction 2 θ low 0.2 than the diffraction maximum of the face that belongs to this composite oxide particle [101] have the diffraction maximum of coating layer,
(chemical formula 3)
Li (1+x)Co (1-y)M yO (2-z)
Wherein M represents to be selected from least a of magnesium (Mg), aluminium (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), tungsten (W), zirconium (Zr), yttrium (Y), niobium (Nb), calcium (Ca) and strontium (Sr); And the value of x, y and z respectively-0.10≤x≤0.10,0≤y＜0.50 and-scope of 0.10≤z≤0.20 in.
6, positive electrode active materials according to claim 5, wherein nickel in this coating layer and the ratio of components between the manganese are with nickel: the mol ratio of manganese is illustrated in 100: 0 to 20: 80 the scope.
7, positive electrode active materials according to claim 1, wherein the oxide of this coating layer further comprises and is selected from least a of cobalt (Co), magnesium, aluminium, titanium, zirconium, boron, vanadium, chromium, iron, copper, zinc, molybdenum, tin, tungsten, yttrium, niobium, calcium and strontium.
8, positive electrode active materials according to claim 1, wherein the amount of this coating layer at 0.5 weight % of this composite oxide particle in the scope of 50 weight %.
9, positive electrode active materials according to claim 1, wherein average grain diameter at 2.0 μ m in the scope of 50 μ m.
10, a kind of method of making positive electrode active materials may further comprise the steps:
Have 12 or the aqueous solution of bigger hydrogen ion exponent pH in, at the inside precursor layer that forms the hydroxide that contains nickel (Ni) and manganese (Mn) to the small part of composite oxide particle with average composition of representing with chemical formula 4 or chemical formula 5;
After forming inner precursor layer, by changing the chemical valence of the manganese ion that in the aqueous solution, is comprised, has outside precursor layer than the hydroxide of the manganese concentration of inner precursor floor height in the formation to the small part of composite oxide particle; And
By heat treatment should the inside precursor layer and this outside precursor layer form the coating layer that makes by the oxide that contains lithium, nickel and manganese, wherein outside composite oxide particle is to small part the manganese concentration of layer segment greater than the manganese concentration of interior layer segment,
(chemical formula 4)
Li (1+w)Co (1-x-y)M1 xM2 yO (2-z)
Wherein M1 represents to be selected from least a of magnesium (Mg), aluminium (Al), titanium (Ti) and zirconium (Zr); M2 represents to be selected from least a of boron (B), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), tungsten (W), yttrium (Y), niobium (Nb), calcium (Ca) and strontium (Sr); And the value of w, x, y and z respectively-0.10≤w≤0.10,0.001＜x＜0.10,0≤y＜0.40 and-scope of 0.10≤z≤0.20 in,
(chemical formula 5)
Li (1+x)Co (1-y)M yO (2-z)
Wherein M represents to be selected from least a of magnesium (Mg), aluminium (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), tungsten (W), zirconium (Zr), yttrium (Y), niobium (Nb), calcium (Ca) and strontium (Sr); And the value of x, y and z respectively-0.10≤x≤0.10,0≤y＜0.50 and-scope of 0.10≤z≤0.20 in.
11, the method for manufacturing positive electrode active materials according to claim 10 is wherein in the step that forms outside precursor layer, by be blown into the chemical valence that oxidizing gas changes manganese ion in the aqueous solution.
12, the method for manufacturing positive electrode active materials according to claim 10 is wherein added lithium hydroxide among the aqueous solution to.
13, a kind of positive pole comprises:
Positive electrode active materials wherein is being provided with coating layer to the small part composite oxide particle,
Wherein this composite oxide particle is made by the oxide that contains lithium (Li) and cobalt (Co) at least, and
This coating layer makes by containing oxide at least a in lithium and nickel and the manganese.
14, positive pole according to claim 13, wherein the average composition of this composite oxide particle is represented with chemical formula 6,
(chemical formula 6)
Li (1+w)Co (1-x-y)M1 xM2 yO (2-z)
Wherein M1 represents to be selected from least a of magnesium (Mg), aluminium (Al), titanium (Ti) and zirconium (Zr), and M2 represents to be selected from least a of boron (B), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), tungsten (W), yttrium (Y), niobium (Nb), calcium (Ca) and strontium (Sr); And the value of w, x, y and z respectively-0.10≤w≤0.10,0.001＜x＜0.10,0≤y＜0.40 and-scope of 0.10≤z≤0.20 in.
15, positive pole according to claim 13, wherein the average composition of this composite oxide particle is represented with chemical formula 7, and
The height of the concentration ratio of the manganese outside this coating layer in the layer segment in the interior layer segment of this coating layer,
(chemical formula 7)
Li (1+x)Co (1-y)M yO (2-z)
Wherein M represents to be selected from least a of magnesium (Mg), aluminium (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), tungsten (W), zirconium (Zr), yttrium (Y), niobium (Nb), calcium (Ca) and strontium (Sr); And the value of x, y and z respectively-0.10≤x≤0.10,0≤y＜0.50 and-scope of 0.10≤z≤0.20 in.
16, positive pole according to claim 15, wherein nickel in this coating layer and the ratio of components between the manganese are with nickel: the mol ratio of manganese is illustrated in 100: 0 to 20: 80 the scope.
17, positive pole according to claim 13, wherein the average composition of this composite oxide particle is represented with chemical formula 8, and
In the diffraction maximum that obtains by CuK α powder x-ray diffraction, on spending a side of angle in the 1.0 degree scopes, angle of diffraction 2 θ low 0.2 than the diffraction maximum of the face that belongs to this composite oxide particle [101] have the diffraction maximum of coating layer,
(chemical formula 8)
Li (1+x)Co (1-y)M yO (2-z)
Wherein M represents to be selected from least a of magnesium (Mg), aluminium (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), tungsten (W), zirconium (Zr), yttrium (Y), niobium (Nb), calcium (Ca) and strontium (Sr); And the value of x, y and z respectively-0.10≤x≤0.10,0≤y＜0.50 and-scope of 0.10≤z≤0.20 in.
18, positive pole according to claim 17, wherein nickel in this coating layer and the ratio of components between the manganese are with nickel: the mol ratio of manganese is illustrated in 100: 0 to 20: 80 the scope.
19, positive pole according to claim 13, wherein the oxide of this coating layer further comprises and is selected from least a of cobalt (Co), magnesium, aluminium, titanium, zirconium, boron, vanadium, chromium, iron, copper, zinc, molybdenum, tin, tungsten, yttrium, niobium, calcium and strontium.
20, positive pole according to claim 13, wherein the amount of this coating layer at 0.5 weight % of this composite oxide particle in the scope of 50 weight %.
21, positive pole according to claim 13, wherein the average grain diameter of this positive electrode active materials at 2.0 μ m in the scope of 50 μ m.
22, positive pole according to claim 13, wherein, by have 12 or the aqueous solution of bigger hydrogen ion exponent pH in, the inside precursor layer that forms the hydroxide that contains nickel and manganese to the small part at composite oxide particle, subsequently by changing the chemical valence of the manganese ion that in this aqueous solution, is comprised, formation has the outside precursor layer than the hydroxide of the manganese concentration of inner precursor floor height, and inner precursor layer and outside precursor layer heat-treated, obtain positive electrode active materials.
23, a kind of battery comprises:
Anodal;
Negative pole; With
Electrolyte,
Wherein this positive pole contains positive electrode active materials, wherein to the small part composite oxide particle coating layer is being set,
This composite oxide particle is made by the oxide that contains lithium (Li) and cobalt (Co) at least, and
This coating layer makes by containing oxide at least a in lithium and nickel and the manganese.
24, battery according to claim 23, wherein the average composition of this composite oxide particle is represented with chemical formula 9,
(chemical formula 9)
Li (1+w)Co (1-x-y)M1 xM2 yO (2-z)
Wherein M1 represents to be selected from least a of magnesium (Mg), aluminium (Al), titanium (Ti) and zirconium (Zr), and M2 represents to be selected from least a of boron (B), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), tungsten (W), yttrium (Y), niobium (Nb), calcium (Ca) and strontium (Sr); And the value of w, x, y and z respectively-0.10≤w≤0.10,0.001＜x＜0.10,0≤y＜0.40 and-scope of 0.10≤z≤0.20 in.
25, battery according to claim 23, wherein the average composition of this composite oxide particle is represented with Chemical formula 10, and
The height of the concentration ratio of the manganese outside this coating layer in the layer segment in the interior layer segment of this coating layer,
(Chemical formula 1 0)
Li (1+x)Co (1-y)M yO (2-z)
Wherein M represents to be selected from least a of magnesium (Mg), aluminium (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), tungsten (W), zirconium (Zr), yttrium (Y), niobium (Nb), calcium (Ca) and strontium (Sr); And the value of x, y and z respectively-0.10≤x≤0.10,0≤y＜0.50 and-scope of 0.10≤z≤0.20 in.
26, battery according to claim 25, wherein nickel in this coating layer and the ratio of components between the manganese are with nickel: the mol ratio of manganese is illustrated in 100: 0 to 20: 80 the scope.
27, battery according to claim 25, wherein the average composition of this composite oxide particle is represented with Chemical formula 11, and
In the diffraction maximum that obtains by CuK α powder x-ray diffraction, on spending a side of angle in the 1.0 degree scopes, angle of diffraction 2 θ low 0.2 than the diffraction maximum of the face that belongs to this composite oxide particle [101] have the diffraction maximum of coating layer,
(Chemical formula 1 1)
Li (1+x)Co (1-y)M yO (2-z)
Wherein M represents to be selected from least a of magnesium (Mg), aluminium (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), tungsten (W), zirconium (Zr), yttrium (Y), niobium (Nb), calcium (Ca) and strontium (Sr); And the value of x, y and z respectively-0.10≤x≤0.10,0≤y＜0.50 and-scope of 0.10≤z≤0.20 in.
28, battery according to claim 27, wherein nickel in this coating layer and the ratio of components between the manganese are with nickel: the mol ratio of manganese is illustrated in 100: 0 to 20: 80 the scope.
29, battery according to claim 25, wherein the oxide of this coating layer further comprises and is selected from least a of cobalt (Co), magnesium, aluminium, titanium, zirconium, boron, vanadium, chromium, iron, copper, zinc, molybdenum, tin, tungsten, yttrium, niobium, calcium and strontium.
30, battery according to claim 25, wherein the amount of this coating layer at 0.5 weight % of composite oxide particle in the scope of 50 weight %.
31, battery according to claim 25, wherein the average grain diameter of this positive electrode active materials at 2.0 μ m in the scope of 50 μ m.
32, battery according to claim 25, wherein, by have 12 or the aqueous solution of bigger hydrogen ion exponent pH in, the inside precursor layer that forms the hydroxide that contains nickel and manganese to the small part at composite oxide particle, subsequently by changing the chemical valence of the manganese ion that in this aqueous solution, is comprised, formation has the outside precursor layer than the hydroxide of the manganese concentration of inner precursor floor height, and inner precursor layer and outside precursor layer heat-treated, obtain positive electrode active materials.
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