CN1856890A - Lithium composite oxide particle for positive electrode material of lithium secondary battery, and lithium secondary battery positive electrode and lithium secondary battery using the same - Google Patents

Abstract

An improved positive electrode material for lithium secondary battery that enhances the low temperature load characteristics of battery and further enhances coatability at the fabrication of positive electrode. In the measurement according to the mercury penetration method, the following condition (A) is satisfied and simultaneously at least one of the following conditions (B) and (C) is satisfied. Condition (A) On the mercury penetration curve, the quantity of mercury penetration at a pressure increase from 50 MPa to 150 MPa is 0.02 cm<3>/g or less. Condition (B) On the mercury penetration curve, the quantity of mercury penetration at a pressure increase from 50 MPa to 150 MPa is 0.01 cm<3>/g or more. Condition (C) The average pore radius is in the range of 10 to 100 nm, and further the pore distribution curve has a main peak whose peak top exists at a pore radius ranging from 0.5 to 50 mum and a subpeak whose peak top exists at a pore radius ranging from 80 to 300 nm.

Description

Be used for lithium composite xoide particle, the cathode plate for lithium secondary battery of positive electrode material of lithium secondary cell and use this anodal lithium secondary battery

Technical field

The present invention relates to lithium composite xoide particle, also relate to the positive pole that is used for lithium secondary battery and adopt this anodal lithium secondary battery as positive electrode material of lithium secondary cell.Positive electrode according to the present invention has demonstrated excellent coating, even and use under low temperature environment the positive pole that is used for secondary cell with excellent part throttle characteristics also can be provided.

Background technology

Recently, because it is as the power supply of miniaturization and light-weighted mobile electronic device and mobile communication equipment with as the purposes of the power supply of vehicle, lithium secondary battery has caused people's attention.Lithium secondary battery can provide high output and high-energy-density usually, and concerning its positive pole, using its standard to form is to use LiCoO ₂, LiNiO ₂, LiMn ₂O ₄Deng the expression lithium-transition metal composite oxide as positive electrode active materials.

In various lithium-transition metal composite oxides, consider fail safe and material cost, noticeable positive electrode active materials is that those have and LiCoO ₂And LiNiO ₂Similar layer structure and its transition metal site are by the material that partly replaces such as other elements such as manganese.Disclosed in non-patent literature 1～3 and patent documentation 1, the example of this type of lithium-transition metal composite oxide is by partly replacing LiNiO with Mn ₂In the Ni site and the LiNi that makes _(1-a)Mn _aO ₂With by partly replacing LiNiO with Mn and Co ₂In Ni site and the LiNi that makes _{(1-alpha-beta)}Mn _αCo _βO ₂

In addition, when this type of lithium-transition metal composite oxide disclosed in non-patent literature 1～3 and the patent documentation 1 is used as positive electrode active materials, described lithium-transition metal composite oxide is formed particulate, thereby increase the contact area of surface of positive electrode active material and electrolyte and improve part throttle characteristics.Yet, lithium-transition metal composite oxide is formed particulate also can reduce positive electrode active materials and enter anodal charging efficiency and limited battery capacity.

On the other hand, disclosed in the patent documentation 2 as the positive electrode active materials that is used for non-aqueous secondary cell, can use the porous particle of lithium composite xoide, it contains at least a element that is selected among Co, Ni and the Mn and as the lithium of main component, it is 0.1 μ m～1 μ m by the average pore radius that the pore radius measure of spread that is pressed into porosimetry with mercury and carries out obtains, and its diameter is that the cumulative volume in hole of 0.01 μ m～1 μ m is more than or equal to 0.01cm ³/ g.The document has also disclosed to use described particle can strengthen the part throttle characteristics of gained battery and can not damage positive electrode active materials and has been filled to charging efficiency in the positive pole.

Patent documentation 3 has disclosed the average diameter of its primary particle for being less than or equal to 3.0 μ m and its specific area more than or equal to 0.2m ²The Li-Mn-Ni-Co composite oxide particle of/g can be used as the positive electrode active materials of lithium secondary battery, and the lithium secondary battery of gained demonstrates high discharge capacity and excellent cycle performance.

Patent documentation 4 has disclosed can be as the positive electrode active materials of lithium secondary battery by Li-Mn-Ni-Co slurry spray drying being calcined subsequently Li-Mn-Ni-Co composite oxide particle that spray-dried particle makes, and the lithium secondary battery of gained demonstrates high discharge capacity and excellent cycle performance.

[non-patent literature 1] Journal of Materials Chemistry, the 6th volume, 1996, the 1149 pages

[non-patent literature 2] Journal of the Electrochemical Society, the 145th volume, 1998, the 1113 pages

The pre-original text collection of [non-patent literature 3] Japan's the 41st primary cell discussion, 2000, the 460 pages

[patent documentation 1] TOHKEMY 2003-17052 communique

[patent documentation 2] TOHKEMY 2000-323123 communique

[patent documentation 3] TOHKEMY 2003-68299 communique

[patent documentation 4] TOHKEMY 2003-51308 communique

Summary of the invention

Problem solved by the invention

Yet, the technology disclosed according to non-patent literature 1～3 and patent documentation 1, when as mentioned above lithium transition-metal oxide being formed particulate, exist the positive electrode active materials anodal charging efficiency of packing into is restricted and therefore can't guarantees the problem of enough part throttle characteristics.

The formation of particulate also is accompanied by such problem, and promptly when described particle was used to be coated with, it is hard and crisp that coating layer can become aspect engineering properties, separates with positive pole in the coiling step of assembled battery easily, therefore can not guarantee enough coatings.As lithium transition-metal oxide LiNi _{(1-alpha-beta)}Mn _αCo _βO ₂Composition in the ratio of Ni: Mn: Co when approaching 1-alpha-beta: α: β (wherein 0.05≤α≤0.5 and 0.05≤β≤0.5) this problem particularly evident.

Lithium composite xoide particle disclosed in the patent documentation 2 demonstrates the coating of improvement, but still has the not enough problem of part throttle characteristics under the low temperature (low temperature part throttle characteristics).

Equally, still there is the problem of part throttle characteristics deficiency under the low temperature in the lithium composite xoide particle that is used for positive electrode material of lithium secondary cell disclosed in the patent documentation 3.

The lithium composite xoide particle that is used for positive electrode material of lithium secondary cell disclosed in the patent documentation 4 tends to demonstrate very low bulk density and has the problem of relevant coating.

Consider the problems referred to above, the purpose of this invention is to provide the lithium composite xoide particle that is used for positive electrode material of lithium secondary cell, described particle can improve the low temperature part throttle characteristics of gained lithium secondary battery, and demonstrates excellent coating in the manufacturing of positive pole.

The means that are used to deal with problems

As for addressing the above problem the result who makes great efforts to study, the inventor finds to satisfy the lithium composite xoide particle of following condition can be as preferably having the low temperature part throttle characteristics of improvement and have the positive electrode material of lithium secondary cell of excellent coating in the manufacturing of positive pole.Promptly, according to be pressed into the mensuration that porosimetry carries out with mercury, (A) volume that is pressed into of mercury is equal to or less than preset upper limit under the certain high pressure load, (B) volume that is pressed into of described mercury is equal to or greater than predetermined lower limit, or (C) when the pore size distribution curve has the inferior peak of summit in predetermined pore radius scope except traditional main peak, the average pore radius is in preset range.Based on above-mentioned discovery, the inventor has realized the present invention.

According to an aspect of the present invention, a kind of lithium composite xoide particle that is used for positive electrode material of lithium secondary cell is provided, when being pressed into porosimetry with mercury and measuring, described particle satisfies following condition (A), and satisfies following condition (B) or at least one condition in the condition (C).

Condition (A)

Be pressed into curve according to mercury, when 50MPa increased to 150MPa, mercury was pressed into volume for being less than or equal to 0.02cm at pressure ³/ g.

Condition (B)

Be pressed into curve according to mercury, when 50MPa increased to 150MPa, mercury was pressed into volume for more than or equal to 0.01cm at pressure ³/ g.

Condition (C)

The average pore radius is 10nm～100nm, and the pore size distribution curve has the main peak that summit is positioned at the pore radius place of 0.5 μ m～50 μ m, and summit is positioned at the inferior peak at the pore radius place of 80nm～300nm.

As preferable feature, the lithium composite xoide particle contains Ni and Co at least.

As another preferable feature, the lithium composite xoide particle has being made up of following composition formula (1) expression:

Li _xNi _(1-y-z)Co _yM _zO ₂ (1)

Wherein the M representative is selected from least a element among Mn, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn and the Nb, and x represents the numerical value of 0＜x≤1.2, and y represents the numerical value of 0.05≤y≤0.5 and the numerical value that z represents 0.01≤z≤0.5.

According to a further aspect in the invention, provide a kind of positive pole that is used for lithium secondary battery, described positive pole comprises: current-collector; With the anode active material layer that is arranged on the described current-collector; Wherein said anode active material layer contains the above-mentioned lithium composite xoide particle that is used for positive electrode material of lithium secondary cell at least.

In accordance with a further aspect of the present invention, provide a kind of lithium secondary battery, described battery contains: the positive pole that can discharge and absorb lithium; Can absorb and discharge the negative pole of lithium; With contain lithium salts as electrolytical organic electrolyte; Wherein said positive pole is the above-mentioned positive pole that is used for lithium secondary battery.

Advantageous effects of the present invention

Lithium composite xoide particle of the present invention can improve the low temperature part throttle characteristics of gained lithium secondary battery, and has excellent coating when using in the manufacturing positive pole.Given this, lithium composite xoide particle of the present invention be preferably used as lithium secondary battery positive electrode.In addition, use lithium composite xoide particle of the present invention can provide positive electrode material of lithium secondary cell and lithium secondary battery with excellent low temperature part throttle characteristics as positive electrode.

Description of drawings

Fig. 1 is the curve chart of pore size distribution curve that shows the lithium composite xoide particle (positive electrode) of embodiment 1 and comparative example 1,2.

Fig. 2 is the part enlarged drawing of the curve chart of Fig. 1.

Embodiment

Below, will describe embodiments of the present invention in detail, but the present invention never is confined to following description, and allows in main idea scope of the present invention, to carry out various variations.

I. lithium composite xoide particle

Mercury is pressed into porosimetry

Be characterised in that as the lithium composite xoide particle of positive electrode material of lithium secondary cell (hereinafter be also referred to as " lithium composite xoide particle of the present invention ", or abbreviate as " particle of the present invention ") these particles satisfy certain conditions when being pressed into porosimetry with mercury and measuring.For a better understanding of the present invention, at first mercury being pressed into porosimetry before describing particle of the present invention is briefly described.

It is such method that mercury is pressed into porosimetry, wherein mercury is forced to be pressed in the hole such as samples such as porous particles, thereby based on the pressure of mercury be pressed between the amount of the mercury to the hole and concern, obtain to distribute and other information about specific area, pore radius.

Particularly, the container that sample is housed is vacuumized, then with filled with mercury.Because the mercury surface tension is big, thereby can spontaneously not enter in the pore on the sample surfaces.When the pressure on the mercury in being applied to container increased gradually, mercury began to enter the hole from the bigger hole of diameter gradually, entered then in the less hole of diameter.Along with continuing to increase of pressure, the liquid level (that is, being pressed into the volume of the mercury in the hole) by monitoring mercury can obtain mercury and be pressed into curve, and on behalf of the pressure that is applied on the mercury and mercury, described curve be pressed into relation between the volume.

Suppose that the hole is a cylindrical shape, then the power on the direction that mercury is extruded from the hole represents that with-2 π r δ (cos θ) wherein r represents the mean radius in hole, and δ represents the surface tension of mercury, and θ represents contact angle (when θ＞90 °, θ get on the occasion of).On the other hand, the power on the direction that mercury is pressed in the hole is with π r ²P represents, wherein the P representative pressure.Derive following equation (1) and (2) by these two equilibrium of forces.

-2πrδ(cosθ)＝πr ²P (1)

Pr＝-2δ(cosθ) (2)

Usually the surface tension δ of supposition mercury is about 480 dynes per centimeter (dyn/cm), and the contact angle θ of mercury is about 140 °.According to these approximations, the radius in the hole that mercury was pressed into is represented by following equation (A) under pressure P.

$r\left(\mathrm{nm}\right)=\frac{7.5\&times;{10}^8}{P\left(\mathrm{Pa}\right)}---\left(A\right)$

Thereby, be in application between the radius r in the pressure P of mercury and the hole that mercury is pressed into and have correlation.Therefore, mercury is pressed into curve can be converted to the pore size distribution curve, and it is representing the relation between the volume of pore radius and sample.For example, when pressure P when 0.1MPa is changed to 100MPa, can measure the hole in about 7500nm～7.5nm scope.

The approximate extents that is pressed into the pore radius that porosimetry measures with mercury is that lower limit is about to be about more than or equal to 3nm and the upper limit and is less than or equal to 200nm.Thereby compare with nitrogen adsorption method described below, mercury is pressed into porosimetry and is more suitable for its distribution of pores than the macrovoid radius region is analyzed.

Being pressed into the mensuration that porosimetry carries out with mercury can carry out such as equipment such as mercury porosimeters by using, the example comprises the Autopore  of Micromeritics Corporation manufacturing and the PoreMaster  that Quantachrome Corporation makes.

Particle of the present invention is characterised in that, when being pressed into porosimetry with mercury it is measured, described particle satisfies condition (A), and satisfy condition (B) or condition (C) at least one condition, the following qualification of these conditions.

Condition (A)

Be pressed into curve according to mercury, when 50MPa increased to 150MPa, mercury was pressed into volume for being less than or equal to 0.02cm at pressure ³/ g.

Condition (B)

Be pressed into curve according to mercury, when 50MPa increased to 150MPa, mercury was pressed into volume for more than or equal to 0.01cm at pressure ³/ g.

Condition (C)

The average pore radius is 10nm～100nm, and

The pore size distribution curve has the main peak that summit is positioned at the pore radius place of 0.5 μ m～50 μ m, and summit is positioned at the inferior peak at the pore radius place of 80nm～300nm.

Be pressed into the relevant condition of curve (condition (A) and (B)) with mercury

When mercury is pressed into curve and pore size distribution curve is by be pressed into porosimetry with mercury particle of the present invention to be measured when obtaining, it is that the pressure area of 50MPa～150MPa is the pore radius district of 15nm～5nm corresponding to scope that mercury is pressed into scope on the curve, that is minimum pore radius district.Because this pore radius district approaches above-mentioned measurement lower limit, therefore mercury is pressed into the fact that volume is in the above particular range and does not mean that particle of the present invention has the pore radius that is in the respective range under aforementioned pressure.On the contrary, according to judging that particle of the present invention has so small hole hardly, this is because following nitrogen adsorption method shows that the cumulative volume that radius is less than or equal to the hole of 50nm is less than or equal to 0.01cm usually ³/ g.Thereby, it is believed that under the pressure of 50MPa～150MPa being pressed into the relevant feature of volume with mercury is not that existence by hole small in the particle of the present invention is caused.

Although the inventor's research is not illustrated as yet, being pressed into scope in the curve at above-mentioned mercury by inference is the pressure area that the pressure area of 50MPa～150MPa changes because of high pressure load corresponding to grain structure.Thereby it is believed that because mercury in this pressure area is pressed into volume and satisfies above-mentioned condition, therefore the measuring body structural strength of particle of the present invention is positioned at particular range, can be not too high or too low, and structural strength that should the best has produced the various preferred properties as the particle of the present invention of positive electrode.

Particularly, be pressed into curve according to mercury, when pressure increased to 150MPa by 50MPa, the mercury of particle of the present invention was pressed into the upper limit such as above-mentioned condition (A) defined of volume, is less than or equal to 0.02cm usually ³/ g preferably is less than or equal to 0.0195cm ³/ g is more preferably less than or equals 0.019cm ³/ g.Mercury is pressed into the particle that volume surpasses the upper limit can become thinner particle because of its low structural strength Hypersegmentation, cause coating to worsen.If these particles are used for being coated with positive pole, then the gained coating layer can become hard and crisp aspect engineering properties, and is easy to separate with positive pole in the coiling step of assembled battery.Thereby this particle is not suitable for positive pole.

On the other hand, the mercury of particle of the present invention is pressed into the preferred lower limit such as above-mentioned condition (B) defined of volume, is generally more than or equal to 0.01cm ³/ g, more preferably greater than or equal 0.011cm ³/ g further is preferably greater than or equals 0.012cm ³/ g.Mercury is pressed into effective contact area that anodal particle that volume is lower than described lower limit can not be guaranteed itself and electrolyte of enough degree, thereby the part throttle characteristics of gained battery descends.

The character relevant (condition (C)) with pore radius

The average pore radius

The average pore radius of particle of the present invention such as above-mentioned condition (C) defined usually more than or equal to 10nm, are preferably greater than or equal 12nm, and be less than or equal to 100nm, preferably are less than or equal to 50nm.The average pore radius that is in the above-mentioned scope means in particle of the present invention, compares with traditional lithium composite xoide particle, has formed the hole with suitable size below between the primary particle that will describe.The particle that the average pore radius surpasses the described upper limit is not preferred, this is because they have the hole area of so little unit volume, so that when they are used as positive electrode active materials, reduced the contact area of surface of positive electrode active material and electrolyte, the gained battery demonstrates not enough part throttle characteristics.On the contrary, the particle that the average pore radius is lower than described lower limit is not preferred, and this is that the gained battery demonstrates the part throttle characteristics of deterioration because when as positive electrode active materials, they can cause lithium ion can not fully diffuse in the hole of positive electrode active materials.Point out that in passing in the present invention, in order to eliminate the influence in the space between the second particle, being pressed into average pore radius that porosimetry measures according to mercury is to be that the pore of 0.005 μ m～0.5 μ m is a calculation and object with radius.

The pore size distribution curve

According to be pressed into the pore distribution curve that porosimetry is measured with mercury, particle of the present invention demonstrates main peak and Ya Feng as described below usually.

In this manual, term " pore size distribution curve " is meant scattergram, its abscissa is represented the pore radius of each point, and its ordinate is represented by the radius of Unit Weight (being generally 1g) is carried out the resulting value of differential more than or equal to the cumulative volume in the hole of the pore radius of each point to the logarithm of pore radius.The form of the chart that the pore size distribution curve couples together with the point that will do usually shows.Especially, will measure resulting pore size distribution curve to particle of the present invention and be called " according to pore size distribution curve of the present invention " by be pressed into porosimetry with mercury.

And in this manual, the maximum peak in the peak on the pore size distribution curve represented in term " main peak ", its usually with second particle between the space that forms relevant, this will make an explanation below.Term " inferior peak " representative is at each peak except that described main peak on the pore size distribution curve.

In addition, in this manual, term " summit " is meant the point that has the maximum ordinate value in each peak of pore size distribution curve.

Main peak

Main peak according to pore size distribution curve of the present invention has summit, its pore radius is usually more than or equal to 0.5 μ m, is preferably greater than or equals 0.7 μ m, and be less than or equal to 50 μ m usually, preferably be less than or equal to 20 μ m, be more preferably less than or equal 15 μ m.If its main peak summit is surpassed the positive electrode of the porous particle of the described upper limit as battery, then the gained battery can be because the diffusion of lithium in positive pole be insufficient or the shortage of conductive channel and cause the deterioration of part throttle characteristics.On the other hand, if the porous particle that its main peak summit is lower than described lower limit is as making anodal material, then because the increase of the amount of required electric conducting material and adhesive, active material pack into positive pole (promptly, cathode collector) charging efficiency can be restricted, and causes the reduction of battery capacity thus.In addition, thinner along with particle is made, the coating layer that contains described particle can hardening aspect engineering properties or is become fragile, and is easy to separate with positive pole in the coiling step of assembled battery.

In addition, according to pore size distribution curve of the present invention, the pore volume of main peak is usually more than or equal to 0.1cm ³/ g is preferably greater than or equals 0.15cm ³/ g, and be less than or equal to 0.5cm usually ³/ g preferably is less than or equal to 0.4cm ³/ g.The pore volume of its main peak surpasses the space that the particle of the described upper limit tends between second particle and has so big volume, so that when as positive electrode, and pack into the charging efficiency of positive pole of active material can be restricted, and causes the reduction of battery capacity thus.On the contrary, the particle that the pore volume of its main peak is lower than described lower limit tends to have in the space between the second particle so little volume so that when as positive electrode, the lithium diffusion between the second particle is suppressed, the part throttle characteristics decline of gained battery.

Inferior peak

Pore size distribution curve according to the present invention is except above-mentioned main peak, preferably has specific inferior peak (hereinafter referred to as " specific inferior peak "), its summit is in usually more than or equal to 80nm, be preferably greater than or equal 100nm, more preferably greater than or equal 120nm, and be less than or equal to 300nm usually, preferably be less than or equal in the pore radius scope of 250nm.The existence at specific inferior peak shows to exist to have the space that is in the pore radius in the above-mentioned scope between primary particle of the present invention (below will be described).Make particle of the present invention low temperature part throttle characteristics and favourable coating characteristics can be combined according to the existence of judging described space.The particle that the summit at its specific inferior peak surpasses the upper limit of above-mentioned scope is not preferred, and reason is that surface of positive electrode active material and electrolytical contact area reduce when they are used as positive electrode active materials, and the part throttle characteristics of gained battery descends.On the other hand, the particle that the summit at its specific inferior peak is lower than the lower limit of above-mentioned scope is not preferred, and reason is when in the manufacturing that they is used in lithium secondary battery, and the diffusion of lithium ion in the hole is suppressed, and part throttle characteristics descends.

The pore volume at specific inferior peak (that is the ordinate value at the summit place at specific inferior peak) is usually more than or equal to 0.005cm ³/ g is preferably greater than or equals 0.01cm ³/ g, and be less than or equal to 0.05cm usually ³/ g preferably is less than or equal to 0.03cm ³/ g.The particle that the pore volume at its specific inferior peak surpasses the described upper limit is not preferred, reason is when they are used to be coated with, the gained coating layer is understood hardening or is become fragile aspect engineering properties, and is easy to separate with positive pole in the coiling step of making battery, causes the deterioration of coating.On the other hand, the particle that the pore volume at its specific inferior peak is lower than described lower limit is not preferred, reason be when in battery is made with them during as positive electrode, the diffusion of lithium is easy to be suppressed in the positive pole, and part throttle characteristics descends.

The ratio of the pore volume of main peak and the pore volume at specific inferior peak (promptly, the ratio of the ordinate value of main peak summit and the ordinate value on specific inferior peak-to-peak top), with [inferior peak]: the form of [main peak] is represented, be generally more than or equal to 1: 100, be preferably greater than or equal 1: 50, and be less than or equal to 1: 2 usually, preferably be less than or equal to 1: 5.The pore volume at inferior peak is excessive with the ratio of the pore volume of main peak to be not preferred, and this is because can tend to make coating to worsen.On the other hand, the pore volume at inferior peak is too small with the ratio of the pore volume of main peak to be not preferred, and this is because can tend to cause the low temperature part throttle characteristics to descend.

Other

As long as satisfy above-mentioned restrictive condition, particle of the present invention can have some hole outside the scope at main peak and inferior peak.Yet, equally in this case, preferably in than the little pore radius district of the pore radius at main peak summit place, have the pore volume of maximum as the specific inferior peak of feature of the present invention.

The reason of advantageous effects of the present invention

Although the inventor studies, when particle of the present invention is used for positive pole, can produce low temperature part throttle characteristics that strengthens the gained battery and the reason of improving the advantageous effects of coating why and not illustrate fully as yet, yet can probably carry out following supposition.

Lithium composite xoide particle of the present invention has the grain structure of suitable intensity, different with the lithium composite xoide particle commonly used that in lithium secondary battery, is used as positive electrode traditionally, along with described particle volume because of the charging and discharge change, this structure can make particle little by little and moderately split into thinner particle.Increase effective contact area of particle of the present invention and electrolyte thus, thereby improved the part throttle characteristics under battery required part throttle characteristics, the especially low temperature.Infer that from above-mentioned reason particle of the present invention can be realized the low temperature part throttle characteristics and the excellent coating that improve simultaneously.

In addition, owing between primary particle, have the hole of suitable size, therefore, different with traditional particle, when using in the manufacturing at battery, lithium composite xoide particle of the present invention can increase the contact area of itself and electrolyte and can excessively not increase its pore volume, improves the required part throttle characteristics of positive electrode active materials, especially the part throttle characteristics under the low temperature.This may be particle of the present invention can combine the low temperature part throttle characteristics of improving simultaneously with the coating of excellence another reason.

In order to realize above-mentioned advantageous effects (that is, improve the low temperature part throttle characteristics of battery and improve coating in anodal the manufacturing), particle of the present invention must always satisfy condition (A).About remaining condition (B) and (C), at least one condition in (B) or the condition of satisfying condition (C) is just enough.Yet,, preferably except that condition (A), to satisfy condition at least (B) in order to realize above-mentioned advantageous effects to a greater degree.

Other preferred implementation

Following will other character about particle of the present invention being described, but they should only be regarded as preferred feature.As long as particle of the present invention has above-mentioned character, described particle never should be subject to these character especially.

The character relevant with nitrogen adsorption method

Except be pressed into the above-mentioned feature of porosimetry about mercury, the feature that particle of the present invention preferably has is that the cumulative volume that its pore radius of measuring by BJH (Barret-Joyer-Halenda) method with the nitrogen absorption process is less than or equal to the hole of 50nm is that the Unit Weight of described particle is less than or equal to 0.01cm ³/ g.

Nitrogen adsorption method (BJH method) is such method, wherein makes such as absorption of sample nitrogen such as porous particles, thereby obtains such as the various information about specific area etc. such as pore radius distribution based on the relation between the adsorbance of nitrogen gas pressure and nitrogen.

Can optionally use various device to carry out according to the concrete mode of analyzing the pore radius distribution by the mensuration that nitrogen adsorption method carries out.The exemplary of this equipment is the measurement mechanism that is used for the nitrogen adsorption distribution of pores, such as the Autosorb  of Quantachrome Corporation manufacturing.

According to particle of the present invention, its radius that obtains by nitrogen adsorption method is that the cumulative volume that is less than or equal to the hole of 50nm is preferably as mentioned above and is less than or equal to 0.05cm ³/ g more preferably is less than or equal to 0.01cm ³/ g more preferably is less than or equal to 0.008cm ³/ g.The cumulative volume in aforesaid hole is not preferred greater than the particle of the described upper limit, and reason is that they contain a large amount of holes with minor diameter, thereby demonstrates lower active material and be filled to charging efficiency in the positive pole, causes battery capacity to reduce.

Grain shape

Coating of particles of the present invention is not done concrete qualification, but they are similar to the traditional lithium composite xoide coating of particles that is used as lithium secondary battery positive active material usually usually.Particularly, make primary particle gathering or sintering to form second particle, each second particle is dimensionally all greater than single primary particle.Hereinafter, term " particle of the present invention " is meant second particle.

Specific area

Specific area to particle of the present invention never should be done concrete qualification, but preferred specific area is usually more than or equal to 0.1m ²/ g, more preferably greater than or equal 0.2m ²/ g, and be less than or equal to 2m usually ²/ g is more preferably less than or equals 1.8m ²/ g.The specific area of particle mainly is subjected to the influence of the sintering degree of the diameter of primary particle and primary particle.The upper limit as described in surpassing as the specific area of fruit granule, then be used to be coated with the amount increase of required decentralized medium, the requirement of electric conducting material and adhesive also increases simultaneously, and the charging efficiency that causes active material to be filled in the positive pole is restricted, thereby battery capacity is tending towards descending.On the contrary, if specific area less than described lower limit, then the contact area between particle surface and the electrolyte descends in the positive pole, causes the part throttle characteristics of gained battery to descend.

In this manual, term " specific area " is meant the specific area (BET specific area) that obtains by BET (Brunauer, Emmett, the and Teller) method of using nitrogen adsorption method.The BET method is such method, and wherein the monolayer adsorbance of nitrogen is obtained by adsorption isotherm, and surface area is definite by the cross section of adsorbed nitrogen molecule, thus the specific area of calculation sample (BET specific area).Can be undertaken by using various types of BET measurement mechanisms with the mensuration that the BET method is carried out.

The diameter of primary particle

Diameter to the primary particle that forms particle of the present invention (second particle) should not done concrete qualification, but preferably usually more than or equal to 0.5 μ m, more preferably greater than or equal 0.6 μ m, and be less than or equal to 2 μ m, be more preferably less than or equal 1.8 μ m.The diameter of primary particle can be subjected to such as the diameter of the pulverized particles of raw material and the influence of factors such as temperature in the calcination process and atmosphere.If the diameter of primary particle surpasses the upper limit of above-mentioned scope, then the conduction of the diffusion of lithium ion and electronics is tending towards descending in the primary particle, causes part throttle characteristics to descend.On the contrary, if the diameter of primary particle is lower than the lower limit of above-mentioned scope, the amount that then is coated with required decentralized medium increases, and the requirement of electric conducting material and adhesive also increases, the charging efficiency that causes active material to be filled in the positive pole reduces, and battery capacity thereby be tending towards descending.

The diameter of primary particle is by measuring with scanning electron microscopy (SEM).Particularly, the diameter of primary particle can be with amplifying 10,000 times photo calculates, for example can pass through each primary particle in optional 50 primary particles, obtain the maximum length of the left end of particle, and the length of 50 described primary particles is averaged and tries to achieve to the horizontal intercept of right-hand member.

Tap density

Tap density to particle of the present invention never should be done concrete qualification, but usually more than or equal to 1.4g/cm ³, be preferably greater than or equal 1.5g/cm ³, and be less than or equal to 2.5g/cm usually ³, preferably be less than or equal to 2g/cm ³In this manual, term " tap density " is meant such value, and this value is represented jolt ramming and is filled in the powder weight of the flat powder volume in the container.The shown tap density that goes out of particle is high more, thinks that then particle can provide better fill volume more.Surpass the upper limit of above-mentioned scope as the tap density of fruit granule, then lithium ion is restricted by the diffusion as the electrolyte of medium in the positive pole, causes part throttle characteristics to descend.On the other hand, be lower than the lower limit of above-mentioned scope as the tap density of fruit granule, the amount that then is coated with required decentralized medium increases, and the requirement of electric conducting material and adhesive also increases, the charging efficiency that causes active material to be filled in the positive pole reduces, battery capacity thereby be tending towards descending.

Tap density can obtain by the method for JIS (Japanese Industrial Standards) K5101 defined, or by the particle of predetermined weight is put into graduated cylinder, and the particle that jolt ramming is put into is also measured the volume of particle and obtained.

Median particle diameter

The mean value of the diameter of particle of the present invention (second particle) (hereinafter being also referred to as " median particle diameter ") is usually more than or equal to 1 μ m, is preferably greater than or equals 2 μ m, and be less than or equal to 20 μ m usually, preferably is less than or equal to 15 μ m.The particle that its median particle diameter surpasses the upper limit of above-mentioned scope is not preferred, reason is when being used as positive electrode in their manufacturings at battery, lithium diffusion in the positive pole is suppressed, and the deficiency of conductive channel can occur, causes the part throttle characteristics of gained battery to descend.On the other hand, the particle that its median particle diameter is lower than the lower limit of above-mentioned scope is not preferred, reason is that they can increase and make the anodal required electric conducting material and the amount of adhesive, and the charging efficiency that active material enters positive pole (cathode collector) reduces, and causes battery capacity to reduce.In addition, when thinner particle was used to be coated with, coating layer was being understood hardening or is being become fragile aspect its engineering properties, and is easy to separate with positive pole in the coiling step of assembled battery.The median particle diameter of particle can pass through laser diffraction/scattering method.

Form

Composition to particle of the present invention never should limit, but considers the stability in energy density and the crystal structure, preferably contains Ni and Co at least.

At first, particle of the present invention preferably has being made up of following composition formula (1) expression.

Li _xNi _(1-y-z)Co _yM _zO ₂Composition formula (1)

In above-mentioned composition formula (1), the M representative is selected from least a element among Mn, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn and the Nb.Preferred M is Mn and/or Al, and more preferably M is Mn.

In addition, in composition formula (1), x is usually greater than 0 value, is preferably greater than or equals 0.1, and be less than or equal to 1.2 usually, preferably is less than or equal to 1.1.If x surpasses the upper limit of above-mentioned scope, then exist particle not form single crystalline phase and lithium by the possibility that the transition metal site is replaced, cause the charging of gained lithium secondary battery and discharge capacity to be tending towards descending.On the other hand, x is roughly the charged state that the composition of lower limit is released corresponding to lithium, is not preferred with battery charge to the degree that x is lower than described lower limit, and this is because the crystal structure of particle may worsen.

In above-mentioned composition formula (1), y gets the value more than or equal to 0.05 usually, is preferably greater than or equals 0.1, and be less than or equal to 0.5 usually, preferably is less than or equal to 0.4.Having y is not preferred greater than the particle of the composition of the described upper limit, reason be when they during as positive electrode, the capacity of gained battery is tending towards descending, and considers that cost also is not preferred, because Co is rare and expensive resources.On the other hand, have the particle that y is lower than the composition of described lower limit and tend to have lower crystal structural stability, thereby be not preferred.

In addition, in above-mentioned composition formula (1), z is normally more than or equal to 0.01 value, is preferably greater than or equals 0.02, and be less than or equal to 0.5 usually, preferably is less than or equal to 0.4.Having z is not preferred greater than the particle of the composition of the described upper limit because they are difficult to form single crystalline phase, and because when they during as positive electrode active materials, the discharge capacity of gained lithium secondary battery is tending towards decline.Having z also is not preferred less than the particle of the composition of described lower limit, and this is because the stability of the crystal structure of particle is tending towards descending.

II. the manufacture method of lithium composite xoide particle

Below, will be described its manufacture method (hereinafter referred to as " manufacture method of the present invention ") that consists of by the particle of following formula (1) expression, with example as the manufacture method of particle of the present invention.Certain particle of the present invention never should be limited to the product that obtains by following manufacture method.In addition, its manufacture method that consists of the particle of being represented by formula (1) never should be limited to following method.

Manufacture method of the present invention uses the raw material of lithium raw material, nickel raw material, cobalt raw material and element M to make particle of the present invention as raw material.

Raw material

The lithium raw material

The lithium raw material is not done concrete qualification, as long as it contains lithium.

The example of lithium raw material comprises: such as Li ₂CO ₃And LiNO ₃Inorganic lithium salt; Such as LiOH and LiOHH ₂The lithium hydroxide of O; Lithium halide such as LiCl and LiI; Such as Li ₂The inorganic lithium compound of O; With organo-lithium compound such as lithium alkylide and fatty acid lithium.In above-mentioned example, preferred Li ₂CO ₃, LiNO ₃, LiOH and lithium acetate.Wherein, Li ₂CO ₃With the both nonnitrogenous also not sulfur-bearing of LiOH, thereby has the advantage that in calcination process, can not produce noxious substance.

The example of above-mentioned lithium raw material can use separately, or any two or more is used in combination with arbitrary proportion.

The nickel raw material

The nickel raw material is not done concrete qualification, as long as it contains nickel.

The nickel raw material can exemplify Ni (OH) ₂, NiO, NiOOH, NiCO ₃2Ni (OH) ₂4H ₂O, NiC ₂O ₄2H ₂O, Ni (NO ₃) ₂6H ₂O, NiSO ₄, NiSO ₄6H ₂O, contain the aliphatic acid of nickel and the halide of nickel.Wherein, such as Ni (OH) ₂, NiO, NiOOH, NiCO ₃2Ni (OH) ₂4H ₂O and NiC ₂O ₄2H ₂The both nonnitrogenous also not compound of sulfur-bearing such as O is preferred, and this is because they can not produce noxious substance in calcination process.Ni (OH) ₂, NiO and NiOOH be particularly preferred, this is because they can be used as the raw material of industry and obtain with low cost, and because their high responses in calcination process.

The example of above-mentioned nickel raw material can use separately, or any two or more is used in combination with arbitrary proportion.

Cobalt raw material

Cobalt raw material is not done concrete qualification, as long as it contains cobalt.

Cobalt raw material can exemplify CoO, Co ₂O ₃, Co ₃O ₄, Co (OH) ₂, CoOOH, Co (NO ₃) ₂6H ₂O, CoSO ₄7H ₂The halide of O, organic cobalt compound and cobalt.Wherein, CoO, Co ₂O ₃, Co ₃O ₄, Co (OH) ₂With CoOOH be preferred.

The example of above-mentioned cobalt raw material can use separately, or any two or more is used in combination with arbitrary proportion.

The raw material of element M

Raw material to element M is not done concrete qualification, as long as it contains defined element M in the explanation to composition formula (1).

Similar with cobalt raw material to above-mentioned nickel raw material, the raw material of element M can exemplify oxide, hydroxide, oxyhydroxide, soap and the halide of element M.Wherein, oxide, hydroxide, oxyhydroxide are preferred.

The example of the raw material of above-mentioned element M can use separately, or any two or more is used in combination with arbitrary proportion.

The raw material of part or all nickel raw material, cobalt raw material and element M also can be selected from: the co-precipitation hydroxide and the co-precipitation carbonate that are selected from two or more element in nickel, cobalt and the element M; With by calcining any composite oxides that obtain in described co-precipitation hydroxide and the co-precipitation carbonate.

The pulverizing of the raw material of nickel raw material, cobalt raw material and element M and mixing

The raw material of nickel raw material, cobalt raw material and element M is dispersed in the decentralized medium and it is pulverized and mixes to make slurry with wet method.In this stage, can add the required lithium raw material of part in advance so that lithium is present in the slurry with the form of the aqueous solution or particle.

Employed decentralized medium can be any liquid in this stage, but considers carrying capacity of environment, and water is particularly preferred.Yet if use the raw material of water soluble compound as nickel raw material, cobalt raw material and/or element M, any liquid in the raw material of described nickel raw material, cobalt raw material and element M is not dissolved in preferred selection.Otherwise may obtain hollow particle by following spray drying, and active material enters anodal charging efficiency and therefore is restricted.

Never should limit the equipment that is used to pulverize and mixes described raw material, but can select arbitrarily, described equipment can exemplify ball mill, ball mill and vibration milling.

The raw material pulverizing of nickel raw material, cobalt raw material and element M to such degree, is made to be less than or equal to 2 μ m usually by the median particle diameter of pulverizing the feed particles in the slurry that obtains, preferably be less than or equal to 1 μ m, further preferably be less than or equal to 0.5 μ m.If the median particle diameter of feed particles is greater than above-mentioned scope, then the reactivity in the calcination process descends.In addition, the sphericity of the particle that obtains by following spray drying can suffer damage, thereby causes the final packed density of particle to descend.Above-mentioned trend is particularly evident when attempting to make median particle diameter and be less than or equal to the particle of 20 μ m.

On the other hand, owing to raw meal is broken into meticulous powder can increases the pulverizing cost, therefore preferably pulverize raw material its median particle diameter is generally more than or equal to 0.01 μ m, be preferably greater than or equal 0.02 μ m, further be preferably greater than or equal 0.1 μ m.

Granulation/drying

After raw material case of wet attrition and mixing with nickel raw material, cobalt raw material and element M, the particle aggregation that is dispersed in the slurry forms bigger granular substance (aggregated particle, second particle),, carries out granulation that is, simultaneously dry described granular substance.As granulation and dry method, the preferred spray drying of using spray dryer that adopts, reason is that the granular substance (aggregated particle) of gained has excellent homogeneity, powder flowbility and powder-processed performance, and, because granulation and drying are carried out simultaneously, therefore can form second particle effectively.

The diameter of the granular substance that obtains by spray drying almost can limit the diameter as the second particle of particle of the present invention exactly.Given this, the particle diameter of the granular substance that obtains by drying is usually more than or equal to 1 μ m, is preferably greater than or equals 2 μ m, and be less than or equal to 20 μ m usually, preferably is less than or equal to 15 μ m.Particle diameter also can be controlled by selecting spray pattern, the supply rate of gas-pressurized, feed speed, baking temperature and/or the other factors of slurry.

As selection, granulation and dry other method that also can pass through except that spray drying are implemented.Another example of prilling process is a coprecipitation, and the aqueous solution and the alkaline aqueous solution that wherein contain nickel, cobalt and element M react to obtain hydroxide, and wherein stir speed (S.S.), pH value and temperature are suitably determined.

In this case, to processing such as the hydroxide by the coprecipitation granulation filter and for example washs, carry out drying with drying oven etc. subsequently.

Mix with the lithium raw material

To do mixed by granular substance and lithium raw material that above-mentioned granulation and dry run obtain then to make mix powder.

In order to improve with the mixing efficiency of the granular substance that obtains by spray drying and to improve the capacity of gained battery, the average particulate diameter of lithium raw material is less than or equal to 500 μ m usually, preferably be less than or equal to 100 μ m, further preferably be less than or equal to 50 μ m, most preferably be less than or equal to 20 μ m.Yet, because too small average particulate diameter can cause the stability of particle in atmosphere lower, therefore, the lower limit of average particulate diameter is usually more than or equal to 0.01 μ m, be preferably greater than or equal 0.1 μ m, more preferably greater than or equal 0.2 μ m, be preferably greater than at most or equal 0.5 μ m.

Should not limit doing the method for mixing, but preferably use employed powder mixer in the general industrial purposes.Granular substance and lithium raw material can mix with arbitrary proportion, and this depends on composition or other character of target porous particle.

Classification/calcining

Subsequently, make the mixed-powder experience calcination process that obtains, by this process with the primary particle sintering to form second particle.

Calcination process can for example use box furnace, tube furnace, continuous tunnel furnace, rotary furnace etc. to carry out in any way.Calcination process generally includes three steps: heat up; Keep maximum temperature; And cooling.Second step (maintenance maximum temperature) never was limited to the single stage, but can have as required two or more stages.

And in calcination process, steps such as above-mentioned intensification, maintenance maximum temperature and cooling can repeat more than twice or twice.Can also optionally carry out inserting crushing process between a series of two calcination process, this crushing process decomposes to aggregation the degree that can not destroy second particle.

Heating step

In heating step, the temperature in the stove rises with the heating rate of common 0.2 ℃/min～20 ℃/min.Crossing low heating rate needs long time, thereby considers it is disadvantageous from industrial aspect.On the contrary, too high heating rate can cause the design temperature of interior actual temperature of stove and stove inconsistent.

Maximum temperature keeps step

Calcining heat in the maximum temperature maintenance step changes according to kind, ratio of components and the mixing of the raw material of employed lithium raw material, nickel raw material, cobalt raw material and element M opportunity, but usually more than or equal to 500 ℃, be preferably greater than or equal 600 ℃, more preferably greater than or equal 800 ℃, and be less than or equal to 1200 ℃ usually, preferably be less than or equal to 1100 ℃.If calcining heat is lower than above-mentioned lower limit, then, there is the trend that needs long calcination time in order to obtain having the particle of well-crystallized and suitable intensity.On the other hand, if calcining heat is higher than the above-mentioned upper limit, then the gained porous particle has excessive intensity or has such as lacking many defectives such as oxygen.Thereby, if this porous particle as positive electrode active materials, then the low temperature part throttle characteristics can take place and descends in the gained lithium secondary battery, or since the crystalline texture of particle worsen because of charging and discharge destroy.

Maximum temperature keeps the temperature hold-time in the step to select in 1 hour～100 hours very wide scope usually.Too short calcination time is difficult to obtain having the particle of well-crystallized and suitable intensity.

Cooling step

In cooling step, the temperature in the stove reduces with the rate of temperature fall of 0.1 ℃/min～20 ℃/min usually.Crossing low speed needs the longer time, thereby considers it is disadvantageous from industrial aspect, and too high speed can make product lack homogeneity and quicken the deterioration of container.

Other

The intensity of particle of the present invention also changes according to the atmosphere of calcining.Suppose that calcining heat is identical, then the oxygen that contains in the calcination atmosphere is few more, and the structure of gained particle is hard more.Thereby the atmosphere in the calcination process should be considered calcining heat and suitably chooses.Usually, calcination process preferably carries out in for example air etc. has atmosphere more than or equal to the oxygen of 10 volume %.Cross many defectives that low oxygen content may cause particle to have for example to lack oxygen.

If desired, the lithium composite xoide that obtains by calcining is carried out size degradation and classification and as particle of the present invention.Size degradation and classification can be undertaken by for example using the known method of the vibrating screen that has the jolt ramming ball.

Attention thing top during production

In order to obtain particle of the present invention, consider that with producing some relevant aspects be very important, these aspects are as described below.

The case of wet attrition raw material of control nickel, cobalt and element M and the admixture of lithium raw material are important.Particularly, determined that before carrying out calcination process it is important that in mix powder most of lithium raw material is stayed the outside of the granulated pellet that the granulation of the case of wet attrition raw material by nickel, cobalt and element M makes.This mix powder is carried out calcination process can make particle with suitable intensity.

Yet when the raw material of nickel, cobalt and element M is during by the coprecipitation granulation, even most of lithium raw material is in the granulated pellet outside in the mix powder, the particle that obtains by calcination process structurally also tends to really up to the mark.Thereby, if the raw material of nickel, cobalt and element M is by the coprecipitation preparation, then, be a granulated into granulated pellet then at first with these raw material case of wet attrition, it is important doing mixed with the lithium raw material subsequently.Thus, can obtain particle of the present invention.

If the lithium raw material of major part is carrying out the granulated pellet the inside that granulation obtains by the case of wet attrition raw material with nickel, cobalt and element M, a little less than then the particle that obtains by calcination process structurally tended to.Even in this case, also can improve the intensity of particle by the mixed sintering agent, but the use of this agglutinant is difficult to control, and the gained particle tends to structurally really up to the mark.

For above-mentioned reasons, in order to obtain particle of the present invention, with the case of wet attrition raw material of nickel, cobalt and element M, or the granulated pellet that is obtained by the granulation of case of wet attrition co-precipitation raw material and lithium raw material are done, and to mix be important.

The concrete operation that obtains particle of the present invention is never limited, and can consider the kind of employed every kind of raw material and from variety of way, choose.For example, if NiO, Co (OH) ₂With such as Mn ₃O ₄Be used separately as the raw material of nickel raw material, cobalt raw material and element M Deng the manganese raw material, then as described in the following examples, the example of described operation is with NiO and cobalt raw material and manganese raw material wet-mixed, carries out spray drying then, finally does mixed with the lithium raw material.

II. the positive pole that is used for lithium secondary battery

The positive pole that is used for lithium secondary battery of the present invention is characterised in that the anode active material layer that is formed on the current-collector contains above-mentioned particle of the present invention and adhesive.

The positive pole that is used for lithium secondary battery of the present invention is to make by form the anode active material layer that contains particle of the present invention and adhesive on current-collector.

The positive pole that manufacturing contains particle of the present invention can be realized according to conventional method.Particularly, particle of the present invention and adhesive are optionally done to mix forming sheet material, and are made it attached on the cathode collector with pressure with for example other composition such as electric conducting material and thickener when needs.As selection, with the dissolving of these compositions or be dispersed in the decentralized medium forming slurry, described slurry coated on the cathode collector and dry.Perhaps adopt any one method that on current-collector, to make anode active material layer.

Preferably use particle of the present invention by this way, so that the content of described particle in anode active material layer is usually more than or equal to 10 weight %, be preferably greater than or equal 30 weight %, more preferably greater than or equal 50 weight %, and be less than or equal to 99.9 weight % usually.If described content is lower than above-mentioned scope, then can not guarantee enough conducting capacity.On the contrary, if described content is higher than above-mentioned scope, Zheng Ji undercapacity then.

As adhesive, can use any material, as long as it is stable in decentralized medium.Binder substance can be enumerated: such as resinae macromolecules such as polyethylene, polypropylene, polyethylene terephthalate, polymethyl methacrylate, aromatic polyamide, cellulose and nitrocelluloses; Such as rubber-like macromolecules such as SBR (styrene butadiene rubbers), NBR (acrylonitrile-butadiene rubber), fluorubber, isoprene rubber, butadiene rubber and ethylene-propylene rubber; Such as thermoplastic elastomer (TPE) shape macromolecules such as SBS and hydride, EPDM (ethylene-propylene-diene terpolymer), styrene-ethylene-butadiene vinyl copolymer, SIS and hydride thereof; Such as a rule-1, barras shape macromolecules such as 2-polybutadiene, polyvinyl acetate, vinyl-vinyl acetate copolymer and propylene-alpha-olefin copolymers; Such as fluoride macromolecules such as polyvinylidene fluoride, polytetrafluoroethylene, perfluor polyvinylidene fluoride and polytetrafluoroethylene-ethylene copolymers; Polymer composite with ionic conductivity with alkali metal ion (particularly lithium ion).The example of above-mentioned adhesive can use separately, or is used in combination with any two or more of arbitrary proportion.

Preferably use adhesive by this way, so that its content in anode active material layer is usually more than or equal to 0.1 weight %, be preferably greater than or equal 1 weight %, further be preferably greater than or equal 5 weight %, and be less than or equal to 80 weight % usually, preferably be less than or equal to 60 weight %, further preferably be less than or equal to 40 weight %.If the content of adhesive is lower than above-mentioned scope, then positive electrode active materials can not be fully fixing, thereby cause anodal mechanical strength not enough and descend such as battery performances such as cycle performances.On the other hand, if the content of adhesive is higher than above-mentioned scope, then battery capacity or conductivity descend.

As electric conducting material, can use any known electric conducting material.Electric conducting material can be enumerated various materials, comprising: such as the metal material of copper and mickel; Such as graphite such as native graphite and Delaniums; Such as carbon blacks such as acetylene blacks; With material with carbon elements such as amorphous carbon such as needle coke.Described electric conducting material can use separately, or is used in combination with any two or more of arbitrary proportion.

Preferably use electric conducting material by this way, so that its content in positive electrode active materials is usually more than or equal to 0.01 weight %, be preferably greater than or equal 0.1 weight %, more preferably greater than or equal 1 weight %, and be less than or equal to 50 weight % usually, preferably be less than or equal to 30 weight %, be more preferably less than or equal 15 weight %.If the content of electric conducting material is lower than described scope, then can not guarantee enough conductivity.On the contrary, if the content of electric conducting material is higher than described scope, then battery capacity descends.

Never should limit the decentralized medium that is used to prepare slurry, as long as it can dissolve or disperse positive electrode, adhesive, electric conducting material and thickener, and it can be aqueous medium or organic media.

The example of aqueous medium comprises water and alcohols.

The example of organic media is: such as aliphatic hydrocarbons such as hexanes; Aromatic hydrocarbon based such as benzene,toluene,xylene and methyl naphthalene etc.; Such as heterocyclic compounds such as quinoline and pyridines; Such as ketones such as acetone, methyl ethyl ketone and cyclohexanone; Such as ester classes such as methyl acetate and methyl acrylates; Such as amines such as Diethylenetriamine and N-N-dimethylamino propylamines; Such as dimethyl ether, ethylene oxide and oxolane ethers such as (THF); Such as amide-types such as N-methyl pyrrolidone (NMP), dimethyl formamide and dimethylacetylamides; With such as sprotic polar solvents such as hexamethyl-phosphoramide and dimethyl sulfoxide (DMSO)s.Particularly when aqueous medium when the decentralized medium, decentralized medium is mixed with thickener and use such as latexes such as SBR and make slurry.The example of decentralized medium can use separately, or is used in combination with any two or more of arbitrary proportion.

Anode active material layer preferably has the thickness of 10 μ m～200 μ m.

Material to cathode collector is not done concrete qualification, can be selected from known materials arbitrarily.The example of described material is: such as metal materials such as aluminium, stainless steel, electronickelling, titanium and tantalums; With such as material with carbon elements such as carbon intersection (carbon cross) and carbon papers.Wherein, preferably use metal material, particularly aluminium.

Current-collector can be made Any shape, the example comprises: in the situation of metal material, metal forming, metal column, wire coil, metallic plate, metal film, metal lath, punch metal, metal foam and other shape are arranged; In the situation of material with carbon element, be selected from carbon slab, carbon membrane, charcoal post and other shape; Metal film is preferred in described example.If current-collector is made film, then can be as required that its formation is netted.The thickness of film does not limit, but usually more than or equal to 1 μ m, be preferably greater than or equal 3 μ m, more preferably greater than or equal 5 μ m, and be less than or equal to 1mm usually, preferably be less than or equal to 100 μ m, be more preferably less than or equal 50 μ m.Thickness is lower than the film of above-mentioned scope as the required undercapacity of current-collector.The film that thickness is higher than above-mentioned scope then is difficult to processing.

In order to increase the packed density of positive electrode active materials, preferably with roll squeezer to pressurizeing through coating and the dry anode active material layer that forms.

III. lithium secondary battery

To be described lithium secondary battery of the present invention below.

Lithium secondary battery of the present invention comprises the positive pole and the negative pole that can absorb and discharge lithium ion and contains lithium salts as electrolytical organic electrolyte, it is characterized in that described positive pole makes with particle of the present invention.

Do not do concrete qualification for the employed negative pole of lithium secondary battery of the present invention, as long as described negative pole can absorb and discharge lithium.Described negative pole can use any method, for example, makes by form anode active material layer on anode collector.

The material of anode collector can be selected from any known material.The example of described material has: such as metal materials such as copper, nickel, stainless steel and nickel-plated steels; With such as material with carbon elements such as carbon intersection (carbon cross) and carbon papers.Metal material can be made shapes such as being selected from metal forming, metal column, wire coil, metallic plate, metal film, and material with carbon element can be made shapes such as being selected from carbon slab, carbon membrane and charcoal post.Wherein, metal film is preferred.If current-collector is made film, then can be as required that its formation is netted.The thickness of film is not done to limit but usually more than or equal to 1 μ m, is preferably greater than or equals 3 μ m, more preferably greater than or equal 5 μ m, and be less than or equal to 1mm usually, preferably be less than or equal to 100 μ m, be more preferably less than or equal 50 μ m.Thickness is lower than the film of above-mentioned scope as the required undercapacity of current-collector.On the other hand, the thickness film that is higher than above-mentioned scope is difficult to processing.

The negative active core-shell material that is contained in the anode active material layer can be made by any material, as long as this material can absorb and discharge lithium ion on electrochemistry, but because material with carbon element safe, negative active core-shell material is made by the material with carbon element that can absorb and discharge lithium ion usually.

The example of material with carbon element comprises: such as graphite such as Delanium and native graphites; Thermal decomposition product with the organic compound that under various thermal decomposition conditions, obtains.The thermal decomposition product of organic compound can be enumerated: the carbide of coal coke, petroleum coke, coal tar pitch; The carbide of petroleum asphalt; The coal of oxidation or the carbide of petroleum asphalt; Needle coke, pitch coke, phenol resin, avicel cellulose etc.; By the material with carbon element that above-mentioned material part graphitization is obtained; With furnace black, acetylene black, asphalt-based carbon fiber and other material.In above-mentioned example, preferably use graphite, especially through the Delanium of various surface-treateds by the tin-graphite pitch of being made by various materials being carried out high-temperature heat treatment and make, native graphite and their bitumeniferous graphite material through purifying.The example of above-mentioned material with carbon element can use separately, or any two or more is used in combination.

When using graphite material, preferably the d value (interlamellar spacing) of the lattice plane (002 face) that obtains with X-ray diffraction by Gakushin method (Japan Society for thePromotion of Science regulation method) is generally more than or equal to 0.335nm and is less than or equal to 0.34nm usually, particularly is less than or equal to the material of 0.337nm.With respect to the weight of graphite material, the content of ashes in the graphite material is less than or equal to 1 weight % usually, preferably is less than or equal to 0.5 weight %, is more preferably less than or equals 0.1 weight %.The crystalline size (Lc) of the graphite material that obtains with X-ray diffraction by the Gakushin method is usually more than or equal to 30nm, be preferably greater than or equal 50nm, more preferably greater than or equal 100nm.The median particle diameter of the graphite material that obtains with laser diffraction/scattering method is usually more than or equal to 1 μ m, be preferably greater than or equal 3 μ m, more preferably greater than or equal 5 μ m, further be preferably greater than or equal 7 μ m, and be less than or equal to 100 μ m usually, preferably be less than or equal to 50 μ m, be more preferably less than or equal 40 μ m, further preferably be less than or equal to 30 μ m.

The specific area of the graphite material that records according to the BET method is usually more than or equal to 0.5m ²/ g is preferably greater than or equals 0.7m ²/ g, more preferably greater than or equal 1.0m ²/ g further is preferably greater than or equals 1.5m ²/ g, and be less than or equal to 25.0m usually ²/ g preferably is less than or equal to 20.0m ²/ g is more preferably less than or equals 15.0m ²/ g further preferably is less than or equal to 10.0m ²/ g.When using argon laser beam graphite material to be measured, at 1580cm with Raman spectrum analysis ^-1～1620cm ^-1The peak P that arrives of range detection _AWith at 1350cm ^-1～1370cm ^-1The peak P that arrives of range detection _BBetween strength ratio I _A/ I _BBe preferably greater than or equal 0 and be less than or equal to 0.5, peak P _AThe half-peak breadth value preferably be less than or equal to 26cm ^-1, be more preferably less than or equal 25cm ^-1

The example of the negative active core-shell material except material with carbon element comprises: such as the metal oxide of tin oxide and silicon dioxide; Pure lithium and such as lithium alloys such as lithium-aluminium alloys; Or the like.These examples can use separately or any two or more is used in combination, and can be used in combination with material with carbon element.

Anode active material layer can use the mode identical with anode active material layer to form.Particularly, with negative active core-shell material and adhesive and optionally thickener and electric conducting material make slurry with decentralized medium, then this slurry is coated anode collector and dry to form anode active material layer.As the employed decentralized medium of negative active core-shell material, adhesive, electric conducting material and thickener, can use and the employed identical materials of positive electrode active materials.

Electrolyte can be enumerated organic electrolyte, polymer solid electrolyte, gel electrolyte and inorganic solid electrolyte, and wherein organic electrolyte is preferred.

As organic electrolyte, can use any known organic solution.The example of organic solution has: such as carbonic esters such as dimethyl carbonate, diethyl carbonate, propylene carbonate, ethylene carbonate and vinylene carbonates; Such as oxolane, 2-methyltetrahydrofuran, 1,4-two  alkane, 1,2-dimethoxy-ethane, 1,2-diethoxyethane, 1,3-dioxolanes, 4-methyl isophthalic acid, ethers such as 3-dioxolanes and Anaesthetie Ether; Ketone such as 4-methyl-2 pentanone etc.; Such as sulfolane compounds such as sulfolane and methyl sulfolanes; Such as sulfoxide compounds such as dimethyl sulfoxide (DMSO)s; Such as lactones such as gamma-butyrolactons; Such as nitriles such as acetonitrile, propionitrile, benzonitrile, butyronitrile and valeronitriles; Such as 1, hydrocarbon chlorides such as 2-dichloroethanes; Amine; The ester class; Such as amide-types such as dimethyl formamides; With such as phosphate compounds such as trimethyl phosphate and triethyl phosphates.These examples can use separately, or two or more is used in combination arbitrarily.

Be the disassociation electrolyte, preferred organic electrolyte contains at 25 ℃ of relative dielectric constants more than or equal to 20 high dielectric media.Wherein, organic electrolyte preferably contain be selected from that the inferior second of carbonic acid is cruel, the organic media of derivative that propylene carbonate and their any hydrogen atom are replaced by halogen atom, alkyl etc.With respect to whole organic electrolytes, the content of high dielectric media in organic electrolyte is usually more than or equal to 20 weight %, be preferably greater than or equal 30 weight %, more preferably greater than or equal 40 weight %.Optionally also preferred for example gas is (such as CO ₂, N ₂O, CO and SO ₂) and polysulfide S _x ^2-Be added in the organic electrolyte with arbitrary proportion Deng additive, make the required coating layer of formation on the surface of negative pole, thereby can carry out the charge/discharge of lithium ion effectively.

As solute, can use any known lithium salts.The example of lithium salts has LiClO ₄, LiAsF ₆, LiPF ₆, LiBF ₄, LiB (C ₆H ₅) ₄, LiCl, LiBr, CH ₃SO ₃Li, CF ₃SO ₃Li, LiN (SO ₂CF ₃) ₂, LiN (SO ₂C ₂F ₅) ₂, LiC (SO ₂CF ₃) ₃And LiN (SO ₃CF ₃) ₂These salt can use separately, or are used in combination with any two or more of arbitrary proportion.

The concentration of lithium salts is usually more than or equal to 0.5mol/L and be less than or equal to 1.5mol/L in the electrolyte.If excessive concentration or low excessively, then conductivity descends and the battery performance deterioration.Thereby the lower limit of preferred concentration is less than or equal to 1.25mol/L more than or equal to the 0.75mol/L and the upper limit.

When inorganic solid electrolyte is used for organic electrolyte, can from any known material that can be used as inorganic solid electrolyte, choose, both can be crystalline also can be unbodied.The example of crystallinity inorganic solid electrolyte has LiI, Li ₃N, Li _(1+x)M ¹ _xTi _(2-x)(PO ₄) ₃And Li _(0.5-3x)RE _(0.5+x)TiO ₃(M wherein ¹Be Al, Sc, Y or La, RE is La, Pr, Nd or Sm, and x is the numeral that satisfies 0≤x≤2).The example of amorphous inorganic solid electrolyte is an oxide glass, for example 4.9LiI-34.1Li ₂O-61B ₂O ₅And 33.3Li ₂O-66.7SiO ₂These examples can use separately, or are used in combination with any two or more of arbitrary proportion.

In order to prevent to occur short circuit between electrode, secondary cell preferably has the dividing plate that is inserted between positive pole and the negative pole and keeps non-aqueous electrolyte.

Dividing plate can be formed with Any shape by any material, as long as it is stablized, has the excellent liquid retentivity, and can guarantee to prevent to occur between electrode short circuit electrolyte.For example, dividing plate can be microporous barrier, sheet material or the nonwoven fabrics made by any macromolecular material.The example of macromolecular material has nylon, cellulose acetate, nitrocellulose, polysulfones, polyacrylonitrile, Kynoar and such as polyolefin macromolecules such as polypropylene, polyethylene and polybutene.Wherein consider chemical stability and electrochemical stability, the preferred polyolefm macromolecule is considered the self-blocking temperature of gained battery, and polyethylene is preferred.As polyethylene, ultra-high molecular weight polyethylene is preferred, and this is because it at high temperature has excellent shape retention energy.Poly molecular weight is preferably greater than or equals 5.0 * 10 ⁵And be less than or equal to 5.0 * 10 ⁶The less polyethylene of molecular weight can not at high temperature be kept identical molecular shape.Thereby molecular weight is preferably greater than or equals 1.0 * 10 ⁶, more preferably greater than or equal 1.5 * 10 ⁶On the contrary, had ultra high molecular weight polyethylene and had so low flowability, consequently the Kong Buhui obturation of dividing plate when heating.Consider above-mentioned aspect, poly molecular weight preferably is less than or equal to 4.0 * 10 ⁶, be more preferably less than or equal 3.0 * 10 ⁶

The shape of lithium secondary battery can be selected from various common shape according to purposes.The example of described shape has: cylindrical, wherein pellet electrode and dividing plate are made helical form; The outer carbon formula of interior zinc is cylindric, wherein with pellet electrode and dividing plate combination; Button-type, wherein lamination has pellet electrode and dividing plate.Lithium secondary battery of the present invention can be according to required cell shapes with any known method manufacturing.

Embodiment

Below, reference example is described in more detail the present invention, but the present invention never is limited to the following examples.

The manufacturing of lithium composite xoide particle

Embodiment 1

Take by weighing respectively NiO, Co (OH) as nickel, cobalt and manganese raw material ₂And Mn ₃O ₄, so that Ni: Co: the mol ratio of Mn is 0.33: 0.33: 0.33.Pure water is added in the raw material that is taken by weighing with the preparation slurry.Under agitation with circulating medium-stirring wet-type ball mill slurry is carried out case of wet attrition then, the average particulate diameter of solids is 0.3 μ m in slurry.

With spray dryer slurry is carried out spray drying then, to form the granulated pellet that is roughly sphere that diameter is about 5 μ m and is made up of nickel, cobalt and manganese raw material.With median particle diameter is that the LiOH powder of 3 μ m is added in the granulated pellet that so obtains, and makes that the mol ratio of Li is 1.05, mixes with high speed agitator subsequently with respect to the total mole number of Ni, Co and Mn.Can obtain the granulated pellet of nickel, cobalt and manganese raw material and the mix powder of lithium raw material thus.

With mix powder air flow down 950 ℃ (heating rate and rate of temperature fall be 5 ℃/min) calcining 12 hours, afterwards the products therefrom size degradation is also sieved with the sieve of 45 μ m sieve meshes, thereby finally obtain lithium composite xoide particle (hereinafter referred to as " the lithium composite xoide particle of embodiment 1 ").

Embodiment 2

Take by weighing respectively NiO, Co (OH) as nickel, cobalt, manganese and lithium raw material ₂And Mn ₃O ₄And LiOHH ₂O makes Ni: Co: Mn: the mol ratio of Li is 0.33: 0.33: 0.33: 0.05.Pure water is added in the raw material that is taken by weighing with the preparation slurry.Under agitation with circulating medium-stirring wet-type ball mill slurry being carried out case of wet attrition then, is 0.20 μ m until the average particulate diameter of solids.

With spray dryer slurry is carried out spray drying then, to form the granulated pellet that is roughly sphere that diameter is about 6 μ m and is made up of nickel, cobalt, manganese and lithium raw material.With median particle diameter is that the LiOH powder of 3 μ m is added in the granulated pellet that so obtains, and makes that the mol ratio of Li is 1.00, mixes with high speed agitator subsequently with respect to the total mole number of Ni, Co and Mn.Can obtain the granulated pellet made by Ni, Co, Mn and lithium raw material and the mix powder of lithium raw material thus.Mix powder is flowed down 955 ℃ of calcinings 15 hours at air in continuous tunnel furnace, the products therefrom size degradation also sieves with the sieve of 45 μ m sieve meshes afterwards, thereby finally obtains lithium composite xoide particle (hereinafter referred to as " the lithium composite xoide particle of embodiment 2 ").

Embodiment 3

Except using CoOOH as the cobalt raw material, operate in the mode identical with embodiment 2, obtain lithium composite xoide particle (hereinafter referred to as " the lithium composite xoide particle of embodiment 3 ") thus.

Comparative example 1

Take by weighing LiOHH ₂O, NiO, Co (OH) ₂And Mn ₃O ₄, so that Li: Ni: Co: the mol ratio of Mn is 1.05: 0.33: 0.33: 0.33.The raw material that is taken by weighing is made slurry, and carry out case of wet attrition in the mode identical with embodiment 1.

With spray dryer slurry is carried out spray drying then, be about 10 μ m and contain NiO, Co (OH) to form diameter ₂, Mn ₃O ₄And LiOHH ₂The granulated pellet that is roughly sphere of O.

In the mode identical with embodiment 1 with granulated pellet calcining and size degradation in air stream, thereby obtain lithium composite xoide particle (hereinafter referred to as " the lithium composite xoide particle of comparative example 1 ").

Comparative example 2

With the mode identical with comparative example 1 with each raw material weigh, case of wet attrition and spray drying, make particle diameter thus and be about 10 μ m and contain NiO, Co (OH) ₂, Mn ₃O ₄And LiOHH ₂The granulated pellet that is roughly sphere of O.

With Bi ₂O ₃Powder is added in the granulated pellet that so obtains, and makes that the mol ratio of Bi is 0.01, mixes with high speed agitator subsequently with respect to the total mole number of Ni, Co and Mn.Thereby, can make and contain NiO, Co (OH) ₂, Mn ₃O ₄And LiOHH ₂The granulated pellet of O and Bi ₂O ₃Mix powder.

Then with mixed-powder 900 ℃ (heating rate and rate of temperature fall be 5 ℃/min) calcining 12 hours, afterwards the products therefrom size degradation is also sieved with the sieve of 45 μ m sieve meshes, thereby finally obtain lithium composite xoide particle (hereinafter referred to as " the lithium composite xoide particle of comparative example 2 ")

Comparative example 3

It is that 0.33: 0.33: 0.33 nickel, cobalt and manganese and average diameter are the particle with the coprecipitation preparation of 15 μ m that use contains mol ratio.With median particle diameter is that the LiOH powder of 3 μ m adds in the described particle, makes that the mol ratio of LiOH is 1.05, mixes subsequently with respect to the total mole number of nickel, cobalt and manganese.Can obtain the mix powder of granulated pellet and lithium raw material thus.

Then mix powder is flowed down 900 ℃ of calcinings 12 hours at air in continuous tunnel furnace, afterwards the sieve of product with 45 μ m sieve meshes sieved, thereby obtain lithium composite xoide particle (hereinafter referred to as " the lithium composite xoide particle of comparative example 3 ")

The evaluation of lithium composite xoide particle

Be pressed into the mensuration of the various character that porosimetry and other method carry out with mercury

The pore size distribution curve of the embodiment 1～3 of gained and the lithium composite xoide particle of comparative example 1～3 is pressed into porosimetry with mercury and measures.The Autopore  III9420 that use is made by Micromeritics is pressed into the measurement mechanism of porosimetry as mercury.Mercury is pressed into porosimetry mensuration at room temperature to carry out, and the pressure of mercury increases to 410MPa from 3.8KPa.The surface tension of supposing mercury is 480dyn/cm, and the contact angle of mercury is 141.3 °.

The pore size distribution curve of the lithium composite xoide particle of embodiment 1 and comparative example 1,2 is represented by the solid line among Fig. 1 and Fig. 2.Fig. 1 and Fig. 2 have all shown the pore size distribution curve, this curve negotiating with the pore radius of lithium composite xoide particle as abscissa to mapping as ordinate and obtain by more than or equal to the cumulative volume in the hole of the pore radius of corresponding abscissa point the logarithm of pore radius being carried out the resulting value of differential with its radius.Fig. 2 is the part enlarged drawing of Fig. 1.

In addition, (Halenda) method is measured the lithium composite xoide particle of embodiment 1～3 and comparative example 1～3 for Barrett, Joyner, distributes with the pore radius that obtains described particle with nitrogen absorption BJH.Use is adsorbed the measuring instrument of BJH method by the Autosorb  1 that Quantachrome Corporation makes as nitrogen, and described being determined under the liquid nitrogen temperature carried out.

In addition, use particle size distribution meter (LA-920 that HORIBA makes) to measure particle size distribution, by this particle size distribution can count particles median particle diameter.

For each lithium composite xoide particle of embodiment 1～3 and comparative example 1～3, table 1 has shown: be pressed into volume by the pressure that above-mentioned pore size distribution curve obtains from the mercury that 50MPa increases to 150MPa with formula (A); The main peak that obtains by the pore size distribution curve and the pore volume at inferior peak and average pore radius; The cumulative volume that is less than or equal to the hole of 50nm with radius in per 1 gram lithium composite xoide particle of nitrogen absorption BJH method mensuration; The BET specific area; With the median particle diameter that obtains with the particle size distribution meter.The influence that causes for the space of eliminating between second particle, the average pore radius shown in is to be that the pore of 0.005 μ m～0.5 μ m is that object obtains with radius here.

The mensuration of other character

Measure median particle diameter, BET specific area, primary particle diameter and the tap density of each lithium composite xoide particle of embodiment 1～3 and comparative example 1～3.The mensuration of median particle diameter is undertaken by using particle size distribution meter (LA-920 that HORIBA makes).The mensuration of BET specific area uses the Autosorb  1 that is made by Quantachrome Corporation to carry out.The mensuration of tap density is by particle (5g) being put into the burette of 10mL and described particle jolt ramming being carried out for 200 times.The mensuration of primary particle diameter is carried out with SEM observation.The results are shown in Table 1.

The mensuration of low temperature part throttle characteristics

Use each lithium composite xoide particle (unless need be distinguished, otherwise hereinafter be collectively referred to as " positive electrode ") of embodiment 1～3 and comparative example 1～3, make secondary cell and measure the low temperature part throttle characteristics of this battery according to following method.

Take by weighing positive electrode (75 weight %), acetylene black (20 weight %) and polytetrafluorethylepowder powder (5 weight %) and fully mixing in mortar.Mixture is formed thin slice and be pressed into the disk that diameter is 12mm, and this disk weight is adjusted to about 17mg.Utilize pressure that disk is attached on the Al system metal lath, obtain positive pole thus.

Using average particulate diameter is the powdered graphite (d of 8 μ m～10 μ m ₀₀₂=3.35 dusts), use Kynoar simultaneously as adhesive as negative active core-shell material.Take by weighing negative active core-shell material and adhesive, make weight ratio (negative active core-shell material: adhesive) be 92.5: 7.5, and in N-crassitude ketone solvent, mix, obtaining the cathode composition slurry, coat on the surface of Copper Foil that thickness is 20 μ m this slurry dry then.Copper Foil is pressed into disk that diameter is 12mm and at 0.5 ton of/square centimeter (ton/cm ²) under suppress, make negative pole thus.

The design battery is so that anodal capacitance balance with negative pole is 1.2～1.5 than R.Capacitance balance than R according to formula R=(Q _a* W _a)/(Q _c* W _c) determine Q wherein _aRepresent negative pole to absorb and can not be settled out the capacity (mAh/g) of the Li ion of Li metal, Q _cRepresent the capacity (mAh/g) of the anodal Li ion that can discharge, W _aAnd W _cRepresent the weight (g) of negative active core-shell material and positive electrode active materials respectively.Q _aAnd Q _cFollowing the carrying out of mensuration: use negative or positive electrode, with as Li metal, dividing plate and the electrolyte of electrode are assembled 2032 type button cells; And under alap current density, for example be less than or equal to 20mA/g (active material), measure charging (Li absorption) capacity or the natural potential between the lower limit of natural potential and the 5mV that is used for negative pole and be used for charging capacity between the 4.2V of positive pole.

Use above-mentioned positive pole and negative pole to assemble button cell with nonaqueous electrolyte, wherein said electrolyte is by with LiPF ₆Be dissolved in the mixed solvent of ethylene carbonate (EC)+dimethyl carbonate (DMC)+ethylmethyl carbonate (EMC) (volume ratio is 3: 3: 4) so that LiPF ₆Concentration be that 1mol/L obtains.Use the battery assembled, the initial adjustment of under alap current density, carrying out two charge/discharge cycle with upper voltage limit and the lower voltage limit of 4.1V and 3.0V respectively.Measure the discharge capacity [Q of the positive electrode active materials of per unit weight in second circulation _d(mAh/g)].

After fully relaxing, battery with the constant current charge of 1/3C 72 minutes, is supposed 1 hour rate current [1C (mA)]=[Q _d(mAh/g) * weight (g) of positive electrode active materials].Left standstill 1 hour, battery is kept above 1 hour under-30 ℃ lower-temperature atmosphere.Under 1/4C, make battery discharge 10 seconds then, the current value (I) when measuring discharge simultaneously and discharging be about to begin preceding and discharged 10 seconds after OCV (open circuit voltage) between difference (Δ V).Resistance (R) calculates with following formula.

R＝ΔV/I

Table 1 has shown the resistance value of battery, and wherein the positive electrode of embodiment 1～3 and comparative example 1～3 is as positive electrode active materials.Resistance value is more little according to estimates, and the low temperature part throttle characteristics is just excellent more.The mensuration of coating

The coating of the positive electrode of embodiment 1～3 and comparative example 1,2 is measured with following method.

Is that the oxalic acid dihydrate of 0.3 weight % is added in the N-methyl pyrrolidone and disperses to form slurry with positive electrode (85 weight %), acetylene black (10 weight %), Kynoar (5 weight %) with the weight with respect to positive electrode.In advance Kynoar and oxalic acid hydrate are dissolved in the N-methyl pyrrolidone.The cumulative volume of positive electrode, acetylene black and Kynoar is adjusted to the value shown in the table 1 (42 weight % or 43 weight %) with respect to the ratio of whole slurries.At 25 ℃ with E type viscometer determining 20s ^-1Shear rate under slurry viscosity.Measured each slurry the same day (first day) at the preparation slurry, and in the next day (second day) of preparation the part slurry is measured.Prepared slurry is sealed and under the room temperature normal pressure, preserve.

List in the table 1 with the viscosity that said method is measured.Viscosity is low more according to estimates, and coating is good more.

Table 1

	Embodiment 1	Embodiment 2	Embodiment 3	Comparative example 1	Comparative example 2	Comparative example 3
							Pressure is that the mercury of 50MPa～150 MPa is pressed into volume (cm 3/g)	0.0183	0.0120	0.0116	0.0213	0.0094	0.0090
The pore radius of main peak (nm)	950	1200	1400	1200	2000	2900
							The pore radius (nm) at inferior peak	170	210	72	- *	400	73
Pore volume (the cm of main peak 3/g)	0.326	0.310	0.294	0.617	0.341	0.009
							Pore volume (the cm at inferior peak 3/g)	0.020	0.037	0.012	- *	0.049	0.216
Average pore radius (nm)	20.8	31.5	14.8	13.3	41.5	13.8
							Pore volume (the cm that the BJH method is measured 3/g)	0.003	- **	- **	0.002	0.002	- **
The median particle diameter of particle (μ m)	4.4	5.8	5.7	9.6	9.1	13.3
							BET specific area (m 2/g)	1.20	1.12	0.77	1.00	0.90	0.40
Tap density (g/cm 3)	1.6	1.6	1.9	1.2	1.9	2.6
							Primary particle diameter (μ m)	0.8	1.2	0.7	1.0	- **	0.8
Resistance value under-30 ℃ (Ω)	388	290	286	390	535	516
							Solid contents (weight %)	42	42	42	42	43	- **
Slurry viscosity (first day) (cp)	2830	5230	3814	6625	5682	- **
							Slurry viscosity (second day) (cp)	3342	- **	- **	8280	5290	- **

^*Any inferior peak through identification.

^*Free of data.

The evaluation of data

About the lithium composite xoide particle of comparative example 1, as shown in Figure 1, although do not observe can clear identification inferior peak, on the pore size distribution curve, can observe the main peak that summit is positioned at the 1200nm radius.In addition, can find out obviously that along with pressure increases to 150MPa from 50MPa, it is 0.0213cm that mercury is pressed into volume by table 1 ³/ g, this is worth greater than scope given to this invention.The lithium composite xoide particle of comparative example 1 thereby do not satisfy condition of the present invention (A) simultaneously and (C).

In addition, table 1 shows that clearly the lithium composite xoide particle of comparative example 1 has good resistance value at-30 ℃, but slurry viscosity is very high, sharply increases by first day to second day especially.Described result shows that the lithium composite xoide particle of comparative example 1 fails to obtain enough coatings.

Lithium composite xoide particle about comparative example 2, as shown in Figure 1, except summit is positioned at the main peak of radius of 2000nm, on the pore size distribution curve, also observed inferior peak, yet summit that should the peak, Asia is positioned at the radius of 400nm, and this is worth greater than scope given to this invention.In addition, can find out obviously that it is 0.0094cm that mercury is pressed into volume by table 1 ³/ g fails to reach scope given to this invention.The lithium composite xoide particle that described result shows comparative example 2 all less than the condition (B) of unabridged version invention and (C).

As shown in table 1, the lithium composite xoide particle of comparative example 2 is-30 ℃ of resistance values that have up to 535 Ω, thereby thinks not have enough low temperature part throttle characteristics.

About the lithium composite xoide particle of comparative example 3, the pore size distribution curve display, summit is positioned at the main peak and the Ya Feng of 2900nm radius, however summit that should the peak, Asia is positioned at the radius of 73nm, is lower than scope given to this invention.In addition, as shown in Table 1, it is 0.0090cm that mercury is pressed into volume ³/ g fails to reach scope of the present invention.Thereby the lithium composite xoide particle of comparative example 3 also less than the condition (B) of unabridged version invention and (C).

In addition, also since-30 ℃ resistance value up to 516 Ω, therefore think that the lithium composite xoide particle of comparative example 3 does not have enough low temperature part throttle characteristics.

On the other hand, as shown in table 1, the lithium composite xoide particle of embodiment 1 demonstrates summit and is positioned at the main peak at pore radius place of 950nm and the inferior peak at the pore radius place that summit is positioned at 170nm on the pore size distribution curve.In addition, to be pressed into volume be 0.0183cm to mercury ³/ g, within the scope of the invention.In addition, as shown in table 1, each lithium composite xoide particle of embodiment 2 and embodiment 3 has the inferior peak that is in the scope of the invention on the pore size distribution curve and the mercury that is in the scope given to this invention is pressed into volume.Thereby each lithium composite xoide particle of embodiment 1～3 all satisfies all conditions of the present invention (A)～(C).

In addition, each lithium composite xoide particle that table 1 demonstrates embodiment 1～3 not only has the lower resistance value under-30 ℃ but also has lower slurry viscosity, thereby thinks to have excellent low temperature part throttle characteristics and coating simultaneously.

With reference to concrete execution mode the present invention is described in detail, still it will be obvious to those skilled in the art that under the condition that does not depart from the scope of the present invention, to propose various improvement.

The application is based on the Japanese Patent Application 2003-336335 that submitted on September 26th, 2003, the special 2003-336336 of hope and the special 2003-336337 of hope, and the specification of the Japanese Patent Application 2004-278953 of submission on September 27th, 2004, its full content is incorporated herein by reference hereby.

Industrial applicibility

Lithium composite xoide particle for positive electrode material of lithium secondary cell according to the present invention can together use with adhesive, to form active material layer at current-collector, the gained positive pole is applicable to the purposes of the very wide lithium secondary battery of scope, such as mobile electronic device, communication equipment and vehicle drive power etc. Thereby the present invention has great industrial value.

Claims (6)

1. lithium composite xoide particle that is used for positive electrode material of lithium secondary cell, wherein when being pressed into porosimetry with mercury and measuring, described lithium composite xoide particle satisfies condition (A), and satisfy condition (B) or condition (C) at least one condition, wherein:

Condition (A) representative is pressed into curve according to mercury, and when 50MPa increased to 150MPa, mercury was pressed into volume for being less than or equal to 0.02cm at pressure ³/ g;

Condition (B) representative is pressed into curve according to mercury, and when 50MPa increased to 150MPa, mercury was pressed into volume for more than or equal to 0.01cm at pressure ³/ g; With

It is 10nm～100nm that condition (C) is represented the average pore radius, and the pore size distribution curve has the main peak that summit is positioned at the pore radius place of 0.5 μ m～50 μ m, and summit is positioned at the inferior peak at the pore radius place of 80nm～300nm.

2. the lithium composite xoide particle that is used for positive electrode material of lithium secondary cell as claimed in claim 1, wherein when measuring with nitrogen adsorption method, the cumulative volume that radius is less than or equal to the hole of 50nm in the described lithium composite xoide particle of every gram is less than or equal to 0.01cm ³

3. the lithium composite xoide particle that is used for positive electrode material of lithium secondary cell as claimed in claim 1 or 2, wherein said lithium composite xoide particle contains Ni and Co at least.

4. as each described lithium composite xoide particle that is used for positive electrode material of lithium secondary cell of claim 1～3, wherein form by following formula (1) expression,

Li _xNi _(1-y-z)Co _yM _zO ₂ (1)

Wherein

The M representative is selected from least a element among Mn, Al, Fe, Ti, Mg, Cr, Ga, Cu, Zn and the Nb,

X represents the numerical value of 0＜x≤1.2,

Y represent 0.05≤y≤0.5 numerical value and

Z represents the numerical value of 0.01≤z≤0.5.

5. positive pole that is used for lithium secondary battery, described positive pole comprises:

Current-collector; With

Be arranged on the anode active material layer on the described current-collector;

Wherein said anode active material layer contains each described lithium composite xoide particle that is used for positive electrode material of lithium secondary cell of adhesive and claim 1～4 at least.

6. lithium secondary battery, described battery comprises:

Can absorb and discharge the positive pole of lithium;

Can absorb and discharge the negative pole of lithium; With

Contain lithium salts as electrolytical organic electrolyte;

Wherein said positive pole is the described positive pole that is used for lithium secondary battery of claim 5.

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