CN103700849B - A kind of lithium ion battery - Google Patents
A kind of lithium ion battery Download PDFInfo
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- CN103700849B CN103700849B CN201210373269.5A CN201210373269A CN103700849B CN 103700849 B CN103700849 B CN 103700849B CN 201210373269 A CN201210373269 A CN 201210373269A CN 103700849 B CN103700849 B CN 103700849B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/364—Composites as mixtures
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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Abstract
The invention provides a kind of lithium ion battery, the electrode group comprising housing and be sealed in housing and electrolyte, described electrode group comprises positive pole, negative pole and the barrier film between positive pole and negative pole, the positive electrode material layer that described positive pole comprises positive conductive matrix and is attached on positive conductive matrix, described positive electrode material layer comprises lithium iron phosphate anode active material, ferric phosphate, conductive agent and positive electrode binder; The smallest particles particle diameter of described ferric phosphate is not less than 20 microns; The negative electrode material layer that described negative pole comprises negative conductive matrix and is attached on negative conductive matrix; Described negative electrode material layer comprises anode active material layer, and described anode active material layer comprises lithium and/or lithium alloy, negative active core-shell material and negative electrode binder; Or described negative electrode material layer comprises anode active material layer and the lithium that is attached in anode active material layer and/or lithium alloy, the lithium ion battery of preparation itself is anti-, and to cross exoergic power excellent.
Description
Technical field
The present invention relates to a kind of lithium ion battery.
Background technology
Compared with other chemical power source, lithium ion battery has the performance of many excellences, as high in energy density, have extended cycle life, the advantage such as open circuit voltage is high, memory-less effect, safety non-pollution.Through the develop rapidly of recent two decades, lithium ion battery has been widely used in the fields such as mobile phone, notebook computer, digital camera.Along with the rise of global oil price and the enhancing of people's environmental consciousness, no matter be research institution or enterprise, all sight be concerned about in the exploitation of electric automobile.Researcher generally believes that lithium ion battery is a kind of most potential chemical power source be applied on electric automobile.Compare with other mobile device, electric automobile proposes higher requirement to performances such as the cycle life of battery, energy density, consistency of battery pack and large current discharging capabilities.
The battery pack of electric automobile is made up of the connection in series-parallel of a large amount of monomer battery core, in battery pack, the consistency of monomer battery core is a huge test, because the self discharge of monomer battery core in battery pack can not be completely the same, cause SOC between battery core inconsistent, and then in battery power discharge or storing process, have partial monosomy battery core can occur to put, i.e. brownout, close to even reaching 0V time the most dangerous, at this moment negative pole current potential usually can rise to and analyse copper current potential (about 3.5V), anodic potentials also easily drops to the current potential (about-1V) that aluminium dissolves, the copper of separating out or the aluminium again reduced after dissolving can puncture barrier film and cause serious internal short-circuit, reduce the life-span of battery pack, also easily potential safety hazard is caused.Also there is the ubiquitous charged transportation problem of battery thus, namely nearly all battery is all charged transport, also can bring safety problem, for lithium ion battery, even electric discharge transport, its voltage is higher (if cobalt acid lithium battery discharge voltage is at about 3.0V) also, still with electricity, if voltage put to or close to 0V, battery easily occurred to put, and caused short-circuit risks, as the accident such as got into an accident, can cells burst be caused, even explode.
The particularly focus of existing research, lithium iron phosphate anode active material is used for battery prepared by positive pole, because the discharge platform current potential of lithium iron phosphate anode active material is about 3.45V, this platform is very flat, almost can think a straight line being parallel to X-axis, but arrive electric discharge end, its curve is almost in an angle of 90 degrees straight glide, like this at discharge voltage to below 2.0V (general arrange discharge voltage limit), LiFePO4 remains how many capacity hardly, namely under identical discharging current condition, discharge time is very short, negative pole does not have lithium to deviate from substantially, to such an extent as to negative pole current potential is easy to rising reaches and analyse copper current potential, thus form copper dendrite, easily pierce through barrier film and cause battery short circuit, produce safety problem, LiFePO4 is put as the mistake of positive electrode active materials, the probability of short circuit is larger, even reach 100%.
In order to improve the security performance of lithium ion battery; prevent the mistake of lithium ion battery from putting; avoid charged transport as far as possible; usually protective circuit is adopted to be protected battery in prior art; but adopt the cost of protective circuit higher, and adopt protective circuit not delay or to stop battery core to cross to put to close to the potential safety hazard occurred during 0V and solution 0V voltage transportation problem.Therefore, need to find a kind of more suitable technical scheme preventing from lithium ion battery from crossing putting.
Summary of the invention
The present invention puts the dissatisfactory technical problem of scheme to solve the anti-mistake of existing lithium ion battery, provides a kind of anti-mistake to put the lithium ion battery of excellent performance.
The object of this invention is to provide a kind of lithium ion battery, the electrode group comprising housing and be sealed in housing and electrolyte, described electrode group comprises positive pole, negative pole and the barrier film between positive pole and negative pole, the positive electrode material layer that described positive pole comprises positive conductive matrix and is attached on positive conductive matrix, described positive electrode material layer comprises lithium iron phosphate anode active material, ferric phosphate, conductive agent and positive electrode binder; The smallest particles particle diameter of described ferric phosphate is not less than 20 microns; The negative electrode material layer that described negative pole comprises negative conductive matrix and is attached on negative conductive matrix; Described negative electrode material layer comprises anode active material layer, and described anode active material layer comprises lithium and/or lithium alloy, negative active core-shell material and negative electrode binder; Or described negative electrode material layer comprises anode active material layer and the lithium that is attached in anode active material layer and/or lithium alloy, described anode active material layer comprises negative active core-shell material and negative electrode binder.
The present invention surprisingly finds that the anti-exoergic power excessively of lithium ion battery itself prepared by the present invention is excellent, infer that reason may because the polarization of oarse-grained ferric phosphate be large, difference of magnification, embedding lithium is slower, platform is lower, can delay anodic potentials and decline, simultaneously, ferric phosphate returns embedding lithium amount and can balance LiFePO4 and be discharged the rear lithium amount additionally provided, the copper dendrite preventing negative pole from being formed; Containing lithium and/or lithium alloy in negative pole, can embed a certain amount of lithium in advance in negative pole, as extra lithium source, lithium embedding in advance can ensure that after LiFePO4 electric discharge, continue electric discharge still has lithium to deviate from from negative pole, prevents the rising of negative pole current potential.After battery core is discharged to 2.0V, continue electric discharge close to 0V, the downward trend of anodic potentials curve tends towards stability, and negative pole potential curve not yet rises too high (generally not higher than 1.5V), and two potential curves are close or intersect at 0V.Not only can prevent from putting, ensure the safety of monomer battery core, and low-potential energy can be realized or unchargedly to transport safely.Particularly the present invention can solve when battery cathode adds lithium or lithium alloy and easily generates Li dendrite, by improving the combination property of battery with interaction energy of the present invention, the present invention well can apply lithium and/or lithium alloy in negative pole, not supplementing of the simple lithium of routine, irreversible after there will not be lithium and lithium alloy to embed negative pole in advance, this part lithium can interact with positive pole of the present invention, can recycle, the cycle performance of battery is excellent, the anti-mistake of battery puts consistency of performance, and anti-exoergic power is excessively excellent.
Accompanying drawing explanation
Fig. 1 is the lithium ion battery three electrode charge and discharge voltage curve prepared of the embodiment of the present invention 1 and positive and negative reference potential curve (a is cell voltage profiles b be positive pole-reference voltage curve c be negative pole-reference voltage curve).
Fig. 2 is the discharge voltage curve chart over time of the lithium ion battery of comparative example 1 of the present invention preparation.
Embodiment
In order to make technical problem solved by the invention, technical scheme and beneficial effect clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.
The invention provides a kind of lithium ion battery, the electrode group comprising housing and be sealed in housing and electrolyte, described electrode group comprises positive pole, negative pole and the barrier film between positive pole and negative pole, the positive electrode material layer that described positive pole comprises positive conductive matrix and is attached on positive conductive matrix, described positive electrode material layer comprises lithium iron phosphate anode active material, ferric phosphate, conductive agent and positive electrode binder; The smallest particles particle diameter of described ferric phosphate is not less than 20 microns; The negative electrode material layer that described negative pole comprises negative conductive matrix and is attached on negative conductive matrix; Described negative electrode material layer comprises anode active material layer, and described anode active material layer comprises lithium and/or lithium alloy, negative active core-shell material and negative electrode binder; Or described negative electrode material layer comprises anode active material layer and the lithium that is attached in anode active material layer and/or lithium alloy, described anode active material layer comprises negative active core-shell material and negative electrode binder, now still can contain lithium and/or lithium alloy in anode active material layer, the present invention does not limit.Lithium and/or lithium alloy can be coated in negative conductive matrix surface be configured to cathode size together with negative active core-shell material after, also can be prepare one deck lithium and/or lithium alloy on anode active material layer surface again after first applying conventional anode slurry, also can be in anode active material layer and anode active material layer surface all containing lithium and/or lithium alloy.Lithium iron phosphate anode active material of the present invention can be the positive electrode active materials based on LiFePO4 such as LiFePO4 of the coated composite ferric lithium phosphate material of LiFePO4, carbon, metal-doped modification.
Further preferably, the particle primary particle size of ferric phosphate is 30 ~ 50 microns, primary particle median particle diameter D
50=35 ~ 45 microns.
Preferably, relative to the lithium iron phosphate anode active material of 100 weight portions, the content of described ferric phosphate is 5-20 weight portion, more preferably 8-12 weight portion.
Preferably, the amount of lithium and/or lithium alloy meets k/L < x < (n-m)/L, wherein, x represents the quality of Li element in lithium and/or lithium alloy, L represents the theoretical specific capacity of lithium, m represents the initial charge capacity of positive pole, and n represents the initial charge capacity of negative pole, and k represents the first charge-discharge irreversible capacity of negative pole.
Preferably, relative to the negative active core-shell material of 100 weight portions, the content of described lithium and/or lithium alloy is 0.3 ~ 5 weight portion, more preferably 0.5-3 weight portion, when negative active core-shell material is graphite, further preferably, relative to the graphite of 100 weight portions, the content of described lithium and/or lithium alloy is 0.5 ~ 5 weight portion, more preferably 0.8-3 weight portion.
Preferably, lithium alloy is selected from one or more in Li-M alloy, and described M is selected from one or more in Be, Mg, Ti, Zr, V, Nb, Cr, Cu and Al.
Preferably, positive electrode also comprises carbon, and the specific area of described carbon is not less than 50m
2/ g, more preferably 200 ~ 600m
2/ g, utilizes the carbon of this special specific surface that capacity effect can occur in the application of lithium iron phosphate anode active material and delays anodic potentials decline; Carbon can adsorb lithium because of capacity effect, and the lithium amount of its absorption can balance LiFePO4 and be discharged the rear lithium additionally provided, and improves the performance of battery further.
Preferably, relative to the lithium iron phosphate anode active material of 100 weight portions, the content of described carbon is 5-15 weight portion, more preferably 8-10 weight portion.
Preferably, positive electrode also comprises containing lithium additive, and the described lithium additive that contains is selected from Li
x1ni
y1mn
z1o
2, Li
x2m1
y2o
z2, silicate positive electrode active materials, Li
x3m2(WO
z3) in one or more, wherein, 0.8≤x1≤2,0≤y1 < 1,0≤z1 < 1, 0.8≤x2≤7,0 < y2≤5,0 < z2≤8, 0.8≤x3≤7,2≤z3≤4, M1 is one or more in Fe, Co, Ni, Mn, Cu, Zn, Ti, V, Al or Mg, M2 is Fe, Co, Ni, Mn, Cu, Zn, Ti, V, one or more in Al or Mg, W is V, Mo, Ti, Nb, Zn, Sn, B, Y, one or more in Ge or As, preferably, relative to the lithium iron phosphate anode active material of 100 weight portions, the described content containing lithium additive is not higher than 15 weight portions, further preferably, content containing lithium additive is 8-10 weight portion, namely the positive electrode active materials of the special construction of a small amount of special ratios is added with in lithium iron phosphate anode active material, the positive electrode active materials of this special construction is at initial charge rear section structure meeting inactivation, be equivalent to a certain amount of lithium of pre-embedding in negative pole, the embedding in advance lithium of this part can ensure still have lithium to deviate from from negative pole when continuing electric discharge after LiFePO4 electric discharge, simultaneously, Li
x2m1
y2o
z2and Li
x3m2(WO
z3) at 3.2V(LiFePO4 discharge platform) still there is discharge platform below, the decline of anodic potentials can also be cushioned, and it not uses as the main positive electrode active materials of positive pole, but as additive, utilize the interaction of its structure and LiFePO4, the performance of LiFePO4 can be improved, and other performances of battery can not be affected, the performance of battery can be improved further.
Preferably, Li is selected from containing lithium additive
0.95ni
0.84mn
0.21o
2, LiNi
0.5mn
0.5o
2, Li
2niO
2, Li
1.01ni
0.85mn
0.15o
2, Li
1.01ni
0.89mn
0.1o
2, Li
1.076ni
0.628mn
0.624o
2, Li
1.2ni
0.2mn
0.6o
2, Li
3feO
3, Li
5feO
4, Li
2mn
2o
4, Li
2mnO
3, Li
2cuO
2, Li
2feSiO
4, Li
2mnSiO
4, Li
2coSiO
4, Li
2niSiO
4, LiFeBO
3, Li
1.2niVO
4, LiFeMoO
4, LiCoTiO
4or LiMnSnO
4in one or more, improve further the performance of battery.
Negative active core-shell material the present invention do not limit, the various negative active core-shell materials that can be known to the skilled person, preferably, negative active core-shell material comprises lithium titanate, with the total amount of negative active core-shell material for benchmark, the content of described lithium titanate is 3 ~ 20wt%, more preferably 5 ~ 12wt%.Other negative active core-shell materials except lithium titanate can be graphite etc., when negative active core-shell material be graphite and lithium titanate time, relative to the graphite of 100 weight portions, the content of lithium titanate is 5 ~ 20 weight portions, more preferably 8 ~ 12 weight portions.
LiFePO4 the present invention do not limit, improvements of the present invention are to interact by adding oarse-grained ferric phosphate, the positive electrode active materials of other special constructions and LiFePO4, and match with the negative pole containing ad hoc structure, be applied to battery, can prevent from when battery charging and discharging putting, generally the present invention can be realized for various LiFePO4, lithium iron phosphate anode active material can be purchased, the present invention is in order to improve the performance of battery, preferably, particle primary particle size not higher than 10 microns, more preferably 0.1 ~ 2 micron.
Preferably, the initial charge capacity of (the initial charge capacity+lithium of lithium iron phosphate anode active material and/or the capacity of lithium alloy) * coefficient of safety=negative pole, wherein coefficient of safety is more than or equal to 0.8 and is less than or equal to 1.4.
Wherein, positive conductive matrix is positive conductive matrix known in those skilled in the art, such as, can be selected from aluminium foil, Copper Foil or various Punching steel strip.
Attachment can adopt and well known to a person skilled in the art various adherence method, such as, spray, coating etc., generally can by after positive electrode is obtained anode sizing agent again slurry etc. be coated on positive conductive matrix.The anode sizing agent of coating, except containing except above-mentioned positive electrode of the present invention, generally comprises the solvent etc. of dispersion, also containing other functional additives etc., namely also can contain other functional additives in positive electrode.
Conductive agent, positive electrode binder and above-mentioned solvent etc. can be various material known in those skilled in the art, ratio the present invention of lithium iron phosphate anode active material, conductive agent, positive electrode binder and solvent etc. is also not particularly limited, can adjust flexibly material concentration according to the viscosity of slurry coating of the composition of battery electrode positive electrode and positive electrode to be prepared and the requirement of operability, mode is conventionally known to one of skill in the art.
Improvements of the present invention are positive electrode, the preparation of positive pole can adopt various technology well known in the art, such as, anode sizing agent is coated in the surface of positive conductive matrix, rear drying, calendering etc., wherein, dry, the step of calendering, like the prior art, namely drying is usually under vacuum at 50-160 DEG C, carries out at preferred 80-150 DEG C, and dry rear dispersant can exist and also can not exist in pole piece.The rolling condition that calendering can adopt this area conventional, such as 0.5-3.0 MPa.The preparation of positive pole can also comprise other steps, and such as, the cut-parts of reprocessing, cut-parts are known to the skilled person, and after having rolled, cut, obtain anode pole piece according to the positive pole size of prepared battery request.
Negative conductive matrix can adopt the various negative conductive matrixes for lithium ion battery negative in prior art, as stamped metal, metal forming, net metal and foamed metal, and preferred Copper Foil.
The kind of negative electrode binder and content are conventionally known to one of skill in the art, and such as fluorine resin and polyolefin compound are as one or more in polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), butadiene-styrene rubber (SBR) and sodium carboxymethylcellulose (CMC); In general, according to the difference of binding agent kind used, relative to the negative electrode active material of 100 weight portions, the content of negative electrode binder is 0.005-8 weight portion, is preferably 0.008-5 weight portion.Also the conductive agent strengthening negative active core-shell material conductivity or other function additives etc. can be contained in cathode size.
The preparation of negative pole can be first by lithium and/or lithium alloy, negative active core-shell material and negative electrode binder are configured to slurry together and are attached on negative conductive matrix, such as can by lithium and/or lithium alloy, after negative active core-shell material and negative electrode binder etc. are dry mixed, the method of spraying is adopted to be attached on negative conductive matrix, also can by lithium and/or lithium alloy, negative active core-shell material and negative electrode binder etc. and solvent, after selectivity adds the wet mixings such as dispersant, the methods such as slurry coating are adopted to be attached on negative conductive matrix, the general solvent now adopted is oil-based solvent, binding agent is oiliness binding agent.And then drying, calendering etc., wherein, dry, the step of calendering, like the prior art, namely drying is usually under vacuum at 50-160 DEG C, carries out at preferred 80-150 DEG C, and dry rear dispersant can exist and also can not exist in pole piece.The rolling condition that calendering can adopt this area conventional, such as 0.5-3.0 MPa.The preparation of negative pole can also comprise other steps, and such as, the cut-parts of reprocessing, cut-parts are known to the skilled person, and after having rolled, cut, obtain cathode pole piece according to the negative pole size of prepared battery request.
Also first negative active core-shell material and negative electrode binder can be configured to together slurry be attached on negative conductive matrix and prepare anode active material layer, attachment can adopt and well known to a person skilled in the art various adherence method, such as spray, coating etc., and then drying, calendering etc., wherein, dry, the step of calendering, like the prior art, do not repeating at this.Can while calendering, the lithium of predetermined amount and/or lithium alloy be rolled on anode active material layer surface, also can be after cutting, lay one deck predetermined amount on the surface of negative plate lithium and/or lithium alloy, and then roll, at anode active material layer surface attachment one deck lithium and/or lithium alloy.Generally add the dew point of fashionable environment at subzero less than 50 DEG C at lithium and/or lithium alloy.
Wherein, barrier film can be selected from and well known to a person skilled in the art various barrier films used in lithium ion battery, such as polyolefin micro porous polyolefin membrane (PP), polyethylene felt (PE), glass mat or ultra-fine fibre glass paper or PP/PE/PP.As one preferred embodiment, described barrier film is PP/PE/PP.
Electrolyte contains lithium salts and nonaqueous solvents, and lithium salts can be one or more in lithium hexafluoro phosphate, LiBF4, hexafluoroarsenate lithium, lithium perchlorate, trifluoromethyl sulfonic acid lithium, perfluoro butyl Sulfonic Lithium, lithium aluminate, chlorine lithium aluminate, fluoro sulfimide lithium, lithium chloride and lithium iodide; Nonaqueous solvents can be gamma-butyrolacton, methyl ethyl carbonate, methyl propyl carbonate, dipropyl carbonate, acid anhydrides, 1-METHYLPYRROLIDONE, N-METHYLFORMAMIDE, N-methylacetamide, acetonitrile, DMF, sulfolane, methyl-sulfoxide, dimethyl sulfite and other is fluorine-containing, sulfur-bearing or containing one or more in the ring-type organic ester of unsaturated bond.Lithium salts concentration in the electrolytic solution can be 0.3-4 mol/L, is preferably 0.5-2 mol/L.
Housing the present invention do not limit, and can adopt and well known to a person skilled in the art various battery container, such as the duricrust such as box hat or aluminum hull, and can be also the flexible package shells such as aluminum plastic film, shape and large I design according to practical situation.
The preparation method of lithium ion battery provided by the invention can be well known for the person skilled in the art method, in general, the method comprises the formation pole piece that positive pole, negative pole and the barrier film between positive pole and negative pole to be reeled successively, pole piece is inserted in battery case, add electrolyte, then seal, wherein, the method for winding and sealing is that those skilled in the art are known.The consumption of electrolyte is conventional amount used.
Unless stated otherwise, various solvent of the present invention and reagent are commercially available analytical reagent.
Below in conjunction with specific embodiment, the present invention is further described.
Embodiment 1
(1) preparation of positive pole:
By the LiFePO4 (D of the maximum primary particle particle diameter 4 microns of 90g
50=0.3 micron), the ferric phosphate (D of the minimum primary particle particle diameter 30 microns of 10g
50=35 microns), the binding agent Kynoar (PVDF) of 4g, the super conductive black of conductive agent SP(of 5g), the polyethylene of dispersing agent pyrrolidones (PVP) of 0.5g and the 1-METHYLPYRROLIDONE of 120g join in de-airing mixer to stir and form uniform anode sizing agent.This anode sizing agent is uniformly coated on the both sides of the aluminium foil of thickness 16 microns, then dries at 150 DEG C.Again through roll-in, cut the positive plate obtaining size 453*40 millimeter.
(2) preparation of negative pole:
By 50g native graphite, 1g binding agent butadiene-styrene rubber breast (SBR), 0.5g binding agent carboxymethyl cellulose (CMC), 0.025g lithium metal powder (purity 99.9%), the NMP of 125g joins in de-airing mixer to stir and forms uniform cathode size.This cathode size is coated on the both sides that thickness is the Copper Foil of 12 microns equably, then dries at 90 DEG C.Again through roll-in, cut, the obtained negative plate being of a size of 455*41 millimeter.
(3) preparation of battery:
Respectively above-mentioned positive and negative electrode and polypropylene screen are wound into the pole piece of a square lithium ion battery, subsequently by LiBF
4be dissolved in by the concentration of 1 mol/L in the mixed solvent of EC/EMC/DEC=1:1:1 and form nonaqueous electrolytic solution, this electrolyte is injected battery aluminum shell with the amount of 3.8g/Ah, sealing, changes into, makes lithium ion battery.
Embodiment 2
The method identical with embodiment 1 and step is adopted to prepare positive pole, negative pole and battery, configuration unlike anode sizing agent: by the LiFePO4 (primary particle particle diameter D50=0.4 micron) of 93g, the ferric phosphate (primary particle particle diameter D50=45 micron) of the minimum grain size 30 microns of 7g, the binding agent Kynoar (PVDF) of 4g, the super conductive black of conductive agent SP(of 5g), the polyethylene of dispersing agent pyrrolidones (PVP) of 0.5g and the 1-METHYLPYRROLIDONE of 120g join in de-airing mixer to stir and form uniform anode sizing agent.The preparation of negative pole: by 50g native graphite, 1g binding agent butadiene-styrene rubber breast (SBR), 0.5g binding agent carboxymethyl cellulose (CMC), the deionized water of 125g joins in de-airing mixer to stir and forms uniform cathode size.This cathode size is coated on the both sides that thickness is the Copper Foil of 12 microns equably, then dries at 90 DEG C.Again through roll-in, cut, the obtained negative plate being of a size of 455*41 millimeter, then the lithium-aluminium alloy powder (aluminium content 3 % by weight) of 0.025 gram is sprayed on anode active material layer surface, then roll-in obtains negative plate.
Embodiment 3
The method identical with embodiment 1 and step is adopted to prepare positive pole, negative pole and battery, configuration unlike cathode size: by 50g native graphite, 1g binding agent butadiene-styrene rubber breast (SBR), 0.5g binding agent carboxymethyl cellulose (CMC), 0.016g lithium metal powder (purity 99.9%), the NMP of 125g joins in de-airing mixer to stir and forms uniform cathode size.
Embodiment 4
The method identical with embodiment 1 and step is adopted to prepare positive pole, negative pole and battery, configuration unlike anode sizing agent: by the LiFePO4 (primary particle particle diameter D50=0.4 micron) of 90g, the ferric phosphate (primary particle particle diameter D50=25 micron) of the minimum grain size 30 microns of 10g, the binding agent Kynoar (PVDF) of 4g, the super conductive black of conductive agent SP(of 5g), the polyethylene of dispersing agent pyrrolidones (PVP) of 0.5g and the 1-METHYLPYRROLIDONE of 120g join in de-airing mixer to stir and form uniform anode sizing agent.
Embodiment 5
The method identical with embodiment 1 and step is adopted to prepare positive pole, negative pole and battery, configuration unlike anode sizing agent: by the LiFePO4 (primary particle particle diameter D50=0.4 micron) of 90g, the ferric phosphate (primary particle particle diameter D50=50 micron) of the minimum grain size 30 microns of 10g, the binding agent Kynoar (PVDF) of 4g, the super conductive black of conductive agent SP(of 5g), the polyethylene of dispersing agent pyrrolidones (PVP) of 0.5g and the 1-METHYLPYRROLIDONE of 120g join in de-airing mixer to stir and form uniform anode sizing agent.
Embodiment 6
The method identical with embodiment 1 and step is adopted to prepare positive pole, negative pole and battery, configuration unlike anode sizing agent: by the LiFePO4 (primary particle particle diameter D50=0.4 micron) of 90g, the ferric phosphate (primary particle particle diameter D50=45 micron) of the minimum grain size 30 microns of 7g, the binding agent Kynoar (PVDF) of 4g, the super conductive black of conductive agent SP(of 5g), the polyethylene of dispersing agent pyrrolidones (PVP) of 0.5g and the 1-METHYLPYRROLIDONE of 120g join in de-airing mixer to stir and form uniform anode sizing agent.
Embodiment 7
The method identical with embodiment 1 and step is adopted to prepare positive pole, negative pole and battery, the configuration unlike anode sizing agent: by 90g LiFePO4, the minimum grain size of 7 grams is the ferric phosphate of 30 microns, and 5 grams of specific areas are 120m
2the material with carbon element of/g, 4g Kynoar (PVDF), the polyethylene of dispersing agent pyrrolidones (PVP) of the conductive agent SP of 5g, 0.5g and the 1-METHYLPYRROLIDONE of 120g join in de-airing mixer to stir and form uniform anode sizing agent.
Embodiment 8
The method identical with embodiment 1 and step is adopted to prepare positive pole, negative pole and battery, the configuration unlike anode sizing agent: by 90g LiFePO4, the minimum grain size of 7 grams is the ferric phosphate of 30 microns, and 7 grams of specific areas are 1200m
2the material with carbon element of/g, 4g Kynoar (PVDF), the polyethylene of dispersing agent pyrrolidones (PVP) of the conductive agent SP of 5g, 0.5g and the 1-METHYLPYRROLIDONE of 120g join in de-airing mixer to stir and form uniform anode sizing agent.
Embodiment 9
The method identical with embodiment 1 and step is adopted to prepare positive pole, negative pole and battery, the configuration unlike anode sizing agent: by 90g LiFePO4, the minimum grain size of 7 grams is the ferric phosphate of 30 microns, and 8 grams of specific areas are 1000m
2the material with carbon element of/g, 4g Kynoar (PVDF), the polyethylene of dispersing agent pyrrolidones (PVP) of the conductive agent SP of 5g, 0.5g and the 1-METHYLPYRROLIDONE of 120g join in de-airing mixer to stir and form uniform anode sizing agent.
Embodiment 10
The method identical with embodiment 1 and step is adopted to prepare positive pole, negative pole and battery, configuration unlike anode sizing agent: adopt the method identical with embodiment 1 and step to prepare positive pole, negative pole and battery, configuration unlike anode sizing agent: by 90g LiFePO4, the Li of 5g
2mnSiO
4, 3 grams of Li
5feO
4the minimum grain size of 7 grams is the ferric phosphate of 30 microns, 4g Kynoar (PVDF), the polyethylene of dispersing agent pyrrolidones (PVP) of the conductive agent SP of 5g, 0.5g and the 1-METHYLPYRROLIDONE of 120g join in de-airing mixer to stir and form uniform anode sizing agent; The lithium salts of the electrolyte injected is LiNF
2s
2o
4.
The configuration of cathode size: by 50g native graphite, the lithium titanate of 4.5g, 1g binding agent butadiene-styrene rubber breast (SBR), 0.5g binding agent carboxymethyl cellulose (CMC), 0.016g lithium metal powder (purity 99.9%), the NMP of 125g joins in de-airing mixer to stir and forms uniform cathode size.
Comparative example 1
(1) preparation of positive pole:
By 100g LiFePO4,4g Kynoar (PVDF), 5g conductive agent SP, 0.5g polyethylene of dispersing agent pyrrolidones (PVP), the 1-METHYLPYRROLIDONE of 120g joins in de-airing mixer to stir and forms uniform positive electrode.This positive electrode is uniformly coated on the both sides of the aluminium foil of thickness 20 microns, then dries at 150 DEG C.Again through roll-in, cut the positive plate obtaining size 453*40 millimeter.
(2) preparation of negative pole:
By 50g native graphite, 1g binding agent butadiene-styrene rubber breast (SBR), 0.5g binding agent carboxymethyl cellulose (CMC), the NMP of 125g joins in de-airing mixer to stir and forms uniform cathode size.This cathode size is coated on the both sides that thickness is the Copper Foil of 12 microns equably, then dries at 90 DEG C.Again through roll-in, cut, the obtained negative plate being of a size of 455*41 millimeter.
(3) preparation of battery:
Respectively above-mentioned positive and negative electrode and polypropylene screen are wound into the pole piece of a square lithium ion battery, subsequently by LiPF
6be dissolved in by the concentration of 1 mol/L in the mixed solvent of EC/EMC/DEC=1:1:1 and form nonaqueous electrolytic solution, this electrolyte is injected battery aluminum shell with the amount of 3.8g/Ah, sealing, changes into, makes lithium ion battery.
Electrochemical property test:
Battery prepared by embodiment 1-10 and comparative example 1 is placed on new Weir-3000 type electrochemical property test instrument, charges to 3.6V with 0.1C respectively, shelve 10 minutes, after be discharged to 2.0V with 0.1C.Then this battery is prepared into three electrodes, charges to 3.6V with 0.5C, shelve 10 minutes, after be discharged to 2.0V with 0.5C, uninterruptedly, then continue to discharge into 0V with 0.5C.Record battery the discharge capacity of 2.0-0V and battery at more than 2.0V time discharge capacity, the ratio value of the discharge capacity shared by the discharge capacity of battery under 2.0-0V during more than 2.0V is recorded in table 1.Meanwhile, during by battery discharge to 0V, the potential value of battery cathode is recorded in table 1.Curve is as Fig. 1 over time for the three-electrode voltage of embodiment 1 drafting, and comparative example 1 draws voltage curve chart over time, as Fig. 2.
Table 1
| Embodiment | The discharge capacity (%) of discharge capacity/more than the 2.0V of 2.0V ~ 0V | When battery discharge is to 0V, the current potential (V) of battery cathode |
| Embodiment 1 | 24 | 1.13 |
| Embodiment 2 | 22 | 1.04 |
| Embodiment 3 | 19 | 1.13 |
| Embodiment 4 | 16 | 1.28 |
| Embodiment 5 | 21 | 0.89 |
| Embodiment 6 | 19 | 0.99 |
| Embodiment 7 | 16 | 1.13 |
| Embodiment 8 | 28 | 0.86 |
| Embodiment 9 | 19 | 0.88 |
| Embodiment 10 | 14 | 1.65 |
| Comparative example 1 | 0.8 | 2.4 |
As can be seen from data in table 1, the battery of the embodiment 1-10 discharge capacity under 2.0-0V condition is relative to the discharge capacity of battery under more than 2.0V condition, proportion is higher, and the capacity that comparative example 1 can be released under 2.0-0V condition is low-down, the battery of embodiment 1-10 is described, and put under condition can stable negative electrode potential crossing, negative pole current potential is made to be unlikely to be raised to fast and to analyse copper current potential, cause short circuit, thus playing the effect preventing from or delayed putting, battery is significantly improved in the security performance under to one's heart's content condition.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.
Claims (15)
1. a lithium ion battery, is characterized in that, comprise housing and the electrode group that is sealed in housing and electrolyte, described electrode group comprises positive pole, negative pole and the barrier film between positive pole and negative pole,
The positive electrode material layer that described positive pole comprises positive conductive matrix and is attached on positive conductive matrix, described positive electrode material layer comprises lithium iron phosphate anode active material, ferric phosphate, conductive agent and positive electrode binder; The particle primary particle size of described ferric phosphate is not less than 20 microns;
The negative electrode material layer that described negative pole comprises negative conductive matrix and is attached on negative conductive matrix;
Described negative electrode material layer comprises anode active material layer, and described anode active material layer comprises additive, negative active core-shell material and negative electrode binder;
Or described negative electrode material layer comprises anode active material layer and is attached to the additive in anode active material layer, described anode active material layer comprises negative active core-shell material and negative electrode binder;
Described additive is lithium and/or lithium alloy.
2. lithium ion battery according to claim 1, is characterized in that, the particle primary particle size of described ferric phosphate is 30 ~ 50 microns, primary particle median particle diameter D
50=35 ~ 45 microns.
3. lithium ion battery according to claim 1, is characterized in that, relative to the lithium iron phosphate anode active material of 100 weight portions, the content of described ferric phosphate is 5-20 weight portion.
4. lithium ion battery according to claim 3, is characterized in that, relative to the lithium iron phosphate anode active material of 100 weight portions, the content of described ferric phosphate is 8-12 weight portion.
5. lithium ion battery according to claim 1, it is characterized in that, the amount of described additive meets k/L < x < (n-m)/L, wherein, x represents the quality of Li element in additive, and L represents the theoretical specific capacity of lithium, and m represents the initial charge capacity of positive pole, n represents the initial charge capacity of negative pole, and k represents the first charge-discharge irreversible capacity of negative pole.
6. lithium ion battery according to claim 1, is characterized in that, relative to the negative active core-shell material of 100 weight portions, the content of described additive is 0.3 ~ 5 weight portion.
7. lithium ion battery according to claim 1, is characterized in that, described lithium alloy is selected from one or more in Li-M alloy, and described M is selected from one or more in Be, Mg, Ti, Zr, V, Nb, Cr, Cu and Al.
8. lithium ion battery according to claim 1, is characterized in that, described lithium iron phosphate anode active material also comprises carbon, and the specific area of described carbon is not less than 50m
2/ g.
9. lithium ion battery according to claim 8, is characterized in that, relative to the lithium iron phosphate anode active material of 100 weight portions, the content of described carbon is 5-15 weight portion; The specific area of described carbon is 200 ~ 600m
2/ g.
10. lithium ion battery according to claim 1, is characterized in that, described lithium iron phosphate anode active material also comprises containing lithium additive, and the described lithium additive that contains is selected from Li
x2m1
y2o
z2, silicate positive electrode active materials or Li
x3m2(WO
z3) in one or more, wherein, 0.8≤x2≤7,0 < y2≤5,0 < z2≤8; 0.8≤x3≤7,2≤z3≤4; M1 is one or more in Fe, Co, Ni, Mn, Cu, Zn, Ti, V, Al or Mg; M2 is one or more in Fe, Co, Ni, Mn, Cu, Zn, Ti, V, Al or Mg, and W is one or more in V, Mo, Ti, Nb, Zn, Sn, B, Y, Ge or As; Relative to the lithium iron phosphate anode active material of 100 weight portions, the described content containing lithium additive is not higher than 15 weight portions.
11. lithium ion batteries according to claim 10, is characterized in that, described is Li containing lithium additive
x1ni
y1mn
z1o
2, wherein, 0.8≤x1≤2,0≤y1 < 1,0≤z1 < 1.
12. lithium ion batteries according to claim 10, is characterized in that, the described lithium additive that contains is selected from Li
0.95ni
0.84mn
0.21o
2, LiNi
0.5mn
0.5o
2, Li
2niO
2, Li
1.01ni
0.85mn
0.15o
2, Li
1.01ni
0.89mn
0.1o
2, Li
1.076ni
0.628mn
0.624o
2, Li
1.2ni
0.2mn
0.6o
2, Li
3feO
3, Li
5feO
4, Li
2mn
2o
4, Li
2mnO
3, Li
2cuO
2, Li
2feSiO
4, Li
2mnSiO
4, Li
2coSiO
4, Li
2niSiO
4, LiFeBO
3, Li
1.2niVO
4, LiFeMoO
4, LiCoTiO
4or LiMnSnO
4in one or more.
13. lithium ion batteries according to claim 1, is characterized in that, described negative active core-shell material comprises lithium titanate, and with the total amount of negative active core-shell material for benchmark, the content of described lithium titanate is 3 ~ 20wt%.
14. lithium ion batteries according to claim 1, is characterized in that, the particle primary particle size of described lithium iron phosphate anode active material is not higher than 10 microns.
15. lithium ion batteries according to claim 1, it is characterized in that, the initial charge capacity of (capacity of the initial charge capacity+additive of described lithium iron phosphate anode active material) × coefficient of safety=negative pole, wherein coefficient of safety is more than or equal to 0.8 and is less than or equal to 1.4.
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