CN1322615C

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Info

Publication number: CN1322615C
Application number: CNB2005100195528A
Authority: CN
Inventors: 黎彦希
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-10-03
Filing date: 2005-10-03
Publication date: 2007-06-20
Anticipated expiration: 2025-10-03
Also published as: CN1770514A

Abstract

The present invention relates to a doping and surface coating lithium nickel cobalt dioxide and a preparation method thereof of the positive electrode material of a lithium ion battery, which is characterized in that nucleus in material particles are LiNixCoyMgzO2 or LiNixCoyMnzO2, Mg, Mn, vanadium or earth metal is doped, and the outer surface layer is nanometer stage MgO. The preparation method adopts three-time feeding, three-time preheating and a particle surface covered solid phase synthesis method, wherein a temperature can be kept at 800 DEG C. The present invention has the advantages of well-crystallized product, regular structure, good particle pattern, great bulk density, good flow, high discharge platform for an old battery, high ratio capacity and good cycle performance, and furthermore, the raw material has the advantages of low cost, no pollution and low production cost, and is suitable for the commercial process; the material is suitable for high performance battery preparation.

Description

The preparation method of doping and surface coated lithium nickel cobalt dioxide

(1) technical field

The present invention relates to a kind of lithium ion secondary battery anode material, particularly relate to a kind of doping and surface coated lithium nickel cobalt dioxide and preparation method thereof.

(2) technical background

People such as B.Goodenough were at first by cobalt carbonate and the at high temperature synthetic cobalt acid of lithium carbonate lithium (LiCoO in 1980₂), and studied it and made the performance of battery.1991, realized by LiCoO₂Do the commercialization production of the lithium rechargeable battery of positive electrode, because of its have output voltage height, energy density big, have extended cycle life, advantages such as memory-less effect are used widely in fields such as mobile communication, mobile computer, movable electrical appliances, electric automobile, Aero-Space, biological medicine engineerings.LiCoO₂Has good performance at aspects such as voltage stability, invertibity, discharge capacity, efficiency for charge-discharges, and its production technology is simple, be easy to suitability for industrialized production, it is the widely used positive electrode of present lithium ion battery, because the cobalt raw material resource is few and factor such as cobalt price height plays restrictive function to its application again, so novel substitute material of searching or the research that improves its material high energy activity become the research focus of anode material for lithium-ion batteries.Before not finding better replacement anode material for lithium-ion batteries, its material application life also has 20 years at least.At present, the lithium ion battery future thrust has four: one, the raising of battery capacity; The 2nd, improve the cycle life of electrode; The 3rd, the safety issue of solution battery; The 4th, reduce its manufacturing cost.Solve the problem of lithium ion battery, just will solve the problem of anode material for lithium-ion batteries.The theoretical voltage of cobalt acid lithium material but on average has only 3.6V, the highest 4.0V that also do not reach at present more than 4.2V; Theoretical specific capacity is 260mAh/g, actual specific capacity 130mAh/g, and capacity descends with the cycle-index increase.Over past ten years, scientist and engineers and technicians are to optimizing anode material for lithium-ion batteries, improve its activity, done making unremitting efforts effort, the parameter such as architectural feature, bulk density, specific area, tap density, uniform particles degree of having found the quality of lithium ion battery performance and anode material for lithium-ion batteries has very big relation, should optimize these parameters, reduce production costs again, be quite very difficult.At present, the positive electrode method of synthesizing lithium ion battery is divided solid-phase synthesis, liquid phase synthesizing method two big class methods, solid-phase synthesis divides two kinds of high temperature solid phase synthesis and low temperature solid-phase synthesis again, liquid phase synthesizing method divides sol-gel method and antenatal two kinds of the body fluid phase synthesis that drive of Mr. again, and the whole bag of tricks all has pros and cons.

Chinese patent application number 03112435.6 has been announced " being the method for feedstock production lithium ion cell anode material lithium cobaltate with the nano-cobaltic-cobaltous oxide ", though this method can be produced good cobalt acid lithium particle pattern, but usefulness is expensive cobalt raw material, and the cost of material of product can not be fallen.Chinese patent application number 03129498.7 has been announced " lithium ion battery anode material nickel cobalt acid lithium and preparation method thereof ", with the cobalt that the many nickel of low price, resource has replaced partly costing an arm and a leg, resource is few, certain advantage is arranged, but production technology adopts Mr. of liquid phase synthesizing method to produce the liquid phase synthesizing method of presoma.Production technology is long, cost increases, and sewage discharge is arranged again simultaneously.Chinese patent application number 02155659.8 has been announced " preparation method of anode active material of lithium ion battery cobalt acid lithium ", this method adopts high temperature solid phase synthesis to produce cobalt acid lithium, the water washing product that a usefulness contains precipitation reagent, the technological process of removing alkalescence residual in the former elementary product have been increased, belong to a kind of measure of optimizing cobalt acid lithium, but pure cobalt acid lithium, do not mix, the products material cost is too high.Because of having increased water-washing process one time, simultaneously, also improved production cost.Lack market competition advantage.

(3) summary of the invention

The objective of the invention is at the deficiencies in the prior art, the good lithium ion battery anode material doped and surface coated lithium nickel cobalt dioxide of a kind of electrode performance and the industrial production preparation method of this material are provided.Advantages such as the lithium ion battery made from this material has discharge platform height, height ratio capacity, good cycle advantage, and preparation methods has that simple, the pollution-free and no waste discharge of production technology, equipment are simple, raw material and production cost are low.

The technical scheme that realizes the object of the invention is:

A kind of doping and surface coated lithium nickel cobalt dioxide, it is LiNi that its granule interior nucleus contains chemical molecular formula_xCo_yMg_zO₂Material, wherein x, y, z value sum equal 1, x, y, z are molfraction, span: X is 0.4～0.6, y is 0.3～0.5, z is 0～0.2; Doping and surface coated lithium nickel cobalt dioxide particle external surface layer contain the material that chemical molecular formula is MgO, and wherein MgO is the nanometer fine particle, and MgO nanometer fine particle particle diameter is 3～50nm.

Available Mn replaces LiNi_xCo_yMg_zO₂In Mg; Available vanadium or rare earth doped instead of part Mg or Mn, the doping of vanadium or rare earth element equals the reduction of Mg or Mn, and maximum doping is no more than the molfraction of 0.01 replacement metallic element.

Above-mentioned doping and surface coated lithium nickel cobalt dioxide, its preparation method operating procedure comprises:

(1) oxide with oxide, magnesium salts or the magnesium of oxide, cobalt salt or the cobalt of lithium salts, nickel salt or nickel mixes after the weighing in proportion, and wherein the mole ratio of Li: Ni: Co: Mg is 1: (0.4～0.6): (0.3～0.5): (0～0.2);

(2) the ceramic flat alms bowl of packing into behind the mixture mix grinding with step (1) is put in the heating furnace and is heated, and heat-treating atmosphere is air or oxygen and Air mixing gas, the intensification The pre-heat treatment, 5～30 ℃/min of heating rate, 250～350 ℃ of insulation scopes, temperature retention time 0.5～1 hour;

(3) the ceramic flat alms bowl that mixture is housed with step (2) withdraws from heating furnace, reinstalls the mixture of a step (1), and it is flat to shake, and heats in the replacement heating furnace, and heat-treating atmosphere, programming rate, insulation scope, the same step of temperature retention time (2) are the same;

(4) operation of repeating step (3) once;

(5) with this moment of three mixtures of packing into of the ceramic flat alms bowl intensification heating in heating furnace in the step (4), heat-treating atmosphere is air or oxygen and Air mixing gas, and heating and heat preservation is handled, 5～20 ℃/min of heating rate, 750～850 ℃ of insulation scopes, temperature retention time 7～10 hours;

(6) cooling of the ceramic flat alms bowl of the synthetic that being equipped with in the step (5) reacted completely is handled, 10～20 ℃/min of rate of temperature fall, reduce to room temperature after, the synthetic in the flat alms bowl of pottery poured out and concentrates pulverize, screening, obtaining nucleus is LiNi_xCo_yMg_zO₂The synthetic particle, particle diameter is 2～7.3 μ m;

(7) the nanoscale MgO powder of 3～20nm is poured in the pure deionized water, stirred;

(8) in the container that densification is closed, the synthetic particle that step (6) is obtained is sprayed into dust-like, again the pure deionized water that contains the MgO particle in the step (7) is sprayed into the water smoke shape, the synthetic dust granules sticks water smoke outward, collect moistening synthetic, put into the rearmounted heating furnace heating of ceramic flat alms bowl 0.5 hour, temperature is 200～300 ℃, come out of the stove, lower the temperature, pulverize, sieve, obtain the LiNi that the surface is coating the doping of MgO_xCo_yMg_zO₂Particle, particle diameter are no more than 7.5 μ m.

The lithium salts that is adopted among the above-mentioned preparation method, nickel salt, cobalt salt, magnesium salts can select carbonate, oxalates, acetate, because of lithium is volatile damaged when the high temperature, so during the weighing lithium salts, excessive 0.1～1% (W).

If preparation LiNi_xCo_yMn_zO₂During material, in step (1), replace the oxide of magnesium salts or magnesium with the oxide of manganese salt or manganese.

In step (1), raw materials weighing when batching, allocate maximum into and be no more than the magnesium salts of molfractions such as carbonate replacement of the vanadium of 0.01 molfraction or rare earth element or the oxide of magnesium.

The present invention is low, pollution-free from high discharge platform, high capacitance, good cycle, raw material and production cost, be convenient to theory such as large-scale production goes out to send design anode material for lithium-ion batteries and preparation method.Adopt Ni replaced C o, can reduce the cost of raw material, can enhance product performance again, adopt micro Mg replaced C o to be because the conductivity of Mg doping system far above parent LiCoO₂Conductivity, 2Co³⁺→ Mg²⁺+ Co⁴⁺, Co like this⁴⁺Hole density increase, thereby cause the raising that electricity is led.Coat LiNi with the nano-MgO surface_xCo_yMg_zO₂, can improve cyclical stability and promote operating voltage.Can play when the surface is coated on cycle charge-discharge and stablize LiNi_xCo_yMg_zO₂Layer structure is to keep the effect of lithium ion diffusion admittance.Doping has reduced raw material Co consumption, but product LiNi_xCo_yMg_zO₂Still same LiCoO₂The same, be NaFeO₂The layer structure of the hexagonal crystal system of type.Doping makes structure cell C elongate axis, the increase of C value, interlamellar spacing become big, helps Li⁺Embedding and effusion, more excellent charging and discharging stability is arranged.Suggestion of process design also is that pattern is better, specific area 0.7m from producing²/ g, evengranular material set out.Three reinforced pre-thermal responses are too thick for preventing once the reinforced reactant that causes in the ceramic flat alms bowl, are unfavorable for thermally equivalent and contact with oxygen, make alms bowl at the bottom of the product fusion harden, cause the product fineness ratio alms bowl top of alms bowl bottom big.Because of the raw material bed thickness, the CO of bottom₂Generate bulky grain, CO thereby can not overflow₂Existence also promoted the generation of liquid phase, increased the sintering cohesion of powder.Heating-cooling speed, holding temperature scope, temperature retention time design also are to go out with experimental summary through science calculating, are lower than 700 ℃, can not get pure crystalline phase, and when being higher than 850 ℃, quality has loss, and easily LiO evaporates, and causes Li⁺The metering skew.Li⁺Quantity is damaged, and capacitance is on the low side, because of Li⁺Easily damaged, so during the raw material proportioning, lithium salts is wanted stoichiometric 0.1～1% (W) on the high side.

The invention has the beneficial effects as follows:

(1) doping and surface coated lithium nickel cobalt dioxide have replaced the expensive cobalt of part with low-cost nickel, and the cost of raw material of the present invention reduces many; Because of reducing with the cobalt amount, environmental pollution also reduces simultaneously;

(2) when reducing cost of material of the present invention, its synthetic chemical property is good because of mixing, good cycle, height ratio capacity, discharge platform height;

(3) three reinforced preheating insulations make LiNi_xCo_yMg_zO₂Powder crystallization is good, and compound with regular structure coats because of the surface again, and granule-morphology is good, particle diameter is moderate, even particle size distribution, bulk density are big, flow, make it to have good electrochemical;

(4) because of adopting high temperature solid phase synthesis and optimizing technological design, production technology is simple, the production time is short, power consumption is low, without sewage discharge, if design with tunnel heating furnace production line, and industrial scale production then preferably, production cost is low.

(4) description of drawings

Accompanying drawing 1 is a process route block diagram of the present invention.

Accompanying drawing 2 is cyclic curve figure that sample that the present invention produces is made lithium ion Experimental cell 063048.

Curve 1 is a 4.4V discharge cycles curve among the figure.

Curve 2 is 4.2V discharge cycles curves among the figure.

Accompanying drawing 3 is that the sample that the present invention produces is made lithium ion Experimental cell 063048 at the 2.75V discharge curve.

Curve 1 is the 4.4V discharge curve among the figure.

Curve 2 is 4.2V discharge curves among the figure.

With reference to the accompanying drawings 3: on the automatic battery tester, test discharge cut-off voltage 2.75～4.2V, 2.75～4.4V.2.75～4.2V discharge gram volume 139.5mAh/g, each loop attenuation is less than 0.06%, and 3.6V platform efficient is greater than 45%; 2.75～4.4V discharge gram volume 170mAh/g, each loop attenuation is less than 0.065%, and 3.3V platform efficient is greater than 80%.

(5) embodiment

The invention will be further described below in conjunction with embodiment, but be not limited thereto.

Embodiment 1:

(1) in Li: the molfraction ratio of Ni: Co: Mg is 1.01: 0.5: 0.4: 0.1 ratio takes by weighing purity higher reactant feed lithium carbonate, nickelous carbonate, cobalt carbonate, magnesium carbonate, mixing, mix grinding;

(2) heater of employing electric heating tunnel heating furnace, the mixture material that mix grinding is the good flat ceramic alms bowl of packing into, / 4th of an alms bowl capacity of packing into is measured, the mixture surface shakes flat, and heap is not sharp, and the ceramic flat alms bowl that installs raw material in a row is sent in the tunnel heating furnace by porcelain roller and heated, air atmosphere, press 20 ℃/min of heating rate and heat up, when reaching 300 ℃ of temperature, be incubated 0.5 hour;

(3) the ceramic flat alms bowl with step (2) withdraws from stove, wait cooling after, reinstall the mixture of alms bowl 1/4th capacity, the plane surface that shakes heats air atmosphere in the replacement heating furnace, press 20 ℃/min of heating rate and heat up, when reaching 300 ℃ of temperature, be incubated 0.5 hour;

(4) operation of repeating step (3) once;

(5) the flat alms bowl of pottery is heated up heating, air atmosphere, 15 ℃/min of heating rate, reach 800 ℃ after, insulation is handled, temperature retention time 10 hours;

(6) with the rate of temperature fall of 15 ℃/min with the flat alms bowl cooling of pottery, reduce to room temperature after, the synthetic that generates reacting completely in the alms bowl is poured out to concentrate and is pulverized, levigate with the porcelain mill machine, do not want contaminated or introduce other impurity, screening, average grain diameter 5 μ m, the molecular formula of the synthetic that obtain this moment is LiNi_0.5Co_0.4Mg_0.1O₂

(7) the MgO powder of particle diameter 20nm is poured in the pure deionized water, stirred;

(8) in airtight close device, with the LiNi of step (6) acquisition_0.5Co_0.4Mg_0.1O₂Powder is sprayed into dust-like, has the deionized water of nano-MgO to be sprayed into the water smoke shape in again step (7) being obtained, cloud, water smoke blending, and the blower fan air blast is stirred.At this moment, moistening dust falls at the bottom of the close device, collects, and puts into ceramic flat alms bowl, puts alms bowl capacity 3/4ths amounts;

(9) the ceramic flat alms bowl of step (8) is put in the heating furnace heating 0.5 hour, temperature is 300 ℃;

(10) alms bowl is come out of the stove, lower the temperature, pulverize, put levigate in the porcelain mill machine, screening, particle diameter is according to the needs of making battery, and maximum particle diameter is no more than 7.5 μ m, and at this moment, obtaining nucleus is LiNi_0.5Co_0.4Mg_0.1O₂, brilliant shell is the surface coated lithium nickel cobalt dioxide particle of MgO, doped with Mg in the nucleus.

The product of taking the inventive method to produce is that class sphere, particle mean size are 5 μ m, and tap density is 1.55g/cm³, make lithium ion battery after, 2.75～4.2V discharge gram volume 139.5mAh/g, each loop attenuation is less than 0.06%, 3.6V platform efficient is greater than 45%; 2.75～4.4V discharge gram volume 170mAh/g, each loop attenuation is less than 0.065%, and 3.3V platform efficient is greater than 80%.

Embodiment 2:

Difference from Example 1 is: replace magnesium carbonate with manganese carbonate, consumption also is that the molfraction of manganese is 0.1.

Embodiment 3:

With embodiment 1 different being: replace nickelous carbonate, cobalt carbonate, magnesium carbonate among the embodiment 1, each metallic element molfraction constant rate with nickel oxide, cobalt oxide, magnesium oxide.

Embodiment 4:

Replace magnesium oxide with embodiment 3 different being with manganese oxide.

Embodiment 5:

Difference from Example 1 is with the metallic element molfraction to be the magnesium carbonate of molfractions such as 0.01 carbonic acid vanadium or rare earth carbonate replacement.

Claims

1. a doping and the surface coated nickel preparation method that bores sour lithium is characterized in that operating procedure comprises:

(1) oxide with oxide, magnesium salts or the magnesium of oxide, cobalt salt or the cobalt of lithium salts, nickel salt or nickel mixes after the weighing in proportion, and wherein the molfraction of Li: Ni: Co: Mg ratio is 1: (0.4～0.6): (0.3～0.5): (0～0.2);

(3) the ceramic flat alms bowl that mixture is housed with step (2) withdraws from heating furnace, reinstalls the mixture of a step (1), and it is flat to shake, and heats in the replacement heating furnace, and heat-treating atmosphere, heating rate, insulation scope, the same step of temperature retention time (2) are the same;

(4) operation of repeating step (3) once;

(6) cooling of the ceramic flat alms bowl of the synthetic that being equipped with in the step (5) reacted completely is handled, 10～20 ℃/min of rate of temperature fall, reduce to room temperature after, the synthetic in the flat alms bowl of pottery poured out and concentrates pulverize, screening, obtaining nucleus is LiNi_xCo_yMg_zO₂The synthetic particle, particle diameter is 2～7.3 μ m, wherein x, y, z value sum equal 1, x, y, z are molfraction, span: x is 0.4～0.6, y is 0.3～0.5, z is 0～0.2;

(7) it is even to pour the nanoscale MgO powder of 3～20nm into pure deionized water for stirring;

(8) in closed unit, the synthetic particle that step (6) is obtained is sprayed into dust-like, again the pure deionized water that contains the MgO particle in the step (7) is sprayed into the water smoke shape, the synthetic dust granules sticks water smoke outward, collect moistening synthetic, put into the rearmounted heating furnace heating of ceramic flat alms bowl 0.5 hour, temperature is 200～300 ℃, come out of the stove, lower the temperature, pulverize, sieve, obtain the LiNi that the surface is coating the doping of MgO_xCo_yMg_zO₂Particle, particle diameter are 2～7.5 μ m.

2. the preparation method of a kind of doping as claimed in claim 1 and surface coated lithium nickel cobalt dioxide is characterized in that described lithium salts, nickel salt, brill salt, magnesium salts selection carbonate, oxalates, acetate, during the weighing lithium salts, and excessive 0.1～1% (W).

3. the preparation method of a kind of doping as claimed in claim 1 and surface coated lithium nickel cobalt dioxide is characterized in that in step (1) with the oxide replacement magnesium salts of manganese salt or manganese or the oxide of magnesium.

4. the preparation method of a kind of doping as claimed in claim 1 and surface coated lithium nickel cobalt dioxide, when it is characterized in that in step (1) the raw materials weighing batching, it is 0.01 the magnesium salts or the oxide of magnesium that the carbonate of allocating vanadium or rare earth element into replaces being no more than molfraction.