CN102522541A - Anode material and preparation method thereof - Google Patents
Anode material and preparation method thereof Download PDFInfo
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- CN102522541A CN102522541A CN2011103951734A CN201110395173A CN102522541A CN 102522541 A CN102522541 A CN 102522541A CN 2011103951734 A CN2011103951734 A CN 2011103951734A CN 201110395173 A CN201110395173 A CN 201110395173A CN 102522541 A CN102522541 A CN 102522541A
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Abstract
A method for preparation of an anode material comprises (1) providing a mixture of an iron source, a lithium source, a phosphorous source and an oxygen source; and (2) sintering the mixture, adding a magnesium element prior to the sintering process or during the sintering process, and enabling the magnesium element to be partially or fully volatilized. By means of the method, purity of a product is between 90%-95%, capacity ratio per gram is 150-160 mAh/g, and the initial crystalline particle size can be controlled within the range of 1-5mu and does not exceed 10mu at most.
Description
Technical field
The present invention is relevant with cell positive material, and is special, relevant at the positive electrode of the lithium ion battery of electric tool, consumer electronics, electric motor car with use, for example LiFePO 4 (chemical formula: LiFePO
4).
Background technology
Lithium ion battery is meant lithium ion (Li wherein
+) embedding and take off a kind of battery that discharges and recharges of embedding positive and negative pole material, its anodal general lithium intercalation compound that adopts is like the cobalt acid lithium (LiCoO of layered crystal structure
2), lithium nickelate (LiNiO
2) with the LiMn2O4 (LiMn of spinel crystal structure
2O
4).During charging, Li
+Take off embedding from positive pole, be embedded into negative pole through electrolyte, the compensation charge of electronics supplies to negative pole from external circuit simultaneously; Then opposite during discharge, Li
+Take off embedding from negative pole, be embedded into positive electrode through electrolyte.
LiFePO
4The general preparation methods such as high temperature solid-state is synthetic, the chemical Shen Dian of being total to that adopt are synthetic, and the synthetic employing of wherein general high temperature solid-state is with lithium (Li) compound, iron (Fe) compound and phosphoric acid (PO
4) after the compound, extrusion forming, put into sintering furnace, with the synthetic LiFePO of the temperature sintering of 550 to 1200 degree Celsius
4Powder; General chemistry is total to Shen Dian then with lithium (Li) compound, iron (Fe) compound and phosphoric acid (PO
4) compound adds in the solution and react, and after super-dry, obtains LiFePO again
4Powder.
LiFePO in preparation
4In the positive electrode, promote LiFePO with purity
4The hardness of powder is high more, and machining is difficult more, is difficult for powder is ground, and can't effectively control LiFePO
4Particle size, excessive particle appears easily, if sieve powder step has omission, excessive powder granule can cause the battery short circuit made.
This just need provide a kind of new preparation method, under the situation that improves purity, carries out machining easily, and acquisition needs the particle size size easily, and does not allow particle excessive.
Summary of the invention
On the one hand, the present invention provides a kind of positive electrode, following general formula LiMg
yFePO
4, 0.002 ≦ y ≦ 0.05 wherein.
On the other hand, the present invention provides a kind of method for preparing positive electrode, and this method comprises: the compounding substances that 1, the compound of source of iron, lithium source, phosphorus source, oxygen source is provided; 2, compounding substances is carried out sintering, add magnesium elements before sintering process or in the sintering process, wherein, in sintering process, let part or all of magnesium elements vapor away.In some preferred modes; Let behind the magnesium elements its and other compound or element reaction formation contain the compound of magnesium earlier through adding; From compound or crystal, volatilize by magnesium elements is all or part of through sintering then, let the hardness of crystal reduce like this, grind easily; Thereby effectively the size of crystallization control particle can not let particle size excessive.
In some concrete modes, this method comprises: 1, the compounding substances that source of iron, lithium source, phosphorus source, oxygen source are provided is carried out sintering; 2, in the product of step 1, behind the material of adding magnesium source, carry out sintering again and remove part or all of magnesium elements again.In some preferred modes, in step 1, spend to 400 degree, through 2-8 hour sintering with Celsius temperature 150.Preferred, the sintering of step 1 carries out under vacuum environment.Preferably; The sintering step of step 2 can be divided into: step (3), to the product (after having added the magnesium source) of step (2) in reduction (hydrogen) or inert atmosphere (nitrogen or argon gas); To 600 degree sintering, through 4-24 hour, making became semi-finished product with 450 degree Celsius; Make raw material reaction and remove reaction discarded object (like ammonia, carbon dioxide etc.), and let magnesium and other material react.Preferably; Can also comprise step (4) after the step (3): let the product of step (3) in reduction (hydrogen) or inert atmosphere (nitrogen or argon gas), with 600 degree Celsius to 1200 degree sintering, through 4-24 hour; Make material crystallize into particle, letting simultaneously becomes end product after the magnesium elements volatilization.
In other concrete modes, this method comprises: 1, provide source of iron, lithium source, phosphorus source, oxygen source and magnesium source material to mix; 2, mixture is carried out sintering.Sintering step is: sintering step 1: earlier mixture is spent to 400 degree sintering, through 2-8 hour with Celsius temperature 150; Sintering step 2: and then let sintering step 1 product in reduction (hydrogen) or inert atmosphere (nitrogen or argon gas); Spend to 600 degree sintering with Celsius 450; Through 4-24 hour, make to become semi-finished product and let magnesium and other compound react to form the compound that contains magnesium; Sintering step 3: the product of relief sintering step 2 to 1200 degree sintering, through 4-24 hour, makes material crystallize into particle with 600 degree Celsius in reduction (hydrogen) or inert atmosphere (nitrogen or argon gas), becomes end product.
Optional, sintering step is: sintering step 1: earlier mixture is spent to 400 degree sintering, through 2-8 hour with Celsius temperature 150; Sintering step 2 and then let sintering step 1 product in reduction (hydrogen) or inert atmosphere (nitrogen or argon gas), to 1200 degree sintering,, make material crystallize into particle with 450 degree Celsius through 4-24 hour, become end product.Preferably, in above all sintering processes, all be under the condition of vacuum, optional, carry out letting sintering step 1 be under the condition of vacuum.
In some preferred modes, the content that adds magnesium (Mg) is 5%-0.2% (molar percentage).
In above some modes of all enforcement, let the not ear of iron, lithium, phosphorus, oxygen element be 1:1:1:4.
In above all modes, source of iron, lithium source substance comprise oxalic acid (C
2O
4 2-), carbonic acid (CO
3 2-) material of root; For example, the ferrous iron source compound is selected from: ferrous oxalate (Fe
2C
2O
4), di-iron trioxide (Fe
2O
3), ferrous oxalate hydrate (Fe
2C
2O
4.2H
2O) one or more in.P source compound is selected from: ammonium di-hydrogen phosphate (NH
2PO
4) or ammonium dihydrogen phosphate (NH
4H
2PO
4) in one or more.For example, the ferrous iron source compound of carbonate is (like Fe
2C
2O
4), the Li source compound of carbonate is (like Li
2CO
3) with the source of phosphoric acid compound (like ammonium dihydrogen phosphate (NH
2PO
4)) etc. raw material react preparation LiFePO 4 (LiFePO
4).
Beneficial effect
The method of the present invention is produced LiMg
y FePO
4 crystalline powder generated split it is easy to achieve the required mechanical polishing powder, and control of the initial crystal grain size of 1 to 5 microns and a maximum of not more than 10 microns.
Description of drawings
Fig. 1 is the process chart (LiFePO 4) of preparation positive electrode of the present invention in the embodiments of the invention 1.
Fig. 2 is the process chart (LiFePO 4) of preparation positive electrode of the present invention in the embodiments of the invention 3.
Embodiment
Illustrate the present invention at present and how to implement, these illustrate just adopt limited example to explain how the present invention implements can not be as restriction to claim scope of the present invention.
Embodiment
1. embodiment 1: add magnesium carbonate and not with vacuum-sintering.
1.1 raw material:
1.1.1 ammonium di-hydrogen phosphate (NH
2PO
4), 39.8 grams
1.1.2 ferrous oxalate (FeC
2O
4), 97.5 grams
1.1.3 lithium carbonate (Li
2CO
3), 8.0 grams
1.1.4 magnesium carbonate (MgCO
3), 0.4 gram
1.2 the preparation method, the embodiment of disrupting agent in the middle of adding: (like Fig. 2)
1.2.1 first blend step, with the 1.1st described ammonium di-hydrogen phosphate, ferrous oxalate, lithium carbonate and magnesium carbonate through mixing, grind to form the homogeneous mixture of powder shape;
1.2.2 first sintering step is heated 1.2.1 item raw material 2 hours with Celsius temperature 250 degree under nitrogen protection, separates liquid, the gaseous impurity that produces in the sintering process with per approximately mode of changing nitrogen in 30 minutes;
1.2.3 second sintering step under nitrogen protection, through 500 degree sintering 2 hours Celsius, and separates the carbon dioxide (CO that produces with 1.2.2 item product
2) and ammonia (NH
3) and oxygen (O
2);
1.2.4 the 3rd sintering knot is rapid, and 1.2.3 item product under nitrogen protection, is spent sintering 5 hours through Celsius 800.
1.2.5 grind sieve powder step, material ground, screen to the LiMg of ultimate size about 1 to 10 micron
yFePO
4Powder, y approximates 0.5%.
1.3 product: add magnesium carbonate and, obtain chemical formula LiMg not with the preparation method of vacuum-sintering
yFePO
4Powder, y=0.5%, the gram volume ratio is about 135 mAh/g, and average grain diameter D
97Be about 9 microns.
3. embodiment 3: add magnesium carbonate and not with the preparation method of vacuum-sintering.
3.1 raw material:
3.1.1 ammonium di-hydrogen phosphate (NH
2PO
4), 43.8 grams
3.1.2 ferrous oxalate (FeC
2O
4), 97.5 grams
3.1.3 lithium carbonate (Li
2CO
3), 8.8 grams
3.1.4 magnesium carbonate (MgCO
3), 0.5 gram
3.2 the preparation method, the embodiment of disrupting agent in the middle of adding: (like Fig. 2)
3.2.1 first blend step, with the 3.1st described ammonium di-hydrogen phosphate, ferrous oxalate, lithium carbonate through mixing, grind to form the homogeneous mixture of powder shape;
3.2.2 first sintering step is heated 3.2.1 item raw material 2 hours with Celsius temperature 300 degree under nitrogen protection, separates liquid, the gaseous impurity that produces in the sintering process with per approximately mode of changing nitrogen in 30 minutes;
3.2.3 second blend step mixes, grinds to form even mixed powder with 3.2.2 item product with magnesium carbonate.
3.2.4 second sintering step under nitrogen protection, through 550 degree sintering 2 hours Celsius, and separates the carbon dioxide (CO that produces with 3.2.3 item product
2) and ammonia (NH
3) and oxygen (O
2);
3.2.5 the 3rd sintering step under nitrogen protection, is spent sintering 3 hour through Celsius 800 with 3.2.4 item product;
3.2.6 grind sieve powder step, material ground, screen to the LiMg of ultimate size about 1 to 10 micron
yFePO
4Powder, y approximates 0.8%.
3.3 product: add magnesium carbonate and, obtain chemical formula LiMg not with the preparation method of vacuum-sintering
yFePO
4Powder, y=0.8 %, the gram volume ratio is about 130 mAh/g, and average grain diameter D
97Be about 8 microns.
5. embodiment 5: add magnesium carbonate and not with the preparation method of vacuum-sintering.
5.1 raw material:
5.1.1 ammonium di-hydrogen phosphate (NH
2PO
4), 39.8 grams
5.1.2 ferrous oxalate (FeC
2O
4), 97.5 grams
5.1.3 lithium carbonate (Li
2CO
3), 8.0 grams
5.1.4 magnesium carbonate (MgCO
3), 0.4 gram
5.2 the preparation method, the embodiment of disrupting agent in the middle of adding: (like Fig. 2)
5.2.1 first blend step, with the 5.1st described ammonium di-hydrogen phosphate, ferrous oxalate, lithium carbonate through mixing, grind to form the homogeneous mixture of powder shape;
5.2.2 first sintering step is heated 5.2.1 item raw material 1 hour with Celsius temperature 350 degree under nitrogen protection, separates liquid, the gaseous impurity that produces in the sintering process with per approximately mode of changing nitrogen in 30 minutes, gets rid of;
5.2.3 second blend step mixes, grinds to form even mixed powder with 5.2.2 item product with magnesium carbonate.
5.2.4 second sintering step under nitrogen protection, through 550 degree sintering 2 hours Celsius, and separates the carbon dioxide (CO that produces with 3.2.3 item product
2) and ammonia (NH
3) and oxygen (O
2);
5.2.5 the 3rd sintering step under nitrogen protection, is spent sintering 3 hour through Celsius 750 with 5.2.4 item product;
5.2.6 grind sieve powder step, material ground, screen to the LiMg of ultimate size about 1 to 10 micron
yFePO
4Powder, y approximates 0.3%.
5.3 product: add magnesium carbonate and, obtain chemical formula LiMg not with the preparation method of vacuum-sintering
yFePO
4Powder, y=0.6%, the gram volume ratio is about 135 mAh/g, and average grain diameter D
97Be about 10 microns.
2. embodiment 2: do not add magnesium carbonate and with the preparation method of vacuum-sintering.
2.1 raw material:
2.1.1 ammonium di-hydrogen phosphate (NH
2PO
4), 39.8 grams
2.1.2 ferrous oxalate (FeC
2O
4), 97.5 grams
2.1.3 lithium carbonate (Li
2CO
3), 8.0 grams
2.2 the preparation method, the embodiment of vacuum-sintering: (like Fig. 1)
2.2.1 first blend step, with the 2.1st described ammonium di-hydrogen phosphate, ferrous oxalate, lithium carbonate through mixing, grind to form the homogeneous mixture of powder shape.
2.2.2 first sintering step is heated 2.2.1 item raw material 2 hours with Celsius temperature 250 degree in vacuum environment, separates the liquid, the gaseous impurity that produce in the sintering process, removes oxalic acid, carbonic acid side by side, stays phosphoric acid;
2.2.3 second sintering step under vacuum environment, through 500 degree sintering 2 hours Celsius, and separates the carbon dioxide (CO that produces with 2.2.2 item product
2) and ammonia (NH
3) and oxygen (O
2);
2.2.4 the 3rd sintering knot is rapid, and 2.2.3 item product under nitrogen protection, is spent sintering 5 hours through Celsius 800;
2.2.5 grind sieve powder step, material ground, screen to the LiFePO of ultimate size about 1 to 10 micron
4Powder.
2.3 product: do not add magnesium carbonate and, can obtain chemical formula LiFePO with the preparation method of vacuum-sintering
4Powder, the gram volume ratio is about 150 mAh/g, and average grain diameter D
97Be about 25 microns.
4. embodiment 4: do not add magnesium carbonate and with the preparation method of vacuum-sintering.
4.1 raw material:
4.1.1 ammonium di-hydrogen phosphate (NH
2PO
4), 39.8 grams
4.1.2 ferrous oxalate (FeC
2O
4), 97.5 grams
4.1.3 lithium carbonate (Li
2CO
3), 8.0 grams
4.3 the preparation method, the embodiment of vacuum-sintering: (like Fig. 1)
4.2.1 first blend step, with the 4.1st described ammonium di-hydrogen phosphate, ferrous oxalate, lithium carbonate through mixing, grind to form the homogeneous mixture of powder shape.
4.2.2 first sintering step is heated 4.2.1 item raw material 2 hours with Celsius temperature 300 degree in vacuum environment, separates the liquid, the gaseous impurity that produce in the sintering process, gets rid of;
4.2.3 second sintering step under vacuum environment, through 500 degree sintering 4 hours Celsius, and separates the carbon dioxide (CO that produces with 4.2.2 item product
2) and ammonia (NH
3) and oxygen (O
2);
4.2.4 the 3rd sintering knot is rapid, and 4.2.3 item product under nitrogen protection, is spent sintering 10 hours through Celsius 700;
4.2.5 grind sieve powder step, material ground, screen to the LiFePO of ultimate size about the 1-5 micron
4Powder.
4.3 product: do not add magnesium carbonate and, can obtain chemical formula LiFePO with the preparation method of vacuum-sintering
4Powder, the gram volume ratio is about 159 mAh/g, and average grain diameter D
97Be about 20 microns.
6. embodiment 6: do not add magnesium carbonate and with the preparation method of vacuum-sintering.
6.1 raw material:
4.1.1 ammonium di-hydrogen phosphate (NH
2PO
4), 39.8 grams
4.1.2 ferrous oxalate (FeC
2O
4), 97.5 grams
4.1.3 lithium carbonate (Li
2CO
3), 8.0 grams
6.3 the preparation method, the embodiment of vacuum-sintering: (like Fig. 1)
6.2.1 first blend step, with the 6.1st described ammonium di-hydrogen phosphate, ferrous oxalate, lithium carbonate through mixing, grind to form the homogeneous mixture of powder shape.
6.2.2 first sintering step is heated 6.2.1 item raw material 2 hours with Celsius temperature 350 degree in vacuum environment, separates the liquid, the gaseous impurity that produce in the sintering process, gets rid of;
6.2.3 second sintering step under nitrogen protection, through 550 degree sintering 4 hours Celsius, and separates the carbon dioxide (CO that produces with 6.2.2 item product
2) and ammonia (NH
3) and oxygen (O
2);
6.2.4 the 3rd sintering knot is rapid, and 6.2.3 item product under nitrogen protection, is spent sintering 10 hours through Celsius 800;
6.2.5 grind sieve powder step, material ground, screen to the LiFePO of ultimate size about 1 to 10 micron
4Powder.
6.3 product: do not add magnesium carbonate and, can obtain chemical formula LiFePO with the preparation method of vacuum-sintering
4Powder, the gram volume ratio is about 164 mAh/g, and average grain diameter D
97Be about 31 microns.
embodiment 7: add magnesium carbonate and with the preparation method of vacuum-sintering.
7.1 raw material:
7.1.1 ammonium di-hydrogen phosphate (NH
2PO
4), 39.8 grams
7.1.2 ferrous oxalate (FeC
2O
4), 97.5 grams
7.1.3 lithium carbonate (Li
2CO
3), 8.0 grams
7.1.4 magnesium carbonate (MgCO
3), 0.5 gram
7.2 the preparation method, the embodiment of vacuum-sintering:
7.2.1 first blend step, with the 7.1st described ammonium di-hydrogen phosphate, ferrous oxalate, lithium carbonate and magnesium carbonate through mixing, grind to form the homogeneous mixture of powder shape.
7.2.2 first sintering step is heated 7.2.1 item raw material 2 hours with Celsius temperature 300 degree in vacuum environment, separates the liquid, the gaseous impurity that produce in the sintering process, gets rid of;
7.2.3 second sintering step under vacuum environment, through 500 degree sintering 4 hours Celsius, and separates the carbon dioxide (CO that produces with 7.2.2 item product
2) and ammonia (NH
3) and oxygen (O
2);
7.2.4 the 3rd sintering knot is rapid, and 7.2.3 item product under nitrogen protection, is spent sintering 10 hours through Celsius 700;
7.2.5 grind sieve powder step, material ground, screen to the LiMg of ultimate size about 1 to 10 micron
yFePO
4Powder, y approximates 0.5%;
7.3 product: add magnesium carbonate and, can obtain chemical formula LiMg with the preparation method of vacuum-sintering
yFePO
4Powder, y approximates 0.5%, and the gram volume ratio is about 160 mAh/g, and average grain diameter D
97Be about 8 microns.
The comparative example
1. the comparative example 1
1.1 the preparation method of the positive active material LiFePO 4 of this Comparative Examples explanation prior art
1.2 Comparative Examples one
1.2.1 raw material:
Ammonium di-hydrogen phosphate (NH
2PO
4) 39.8 grams
Ferrous oxalate (FeC
2O
4) 97.5 grams
Lithium carbonate (Li
2CO
3) 8.0 grams.
1.2.2 under nitrogen protection, the mixture of three kinds of raw materials of 1.2.1 item being formed with 800 degree Celsius carries out once sintered, sintering time is 10 hours.
1.2.3 material is ground, screens to the LiFePO of ultimate size about 1 to 10 micron
4Powder, average grain diameter D
97Be about 50 microns, the gram volume ratio is about 115 Am/h
2. the comparative example 2
2.1 lithium carbonate (Li with 8.0 grams
2CO
3), 97.5 the gram ferrous oxalate (FeC
2O
4), 39.8 the gram ammonium di-hydrogen phosphate (NH
2PO
4) with 0.4 the gram magnesium carbonate (LiCO
3) mix;
2.2 under nitrogen protection, with 800 degree Celsius the mixture of 1.2.2 item is carried out once sinteredly, sintering time is 10 hours
2.3 material is ground, screens to the LiMg of ultimate size about 1 to 10 micron
yFePO
4Powder, y approximates 5%, average grain diameter D
97Be about 40 microns, the gram volume ratio is about 115 Am/h
3. embodiment 8: utilize embodiment 1-7 and comparative example 1-2 to process battery
3.1 anodal preparation
3.1.1 ferrous phosphate powder for lithium, 5 gram alite paste Kynoar (PVDF) and 5 grams that 90 grams are made by embodiment 1-7 and Comparative Examples 1-2) the conductive agent carbon black joins in the N-pyrrolidone methyl (NMP) of 50 grams the uniform anode sizing agent of stirring formation in de-airing mixer.
3.1.2 this anode sizing agent is spread upon the both sides that thickness is 0 micron aluminium foil equably, then in 150 ℃ of following oven dry, roll-in, cut to make and be of a size of 140 * 65 millimeters positive pole, wherein contain the ferrous phosphate powder for lithium of the 5.3 gram active components of having an appointment.
3.2 the preparation of negative pole
3.2.1 90 gram negative electrode active composition native graphites, 5 gram alite paste Kynoar (PVDF) and 5 gram conductive agent carbon blacks are joined in the N-pyrrolidone methyl (NMP) of 100 grams, in de-airing mixer, stir and form uniform cathode size.
3.2.2 this cathode size is spread upon the both sides that thickness is 20 microns Copper Foil equably, then in 90 ℃ of following oven dry, roll-in, cut to make and be of a size of 140 * 65 millimeters negative pole, wherein contain the native graphite of the 3.8 gram active components of having an appointment.
3.3 battery assembling
3.3.1 respectively above-mentioned positive pole, negative pole and polypropylene screen laminate patch are processed the pole piece of a square lithium ion battery;
3.3.2 with LiF
6Be dissolved in by the concentration of 1 mol in the mixed solvent of EC/EMC/DEC=1:1:1 and form nonaqueous electrolytic solution;
Seal 3.3.3 this electrolyte is injected the battery aluminum hull with the amount of 3.8 g/Ah, process lithium rechargeable battery AC1, the AC2 of lithium rechargeable battery A1, A2, A3, A4, A5, A6, A7 and the Comparative Examples of the embodiment of the invention respectively.
4. battery performance test
4.1 lithium ion A1, A2, A3, A4, A5, A6, A7 and AC1, AC2 battery that the 3.3.2 item is made are placed on test respectively cashier's office in a shop, carry out constant current charge with 0.2C earlier, the charging upper limit to 3.75 volt; After shelving 20 minutes, be discharged to 2.0 volts, the discharge capacity first of recording cell from 3.45 volts with the electric current of 0.2C.
4.2 the specific discharge capacity according to this formula counting cell: specific discharge capacity=battery is discharge capacity (MAH)/positive electrode weight (gram) first.
4.3 the result as table 1 as shown in:
Table
battery performance test data
| Embodiment or Comparative Examples | The battery numbering | Battery is discharge capacity (MAH) first | Specific discharge capacity (MAH/gram) |
| Embodiment one | A1 | 769 | 145 |
| Embodiment two | A2 | 816 | 154 |
| Embodiment three | A3 | 800 | 151 |
| Embodiment four | A4 | 843 | 159 |
| Embodiment five | A5 | 822 | 155 |
| Embodiment six | A6 | 869 | 164 |
| Embodiment seven | A7 | 801 | 151 |
| Comparative Examples one | AC1 | 578 | 109 |
| Comparative Examples two | AC1 | 535 | 101 |
4.4 data from table 1 can be found out; LiFePO 4 by the Comparative Examples preparation; Discharge capacity first and the specific discharge capacity performance of battery AC1, the AC2 of preparation are all undesirable; By the LiFePO 4 of embodiment of the invention preparation, the battery A1 of preparation, A2, A3, A4, A5, A6, A7 discharge capacity and specific discharge capacity first are significantly improved.
Claims (13)
1. method for preparing positive electrode, this method comprises: (1), the mixture of the compound of source of iron, lithium source, phosphorus source, oxygen source is provided; (2), mixture is carried out sintering, add magnesium elements before sintering process or in the sintering process; Wherein, let magnesium elements in the process of sintering, partly or entirely volatilize, burn or react with the oxygen source compound.
2. method according to claim 1, wherein, the sintering temperature that lets magnesium elements volatilize is 600-1200 ℃.
3. method according to claim 2, wherein, sintering step may further comprise the steps: let described mixture after temperature is to carry out sintering reaction 1-12 hour under 150-400 ℃, add magnesium elements again.
4. method according to claim 3, wherein, to the mixture after adding magnesium elements in reduction or inert atmosphere, temperature is 450 ℃-600 ℃, carries out 4-24 hour sintering, lets magnesium and other element react.
5. method according to claim 4, wherein, described sintering method also comprises: let the compound that includes magnesium elements in reduction or inert atmosphere, temperature be 600 ℃-1200 ℃ sintering 4-24 hour, let part or all of magnesium elements volatilization.
6. according to the described method of one of claim 1-5, wherein, Fe source compound is selected from ferrous oxalate (Fe
2C
2O
4), ferrous oxalate hydrate ((Fe
2C
2O
4.2H
2O), one or more in ferric carbonate or the ferrous carbonate; Li source compound is selected from one or more in lithium oxalate or the lithium carbonate carbon.
7. according to the described method of one of claim 1-5, wherein, P source compound is selected from: ammonium di-hydrogen phosphate (NH
2PO
4) or ammonium dihydrogen phosphate (NH
4H
2PO
4) in one or more.
8. according to the described method of one of claim 1-5, wherein, the not ear of iron, lithium, phosphorus, oxygen element is 1:1:1:4.
9. according to the described method of one of claim 1-5, the molar percentage of the magnesium elements that is wherein added is 0.2%-5%.
10. according to the described method of one of claim 1-5, the magnesium elements that is wherein added comes from one or both in magnesium oxalate, the magnesium carbonate.
11. according to the described method of one of claim 1-5, wherein sintering carries out under vacuum condition.
12. method according to claim 1, through sintering by magnesium elements all or part of from compound or crystal, wave before, let magnesium elements and other compound or element reaction form to contain the compound or the crystal of magnesium.
13. a positive electrode comprises following general formula LiMg
yFePO
4Powder, wherein 0.002 ≦ y ≦ 0.05.
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| CN2011103951734A CN102522541A (en) | 2011-12-02 | 2011-12-02 | Anode material and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1907844A (en) * | 2006-08-11 | 2007-02-07 | 广州市鹏辉电池有限公司 | High density ultrafine composite ferric lithium phosphate anode material and preparation method |
| CN101081696A (en) * | 2007-05-15 | 2007-12-05 | 深圳市贝特瑞电子材料有限公司 | Ferric phosphate lithium material for lithium ion powder cell and preparation method thereof |
| CN101399342A (en) * | 2007-09-28 | 2009-04-01 | 深圳市比克电池有限公司 | Lithium iron phosphate positive pole material |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1907844A (en) * | 2006-08-11 | 2007-02-07 | 广州市鹏辉电池有限公司 | High density ultrafine composite ferric lithium phosphate anode material and preparation method |
| CN101081696A (en) * | 2007-05-15 | 2007-12-05 | 深圳市贝特瑞电子材料有限公司 | Ferric phosphate lithium material for lithium ion powder cell and preparation method thereof |
| CN101399342A (en) * | 2007-09-28 | 2009-04-01 | 深圳市比克电池有限公司 | Lithium iron phosphate positive pole material |
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