CN105336947A - Lithium manganese phosphate chloride electrode material and preparation method thereof - Google Patents

Abstract

The invention discloses a lithium manganese chlorophosphate electrode material and a preparation method thereof. The electrode material is a particle of nanometer to submicron size coated with a carbon film on the surface, and its chemical formula is Li ₂ MnPO ₄ ·A. In the formula, Mn is positive divalent, and A is one or more of F ^- , Cl ^- , OH ^- . This lithium battery electrode material is prepared by a solid-state reaction method. Manganese source, phosphorus source, lithium source, carbonic acid and anion source are mixed evenly according to the stoichiometric ratio, wet ball milled and spray dried, calcined and cooled under the protection of an inert gas, and the lithium manganous chlorophosphate electrode material is obtained . The organic acid groups contained in the raw materials can prevent manganese from being oxidized during calcination. The lithium manganous chlorophosphate provided by the invention is obviously superior to the existing lithium iron phosphate in terms of charge and discharge capacity and charge and discharge rate, and provides guarantee for energy storage of high-power electrical appliances.

Description

A kind of lithium manganous chlorophosphate electrode material and preparation method thereof

technical field

The invention relates to a lithium manganous chlorophosphate electrode material and a preparation method thereof.

Background technique

Lithium (sub)iron phosphate is currently the most widely used lithium battery electrode material. Compared with other types of lithium battery electrode materials, it has high safety, long service life, good high temperature performance, no memory effect, light weight, and environmental protection. Etc. However, there are also disadvantages such as poor low-temperature performance, poor high-power charge and discharge performance, and low energy density. Therefore, it cannot be used as an energy storage material for high-power electrical appliances such as electric vehicles.

The present invention attempts to provide a lithium battery electrode material with higher energy density than lithium iron phosphate.

Contents of the invention

The object of the present invention is to provide a lithium manganese chlorophosphate electrode material and a preparation method thereof.

A lithium manganese chlorophosphate electrode material, which is a nano-to-submicron particle coated with a carbon film on the surface, the molecular formula is: Li ₂ MnPO ₄ ·A, where Mn is positive divalent, A is anion , is one or more of F ^- , Cl ^- , OH ^- .

The steps of a preparation method of lithium manganous chlorophosphate electrode material are as follows:

1) Mix the manganese source, phosphorus source, lithium source and anion source according to the stoichiometric ratio given by the molecular formula, and add a carbon source equivalent to 0.1% to 1% of the total weight of the manganese source, phosphorus source, and lithium source. Water 3 to 5 times the total weight of raw materials, ball milled for 1 to 3 hours to make a uniform slurry;

The manganese source is one or more of divalent manganese oxides, hydroxides and salt compounds; the phosphorus source is one of ammonium hydrogen phosphate and diammonium hydrogen phosphate; the The lithium source is one or more of lithium acetate, lithium formate, lithium citrate, and lithium oxalate; the anion source is one or more of lithium, manganese, and ammonium chloride, fluoride, and hydroxide ; The carbon source is one or more of water-soluble organic acids, low-viscosity polyvinyl alcohol, and glucose.

2) The resulting pulp is spray-dried at a temperature of 150°C to 260°C to obtain dry powder with uniform particle size;

3) Press the powder into a cylindrical or other shape, keep the temperature at 550°C to 850°C for 2 to 6 hours in a vacuum environment or a protective atmosphere, and cool; the obtained product is lithium manganous phosphate electrode material.

The protective atmosphere is one or more of nitrogen or argon.

The lithium manganous chlorophosphate electrode material provided by the invention has significantly improved charge and discharge capacity and charge and discharge rate, and provides guarantee for energy storage of high-power electrical appliances.

detailed description

The lithium manganese chlorophosphate electrode material provided by the present invention is a nanometer to submicron particle size coated with a carbon film on the surface, and its molecular formula is: Li ₂ MnPO ₄ ·A, where Mn is positive divalent, and A is an anion , is one or more of F ^- , Cl ^- , OH ^- .

Li ₂ MnPO ₄ ·A is the initial state of the electrode material (state before charging). When charging the lithium-ion battery, Li ions in its molecules enter the electrolyte solution, and Mn also changes from positive divalent to positive tetravalent to maintain The electrical neutrality of the molecular structure. Its state after saturated charging is MnPO ₄ ·A, where Mn is positive tetravalent. Compared with the currently used lithium ferrous phosphate, the molar active lithium ion content of the lithium manganese chlorophosphate provided by the present invention is doubled, so its charge and discharge capacity will also be correspondingly increased.

The steps of the preparation method of lithium manganous chlorophosphate electrode material are as follows:

1) Mix the manganese source, phosphorus source, lithium source and anion source according to the stoichiometric ratio given by the molecular formula, and add a carbon source equivalent to 0.1% to 1% of the total weight of the manganese source, phosphorus source, and lithium source. Water that is 3 to 5 times the total weight of raw materials is ball milled for 1 to 3 hours to make a uniform slurry. After the raw materials are mixed, an intermediate product is formed, which is the precursor of the final product. During the grinding process, the precursor and the solution form a homogeneous mixed phase.

The manganese source is one or more of divalent manganese oxides, hydroxides and salt compounds; the phosphorus source is one of ammonium hydrogen phosphate and diammonium hydrogen phosphate; the The lithium source is one or several kinds of lithium acetate, lithium formate, lithium citrate, and lithium oxalate. The direct use of lithium carbonate should be avoided, because the decomposition temperature of lithium carbonate is high, which requires a higher calcination temperature, and may cause sintering of the product at the same time. reduce its electrochemical performance; the anion source is one or more of lithium, manganese, ammonium chloride, fluoride, and hydroxide; the carbon source is water-soluble organic acid, low-viscosity polyethylene One or more of alcohol and glucose.

2) The obtained pulp is spray-dried at a temperature of 150°C to 260°C to obtain dry powder with uniform particle size.

Before spray drying, the slurry should be continuously stirred to prevent its precipitation and stratification; spray drying can quickly dehydrate and dry the material to obtain a powder with uniform composition.

Water-soluble organic acid, low-viscosity polyvinyl alcohol, and glucose added as carbon sources act as dispersants during the spray-drying process and can inhibit particle agglomeration.

3) Press the powder into a cylindrical or other shape, keep the temperature at 550°C to 850°C for 2 to 6 hours in a vacuum environment or a protective atmosphere, and cool; the obtained product is lithium manganous phosphate electrode material.

The protective atmosphere is one or more of nitrogen or argon. The protective atmosphere avoids the use of reducing gases such as hydrogen, so as not to form metal elements in the product.

The purpose of compressing the powder before calcination is to compress the volume of the powder, and at the same time drive out the air and oxygen between the particles, and keep the powder in a reducing environment. One of the reaction examples of the calcination process is as follows:

Mn(CH ₃ COO) ₂ +LiCH ₃ COO+(NH ₄ ) ₂ HPO ₄ +LiCl=Li ₂ MnPO ₄ Cl+3CO ₂ +3CH ₄ +2NH ₃ (1)

In formula (1), manganese acetate provides manganese source, lithium acetate provides part of lithium, diammonium hydrogen phosphate provides phosphorus, and lithium chloride provides chlorine and part of lithium.

In the raw materials, the organic acid radicals act as reducing agents, and the reducing gas released during the calcination and decomposition process keeps the manganese divalent. It is one of the keys of the present invention to keep the variable-valence elements in a low-valence state during the calcination synthesis process.

During the calcination process, the water-soluble organic acid, low-viscosity polyvinyl alcohol, and glucose added as carbon sources are decomposed and carbonized. resistivity.

The obtained product is lithium manganese chlorophosphate, which can be used as electrode material of lithium battery. Compared with LiFePO ₄ used in the past, the molar density of Li ₂ MnPO ₄ ·A active lithium ions provided by the invention is doubled, and the preparation process is simple and the source of raw materials is wide.

The present invention is described in detail below in conjunction with embodiment.

Example 1

1) Weigh 19.67Kg of manganese acetate, 10.57Kg of diammonium hydrogen phosphate, 5.28Kg of lithium acetate, and 3.39Kg of lithium chloride, add 100L of water and 0.2 kg of glucose, stir evenly, pour into a ball mill, and mill for 1 hour.

2) The pulp obtained from ball milling is spray-dried at 150°C to obtain dry powder with uniform particle size.

3) Press the powder into a cylindrical shape with a compression die, put it into a closed calciner, calcinate at 550°C for 6 hours in a vacuum environment, and cool to room temperature to obtain lithium manganous phosphate chloride.

Example 2

1) Weigh 5.68Kg of MnO, 10.57Kg of diammonium hydrogen phosphate, 5.28Kg of lithium acetate, and 2.07Kg of lithium fluoride, add 80L of water, 0.25kg of citric acid, stir evenly, pour into a ball mill, and mill for 2 hours.

2) The slurry obtained by ball milling is spray-dried at 260°C to obtain dry powder with uniform particle size.

3) Press the powder into a cylindrical shape with a compression die, put it into a closed calciner, calcinate at 850°C for 2 hours in a vacuum environment, and cool to room temperature to obtain lithium manganous fluorophosphate.

Example 3

1) Weigh 13Kg of MnCl ₂ 4H ₂ O, 10.57Kg of diammonium hydrogen phosphate, 5.28Kg of lithium acetate, 3.35Kg of lithium hydroxide, add 90L of water, 0.15kg of Tween-40, stir well and pour into a ball mill, and mill for 3 hours .

2) The pulp obtained from ball milling is spray-dried at 200°C to obtain dry powder with uniform particle size.

3) Press the powder into a cylindrical shape with a compression die, put it into a closed calciner, calcinate at 600°C for 3 hours in a vacuum environment, and cool to room temperature to obtain lithium hydroxy manganous phosphate.

Example 4

1) Weigh Mn ₃ (PO ₄ ) ₂ 3H ₂ O 8.18Kg, diammonium hydrogen phosphate 2.64Kg, lithium acetate 3.94Kg, lithium chloride 2.54Kg, add 80L water, 0.17kg low viscosity polyvinyl alcohol, stir well Pour into a ball mill and ball mill for 1 hour.

2) The pulp obtained by ball milling is spray-dried at 180°C to obtain dry powder with uniform particle size.

3) Press the powder into a cylindrical shape with a compression mold, put it into a closed calciner, and calcinate at 700°C for 3 hours in a vacuum environment, and cool to room temperature to obtain lithium manganous phosphate chloride.

Example 5

1) Weigh Mn(NO ₃ ) ₂ 4H ₂ O20Kg, diammonium hydrogen phosphate 10.57Kg, lithium acetate 5.28Kg, lithium chloride 3.39Kg, add 120L water, 0.2 kg benzenesulfonic acid, stir well and pour into the ball mill, Ball mill for 1 hour.

2) The pulp obtained by ball milling is spray-dried at 160°C to obtain dry powder with uniform particle size.

3) Press the powder into a cylindrical shape with a compression mold, put it into a closed calciner, calcinate at 650°C for 2 hours in a vacuum environment, and cool to room temperature to obtain lithium manganous phosphate.

Example 6

1) Weigh 5.68Kg of MnO, 9.21Kg of ammonium dihydrogen phosphate, 5.69Kg of lithium formate, 1.91Kg of lithium hydroxide, add 80L of water, 0.2 kg of dodecylbenzenesulfonic acid, stir well and pour into a ball mill, and ball mill for 2 hours .

2) The pulp obtained by ball milling is spray-dried at 260°C to obtain dry powder with uniform particle size.

3) Press the powder into a cylindrical shape with a compression mold, put it into a closed calciner, calcinate at 650°C for 2 hours in a vacuum environment, and cool to room temperature to obtain lithium hydroxy manganous phosphate.

Example 7

1) Weigh 13Kg of MnCl ₂ 4H ₂ O, 10.57Kg of diammonium hydrogen phosphate, 8.15Kg of lithium oxalate, 2.07Kg of lithium fluoride, add 90L of water, 0.1 kg of cetylbenzenesulfonic acid, stir well and pour into the ball mill, Ball mill for 3 hours.

2) The pulp obtained from ball milling is spray-dried at 200°C to obtain dry powder with uniform particle size.

3) Press the powder into a cylindrical shape with a compression die, put it into a closed calciner, and calcinate at 850°C for 3 hours in a vacuum environment, and cool to room temperature to obtain lithium manganous fluorophosphate.

Example 8

1) Weigh Mn ₃ (PO ₄ ) ₂ 3H ₂ O 8.18Kg, diammonium hydrogen phosphate 2.64Kg, lithium citrate 33.84Kg, ammonium chloride 3.21Kg, add 80L water, 0.5 kg glucose, stir well and pour into the ball mill , ball milled for 1 hour.

2) The pulp obtained by ball milling is spray-dried at 180°C to obtain dry powder with uniform particle size.

3) Press the powder into a cylindrical shape with a compression mold, put it into a closed calciner, calcinate at 650°C for 3 hours in a vacuum environment, and cool to room temperature to obtain lithium manganous chlorophosphate.

Example 9

1) Weigh 19.67Kg of manganese acetate, 10.57Kg of diammonium hydrogen phosphate, 5.28Kg of lithium acetate, and 2.07Kg of lithium fluoride, add 90L of water, 0.5kg of citric acid, stir evenly, pour into a ball mill, and mill for 2 hours.

2) The slurry obtained by ball milling is spray-dried at 165°C to obtain dry powder with uniform particle size.

3) Press the powder into a cylindrical shape with a compression die, put it into a closed calciner, calcinate at 850°C for 5 hours in a vacuum environment, and cool to room temperature to obtain lithium manganous fluorophosphate.

Example 10

1) Weigh Mn ₃ (PO ₄ ) ₂ 3H ₂ O 8.18Kg, diammonium hydrogen phosphate 2.64Kg, lithium acetate 3.96Kg, lithium hydroxide 2.51Kg, add 100L water, stir 0.15kg Tween-40 and pour into In a ball mill, ball mill for 3 hours.

2) The slurry obtained by ball milling is spray-dried at 190°C to obtain dry powder with uniform particle size.

3) Press the powder into a cylindrical shape with a compression die, put it into a closed calciner, and calcinate it at 700°C for 4 hours in a vacuum environment, and cool it to room temperature to obtain lithium hydroxy manganous phosphate.

Example 11

1) Weigh 5.68Kg of MnO, 9.21Kg of ammonium dihydrogen phosphate, 11.38Kg of lithium formate, 8.4Kg of concentrated ammonia water, add 60L of water, 0.2 kg of citric acid, stir evenly, pour into a ball mill, and mill for 2 hours.

2) The slurry obtained by ball milling is spray-dried at 220°C to obtain dry powder with uniform particle size.

3) Press the powder into a cylindrical shape with a compression mold, put it into a closed calciner, calcinate at 600°C for 2 hours in a vacuum environment, and cool to room temperature to obtain lithium hydroxy manganous phosphate.

Example 12

1) Weigh Mn(NO ₃ ) ₂ 4H ₂ O20Kg, diammonium hydrogen phosphate 10.57Kg, lithium acetate 10.56Kg, ammonium fluoride 2.96Kg, add 120L water, 0.04kg dodecylbenzenesulfonic acid, stir evenly and pour Into the ball mill, the ball for 2 hours.

2) The slurry obtained by ball milling is spray-dried at 170°C to obtain dry powder with uniform particle size.

3) Press the powder into a cylindrical shape by using a compression die, put it into a closed calciner, and calcinate it at 600°C for 4 hours in a vacuum environment, and cool it to room temperature to obtain lithium manganous fluorophosphate.

Claims (8)

1. A lithium manganese chlorophosphate electrode material is characterized in that it is a nanometer to submicron particle size coated with a carbon film on the surface, and its molecular formula is: Li ₂ MnPO ₄ A, where Mn is positive di Valence, A is an anion, which is one or more of F ^- , Cl ^- , OH ^- . 2. a kind of preparation method of lithium manganese chlorophosphate electrode material as claimed in claim 1, is characterized in that its steps are as follows: 1) Mix the manganese source, phosphorus source, lithium source and anion source according to the stoichiometric ratio given by the molecular formula, and add a carbon source equivalent to 0.1% to 1% of the total weight of the manganese source, phosphorus source, and lithium source. Water 3 to 5 times the total weight of raw materials, ball milled for 1 to 3 hours to make a uniform slurry; 2) The resulting pulp is spray-dried at a temperature of 150°C to 260°C to obtain dry powder with uniform particle size; 3) Press the powder into a cylindrical or other shape, keep the temperature at 550°C to 850°C for 2 to 6 hours in a vacuum environment or a protective atmosphere, and cool; the obtained product is lithium manganous phosphate electrode material. 3. the preparation method of a kind of lithium manganese chlorophosphate electrode material according to claim 2 is characterized in that described manganese source is a kind of in oxide, hydroxide and salt compound of divalent manganese or several. 4. the preparation method of a kind of lithium manganese chlorophosphate electrode material according to claim 2 is characterized in that described phosphorus source is a kind of in ammonium hydrogen phosphate, diammonium hydrogen phosphate. 5. The preparation method of a lithium manganese chlorophosphate electrode material according to claim 2, wherein said lithium source is one or more of lithium acetate, lithium formate, lithium citrate, and lithium oxalate. 6. the preparation method of a kind of lithium manganese chlorophosphate electrode material according to claim 2 is characterized in that described anion source is a kind of in chloride, fluoride, hydroxide of lithium, manganese, ammonium or several. 7. the preparation method of a kind of lithium manganese chlorophosphate electrode material according to claim 2 is characterized in that described carbon source is water-soluble organic acid, low-viscosity polyvinyl alcohol, nonionic organic surfactant, One or several kinds of glucose. 8. The preparation method of a lithium manganese chlorophosphate electrode material according to claim 2, characterized in that the protective atmosphere is one or more of nitrogen or argon.