Method for doping and processing positive electrode material of lithium iron manganese phosphate lithium battery

Abstract

The invention relates to the technical field of lithium battery positive electrode materials, in particular to a method for doping and processing a lithium iron manganese phosphate positive electrode material of a lithium battery. The method comprises the following steps: 1, mixing lithium manganese iron phosphate powder and doped element powder according to a certain proportion; 2, the mixed powder is put into a furnace to be subjected to high-temperature roasting; 3, the roasted powder is cooled and then subjected to mechanical grinding, and the grinding particle size is smaller than 100 meshes; 4, pressing and forming the ground powder to prepare an electrode plate; step 5, drying the electrode plate at the drying temperature of 60-100 DEG C for 1-3 hours; 6, the dried electrode plate is subjected to secondary roasting, the roasting temperature ranges from 600 DEG C to 800 DEG C, and the roasting time ranges from 1 h to 3 h; and step 7, performing electrolyte soaking treatment on the roasted electrode plate. By introducing doping elements, the electrochemical performance and stability of LMP can be improved, meanwhile, the technological process is simplified, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of lithium battery positive electrode materials, and in particular to a method for doping positive electrode materials of lithium manganese iron phosphate lithium batteries. Background Art

[0002] With the rapid development of energy technology, lithium batteries have been widely used in many fields, such as mobile phones, electric vehicles, etc. The positive electrode material is a key component of lithium batteries, and its performance directly affects the electrochemical performance of lithium batteries. Among them, lithium manganese phosphate (Lithium Manganese Phosphate, referred to as LMP) has become a research hotspot for the positive electrode materials of the new generation of lithium batteries due to its high energy density, good safety performance and stable cycle performance. However, how to improve the electrochemical performance and stability of LMP is still an important problem that needs to be solved at present. In the public literature, there have been some studies on the doping modification of LMP. For example, by introducing transition metal elements (such as Co, Ni, Mn, etc.) for doping, the electrochemical properties of LMP can be improved. However, these methods often involve complex synthesis steps and have high requirements for production equipment, so the cost is high, which is not conducive to large-scale industrial production. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for doping positive electrode materials of lithium manganese iron phosphate batteries.

[0004] The technical solution of the present invention is:

[0005] A method for doping a positive electrode material of a lithium manganese iron phosphate battery comprises the following steps:

[0006] Step 1: Mix lithium iron manganese phosphate powder and doping element powder in a certain proportion;

[0007] Step 2: Place the mixed powder into a furnace for high temperature calcination at a temperature of 800-1000°C for 1-3 hours;

[0008] Step 3: The calcined powder is cooled and then mechanically ground to a particle size of less than 100 mesh;

[0009] Step 4: The ground powder is pressed into shape to form an electrode sheet;

[0010] Step 5: The electrode sheet is dried at a temperature of 60-100°C for 1-3 hours;

[0011] Step 6: The dried electrode sheet is subjected to secondary calcination at a temperature of 600-800°C for 1-3 hours;

[0012] Step 7: The calcined electrode sheet is immersed in electrolyte.

[0013] Preferably, in step one, the surface of the lithium battery positive electrode substrate is uniformly coated with iron phosphate powder, and the lithium battery positive electrode also includes a nanofiber membrane, and the nanofiber membrane includes an upper nanofiber membrane layer, a middle nanocellulose gel layer and a lower nanofiber membrane layer.

[0014] Preferably, in step one, the nanofiber membrane layer is prepared by a combination of an electrospinning method and a sol-gel method, and the fiber diameters of the upper nanofiber membrane layer and the lower nanofiber membrane layer are both 50 to 500 nm, and the thicknesses are both 10 to 20 μm.

[0015] Preferably, in step four, the three-layer structure of the nanofiber diaphragm composite nanofiber battery diaphragm has a tensile strength of 63 MPa, a porosity of 68%, a needle puncture strength of 4.5 N, and a longitudinal and transverse shrinkage rate of 0 at 250°C.

[0016] Preferably, in step 4, the plug of the first KZF hydraulic quick connector is configured to be connected to the mother body of the first KZF hydraulic quick connector to replenish electrolyte into the lithium battery.

[0017] Preferably, in step 4, the fuse is welded to the connecting piece by tin furnace welding; and the fuse is further welded to the busbar circuit board.

[0018] Preferably, in step 4, the lithium battery is formed by attaching the positive electrode tab and / or the negative electrode tab to the side of the battery cell so that the side of the lithium battery forms a conductive surface.

[0019] Preferably, in step four, the lithium battery module is formed by stacking at least two lithium batteries into a group.

[0020] Compared with the prior art, the present invention has the following beneficial effects: through simple and easy process steps, the purpose of doping processing of lithium manganese iron phosphate lithium battery positive electrode material is achieved. By introducing doping elements, the electrochemical performance and stability of LMP can be improved, while simplifying the process flow and reducing production costs. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0022] Example 1

[0023] This embodiment provides a method for doping a positive electrode material of a lithium manganese iron phosphate battery, comprising the following steps:

[0024] Step 1: Mix lithium iron manganese phosphate powder and doping element powder in a certain proportion;

[0025] Step 2: Place the mixed powder into a furnace for high temperature calcination at a temperature of 800-1000°C for 1-3 hours;

[0026] Step 3: The calcined powder is cooled and then mechanically ground to a particle size of less than 100 mesh;

[0027] Step 4: The ground powder is pressed into shape to form an electrode sheet;

[0028] Step 5: The electrode sheet is dried at a temperature of 60-100°C for 1-3 hours;

[0029] Step 6: The dried electrode sheet is subjected to secondary calcination at a temperature of 600-800°C for 1-3 hours;

[0030] Step 7: The calcined electrode sheet is immersed in electrolyte.

[0031] Preferably, in step one, the surface of the lithium battery positive electrode substrate is uniformly coated with iron phosphate powder, and the lithium battery positive electrode also includes a nanofiber membrane, and the nanofiber membrane includes an upper nanofiber membrane layer, a middle nanocellulose gel layer and a lower nanofiber membrane layer.

[0032] Preferably, in step one, the nanofiber membrane layer is prepared by a combination of an electrospinning method and a sol-gel method, and the fiber diameters of the upper nanofiber membrane layer and the lower nanofiber membrane layer are both 50 to 500 nm, and the thicknesses are both 10 to 20 μm.

[0033] Preferably, in step four, the three-layer structure of the nanofiber diaphragm composite nanofiber battery diaphragm has a tensile strength of 63 MPa, a porosity of 68%, a needle puncture strength of 4.5 N, and a longitudinal and transverse shrinkage rate of 0 at 250°C.

[0034] Preferably, in step 4, the plug of the first KZF hydraulic quick connector is configured to be connected to the mother body of the first KZF hydraulic quick connector to replenish electrolyte into the lithium battery.

[0035] Preferably, in step 4, the fuse is welded to the connecting piece by tin furnace welding; and the fuse is further welded to the busbar circuit board.

[0036] Preferably, in step 4, the lithium battery is formed by attaching the positive electrode tab and / or the negative electrode tab to the side of the battery cell so that the side of the lithium battery forms a conductive surface.

[0037] Preferably, in step four, the lithium battery module is formed by stacking at least two lithium batteries into a group.

[0038] Embodiment 1:

[0039] The LMP powder and the Co element powder were mixed in a mass ratio of 1:0.1 and placed in a furnace for high-temperature calcination at 900°C for 2 hours. The calcined powder was cooled and then mechanically ground to a particle size of less than 100 mesh. The ground powder was pressed into shape to form an electrode sheet. The electrode sheet was dried at 70°C for 2 hours. The dried electrode sheet was calcined for a second time at 700°C for 2 hours. The calcined electrode sheet was immersed in an electrolyte.

[0040] Embodiment 2:

[0041] The LMP powder and the Ni element powder were mixed in a mass ratio of 1:0.2 and placed in a furnace for high-temperature calcination at 950°C for 3 hours. The calcined powder was cooled and then mechanically ground to a particle size of less than 100 mesh. The ground powder was pressed and formed into an electrode sheet. The electrode sheet was dried at 80°C for 3 hours. The dried electrode sheet was calcined for a second time at 800°C for 3 hours. The calcined electrode sheet was immersed in an electrolyte.

[0042] Embodiment three:

[0043] LMP powder and Mn element powder are mixed in a mass ratio of 1:0.3 and placed in a furnace for high-temperature calcination at 900°C for 2 hours. The calcined powder is cooled and then mechanically ground to a particle size of less than 100 mesh. The ground powder is pressed and formed into an electrode sheet. The electrode sheet is dried at 75°C for 2 hours. The dried electrode sheet is calcined for a second time at 750°C for 2 hours. The calcined electrode sheet is immersed in an electrolyte.

Claims

1. A method for doping positive electrode materials of lithium manganese iron phosphate lithium battery, characterized in that: The steps include: Step 1: Mix lithium iron manganese phosphate powder and doping element powder in a certain proportion; Step 2: Place the mixed powder into a furnace for high temperature calcination at a temperature of 800-1000°C for 1-3 hours; Step 3: The calcined powder is cooled and then mechanically ground to a particle size of less than 100 mesh; Step 4: The ground powder is pressed into shape to form an electrode sheet; Step 5: The electrode sheet is dried at a temperature of 60-100°C for 1-3 hours; Step 6: The dried electrode sheet is subjected to secondary calcination at a temperature of 600-800°C for 1-3 hours; Step 7: The calcined electrode sheet is immersed in electrolyte.

2. The method for doping the positive electrode material of a lithium manganese iron phosphate battery according to claim 1, characterized in that: In the step 1, the surface of the lithium battery positive electrode substrate is uniformly coated with iron phosphate powder, and the lithium battery positive electrode also includes a nanofiber diaphragm, and the nanofiber diaphragm includes an upper nanofiber membrane layer, a middle nanocellulose gel layer and a lower nanofiber membrane layer.

3. The method for doping the positive electrode material of a lithium manganese iron phosphate battery according to claim 1, characterized in that: In the step 1, the nanofiber membrane layer is prepared by a combination of an electrospinning method and a sol-gel method. The fiber diameters of the upper nanofiber membrane layer and the lower nanofiber membrane layer are both 50 to 500 nm, and the thicknesses are both 10 to 20 μm.

4. The method for doping the positive electrode material of a lithium manganese iron phosphate battery according to claim 1, characterized in that: In the step 4, the three-layer composite nanofiber battery separator of the nanofiber separator has a tensile strength of 63MPa, a porosity of 68%, and a needle puncture strength of 4.5N; the longitudinal and transverse shrinkage rates at 250°C are both 0.

5. The method for doping the positive electrode material of a lithium manganese iron phosphate battery according to claim 1, characterized in that: In the step 4, the plug of the first KZF hydraulic quick connector is configured to be connected to the mother body of the first KZF hydraulic quick connector to replenish the electrolyte in the lithium battery.

6. The method for doping the positive electrode material of a lithium manganese iron phosphate battery according to claim 1, characterized in that: In the step 4, the fuse is welded to the connecting piece by tin furnace welding; the fuse is further welded to the busbar circuit board.

7. The method for doping the positive electrode material of a lithium manganese iron phosphate battery according to claim 1, characterized in that: In the fourth step, the positive electrode tab and / or the negative electrode tab of the lithium battery is attached to the side of the battery cell so that the side of the lithium battery forms a conductive surface.

8. The method for doping the positive electrode material of a lithium manganese iron phosphate battery according to claim 1, characterized in that: In the step 4, the lithium battery module is stacked into a group by at least two lithium batteries.