阅读说明：本技术 一种车规级高能量密度磷酸铁锂动力电池 (High energy density lithium iron phosphate power battery of car scale ) 是由 王瑞州 何永攀 董志诚 王书敬 王武练 于 2020-06-10 设计创作，主要内容包括：本发明公开了一种车规级高能量密度磷酸铁锂动力电池,包含有正极片、负极片、隔膜、电解液、极耳、铝塑膜,正极片包括正极集流体、正极活性物质、正极粘结剂和正极导电剂,正极集流体为涂炭铝箔,正极片组分及重量比为：正极活性物质96-98％,正极粘结剂1-2％,正极导电剂1-2％,负极片包括负极集流体、负极活性物质、负极增稠剂、负极粘结剂和负极导电剂,负极集流体为铜箔,负极片组分及重量比为：负极活性物质92-96％,负极增稠剂1.5-2.5％,负极粘结剂1.5-3.5％,负极导电剂1-2％。本发明具有高能量密度,良好的倍率性能、高低温性能、长循环寿命和安全稳定性,达到车规级要求,可安全、经济的应用于乘用车、大巴车、物流车、电动船、风光储能等动力电池应用领域。(The invention discloses a vehicle-scale high-energy-density lithium iron phosphate power battery, which comprises a positive plate, a negative plate, a diaphragm, electrolyte, a lug and an aluminum-plastic film, wherein the positive plate comprises a positive current collector, a positive active substance, a positive binder and a positive conductive agent, the positive current collector is a carbon-coated aluminum foil, and the positive plate comprises the following components in percentage by weight: 96-98% of positive active substance, 1-2% of positive binder and 1-2% of positive conductive agent, wherein the negative plate comprises a negative current collector, a negative active substance, a negative thickener, a negative binder and a negative conductive agent, the negative current collector is copper foil, and the negative plate comprises the following components in percentage by weight: 92-96% of negative electrode active material, 1.5-2.5% of negative electrode thickening agent, 1.5-3.5% of negative electrode binder and 1-2% of negative electrode conductive agent. The invention has high energy density, good multiplying power performance, high and low temperature performance, long cycle life and safe stability, meets the requirements of vehicle specifications, and can be safely and economically applied to the application fields of power batteries of passenger vehicles, bus cars, logistics vehicles, electric ships, wind and light energy storage and the like.)

1. The utility model provides a car-scale high energy density lithium iron phosphate power battery which characterized in that: comprises a positive plate (1), a negative plate (2), a diaphragm (3), electrolyte (4), a tab (5) and an aluminum-plastic film (6);

the relation among the positive plate (1), the negative plate (2) and the diaphragm (3) in the aluminum-plastic film (6) is as follows: one side surface of a negative plate (2) is tightly attached to the diaphragm (3) after a diaphragm (3) is tightly attached to an aluminum-plastic film (6), the other side surface of the negative plate (2) is tightly attached to one side surface of another diaphragm (3), one side surface of a positive plate (1) is tightly attached to the other side surface of the other diaphragm (3), the other side surface of the positive plate (1) is tightly attached to one side surface of another diaphragm (3), one side surface of another negative plate (2) is tightly attached to the other side surface of the other diaphragm (3), and the like in sequence, electrolyte (4) is filled between the positive plate (1), the negative plate (2) and the diaphragms (3) and among the positive plate (1), the negative plate (2) and the diaphragms (3), the tab (5) comprises a positive tab and a negative tab, the positive plate (1), the negative plate (2) and the diaphragms (3) adopt a lamination mode to form a battery core, the positive electrode lug and the negative electrode lug are welded with the battery cell and are respectively packaged at two sides of the aluminum plastic film (6);

the positive plate comprises a positive current collector, a positive active material, a positive binder and a positive conductive agent, wherein the positive current collector is a carbon-coated aluminum foil, and the positive plate comprises the following components in percentage by weight: 96-98% of positive active material, 1-2% of positive binder and 1-2% of positive conductive agent, wherein the negative plate comprises a negative current collector, a negative active material, a negative thickener, a negative binder and a negative conductive agent, the negative current collector is a copper foil, and the negative plate comprises the following components in percentage by weight: 92-96% of negative electrode active material, 1.5-2.5% of negative electrode thickening agent, 1.5-3.5% of negative electrode binder and 1-2% of negative electrode conductive agent.

2. The vehicle scale high energy density lithium iron phosphate power battery of claim 1, wherein: the positive electrode active material is a carbon-coated lithium iron phosphate material, the positive electrode conductive agent is a mixture of carbon nanotubes and graphene, the graphene is not more than 50%, and the positive electrode binder is polyvinylidene fluoride.

3. The vehicle scale high energy density lithium iron phosphate power battery of claim 2, wherein: the surface density of the positive electrode sheet is 390-420g/m²Within the range, the compaction density of the positive plate is 2.35-2.5g/cm³Within the range.

4. The vehicle scale high energy density lithium iron phosphate power battery of claim 3, wherein: the negative electrode active substance is artificial graphite, the negative electrode conductive agent is conductive carbon black, the negative electrode binder is styrene butadiene rubber, and the negative electrode thickening agent is sodium carboxymethylcellulose.

5. The vehicle scale high energy density lithium iron phosphate power battery of claim 4, wherein: the surface density of the negative electrode sheet is 185-200g/m²Within the range, the compacted density of the negative plate is 1.4-1.6g/cm³Within the range.

6. The vehicle scale high energy density lithium iron phosphate power battery of claim 5, wherein: the electrolyte is lithium hexafluorophosphate organic solution with the concentration of 1.4-1.5 mol/L.

The technical field is as follows:

the invention relates to a power battery, in particular to a vehicle-scale high-energy-density lithium iron phosphate power battery, and belongs to the technical field of new energy automobiles.

Background art:

the electric automobile battery becomes a leading product of the future automobile consumption market, and the development of the power battery is developed into a competition in a global range to preempt the high point of the future industry. Currently, the new energy battery industry is vigorously developed in various developed countries and regions around the world. The rise of the new energy battery industry will cause great changes in a plurality of industries such as automobiles, communication, electric power, IT, building industry, new material industry and the like, and promote a series of novel industries.

The lithium ion power battery using the lithium iron phosphate as the anode material has the advantages of high safety performance, long cycle life, environmental protection, high cost performance and the like. The large-capacity lithium iron phosphate power battery is used in series, and can provide more power for new energy automobiles. At present, the lithium iron phosphate power battery is widely applied to new energy passenger cars, commercial vehicles and special vehicles, but is limited by energy density, so that the application of the lithium iron phosphate power battery in the field of new energy passenger cars is not much. With the higher requirement on the endurance mileage of the electric vehicle and the year-by-year reduction of national subsidies, the requirement on the energy density of the power battery is higher, how to improve the energy density of the power battery and increase the endurance mileage of the new energy vehicle becomes one of the important challenges facing the new energy vehicle industry. At present, the energy density of the single power battery of a ternary system of each large manufacturer generally reaches more than 260wh/kg, and the energy density of the single lithium iron phosphate power battery generally reaches below 160 wh/kg. The lithium iron phosphate is applied to a natural cooling battery system of a commercial vehicle, and the energy density of the system is generally about 140 wh/kg. The liquid cooling/liquid heating battery system of the passenger car has the system energy density generally not exceeding 120wh/kg, the running energy consumption of the whole car is large, and the cost performance of the product is low. The improvement of the energy density of the lithium iron phosphate power battery has great practical significance.

The invention content is as follows:

the invention provides a vehicle-scale high-energy-density lithium iron phosphate power battery for solving the problems in the prior art, and solves the problem that the energy density of the conventional lithium iron phosphate power battery cannot meet the requirement of an electric vehicle on higher driving range. The method is characterized in that a carbon-coated lithium iron phosphate material is selected as a lithium ion battery anode material, artificial graphite is selected as a lithium ion battery cathode material, a current collector and a conductive agent are reasonably selected, process parameters are properly adjusted, the surface density and the compaction density of a positive pole piece and a negative pole piece which are reasonably adapted are selected, and a lamination process is used for preparing the soft package power battery.

The technical scheme adopted by the invention is as follows: a vehicle-scale high-energy-density lithium iron phosphate power battery comprises a positive plate, a negative plate, a diaphragm, electrolyte, a tab and an aluminum-plastic film;

the relation of the positive plate, the negative plate and the diaphragm in the aluminum plastic film is as follows: a diaphragm clings to the diaphragm tightly on one side surface of the negative plate after the aluminum plastic film, the other side surface of the negative plate clings to one side surface of the other diaphragm tightly, one side surface of the positive plate clings to the other side surface of the other diaphragm tightly, the other side surface of the positive plate clings to one side surface of the other diaphragm tightly, one side surface of the other negative plate clings to the other side surface of the other diaphragm tightly, and the like are repeated, the electrolyte is filled among the positive plate, the negative plate and the diaphragms and among the positive plate, the negative plate and the diaphragms, the tabs comprise positive tabs and negative tabs, the positive plate, the negative plate and the diaphragms adopt a lamination mode to form a battery core, and the positive tabs and the negative tabs are welded with the battery core and respectively packaged on two sides of the aluminum plastic film;

the positive plate comprises a positive current collector, a positive active material, a positive binder and a positive conductive agent, wherein the positive current collector is a carbon-coated aluminum foil, and the positive plate comprises the following components in percentage by weight: 96-98% of positive active material, 1-2% of positive binder and 1-2% of positive conductive agent, wherein the negative plate comprises a negative current collector, a negative active material, a negative thickener, a negative binder and a negative conductive agent, the negative current collector is a copper foil, and the negative plate comprises the following components in percentage by weight: 92-96% of negative electrode active material, 1.5-2.5% of negative electrode thickening agent, 1.5-3.5% of negative electrode binder and 1-2% of negative electrode conductive agent.

Further, the positive electrode active material is a carbon-coated lithium iron phosphate material, the positive electrode conductive agent is a mixture of carbon nanotubes and graphene, the graphene is not more than 50%, and the positive electrode binder is polyvinylidene fluoride.

Further, the surface density of the positive electrode sheet is 390-420g/m²Within the range, the compaction density of the positive plate is 2.35-2.5g/cm³Within the range.

Further, the negative active material is artificial graphite, the negative conductive agent is conductive carbon black, the negative binder is styrene butadiene rubber, and the negative thickener is sodium carboxymethylcellulose.

Further, the surface density of the negative plate is 185-200g/m²Within the range, the compacted density of the negative plate is 1.4-1.6g/cm³Within the range.

Further, the electrolyte is lithium hexafluorophosphate organic solution with the concentration of 1.4-1.5 mol/L.

The invention has the following beneficial effects: the lithium iron phosphate power battery with high energy density on the vehicle scale has high energy density, good rate performance, high and low temperature performance, long cycle life and safety stability, meets the requirements on the vehicle scale, and can be safely and economically applied to the application fields of power batteries of passenger vehicles, buses, logistics vehicles, electric ships, wind and light energy storage and the like.

Description of the drawings:

fig. 1 is a schematic diagram of a vehicle-scale high energy density lithium iron phosphate power battery of the present invention.

Fig. 2 is a partial longitudinal sectional view of fig. 1.

Fig. 3 is a graph of 1500 cycles of 1C charging and 3C discharging at 25 ℃ for the battery of example 2 of the present invention.

The specific implementation mode is as follows:

the invention will be further described with reference to the accompanying drawings.

The invention relates to a vehicle-scale high-energy-density lithium iron phosphate power battery, which comprises a positive plate 1, a negative plate 2, a diaphragm 3, an electrolyte 4, a tab 5 and an aluminum-plastic film 6, wherein the positive plate 1, the negative plate 2 and the diaphragm 3 in the aluminum-plastic film 6 have the following relationship: after a diaphragm 3 is tightly attached to the aluminum-plastic film 6, one side surface of the negative plate 2 is tightly attached to the diaphragm 3, the other side surface of the negative plate 2 is tightly attached to one side surface of the other diaphragm 3, and one side surface of the positive plate 1 is tightly attached to the other side surface of the other diaphragm 3. The other side surface of the positive electrode sheet 1 is closely attached to one side surface of the other separator 3. One side surface of the other negative electrode tab 2 is closely attached to the other side surface of the other separator 3. And so on. The electrolyte 4 is filled among the positive plate 1, the negative plate 2 and the diaphragm 3, and among the positive plate 1, the negative plate 2 and the diaphragm 3. The tab 5 includes a positive tab and a negative tab. The positive plate 1, the negative plate 2 and the diaphragm 3 form a battery cell in a lamination mode, and the positive tab and the negative tab are welded with the battery cell and respectively packaged at two sides of the aluminum plastic film 6.

The positive plate 1 comprises a positive current collector, a positive active material, a positive binder and a positive conductive agent. The positive current collector is a carbon-coated aluminum foil, and the positive plate comprises the following components in percentage by weight: 96-98% of positive electrode active substance, 1-2% of positive electrode binder and 1-2% of positive electrode conductive agent. The positive active material is a carbon-coated lithium iron phosphate material. The positive electrode conductive agent is a mixture of carbon nanotubes and graphene, and the graphene is not more than 50%. The positive electrode binder is polyvinylidene fluoride. The surface density of the positive electrode sheet is 390-420g/m²Within the range, the compaction density of the positive plate is 2.35-2.5g/cm³Within the range. The reasonable increase of the area density and the compaction density can increase the discharge capacity of the battery, reduce the internal resistance, increase the amount of the absorbed electrolyte and prolong the cycle life of the battery. The negative plate 2 comprises a negative current collector, a negative active material, a negative thickener, a negative binder and a negative conductive agent. The negative current collector is copper foil, and the negative plate comprises the following components in percentage by weight: 92-96% of negative electrode active material, 1.5-2.5% of negative electrode thickening agent, 1.5-3.5% of negative electrode binder and 1-2% of negative electrode conductive agent. The negative active material is artificial graphite, the negative conductive agent is conductive carbon black, and the negative electrode is bondedStyrene butadiene rubber is used as the thickening agent of the negative electrode, and sodium carboxymethylcellulose is used as the thickening agent of the negative electrode. The surface density of the negative electrode plate is 185-200g/m²Within the range, the surface density of the negative plate is increased and matched with the positive plate, so that the purpose of improving the energy density of the battery is achieved. The compacted density of the negative pole piece is between 1.4 and 1.6g/cm³Within the range, the discharge capacity of the battery can be increased, the internal resistance can be reduced, the amount of the absorbed electrolyte can be increased, and the cycle life of the battery can be prolonged by reasonably increasing the surface density and the compacted density. The electrolyte is lithium hexafluorophosphate organic solution with the concentration of 1.4-1.5 mol/L.

After the positive plate and the negative plate are subjected to sheet production, the positive tab and the negative tab are welded with the battery core, the battery core is packaged in an aluminum plastic film, and the 68Ah flexible package lithium iron phosphate power battery is prepared through the processes of liquid injection, shelving, formation, secondary packaging, post-treatment capacity grading and the like. The water content of the positive plate and the negative plate is tested before liquid injection, the water content of the liquid injection standard positive plate is less than or equal to 80PPM, the water content of the negative plate is less than or equal to 120PPM, and the process control of the water content of the positive plate and the negative plate reduces chemical negative reaction caused by trace water, so that the cycle life and the safety stability of the battery are improved.

The carbon-coated lithium iron phosphate material with high conductivity is selected as the anode material of the lithium ion battery, the isotropic artificial graphite is selected as the cathode material of the lithium ion battery, and the carbon-coated aluminum foil and the strong conductive agent are matched for use, so that the using amount of the conductive agent is reduced, and the active material amount is increased. Properly adjusting the technological parameters and properly increasing the surface density and the compacted density of the positive and negative pole pieces. The surface density and the compacted density have great influence on the performance of the battery and have close relation with the specific capacity, the efficiency, the internal resistance and the cycle performance of the battery, and the proper surface density and the compacted density can increase the discharge capacity of the battery, reduce the internal resistance and prolong the cycle life of the battery. And finally, a lamination process is used for preparing the soft package power battery, so that the energy density of the lithium iron phosphate power battery is greatly improved, and the good rate performance, high and low temperature performance and cycle stability of the lithium iron phosphate power battery are maintained.

The present invention will be described more clearly with reference to specific examples, but the practice of the present invention is not limited to the following examples.