WO2014000133A1

WO2014000133A1 - Lithium iron phosphate battery pack module of large-current discharge technologies

Info

Publication number: WO2014000133A1
Application number: PCT/CN2012/001222
Authority: WO
Inventors: 张忠仁; 马永胜; 杨康; 沈静; 范晔平
Original assignee: 上海广为美线电源电器有限公司; 上海广为电器工具有限公司; 上海广为拓浦电源有限公司
Priority date: 2012-06-28
Filing date: 2012-08-31
Publication date: 2014-01-03
Also published as: CN102820486A

Abstract

A lithium iron phosphate battery pack module of large-current discharge technologies comprises a lithium iron phosphate battery pack (101) and a battery pack control circuit that are electrically connected. The lithium iron phosphate battery pack comprises several single lithium batteries (1011) connected in series. A shorting piece (1012) connects the positive of a single lithium battery to the negative of another single lithium battery. The lithium iron phosphate battery pack further comprises an output anode (1014) and an output cathode (1013). The battery pack control circuit comprises a large-current relay (104) electrically connected to the lithium iron phosphate battery pack, a main control circuit (103) electrically connected to the large-current relay, and a battery pack protection circuit (102) electrically connected to the main control circuit. In the lithium iron phosphate battery pack module, single lithium iron phosphate batteries connected in series replace a lead-acid battery pack, achieving the features of being environmentally friendly, small in size, light, long in cycle life, and low in the self-discharge rate, and achieving the ability of large-current discharge.

Description

Lithium iron phosphate battery module of large current discharge technology

The invention relates to a lithium iron phosphate battery module of a large current discharge technology. Background technique

Conventional vehicles and ships use lead-acid batteries for emergency start-up power supplies. In recent years, with the enhancement of people's environmental awareness, the treatment of lead and sulfuric acid used in lead-acid batteries has become more and more difficult. Lithium batteries are non-polluting and environmentally friendly. Lithium batteries are used instead of lead-acid batteries. As a battery in an emergency start-up power supply, it will become the trend of the future.

However, lithium batteries do not currently have a high discharge rate, the most common is within 30C (1C-1 hour rate rated capacity (A.H); such as: 8AH battery 1C = 8A). For example, a 8AH battery has a maximum discharge current of 30X 8=240 amps. This is far from being able to accommodate large vehicles with large starting currents.

The voltage of each single-cell lithium battery is only 3.2V, but currently many fields require 6V, 12V, 24V, 48V and so on. If the series is not used, the application of the lithium battery cell will be greatly limited. The maintenance-free lead-acid batteries, which are widely used today, are actually composed of a series of cells, each of which is 2V. However, from monomer to series, it is necessary to solve the problems of balanced charge and discharge, temperature protection, overcurrent protection, short circuit protection, etc., in order to truly enter the application. Lead-acid batteries have a history of more than 100 years, and they have come a long way from monomer to series. Nowadays, with the strengthening of environmental awareness, there is an increasing need for a non-polluting lithium battery pack to replace the lead-acid battery pack. Disclosure of invention

The invention provides a lithium iron phosphate battery module with high current discharge technology, which realizes the series connection of multi-cell single cells, and can stably replace the lead-acid battery pack. More prominently, in the high-current discharge technology of the series lithium battery pack, the results have been achieved with a discharge rate of up to 80C and a maximum of 150C. The present invention greatly facilitates the passage of individual lithium batteries into groups and is widely used in various fields. Including but not limited to automotive 12V, 24V systems.

1

Replacement page (Article 26) In order to achieve the above object, the present invention provides a lithium iron phosphate battery module of a high current discharge technology, the lithium iron phosphate battery module comprising a circuit connected lithium iron phosphate battery and a battery control circuit;

The lithium iron phosphate battery pack comprises a plurality of single-cell lithium batteries connected in series, the short connecting piece connects the positive electrode of one single lithium battery to the negative electrode of another single lithium battery, and the whole lithium iron phosphate battery pack further comprises Output positive and output negative;

The battery pack control circuit comprises a large current relay electrically connected to the lithium iron phosphate battery pack, a main control circuit connecting the high current relay, and a battery pack protection circuit connected to the main control circuit; the high current relay The circuit is connected to the output positive pole of the lithium iron phosphate battery pack and the main control circuit.

The shorting piece is made of copper.

The output positive electrode and the output negative electrode surface are gold-plated, and the battery contact resistance pool is less than 0.5 milliohms.

The single-cell lithium battery includes a positive electrode sheet, a negative electrode sheet, a separator, an electrolyte, and an outer casing, and the positive electrode sheet includes a current collector and a positive electrode material coated on the current collector, the positive electrode material including a positive electrode active material, and a bonding material. Agent and conductive agent;

The positive active material comprises nano-scale lithium iron phosphate and micron-sized lithium iron phosphate, and the weight ratio of the nano-sized lithium iron phosphate to the micron-sized lithium iron citrate is 1:7~1:9.

The medium particle size D50 distribution in the nano-scale lithium iron phosphate is 300 nm-900 nm.

The medium particle size D50 distribution in the micron-sized lithium iron phosphate is 2 um to 10 um.

The one-side coating amount of the positive electrode active material on the current collector is 80 to 140 g/m ² .

The battery pack protection circuit comprises a reverse/disconnection protection circuit, a single-cell voltage sampling circuit, a temperature protection circuit, an overcurrent protection circuit and a charging control protection circuit respectively connected to the main control circuit.

The lithium battery discharge technology with the discharge current of 80~150C provided by the invention solves the above problems that have long been plagued by the industry.

The lithium iron phosphate battery pack with high current discharge technology has a high storage energy density, and the lithium battery is lighter than the lead acid battery, and the weight is about one-fifth or one-sixth of that of the lead-acid battery.

Lithium batteries have a relatively long service life and high power endurance. High and low temperature applicability, green and environmental protection, no matter whether it is produced, used or scrapped, it does not contain any lead, mercury and other toxic substances. Harm heavy metal elements and substances.

Compared with the lead-acid battery, the invention fully utilizes the natural advantages of lithium iron phosphate, has the advantages of environmental protection, smaller volume, lighter weight, longer cycle life and lower self-discharge rate, and the invention has many protection functions, such as , temperature protection, over current protection, short circuit protection, charging control, misconnection, reverse alarm and other functional units, can achieve the most important function of large current discharge safely and stably. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a block diagram of the circuit of the present invention;

Figure 2 is a specific circuit diagram of the present invention;

Figure 3 is a control flow chart of the present invention. The best way to implement the invention

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be specifically described with reference to Figs.

As shown in FIG. 1, a lithium iron phosphate battery module of a high current discharge technology according to the present invention comprises a circuit-connected lithium iron phosphate battery pack 101 and a battery pack control circuit;

The lithium iron phosphate battery pack comprises a plurality of single lithium battery cells 1011 connected in series, and the short connecting piece 1012 connects the positive electrode of one single lithium battery to the negative electrode of another single lithium battery, and the entire lithium iron phosphate battery pack comprises Also includes an output positive electrode 1014 and an output negative electrode 1013;

In this embodiment, a four-cell single-cell lithium battery 1011 is used in series to form a lithium iron phosphate battery pack. Each of the single-cell lithium batteries 1011 has a voltage of 3.2 volts, and four sections are connected by a short connecting piece 1012, and the lithium iron phosphate battery pack 101 is connected. The voltage is 3.2 volts X 4 = 12.8 volts, which can replace the ordinary 12V lead-acid battery;

Since the lithium iron phosphate battery pack has a thickness of 1 mm, a width of 20 mm, a length of 38 mm, and a silver plated surface of the copper plate as a short piece, it is connected in series. Make sure it is adequate to withstand the ability of the battery pack to conduct at maximum discharge rate. To discharge at a rate of 80 to 150C, 8AH is used as an example, the discharge current is between 640 and 1200A. Therefore, the shorting tabs used in series undergo various harsh experiments, and finally have a thickness of 1 mm, a width of 20 mm, and a length of 38. The copper piece of millimeters, the experiment proves that it can withstand the discharge current; the other AHs have different sizes of copper sheets;

The output positive electrode 1014 and the output negative electrode 1013 are gold-plated, and the battery contact resistance pool is less than 0.5 milliohms to meet the requirements of large current discharge;

The single lithium battery 1011 includes a positive electrode sheet, a negative electrode sheet, a separator, an electrolyte, and an outer casing. The positive electrode sheet includes a current collector and a positive electrode material coated on the current collector, the positive electrode material including a positive electrode active material, a binder, and a conductive agent;

The positive active material comprises nanometer lithium iron phosphate and micron lithium iron phosphate, the weight ratio of the nanometer lithium iron phosphate to the micron lithium iron phosphate is 1~7: 1~9;

The medium particle diameter D50 distribution in the nano-scale lithium iron phosphate is 300 nm-900 nm _;

The medium particle size D50 distribution in the micron-sized lithium iron phosphate is 2um-10um _;

The single-side coating amount of the positive electrode active material on the current collector is 80 to 140 g/m ² _;

The battery pack control circuit includes a large current relay 104 electrically connected to a lithium iron phosphate battery pack, a main control circuit 103 electrically connected to the large current relay, and a battery pack protection circuit 102 electrically connected to the main control circuit; The high current relay 104 is electrically connected to the output positive pole and the main control circuit of the lithium iron phosphate battery pack;

The working principle of the lithium iron phosphate battery module of the large current discharge technology is: When the external conditions are satisfied, the lithium iron phosphate battery pack is controlled by the main control circuit, and is connected by a large current relay, and the positive electrode of the lithium iron phosphate battery module The negative electrode is externally discharged with a large current, and the battery pack protection circuit protects the normal operation of the lithium iron phosphate battery pack.

As shown in FIG. 2, the battery protection circuit 102 includes a reverse/disconnection protection circuit 1021, a single-cell voltage sampling circuit 1022, a temperature protection circuit 1023, and an overcurrent protection circuit respectively connected to the main control circuit. 1024 and charging control protection circuit 1025;

The main control circuit 103 adopts the single chip MC96F6432Q. When the external condition is satisfied, for example, there is no short circuit externally, the 54th pin of the main control circuit outputs a high level, so that the transistor Q27 is turned on, and then the large current relay 104 is turned on and off. The positive electrode of the lithium iron phosphate battery pack 101, the negative electrode is output to the positive electrode of the lithium iron phosphate battery module of the high current discharge technology, and the negative electrode is externally discharged with a large current, if the lithium iron phosphate battery module of the high current discharge technology works abnormally at this time For example, if the lithium iron phosphate battery pack is overheated, the main control circuit will react to turn off the large current relay to discharge the external current to protect the lithium iron phosphate battery pack module;

The main electronic device of the reverse/disconnection protection circuit 1021 adopts an optocoupler TLP627. When the positive electrode of the lithium iron phosphate battery module of the high current discharge technology is connected with the negative electrode and an external load (such as a battery), the reverse connection/ The optocoupler U8B of the misconnect protection circuit 1021 is turned on, indicating that the external load is connected correctly, and the optocoupler U8B outputs the correct signal to the 9th pin of the MCU of the main control circuit. After receiving the signal, the MCU corrects the program, and then the program makes a correct identification. The MCU outputs the control signal of the large current relay from the 44th pin. The high-current relay is controlled to be turned on, and the lithium iron phosphate battery module of the high-current discharge technology outputs a large current to the outside;

If the optocoupler U8C of the reverse/disconnection protection circuit 1021 is turned on, indicating that the external load is connected incorrectly, the optocoupler U8C outputs a signal to the 10th pin of the MCU of the main control circuit. After receiving the signal, the MCU corrects the program. Then, the MCU outputs the control signal of the large current relay from the 44th pin to control the disconnection of the large current relay, and the lithium iron phosphate battery module of the high current discharge technology cannot output a large current externally;

The main electronic device of the single-cell voltage sampling circuit 1022 adopts an integrated operational amplifier

LM224AD, P-type MOS tube BSS84 and triode S8550, single-cell battery voltage sampling circuit 1022 samples the voltage of four single-cell lithium batteries separately, and the single-chip microcomputer of the main control circuit recognizes the correct voltage as the charging or external large-current discharge. The voltage depends on the input of the single-cell battery voltage sampling circuit 1022, VBAT+, B2, B3, and B4 are respectively connected to the positive electrode of the first battery of the lithium iron phosphate battery, the positive electrode of the second battery, the positive electrode of the third battery, and the fourth The positive pole of the battery; the three parts of the U1 U1A, U1B, U1C and related circuits, the unit voltage of the four-cell single-cell lithium battery is output through the operation summation circuit, and sent to the 28th pin of the single-chip microcomputer of the main control circuit, The 27th pin, the 26th pin and the 25th pin, the single chip microcomputer can obtain the real voltage of the four single cells by the filtering algorithm;

The main electronic device temperature sensor RT2 of the temperature protection circuit 1023 uses an NTC 10K resistor. When the temperature of the lithium iron phosphate battery module exceeds 60 degrees, the corresponding resistance value of the negative temperature coefficient temperature sensor RT2 changes. The voltage of R68 will change. The 34th pin of the main control circuit detects this voltage change. Through the program operation, the temperature of the lithium iron phosphate battery module is recognized. Based on this, the main control circuit will disconnect the iron phosphate. The external power supply of the lithium battery pack module can effectively protect the lithium iron phosphate battery pack;

The main electronic device of the overcurrent protection circuit 1024 adopts the integrated operational amplifier LM358AM. When the lithium iron phosphate battery pack discharges a large current, if the set current value is exceeded, the program will reflect within 0.5 seconds, the main control The circuit will disconnect the external power supply of the lithium iron phosphate battery module, which can effectively protect the lithium iron phosphate battery module; the negative voltage of the lithium iron phosphate battery module of the sampled high current discharge technology is input to the U9B of the operational amplifier through the R119 for voltage amplification. The amplified signal is input to the 31st pin of the main control circuit microcomputer, and the program performs analog-to-digital conversion after detecting the signal, and the MCU obtains the true current of the module after processing the signal program, according to which if the set current value is exceeded. The main control circuit will cut off the external power supply of the lithium iron phosphate battery module to achieve the purpose of overcurrent protection; The main electronic device of the charging control protection circuit 1025 adopts the integrated operational amplifier LM224AD. When charging the lithium iron silicate battery pack, if overcharge occurs, the main control circuit will automatically disconnect the lithium iron phosphate battery module to avoid Overcharge affects its service life; When the single-cell battery voltage of the lithium iron phosphate battery pack sampled by the main control circuit is too low, when the voltage of the lithium iron phosphate battery pack is lower than 8 volts, the main control circuit's MCU 43 output high power Ping, make Q17 in the charge control protection circuit turn on, and then Q28 is also turned on, the external charger charges the lithium iron phosphate battery pack through Q28, and the charge control protection circuit samples the charging current through the resistor R50, through the op amp U1D amplifies the sampling voltage and sends it to the 31st pin of the MCU of the main control circuit. The program detects the charging process in real time. When the lithium iron phosphate battery pack is fully charged, the 43rd pin of the MCU outputs a low level, and the charging circuit is cut off.

As shown in FIG. 3, the control flow of the lithium iron phosphate battery module of the high current discharge technology provided in the embodiment of the present invention comprises the following steps:

Step 1. Start, the high current relay is disconnected;

Step 2, the main control circuit determines whether the voltage of the lithium iron phosphate battery pack is lower than 8.0V, and if so, jumps to step 12, if not, jumps to step 3;

Step 3, the main control circuit determines whether the battery temperature is higher than 60 degrees, and if so, jumps to step 12, and if not, jumps to step 4;

Step 4: The main control circuit determines whether the reverse/disconnection protection circuit works, and if yes, jumps to step 12, and if not, jumps to step 5 _;

Step 5. After the main control circuit judges that all the connections are valid and qualified, the main output connection command is automatically output, so that the large current relay is connected and operated;

Step 6. The main control circuit completes the detection of the discharge current, the battery voltage and the discharge time, and performs steps 12 and 7 simultaneously;

Step 7, the main control circuit determines whether the battery voltage is lower than 8.0V, and if so, jump to step 11, if no, jump to step 8;

Step 8, the main control circuit determines whether the battery temperature is higher than 60 degrees, and if so, jumps to step 11, if no, jumps to step 9;

Step 9, the main control circuit determines whether the current is greater than the setting If the jump to step 11, if not, jump to step 10;

Step 10, the main control circuit determines whether the discharge time reaches 5 seconds, and if so, jumps to step 13, if not, jumps to step 5; Step 11. The main control circuit disconnects the large current relay;

Step 12. The main control circuit records the detection data.

Step 13. Stop discharging and skip to step 1.

Although the present invention has been described in detail by the preferred embodiments thereof, it should be understood that the foregoing description should not be construed as limiting. Various modifications and alterations of the present invention will be apparent to those skilled in the art. Therefore, the scope of the invention should be limited by the appended claims.

Claims

Rights request

A lithium iron phosphate battery module of high current discharge technology, characterized in that the lithium iron phosphate battery module comprises an electrically connected lithium iron phosphate battery pack (101) and a battery control circuit; The lithium battery pack includes a plurality of lithium battery cells (1011) connected in series, and the shorting piece (1012) connects the positive electrode of one single lithium battery to the negative electrode of another single lithium battery, and the entire lithium iron phosphate battery pack includes An output positive electrode (1014) and an output negative electrode (1013) are included; the battery pack control circuit includes a large current relay (104) electrically connected to the lithium iron phosphate battery pack, and a main control circuit (103) electrically connected to the large current relay. And a battery pack protection circuit (102) connected to the main control circuit; the high current relay (104) circuit is connected to the output positive pole and the main control circuit of the lithium iron phosphate battery pack.

2. The lithium iron phosphate battery module of the high current discharge technique according to claim 1, wherein the shorting piece (1012) is made of a copper piece.

3. The lithium iron phosphate battery module of the high current discharge technology according to claim 1, wherein the output positive electrode (1014) and the output negative electrode (1013) are gold plated, and the battery contact resistance pool is less than 0.5. Millions of euros.

4. The lithium iron phosphate battery module of the high current discharge technology according to claim 1, wherein the single lithium battery (1011) comprises a positive electrode sheet, a negative electrode sheet, a separator, an electrolyte, and a casing. The positive electrode sheet includes a current collector and a positive electrode material coated on the current collector, the positive electrode material including a positive electrode active material, a binder, and a conductive agent;

The positive active material comprises nanometer lithium iron phosphate and micron lithium iron phosphate, and the weight ratio of the nano lithium iron phosphate to the micron lithium iron phosphate is 1:7~1:9.

The lithium iron phosphate battery module of the high current discharge technique according to claim 4, wherein the nano-sized lithium iron phosphate has a medium particle diameter D50 distribution of 300 nm to 900 nm.

6. The lithium iron phosphate battery module of the high current discharge technique according to claim 4, wherein the micron-sized lithium iron phosphate has a medium particle diameter D50 distribution of 2 um to 10 um.

7. The lithium iron battery module according to claim 4, wherein the one-side coating amount of the positive electrode active material on the current collector is 80 to 140 g/m ² .

8. The lithium iron phosphate battery module of the high current discharge technology according to claim 1, characterized in that The battery protection circuit (102) includes a reverse/disconnection protection circuit (1021), a single-cell voltage sampling circuit (1022), and a temperature protection circuit (1023) respectively connected to the main control circuit. Overcurrent protection circuit (1024) and charge control protection circuit (1025).