Since the advent of lithium-ion battery has been around it for research, development work has been continuously engaged in the last century, the late 90s has developed a lithium-polymer battery, 2002, introduced after the lithium iron phosphate.

Mainly by the internal lithium-ion battery cathode, anode, electrolyte and membrane composition. Positive and negative electrodes and electrolyte materials, and discusses the differences in batteries of different properties have different and have different names. Currently on the market for lithium-material ion battery cathode is mainly of lithium cobalt oxide (LiCoO2), plus a few used lithium manganese oxide (LiMn2O4) and nickel oxide lithium (LiNiO2 ) as cathode materials for lithium-ion batteries, generally after the two types of positive outcomes materials, lithium-ion battery known as Battery Lithium “manganese” and “nickel-lithium.” The new Iron Battery Lithium Power phosphate is lithium iron phosphate (LiFePO4) cathode material for lithium-ion batteries, lithium-ion battery is a new family member. Latitude D620 battery Latitude D820 battery

Overall electrolyte lithium-ion battery is a liquid, but later developed a solid electrolyte and polymer gel, describes this type of lithium-ion battery for lithium polymer batteries, its performance is better than lithium liquid electrolyte -ion battery.

Full name of the lithium-iron phosphate should be lithium iron phosphate lithium-ion battery, this name is too long, designated lithium iron phosphate. Because of its properties, particularly suitable for power applications, then the name of “power” should be, ie, lithium iron phosphate battery power. Some call it “Lithium Iron (Life) battery.”

LiFePO4 cathode material used to make sense of

Currently used as cathode material for lithium-ion batteries are mainly: LiCoO2, LiMn2O4, LiNiO2 and LiFePO4. The material composition of the battery cathode metal elements, cobalt (Co) the most expensive, and limited storage capacity, nickel (Ni), manganese (Mn) are cheaper, and iron (Fe ) the cheapest. Cathode material prices and prices of these metals in Online Courses. Therefore, using LiFePO4 cathode materials for lithium-ion battery should be made of the cheapest. Another characteristic of the environment, it is pollution. Satellite M45 battery Satellite M50 battery

As a rechargeable battery requirements are: high capacity, high power, responsible for good performance-cycle of discharge, stable output voltage at high current load and emergence, stability and electrochemical performance, the use of security (will not overcharge, over discharge and short circuit caused by the malfunction of fire or explosion), the operating range of temperature, non-toxic or less toxic pollution environment. LiFePO4 as cathode using iron lithium phosphate in these performance requirements are good, especially in the large rejection rate of discharge (5 ~ 10C discharge) the discharge voltage is stable, security (no burning, no explosion), life on the number (cycles), pollution of the environment, it is the best, and is currently the best high current battery power supply.

The structure of LiFePO4 battery and operating principle

Internal structure of LiFePO4 battery shown in Figure 1. The left is the structure of olivine LiFePO4 as a battery anode from the cathode sheet and connected to the middle of a polymer membrane that separates the positive and negative, but the lithium ion Li + by through e-mail can not be on the right is carbon (graphite) to form a battery anode copper foil and the negative terminal of the battery connection. Between the upper and lower ends of the  F4812A HSTNN-lB31 battery electrolyte battery, battery enclosed by a metal housing.

LiFePO4 battery charging, the cathode in lithium-ion Li + migration through the polymer membrane to the cathode in the discharge process, the negative electrode in lithium-ion Li + migration through the membrane to the cathode. Lithium-ion battery Lithium-ion is a charge and discharge because of back and forth when you move and appointed.

Performance of LiFePO4 batteries

Battery voltage nominal LiFePO4 is 3.2V, the termination of the charging voltage is 3.6V, the termination of the discharge voltage is 2.0V. Because each manufacturer uses the material of positive and negative electrode, the electrolyte materials, quality and different processes, their performance will be some differences. For example, the same model (the same package, standard battery), the battery capacity are very different (10% ~ 20%).

Lithium iron phosphate power performance of the main battery shown in Table 1. For further comparison and the rechargeable battery, also listed in the table, the performance of other types of rechargeable batteries. Here, it should be noted that the plant iron phosphate lithium various performance parameters of a battery in all there will be some differences; In addition, there are few performances of the battery are not included, as the stack internal resistance, self-discharge rate, charge and discharge temperature. Aspire 3000 battery LCBTP03003

The capacity of lithium iron phosphate is very different, may be divided into three categories: small, few to several milliamperes 0:00, tens of milliamps of medium to large scale of several hundred milliamps. Different types of batteries there are differences between the same parameters. Here, again describes a common application of a wider package of standard parameters small cylindrical lithium iron phosphate battery power. His profile external dimensions: 18mm diameter, 650mm high (model 18650), its performance parameters, as presented in Table 2.

Typical discharge characteristics and life

A model of iron STL18650 energy of lithium phosphate battery (1100mAh capacity) rate of discharge of various flow characteristics in Figure 2. The minimum rate of 0.5 ° C, the maximum discharge rate of 10C, five different rates of rejection of the constitution of a group of discharge curves. As shown in Figure 2, no matter what type of flow and discharge voltage of the course is very flat (ie, the discharge voltage stable, essentially unchanged), and only near the end of the voltage discharge curve was bending down (800mAh discharge reached only after a downward turn). In the range 0.5 ~ 10C discharge rate, the output voltage is in the range 2.7 ~ 3.2V. This shows that the battery discharge characteristics well.

Figure 2 STL18650 flow characteristics of KD186 NF343

Capacity 1000mAh of STL18650 at different temperatures (-20 ℃ ~ 40) of the discharge curve in Figure 3. If at 23 ℃ when the discharge capacity of 100%, while the discharge capacity at 0 ℃ reduced to 78%, while in -20 ℃, when reduced to 65% at 40 ℃ and discharge flow capacity at just over 100%.

Figure 3 STL18650 in multi-temperature conditions of the discharge curves

STL18650 the prosecution and the curve of the life cycle of the discharge of figure 4. Its charge-discharge cycle conditions are: 1C rate charge fees, to 2C rate discharge after 570 charge discharge cycles. Characteristic curve of Figure 4 can be seen, after 570 charge discharge cycles, its discharge capacity remained unchanged, indicating that the battery has a long lifetime.

Figure 4 STL18650 charge and discharge cycle life curves

Over-discharge to zero voltage test

Use STL18650 (1100mAh) battery discharge lithium iron phosphate zero high voltage tests done. Test conditions: The 0.5C charge rate will 1100mAh battery is full of STL18650 and then use the 1.0C discharge rate of discharge to the battery voltage is 0C. 0V then put the battery divided into two groups: group storage of 7 days, another group of storage 30 days, deposited with the 0.5C charge rate after the expiration of full employment, and 1.0C discharge. Finally the comparison of the two zero voltage should be kept different from the difference. Vostro 1720 battery Vostro 2510 battery

The test results, the zero-battery voltage 7 days with no leakage, good performance, capacity is 100% retained 30 days, no leaks, good performance, capacity, 98% not retained 30 days after three times the battery cycle discharge capacity returned to 100%.

This experiment shows that the battery, even if there has been discharged (or even at 0V), and period of storage time, the battery does not leak, damage. These other types of lithium-ion batteries have the features.

Characteristics of lithium iron phosphate

With this introduction, the characteristics of LiFePO4 battery can be summarized as follows.

1 high output performance: discharge standard for 2 ~ 5C, continuous discharge high current capacity of up to 10C, the discharge pulse instantaneous (10S) of up to 20C;

2 at high temperatures with good performance: external temperature of 65 ℃, when the temperature is as high as 95 ℃, the purpose of discharging the battery temperature to 160 ℃, the structural safety of the battery good condition;

3 Injury even if the internal battery or external battery is not burning, no explosion, security, the better;

4 excellent life cycles, after 500 cycles, its discharge capacity is still above 95%;

5 excessive discharges to zero volts and no damage; PA3396U-1ACA PA3467U-1ACA

6 load faster;

7 low cost;

8 pairs of environmental pollution.

Lithium iron phosphate power applications

As the lithium iron phosphate with the above characteristics, and produce a variety of different sizes of batteries, and soon to be widely used. There are major areas of application are:

A big electric vehicles: buses, electric cars, tour buses and hybrid vehicles and other attractions;

Two light electric vehicle: electric bikes, golf carts, small cars dead battery, forklifts, electric vehicle cleaning wheelchairs, etc.;

3 Power Tools: electric drills, electric saws, lawn mowers, etc.;

4 cars remote control, boats, planes, toys;

5 solar equipment and wind energy storage;

6 UPS and emergency lights, warning lights and a miner’s lamp (safety above);

7 one-camera replacement 3V lithium battery time and 9V Ni-Cd or Ni-MH rechargeable batteries (same size);

8 small medical equipment and portable instruments.

To provide a lithium iron phosphate can cause the battery replacement battery acid sample application. Using 36V/10Ah (360Wh) lead acid batteries, weight 12kg, load a battery can run about 50 km, number of charge cycles is approximately 100 times, the use of time is approximately 1 year. If using the Power Battery Lithium iron phosphate, using the same energy 360Wh (12 10Ah batteries in series), it weighs about 4 kg, charging time can run 80 km or more, number of cycles Load up to 1000 times the service life of up to 3 to 5 years. Although the lithium iron phosphate more expensive than lead-acid batteries is much higher, but the overall economic effects, or the use of lithium iron phosphate power better, and the use of more lighter and better.

On a small scale lithium iron phosphate battery power IBM ThinkPad R32 battery  IBM ThinkPad R50 battery

On a small scale lithium iron phosphate power battery is a standard, there are cylindrical and rectangular. Such that the cylindrical model are 18,650.26650 and so on. Type the first two are in diameter, after two or three very (in mm), or 18,650 of the diameter size of 18, a height of 65. Rectangular models 103450R, 183665R, etc.. The first two is the thickness of the stack, the middle two are the width of the battery, the latter two is the length of pile (mm unit). Factory battery in the model are often preceded by three letters to the Factory standard, as the model of the × × × 18,650