Difference between polymer lithium battery and lithium iron phosphate battery


  Author :Iflowpower – Portable Power Station Supplier

  First, polymer lithium battery outline polymer lithium battery generally refers to the polymer lithium ion battery. Depending on the electrolyte material used in lithium ion batteries, lithium ion batteries are divided into liquid lithium ion batteries (LiquifiedLithium-Ionbattery, referred to as LiB) and polymer lithium ion batteries (PLBATTERY, PLB) or plastic lithium-ion battery (PlasticLithium) , Referred to as PLB). The positive and negative electrode materials used in polymer lithium ion batteries are the same, and the positive electrode materials are divided into lithium cobalt organte, lithium manganate, tri-material and lithium iron phosphate material, and negative extreme graphite, battery work principle is also basically Consistent.

Their main difference is that the electrolyte is different, and the liquid lithium ion battery uses a liquid electrolyte, and the polymer lithium ion battery is replaced by a solid polymer electrolyte. The polymer can be "dry state" or "colloid" Most of the current polymer gel electrolyte. Polymer lithium battery classification: solid: solid polymer electrolyte lithium ion battery electrolyte is a mixture of polymers and salts, such a battery is high at normal temperature, can be used at normal temperature.

Gel: The gel polymer electrolyte lithium ion battery is added to a plasticizer such as a plasticizer in a solid polymer electrolyte, thereby increasing ion conductivity, so that the battery can be used at normal temperature. Polymer: Since the liquid electrolyte is substituted with a solid electrolyte, the polymer lithium ion battery has the advantages of thinner, arbitrary area, and any shape, etc., can be manufactured by an aluminum-plastic composite film.

The outer casing can thus improve the specific capacity of the entire battery; the polymer lithium ion battery can also use a polymer as a positive material, and its mass is more than 20% more than the current liquid lithium ion battery. Polymer lithium ion (Polymerlithium-Ionbattery) has a small amount of miniaturization, thinning, and lightweight. Therefore, polymer batteries will gradually increase in market.

Polymer lithium battery principle: lithium ion battery currently has a liquid lithium-ion battery (LiB) and polymer lithium ion battery (PLB). Among them, liquid lithium-ion battery refers to secondary batteries of Li + embedded compounds. The positive electrode uses lithium compound LiCoO2, LiNiO2 or LiMn2O4, and the negative electrode is used in lithium-carbon layer compound LiXC6, and the typical battery system is: the principle of the polymer lithium ion battery is the same as liquid lithium, the main difference is that the electrolyte is different from liquid lithium.

The main structure of the battery includes three elements of the positive electrode, negative electrode and electrolyte. The so-called polymer lithium ion battery is that at least one or more of the three main structures uses polymer materials as the main battery system. In the currently developed polymer lithium ion battery system, polymer materials are mainly used in positive electrode and electrolyte.

The positive electrode material includes a conductive polymer polymer or an inorganic compound employed in a general lithium ion battery, which can use solid or colloidal polymer electrolyte, or an organic electrolyte, general lithium ion technology using liquid or colloidal electrolyte, therefore Sturdy secondary packaging to accommodate the flammable active ingredient, which increases the weight, and also limits the flexibility of size. The new generation of polymer lithium-ion batteries can be thin in shape (the ATL battery can reach 0.5 mm, corresponding to the thickness of a card), any area of ​​chemical, and any shape, greatly improve the battery design Flexibility, so that you can cooperate with product needs, make batteries of any shape and capacity, provide equipment developers with some design flexibility and adaptation to maximize their product performance.

At the same time, the unit energy of the polymer lithium-ion battery is more than 20% higher than the current general lithium ion battery, and there is a lithium-ion battery than that of the environment, and environmental performance, etc. Polymer lithium battery advantages: Advantages: 1. The operating voltage of the monomer battery is as high as 1.

2V voltage of the nickel-hydrogen and nickel-cadmium battery. 2. Large capacity density, its capacity density is 1.

5 to 2.5 times the nickel-hydrogen battery or nickel-cadmium battery, or higher. 3.

Small self-discharge, the capacity loss is small after standing for a long time. 4. Long life, normal use of its cycle life can reach more than 500 times.

5. There is no memory effect, you don't have to take the remaining electricity quantity before charging, easy to use. 6.

Safety performance Good polymer lithium battery in structure with aluminum-plastic soft packaging, is different from the metal casing of the liquid electrical cell, once a safety hazard occurs, the liquid battery is easily exploded, and the polymer battery is only a drum. 7. Small thickness, can do more thin and thin, battery can assemble into credit card.

Ordinary liquid lithium electricity uses the method of pioneering the outer casing, the rear positive and negative electrode material, the thickness is 3.6mm or less, and the polymer battery does not exist, the thickness can be 1 mm or less, in line with the direction of mobile phone demand. 8.

Weight light use of polymer electrolyte battery without metal shells to be protected as protection. Polymer battery weight is less than 40% of the steel shell of the same capacity specification, 20% light 20% of the aluminum shell battery. 9.

Capacity large polymer battery is more than 10 to 15% of the steel shell battery, 5 to 10% higher than the aluminum shell battery, becoming the preferred choice for color screen mobile phones and MMS mobile phones. Nowadays, new color screens and MMS Most of the mobile phone also uses polymer electrical cells. 10.

The internal resistance of the internal resistance small polymer cell is smaller than the general liquid cell. At present, the internal resistance of the domestic polymer cell can even achieve the following 35MΩ, greatly reduce the self-consuming power of the battery, and extend the standby of the phone. Time, you can fully reach the level of international.

This polymer lithium-lithium-supported polymer that supports large discharge current is ideal for the remote control model, which is the most promising product of alternative nickel-hydrogen batteries. 11. The shape of a custom manufacturer is not limited to standard profile, and it can economically make the right size.

The polymer battery can increase or reduce the thickness of the customer, develop the new battery core model, the price is cheap, the opening die period is short, and some can even do it according to the amount of mobile phone shape to make full use of battery housing space, and improve the battery. capacity. 12.

The discharge characteristics of the discharge characteristic polymer battery use colloidal electrolyte, compared to the liquid electrolyte, the colloidal electrolyte has a smooth discharge characteristics and a higher discharge platform. 13. Simple protection plate design Due to the use of polymeric materials, the cell does not affect the fire, does not explode, the battery cell itself has sufficient safety, so the protective line design of the polymer battery can consider omitting the PTC and fuses, saving battery costs.

Disadvantages: 1. High battery cost, difficulty in electrolyte system purification. 2.

Require protection line control, overcharge, or overlapping the reversibility of the internal chemicals of the battery, which seriously affects the life of the battery. Second, the lithium iron phosphate battery is an overview of lithium iron phosphate cells, refers to a lithium ion battery with lithium iron phosphate as a positive electrode material. The positive electrode material of the lithium-ion battery mainly has lithium cobaltate, lithium manganese acid, lithium nickel, three-dimensional material, lithium iron phosphate, etc.

Among them, lithium cobaltate is a positive material used in most lithium-ion batteries. Space structure of lithium iron phosphate battery: For the positive material of LifePo4, its raw material is relatively wide, the cycle life is long, the safety index is also high, and the environmental pollution is small, and very strong comprehensive performance is reflected in numerous positive materials. It has always been the hot spot material for the preparation of the positive electrode of the lithium-ion battery.

Under the development of recent years, Lifepo4 positive materials have reached a practical level, and even start formal commercial applications, LiFePO4 is an olivine structure, and the spatial structure is shown in Figure 1. Its theoretical specific capacity is 170mahh, when charging is charged, the oxidation reaction occurs, and the lithium-ion Feo6 level is released, flow into the electrolyte, and finally reach the negative electrode, in the external circuit, electronically reaches the negative electrode, the iron will from divalent The iron ion becomes a trivalent iron ion, an oxidation reaction occurs. The discharge process is opposite to the charging process, which occurs the reducing reaction.

Lithium iron phosphate battery Working principle: ferrite lithium phosphate battery refers to a lithium ion battery with lithium iron phosphate as a positive material. The positive electrode material of the lithium-ion battery mainly has lithium cobaltate, lithium manganese acid, lithium nickel, three-dimensional material, lithium iron phosphate, etc. Among them, lithium cobaltate is a positive material used in most lithium-ion batteries.

Significant metal trading market, cobalt (CO) is the most expensive, there is not much storage, nickel (Ni), manganese (MN) is cheaper, and iron (Fe) storage amount is more. The price of the positive electrode material is also consistent with these metal prices. Therefore, the lithium ion battery made by the LIFEPO4 positive electrode material should be very cheap.

Another feature of it is that environmentally friendly pollution. As the rechargeable battery is: high capacity, high output voltage, good charge and discharge cycle performance, output voltage stable, energy-saving charge, electrochemical stability, safety (will not overcharge, over discharge and short circuit Improper operation, causing burning or explosion), wide working temperature range, non-toxic or less toxic, no pollution to the environment. Lithium iron phosphate cells using LiFePO4 are good in these performance requirements, especially in large discharge rate discharge (5 ~ 10c discharge), the discharge voltage is stable, safe (not burning, not exploding), life (number of cycles) ), There is no contamination of the environment, it is the best, and it is the best high current output power battery.

The structural and working principle LIFEPO4 is used as the positive electrode of the battery, and is connected from the battery positive electrode. The intermediate is the diaphragm of the polymer, which is separated from the positive electrode, but the lithium ion Li can pass and the electronic E- cannot pass, the right side is carbon ( Graphite) The battery negative electrode is connected by the negative electrode of the copper foil and the battery. Between the upper and lower ends of the battery, the battery is electrolyte, and the battery is sealed by metal housing.

When the LifePO4 battery is charged, the lithium ion Li in the positive electrode is migrated to the negative electrode through the polymer diaphragm; during the discharge process, the lithium ion Li in the negative electrode migrates through the diaphragm. The lithium-ion battery is named after the lithium ion moves back and forth in the charge and discharge. LifePO4 internal structure Main performance LifePO4 battery nominal voltage is 3.

2V, the termination of the charging voltage is 3.6V, the stop discharge pressure is 2.0V.

Some differences in performance due to the quality and process of each manufacturer, the quality and process of electrolyte materials, the performance of the electrolyte material. For example, with a model (standard battery of the same package), the capacity of its battery has a large difference (10% ~ 20%). It will be described here that there will be some differences in the lithium iron phosphate power cells produced by different plants; in addition, some battery performance is not included, such as battery internal resistance, self-discharge ratio, charge and discharge temperature, etc.

The capacity of lithium iron phosphate power cells has a large difference, which can be divided into three categories: small zero point to several milliants, medium-sized tens of milliamps, large number of hundreds of milliamp. There are also some differences in similar parameters of different types of batteries. Over-discharged to zero voltage test: Exceeding to zero voltage test using STL18650 (1100 mAh) of lithium iron phosphate power cells.

Test conditions: Full of 1100mAh STL18650 battery with 0.5C charging rate, then discharged to the battery voltage to 0C with 1.0C discharge rate.

Then the battery of the 0V is divided into two groups: a group of 7 days, another group is stored for 30 days; after storage expires, use 0.5C charging rate, then discharge with 1.0C.

Finally, compare different differences in different zero voltage deposits. The result of the trial is that the battery has no leakage after 7 days of zero voltage, and the performance is good, the capacity is 100%; after storage for 30 days, there is no leakage, the performance is good, the capacity is 98%; the battery is stored in 30 days, and the battery is used to do 3 charge and discharge cycles. Capacity is restored to 100%.

This test indicates that the lithium iron phosphate battery even has over-discharge (even to 0V), and stores for a certain period of time, the battery does not leak, damaged. This is the characteristic of other types of lithium-ion batteries. Third, polymer lithium battery and lithium iron phosphate battery lithium polymer battery is generated by replacing a conventional liquid organic electrolyte based on a polymer polymer electrolyte on a lithium ion battery basis.

Such a polymer electrolyte can be used as a medium that conducts ions, but also as a spacer film, coupled with a very low reactivity with the metal lithium, thereby effectively avoiding the easily combustion of the lithium ion battery and the phenomenon of easy leakage. And since the lithium ion polymer battery is adsorbed onto a polymer matrix, the electrolyte is not a solid electrolyte, so that the lithium lithium polymer battery is not only Excellent performance of liquid lithium ion batteries can also be made into any shape and size, ultra-thin product, which makes it wide, and has a good development prospect. In addition, the safety is better than the lithium-ion battery.

If it is fever in use, it will only produce swelling or burning without explosion. Lithium phosphate battery refers to a lithium ion battery refers to lithium iron phosphate as a positive electrode material. Long life lead-acid battery cycle life is around 300 times, up to 500 phosphate battery, while lithium iron phosphate power battery, the cycle life reaches more than 2,000 times, standard charging (5 hours), can reach 2000 times.

The same quality lead-acid battery is "new half year, old half year, maintenance and maintenance and half year", up to 1 to 1.5 years, while lithium iron phosphate batteries are used under the same conditions, will reach 7-8 years. Comprehensive consideration, performance price is more than 4 times more than lead acid batteries.

In addition, the polymer lithium battery (3.7V) is light, and the voltage ratio is higher than the lithium phosphate (3.2V).

High temperature resistance is lower than lithium iron phosphate. .

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