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Lifep04 lithium battery (lifep04) cathode material is considered as one of the most promising cathode materials for lithium ion batteries because of its excellent electrochemical properties.  However, its development has been restricted by its low conductivity and slow diffusion rate of lithium ions. In this paper, the effects of ion doping, carbon coating and nano-materials modification on lithium iron phosphate cathode materials for lithium ion batteries and the existing problems are mainly introduced, and the development trend and key research directions of LiFeP04 lithium battery are prospected.

Because the lithium iron phosphate cathode material has poor conductivity and low lithium ion diffusion coefficient, researchers at home and abroad have done a lot of research in these areas, and achieved some good results. Its modification research mainly includes three aspects: doping method, coating method and nano-materials.

Lithium-ion batteries are widely used in mobile phones, notebook computers, digital cameras, electric vehicles, aerospace, military equipment and other fields because of their high energy density, low self-discharge current, high safety, high current charge-discharge, many cycles and long life.

UPS battery backupUps is mainly to prevent power failure of digital products during long-term use. It is a battery backupUps. It is different from the general battery backupUps,which uses four standard AA alkaline batteries. It needs to be shut down for replacement. UPS battery backupUps should belong to mobile power supply in a broad sense. Generally, 18650 lithium-ion batteries or lithium-polymer batteries are used as battery packs to connect charging wires and adapters to achieve continuous functions when digital products are powerless.

The main advantage of uninterruptible power supply is its uninterrupted power supply capability. When the AC input of municipal power is normal, UPS rectifies AC to DC, and then inverts DC to stable AC without impurities, which is used for the later load. Once the AC input of city power is abnormal, such as under-voltage or power failure or abnormal frequency, UPS will turn on the energy-storage battery backupUps, and the rectifier circuit of UPS will turn off. Correspondingly, the DC current of the battery will be inverted into a stable AC without impurities, which will continue to be used for the later load. This is the origin of uninterrupted power supply capability of UPS.

Of course, the uninterrupted power supply time of UPS is not unlimited, which is limited by the storage energy of the battery itself. What if AC power failure occurs? So in the precious time of UPS battery power supply, what you need to do is to quickly restore AC, such as starting standby AC circuit, starting oil engine power generation. If there is no other solution, you can only urgently save the results of labor, and wait for AC to return to normal before continuing.

Rechargeable batteries are rechargeable batteries with limited number of charges, which are used in conjunction with chargers. When its electricity is used up, the current is applied to it. It can convert electrical energy into chemical energy. When the electricity is turned on, the battery converts chemical energy into electrical energy through chemical reaction. In this way, charging-discharging-charging-discharging, it can be recycled.

1. The advantages of rechargeable batteries are that it is economical, and environmentally friendly. It has enough electricity. It is suitable for high-power, long-term use electrical appliances, such as walkman, electric toys and so on.

2. The voltage of rechargeable batteries is lower than that of disposable batteries of the same type. AA batteries (No. 5 charging) are 1.2 volts, and 9V charging batteries are actually 8.4 volts. Now the average number of charges can be about 1000 times.

3. Its cycle life is long. It can charge and discharge more than 200 times. Some rechargeable batteries have higher load than most disposable batteries.

Types of rechargeable batteries 

At present, there are only five kinds: nickel and cadmium, nickel and hydrogen, lithium ion, lead storage, iron and lithium.

1. Nickel-cadmium batteries (Ni-Cd)

Characteristic: It has memory effect and small capacity.

2. Nickel-hydrogen battery (Ni-MH)

Characteristics: It has small memory effect and large capacity. At present, the maximum capacity of domestic No. 5 battery is about 2500 mAh.

3. Lithium-ion batteries (Li-lon)

Characteristic: It has no memory effect, is very thin and has large capacity. Its weight is 30%-40% lighter than that of Ni-MH battery, and its capacity is 60% higher than that of Ni-MH battery. But it can't stand overcharging. If it is overcharged, the temperature will be too high to destroy the structure=> explosion. The electromotive force is 3.6V and 3.7V because of different electrode materials. The performance of lithium batteries is the best of all kinds of batteries. They are small in size, light in weight and large in capacity. It is widely used in digital cameras, laptops, mobile phones and other electronic products.

4. Li-polymer battery

Characteristic: The improved lithium battery has no battery liquid, but can be made into various shapes by using polymer electrolyte, which is more stable than lithium battery.

5. Lead-acid battery (Sealed)

Characteristic: It is a general car battery, which is connected in series with 6 2V to 12V. Water-free batteries have a life of up to 10 years, but their volume and capacity are the largest.

Twenty-four years have passed. Time flies, day and night changes. No matter how the situation changes, the concept of "benefiting the people with the best batteries, touching clients with the best service" remains unchanged. Only battery of dongjin group an do this.

Looking at the history of the battery industry, you will find only powerful enterprises remain in dozens of brands in in a new round of reshuffle. Dongjin Group, the veteran batteries in this field shows its outstanding quality strength every time. In 2012, dongjin group invested 500 million yuan in establishing Jiangxi Dongjin New Energy Co., Ltd. in Ji'an, Jiangxi Province. It played a leading role in both brand influence and productivity improvement. In addition to focusing on building domestic sales channels, we should formulate a differentiation strategy, focus on the global market, and lay out the international market. Our products are exported to more than 50 countries and regions in Israel, Afghanistan, North America, South America, Asia, Middle East and South Africa. Among them, "Dongjin" and "Jinfeng" brands have become the leading brands in the local market. Compared with the same type of batteries, they occupy an absolute market share.

Under the new situation, new changes and adjustments have taken place in the battery energy industry. Dongjin Group, which is well versed in this theory, has been adapting to the trend of development, constantly adjusting its own structure and formulating a two-step marketing strategy: In the domestic market, we should set up professional R&D, production and sales teams, introduce modern equipment, increase control over product quality and technology R&D, and stabilize the domestic market with the advantages of quality and service.

The international market is based on the changes of the global new energy environment and the objective environment of oversupply in the domestic market. Top leaders of Dongjin Group decided to continue to invest more and build the largest battery production base in Bangladesh in December. At that time, the group's daily capacity of nearly 30,000 batteries can be completely digested by foreign trade orders. Domestic and foreign markets are combined to complement each other. It plays back into the attack and defend the action. This makes Dongjin present a unique brand image.

According to the senior management of the group, on the basis of its original strength, Dongjin Group will set up a brand new team, marketing model, product system and nanny-style service system at the end of 2016 to return to the domestic and foreign markets and re-establish the brand value of the enterprise. With the new situation, new environment and new changes, battery of Dongjin group is showing its strong vitality.

Many types of adapters can be used to charge lithium-ion batteries and power the system, and the electrical specifications of each rechargeable lithium battery are usually different. This requires system designers to build portable devices, which meet the safety and reliability requirements when using different adapters. Enhance robust security performance. Dongjin fully integrates input overvoltage, input overcurrent, battery overvoltage and reverse input polarity protection, which can significantly improve the safety of battery power supply system.

The ultimate purpose of parallel lithium battery of rechargeable lithium batteries is to increase capacity. Therefore, parallel lithium battery has some different characteristics in design compared with single lithium batteries, mainly reflected in the consistency of charging current design and parallel batteries.

Generally speaking, the characteristics of parallel lithium batteries are as follows: the voltage is constant, the capacity of batteries is added together, the internal resistance is reduced, and the power supply time is prolonged. The core content of parallel charging is the magnitude and function of parallel current. According to the theory of parallel connection, the trunk current equals the sum of all branch currents. Therefore, in order to achieve the same charging efficiency as a single lithium battery, the charging current should be the sum of the current of N lithium batteries.

Under the formula of I = U / R, this design is reasonable. However, the internal resistance of parallel batteries will also change. According to the formula of parallel internal resistance, the total internal resistance of two parallel lithium batteries is equal to the ratio of the product of internal resistance of two batteries to the sum of their internal resistance, and the parallel resistance will decrease with the increase of the number of parallel batteries. Therefore, the efficiency of parallel charging of lithium batteries can be realized on the basis that the current of lithium batteries in parallel is less than the sum of the current of N lithium batteries in parallel.

Generally, after parallel connection of lithium batteries, there will be a charge protection chip to protect the lithium batteries. As one of the excellent manufacturers of rechargeable lithium batteries, battery of Dongjin has fully considered the changes of lithium batteries after parallel connection, and also designed the current and selected the batteries according to the above requirements. Therefore, users need to charge lithium batteries on time according to the instructions of parallel lithium batteries, so as to avoid possible damage to batteries caused by incorrect charging methods.

The purpose of developing high technology is to make it serve human better. Lithium-ion batteries have developed rapidly since 1990 because of their excellent performance and they have been widely used in society. Lithium-ion batteries have rapidly occupied many fields with incomparable advantages over other batteries. As we all know, mobile phones, laptops, small cameras and so on all involve the application and development prospect of lithium battery, and more and more countries use the batteries for military purposes. The application shows that lithium battery is an ideal small green power supply.

The application and development prospect of lithium battery will expand rapidly in the next five years. The application and development prospect of lithium battery is mainly divided into three parts: consumer electronic products, electric vehicles and industrial energy storage. We can find that application focus of lithium batteries is at the stage of development from small batteries market of consumer electronic products to power batteries market of electric vehicles and industrial energy storage. The order is: consumer electronic products market electric vehicles market industrial energy storage market.

In emerging markets such as tablets, electric vehicles (PHEV + EV) and home energy storage, some lithium-ion batteries are the best choice, while others are the first choice. In the market of power grid energy storage which has not yet arisen, the related demonstration operation projects have been carried out at present.

Lithium-ion batteries are gaining ground in the market mainly because of their rapidly declining prices. In terms of performance, lithium-ion batteries are superior to lead-acid batteries, nickel-cadmium batteries, nickel-hydrogen batteries and other major competitors. Through the advantages of performance, lithium-ion batteries gradually expand the market scale. The growth of demand directly leads to the expansion of production capacity and the reduction of manufacturing costs, which in turn stimulates further growth of market demand. In this way, the lithium battery application industry has embarked on a virtuous cycle of development.

The lithium battery advantages are large capacity and high working voltage. The capacity is twice as large as that of the same nickel-cadmium battery, which is more suitable for long-term communication. The voltage of lithium ion is 3.6v, which is three times as high as that of nickel-cadmium and nickel-hydrogen batteries. Charge retention ability is strong, allowing a wide range of operating temperature. After 30 days of storage in open circuit mode at (20 +5) (?) C, the discharge capacity of lithium-ion batteries at room temperature is more than 85% of the rated capacity. Lithium-ion batteries have excellent discharge performance at high and low temperatures, and can work at - 20 ~+55 (?) C. The discharge performance at high temperature is better than that of other batteries.

Long cycle life. Carbon anode is used in lithium-ion batteries. During charging and discharging, the carbon anode will not produce dendritic lithium, which can avoid damage to the inner dendritic lithium short-circuit ears of batteries. After 1200 consecutive charges and discharges, the capacity of the battery is still not less than 60% of the rated value, which is much higher than other types of batteries and has long-term economic use.

It has high safety and can charge and discharge safely and quickly. Compared with metal lithium batteries, lithium-ion batteries have the characteristics of short circuit resistance, overcharge resistance, overdischarge resistance, impact resistance (10 kg weight falling freely from 1 m height), anti-vibration, shooting, needling (penetration), non-fire and non-explosion. Because its anode uses special carbon electrode instead of metal lithium electrode, it allows rapid discharge and can charge and discharge at a charge rate of 1c. So the security performance is greatly improved.

No environmental pollution. Batteries do not contain harmful substances such as cadmium, lead and mercury, which is a clean "green" chemical energy without memory effect. It can be repeatedly charged and discharged at any time. Especially in emergencies, it shows excellent performance.

It has small volume, light weight and high specific energy. Usually, the specific energy of lithium ion batteries can be more than twice that of nickel-cadmium batteries. Compared with the same capacity nickel-cadmium batteries, the volume and weight of lithium ion batteries can be reduced by 30% and 50%, which is conducive to the miniaturization and lightweight of convenient electronic equipment.

The analysis of the competition pattern of electric vehicles in the seven major automotive countries in the world shows that Germany is in the leading position at the "technology" level, while China is in the leading position at the "industry" level because of its high level of production and value creation. From the "market" point of view, the seven leading automotive powers in the world have gradually narrowed the gap.

As far as the "industry" index is concerned, China has established a leading position. This benefits from the leading level of Chinese battery manufacturers. Battery manufacturing market continues to grow rapidly, and more than 90% of lithium batteries are produced locally.

In the field of battery manufacturing, the advantages of Chinese battery manufacturers are becoming more and more obvious. From the global share of battery production, Chinese battery manufacturers have been in the leading position. With the expansion of market penetration of long-distance endurance pure electric vehicles, the demand for batteries will increase. Together with these two trends, battery of Dongjin will greatly increase investment to ensure the quality and price of batteries to make consumers more satisfied.