Application of New Battery

Since 1859, the French physicist Jiasidun·pulante invented rechargeable lead-acid batteries, and the advent of nickel-cadmium batteries, nickel-metal hydrogen cells, lithium cells, and fuel cells. The emergence and application of new materials have made battery performance. Great progress. Each update of the battery's positive and negative electrode material or electrolyte will improve the overall performance of the battery. The development direction of batteries has been pursuing high capacity, high power, high stability, low pollution, and long service life. With the continuous improvement of performance, its application field has also been expanding.

The miniaturization of electrical equipment has given rise to new batteries

According to the nature of the electrolyte, the battery can be divided into acid batteries and alkaline batteries. Acidic batteries are mainly lead-acid batteries, lead batteries, and electrolytes are sulfuric acid solutions. Lead acid batteries have the advantages of large capacity, high reliability, superior current discharge performance, wide application temperature range, and high cost performance. They are the most widely used secondary batteries at present, accounting for more than 70 % of the market share of secondary batteries. It is mainly used for backup power supply, electric bicycle and car start. Alkaline batteries mainly include cadmium nickel batteries, iron nickel batteries, etc., and their electrolytes are sodium hydroxide and potassium hydroxide. It can mainly be used as a DC power supply for electronic equipment such as automatic control and instrumentation.

With the continuous development of wireless technology, electric power equipment tends to be highly integrated, intelligent, light and miniaturized, and traditional batteries gradually show disadvantages such as large size and harsh environmental temperature requirements. Higher requirements are put forward for the specific energy and temperature range of the backup power supply. In recent years, the battery family has emerged a number of new batteries with many advantages. Lithium-iron phosphate batteries and fuel cells are typical examples of new batteries.

Power supply mode for self-supplied power supply

The indoor distribution system power supply refers to the independent power supply that specifically supplies electricity to the indoor distribution system power equipment (BBU, RRU, and monitoring equipment).

The self-provided backup power supply usually uses self-provided diesel generator sets, battery packs, uninterruptible power supply devices(UPS), and emergency power supply devices(EPS). Due to the different time when power supply is allowed to be interrupted, the choice of backup power supply is also different.

Reverse power backup power supply: The original China Unicom CDMA network uses a large number of reverse power backup power supply methods. The result of long-term operation proves that the backup power supply scheme of the inverter power supply has the disadvantages of low reliability and high maintenance frequency. If the backup power supply scheme of inverter power supply is adopted, the backup power supply equipment of inverter power supply with redundant modularization can be considered, thus improving the reliability of the overall power supply and reducing the cost of operation and maintenance.

UPS power supply: UPS is a power protection device containing energy storage devices, inverter as the main component, voltage stabilization output. The advantage of the UPS power supply scheme is that it has a relatively stable backup time and it is easy to achieve remote AC power supply.

The disadvantage of UPS is also more obvious. If UPS equipment is placed in user-side equipment(such as shafts, elevators, and even basements) where the operating environment is relatively poor, the poor operating environment and the "power pollution" of the city power will cause UPS working life to be greatly shortened; The weak management of small UPS batteries will reduce the service life of batteries; Some frame-type equipment, in order to reduce the volume of the equipment, uses a large number of forced air cooling to increase the output power density. The noise during the operation is relatively large, which can easily cause complaints from owners and increase the difficulty of building stations and future operation and maintenance.

Wall-mounted switch power supply: The use of small UPS can solve the backup power supply problem, but its output efficiency is usually only about 80 %, the entire power supply link from UPS through AC-gt; DC-gt; AC, the conversion process is large, the energy efficiency loss is large, and about 20 % of the energy becomes heat consumed in vain; If the small UPS considers redundant backup, it can only use dual or multi-machine parallel redundancy, which can not achieve modular backup redundancy, and the switch power supply has the characteristics of modular redundant backup and high conversion efficiency. At the same time, the switch power supply can realize the precise control and temperature compensation function, and can effectively provide the integrated management function of the battery.

lithium iron phosphate battery becomes an important direction

Compared with traditional lead-acid batteries, lithium iron phosphate batteries have the following advantages.

1) High energy density, the volume and weight of lithium iron phosphate batteries is only about one-third of that of lead-acid batteries.

2) Lithium-iron phosphate batteries alone can have a cycle life of 3,000 times under ideal conditions, which is much better than lead-acid batteries (500 cycles).

3) The temperature performance is good, especially the high temperature performance is outstanding. The range of work of lithium iron phosphate batteries can reach -20 °C ~ 60 °C, and it can work at high temperatures for a long time without affecting the battery life.

4) Good power performance. Without affecting the battery capacity, lithium-iron phosphate batteries can meet the needs of high current charging and discharging, and solve the problem of excessive battery capacity loss when traditional lead-acid batteries discharge large current. In the same capacity, lithium iron phosphate batteries output about twice as much current as lead-acid batteries. If the lithium iron phosphate battery is used instead of the lead acid battery for the power type power supply UPS, its capacity will be reduced by 50 %.

5) High security. In the harsh conditions such as acupuncture, extrusion, short circuit, overcharging, etc., it is still safe, no deformation, and the capacity retention rate is extremely high.

6) Clean and environmentally friendly, lithium iron phosphate materials do not contain any heavy metals and rare metals, no matter in the production and use process will not cause pollution to the environment, avoiding the pollution of the environment by traditional batteries.

Lithium iron phosphate, as a lithium battery positive electrode material, is currently the safest lithium ion battery positive electrode material. Although the vibration density is low and the voltage platform is low, due to the safety and stability of the positive electrode material, it is still in extrusion, overcharge, short-circuit and other abuse conditions. Safe, Due to its safety and stability, lithium iron phosphate batteries have become an important development direction of lithium ion power cells.

Fuel cells have an integrated cost advantage

Compared with traditional lead-acid batteries, fuel cells also have great advantages.

1) Adapted to a wide range of ambient temperatures, and can maintain stable performance in the range of -15 °C to 45 °C.

2) Work smoothly, the output voltage is stable, and the voltage will not be reduced during the power supply of the lead-acid battery.

3) Light weight, no special load-bearing treatment.

4) Small area, flexible location, can be placed outdoors, greatly saving space. 5) The ability to resist natural disasters is strong, so long as the supply of hydrogen is guaranteed, the power supply will be sustainable.

6) Battery design life(accumulated useful time / cumulative number of switches / storage life) is too long, unlike lead-acid batteries that are replaced every few years.

7) Safety is high, and fuel cells can be monitored remotely.

At present, the procurement cost of fuel cells is higher than that of lead-acid batteries. However, under the premise of mass production, the cost of fuel cells is lower than that of lead-acid batteries, taking into account factors such as site renovation, maintenance costs and service life.

As an important part of the backup power supply, the performance of the battery pack directly affects the reliability of the entire power supply system. It can even be said that the backup power supply is the last line of defense for the safe operation of the power supply system. The commercial use of the new type of cell provides a new way for the application of the back-up battery pack for indoor distributed systems engineering. At the same time, with the continuous improvement of the performance of the new battery itself and the continuous decline of production costs, the application prospects of its indoor distribution system engineering will gradually become clear and clear.

The page contains the contents of the machine translation.