Over the years, nickel-cadmium (NiCd) is the only, such as wireless communications and mobile computing applications, ideal for battery. In 1990, the nickel-metal hydride (NiMH) and lithium-ion battery (Li-ion) appears to provide greater capacity. These two chemicals to fight nose to nose, all claim better performance and smaller size.
Which chemicals will be the real winners, what system would do in the new millennium? The vote is a lithium-ion, especially the portable, with miniaturization.
Lithium-ion is a low maintenance battery, an advantage that no other chemicals can be claimed. No memory and no scheduled cycling is necessary to extend battery life. In addition to high energy density, light weight, self-discharge is less than half than the nickel-cadmium batteries and nickel-metal hydride batteries, and Li Jing modern fuels ideal ion sensor applications.
On the negative lithium-ion is fragile and needs protection circuit to maintain safe operation. The load current is moderate, and the charges must be according to strict standards. In addition, the lithium-ion battery is subject to aging, whether used or not.
In the history of pioneering work for the lithium battery began in 1912 by GN Lewis, but it was not before the early 70s, the first non-rechargeable lithium battery began to put on the market. Attempts to develop rechargeable lithium batteries 80 years later, but failed due to security issues.
Lithium is the lightest of all metals and has the greatest electrochemical potential and to provide the maximum energy. As (the anode) anode lithium metal rechargeable batteries can provide high voltage and excellent capacity, at a very high energy density making.
Rechargeable lithium battery, after a lot of research in the eighties, it was found to change the lithium electrode cycling, thereby reducing its thermal stability, resulting in a potential thermal runaway. If this happens, the battery quickly approaches the melting temperature of lithium, in the intense reaction, the result points.
Of a large number of rechargeable lithium batteries sent to Japan must be recalled that in 1991, after the mobile phone battery release of hot gases, causing severe burns the man's face.
Due to the inherent instability of lithium metal, especially in the charging, research shifted to a non-lithium metal batteries use lithium-ion. Although slightly lower than the energy density of lithium batteries with low metal, in the Lee? Ion is safe, provided that they meet certain preventive measures, charge and discharge. In 1991, Sony commercialized the first Li? Ion batteries.
Other manufacturers followed suit. Today, Lee? Ion is the fastest growing and most promising battery chemistry.
Version of lithium-ion batteries have several types of lithium-ion batteries to happen. Sony's original version of the coke used in the negative electrode (anode). Since 1997, most of the lithium-ion batteries, including Sony, has been transferred to the graphite. This electrode provides a flat discharge voltage curve than coke, and provides a sharp knee bend
Voltage drop from the previous discharge soon after the cut (see Figure 1). Therefore, the graphite system, useful energy, performance of each module can be retrieved only 3.0 volts, while Sony's coke version must be discharged to 2.5 volts to obtain the same performance.
Figure 1: Li? Ion discharge characteristics. Graphite Lithium-ion batteries only need to perform 3.0V/cell, while the coke version must be discharged into the 2.5V/cell to achieve similar performance.
For the positive (cathode), two different chemicals have emerged. They are cobalt and manganese, also known as spinel. In view of cobalt has been used longer, spinel inherently safer and more tolerant, if the abuse. Protection circuit can be simplified, or even canceled.
Spinel prism package can only be a small cell phone, including temperature fuse and temperature sensor. In addition to increasing security, lower raw material cost of cobalt-manganese.
In exchange, the spinel to provide energy density is slightly lower, being higher than 40 degrees Celsius, and faster than the age of cobalt capacity loss. Figure 2 compares the advantages and disadvantages of the two chemicals.
Cobalt-manganese (spinel) energy density (W / kg) 14,011,201 in the overcharge safety, provide additional electrode of lithium cobalt batteries, can form a lithium metal, resulting in a potential security risk, without a secure circuit protection. In overcharge, manganese lithium-run lead to cell electrodes only get warm.
Safety circuit can eliminate the small 1 and 2-cell pack. A wide temperature range of temperature. Most suitable for high temperature operation. Capacity loss of more than 40 degrees Celsius are not durable at higher temperatures. Aging short-term storage possible. Impedance increases with age. A newer version of a longer storage. Slightly less than the Cobalt. Impedance changes of l
ittle the cell's life. Due to continuous improvement, storage, timing is unpredictable. 300 times cycle life, 50% of the 500 cycles capacity. May is shorter than cobalt. The relatively high cost of raw materials; protection circuit increases the cost. Material less than 30% of cobalt. Cost advantage of the simplified protection circuit.
Figure 2: Comparison of cobalt, manganese is a positive electrode. Manganese born safer and more tolerant, if abused, but offers slightly lower energy density. Manganese subjected to temperatures above 40 ° C and faster than the age of cobalt capacity loss.
1 Based on the current generation 18650 cells. Energy density is often low prismatic cells,
Chemicals and additives helps to balance the critical trade-off high-energy density, long storage time, prolonging life and safety. High-energy density can be achieved relatively easily. For example, adding more nickel and cobalt increased ampere / hour rating be replaced by lower manufacturing costs, but the cell less secure.
Although the start-up company may focus on high-energy density, so that rapid market acceptance, security, life and memory may be impaired. Reputable manufacturers such as Sony, Panasonic, Sanyo, and Moli places attach great importance to safety.
Lithium-ion batteries cause less harm than when dealing with lead and cadmium batteries. One lithium-ion battery series, the spinel is a friendly disposal.
Rechargeable lithium-ion battery Lithium-ion battery charger is a pressure limiting device, and similar lead-acid battery charger. The main difference between Li-ion rechargeable battery voltage is higher, tighter voltage tolerance and the absence of trickle or float solely responsible.
While the battery voltage to provide some flexibility in the cut-ion battery Li Hongzhi is a very stringent voltage selection. When the first introduction of the graphite system, the maximum charge voltage of 4.10 volts per cell. Although the high-voltage, providing a higher energy density,
Cell oxidation severely limited in the early graphite cells collected if the above threshold 4.10V/cell life. This effect has now been resolved chemical additives and most of the new lithium-ion batteries are now set to 4.20V. In all Li-ion battery is a tight tolerance of + / - 0.05 volts per cell.
All Li-ion battery charge time is about three hours the first time in IC charge current. The battery charging process to remain calm. After power is to achieve full voltage level of about 3 on behalf of, or about 0.03C% of the maximum threshold voltage and current decline and fall.
Increases the charge current lithium-ion battery charger does not shorten the amount of charging time. Although the voltage peak speeds up to a higher current, first-class fares require a longer time. Figure 3 shows the voltage and a charge current of Li-ion batteries to sign, through the first stage and two passes.
Figure 3: rechargeable lithium-phase of the lithium-ion batteries. Increase in Lebanon? Ion charger charging current does not shorten the amount of charging time. Although the voltage peak speeds up to a higher current, first-class fares require a longer time.
Claim fast charging lithium-ion battery in one hour is usually at a lower level of fees, the results of the battery. This simply to eliminate a two-stage charger will enter the Direct ready 'once the voltage threshold value is reached at the end of the first phase. At this point the level of fees is approximately 70%. Flat fees typically require a long initial charge twice as much.
No trickle charge is due to use of lithium-ion batteries can not absorb the charge. Trickle charge could lead to lithium metal plating, a condition, the cell unstable. On the contrary, a short break to make up a small amount of fees and charges applicable to the self-discharge of the battery and its protection circuit consumption.
Depending on the charger and self-cells, leading the charge may be the implementation of emission once every 500 hours or 20 days. Typically, fees and charges, kicked open the terminal voltage dropped to 4.05 volts per unit shut down when it reaches 4.20V/cell.
Commercial protection circuit of lithium-ion battery pack with extra protective devices to ensure the security under any circumstances. Typically, FET Open, if any of the battery charge voltage to 4.30V, activate and fuse, if the battery temperature close to 90 ℃ (194 ° F) between the. Furthermore,
The pressure switch in each cell permanently interrupts the charge current safe pressure threshold is exceeded, the internal voltage control circuits cut off the low and high-voltage point of the battery. Without exception, prismatic, cylindrical spinel package contains only one or two cells.
Lithium-ion is usually discharged from hospital 3 volts per cell. The lowest low-voltage 'power is 2.5V/cell. In the long storage, but lower than the voltage of discharge is possible. The manufacturer's recommended a 'trickle' charge to increase gradually the battery backup to 'accept' voltage window.
Not all of the charger once the Design and Application of Lithium-ion battery, less than the decline in 2.5V/cell responsible.
Some batteries have an ultra-low-voltage cut-off, permanent disconnect, if a cell dips below 1.5 volts the pack. This preventive measure is to prohibit charging, if the battery voltage is lived in a country illegally. A reason for the deep discharge copper, which will lead to short-circuit the cell.
Most manufacturers do not sell their own lithium-ion batteries, but they provide batteries with protection circuit to complete. It is understandable that preventive measures, take into account the risk of explosion and fire, if the battery charge and subsequent discharge of security restrictions.
One major concern arises if static electricity or a wrong battery charger has managed to undermine the protection circuit. Such damage often leads to solid-state switch fuse without the user's knowledge of the permanent right position. Fault protection circuit of a battery to work, but did not provide the required security.
If you exceed the poorly designed accessory charger safe voltage limit battery power can be heated, and then inflated, in some cases, the exhaust flame. This short-circuit the battery can also be dangerous.
For the lithium-ion batteries in the past analyzer, battery analyzer is used to restore the affected memory 'cells. Today's non-nickel batteries, memory is no longer a problem, an analysis of the focus will shift to the battery performance verification, quality control and rapid detection.
The traditional view, a new battery is always a perfect performance. However, many users are aware that the battery from the breaking of seals are often unable to meet the manufacturer's specifications fresh. With the battery analyzer, all incoming checks the battery can be used as part of quality control procedures. Furthermore,
Warranty claims, but if the capacity of the following provisions of the warranty period at the end of the levels.
A typical life of Li ion is 300-500 discharge / charge cycles or manufacture of two years. The process of gradual loss of battery capacity, often without the user's knowledge. Although fully charged, the battery finally back to a point, may be less than half of its original capacity.
Analysis of the role of the battery is to identify these weak batteries and "weed 'out.
A battery analyzer can also be used to address the reasons for the short running time. The charger may not provide a complete charge or portable device may attract more current than expected. Many of today's battery analyzer can simulate a digital signature and verification of equipment, load on the basis of the existing battery capacity to run.
A modern battery analyzer important feature is its ability to read the battery internal resistance, which is a just a few seconds to furnish. As a natural part of aging, a Li-ion resistance increases gradually, due to cell oxidation. The higher the resistance, the greater the battery can provide.
In order to use as a battery authentication OhmTest, it must be a known good battery performance, consult and read. Since each cell type may be different with reference to the need for each model of reading.
Measure of a country, the health of the battery more reliable method is through rapid testing methods. Cadex has developed a system that uses reasoning algorithms to test the battery capacity. This algorithm is a quick test of the battery usage trends, learning algorithm, similar to the human brain thought process concrete.
Kai up a quick test you can perform 20 to 90 per cent of the level of charges. If the battery charge is insufficient, or there is excessive charges on the analyzer automatically apply the appropriate charge or discharge, within the scope of the test battery. In this context, the different level of charges does not affect the reading.
Testing lasted about two minutes, to support Li-ion/Polymer, nickel-metal hydride batteries and nickel-cadmium batteries.
Kai Kai up a quick test to reach 7200 and 7400 battery analyzer. These platforms feature interchangeable battery adapters, which contains a quick test of the battery configuration code and matrix.
Abstract The performance and reliability of lithium-ion to receive good results. Supply shortages have eased, price competitiveness has become a nickel-based equivalent. Therefore, more portable devices are equipped with lithium-ion battery.
Lithium-ion found in small portable devices and requirements for a powerful market advantage. The most popular use of mobile phones and laptop computers. As the aging, the lithium-ion batteries are the most suited to the busy usage patterns of applications. If the lithium-ion reach in the high-current applications such as power tools,
Cardiac defibrillators and two-way radios to public safety.
Another field in lithium-ion has been proved to be less beneficial to the application only needs an occasional battery. In a mainly by the AC-powered notebook computers, for example, lithium-ion battery, as time goes on all the benefits of aging and the battery can not be achieved. Most notebook computers to high heat levels also led to lithium-ion batteries prematurely. Field test results showed, however,
Is less affected by lithium-ion battery than the nickel-metal hydride heat.
Lithium-ion polymer system is hard to achieve and exceed the performance of Li-ion battery. Restrictions on energy costs, high rate, lithium-ion polymer in small portable devices such as mobile phones. Is expected, once the mass production of lithium-ion polymer of low prices by simplifying packaging lithium ions.