Portable electronic devices on battery power. With the rapid development of portable products, the amount of various battery greatly increased, and developed many new battery. In addition to the more familiar high-performance alkaline batteries, rechargeable nickel-cadmium batteries, nickel metal hydride battery, lithium battery developed in recent years. This paper describes the basic knowledge about lithium. This includes its characteristics, main parameters, the significance of the model, the scope of application and use precautions.
Lithium is a metallic element, its chemical symbol is Li (its English name lithium), a silver-white, very soft, lively and chemical properties of metal, the metal is the lightest. It is used in the atomic energy industry, manufacture of special alloys, special glass (on the TV screen glass) and lithium battery. In lithium battery, use it as a battery anode.
The lithium battery can also be divided into two categories: two categories of non-rechargeable and rechargeable. Non-rechargeable batteries as disposable batteries, it can only chemical energy at once converted into electrical energy, electrical energy can not be restored back to the chemical (or restore performance of very poor). The rechargeable battery is known as secondary batteries (also known as a battery). It will change electrical energy into chemical energy stored chemical energy into electrical energy when in use, and then, it is reversible, such as the main features of the electrical energy chemical energy lithium batteries.
Smart portable electronic products require size, light weight, but compared the size and weight of the battery and other electronic components are often the largest and heaviest. For example, "Big Brother" is quite thick, heavy ", today's mobile phones are so lightweight. Which battery improvements played an important role: the past is a nickel-cadmium batteries, lithium-ion battery.
Lithium is characterized by high specific energy. What is the specific energy? Refers to the specific energy is the energy per unit weight or unit volume. Specific energy, Wh / kg or Wh / L to represent. Wh is a unit of energy, W is watts, h is the hour; kg, kg (weight units), L is the liter (volume units). Give an example to illustrate: nickel-cadmium battery rated voltage of 2V to 1 , the capacity of 800mAh, its energy is 0 96Wh (1 2V x 0 8Ah). On the 5th of the same size lithium - manganese dioxide battery rated voltage is 3V, the capacity of 1200mAh, then the energy of 3 6Wh. The volume of the two batteries are the same, then the lithium - manganese dioxide battery specific energy is 375 times the nickel-cadmium batteries!
A nickel-cadmium batteries, weighing about 23g, and a lithium - manganese dioxide battery weighs about 18g. A lithium - manganese dioxide battery 3V, two nickel-cadmium battery only 2 4V. Uses lithium battery a small number (volume reduction of filial piety and reduce the weight of portable electronic products), and long battery life.
In addition, lithium has a stable discharge voltage, wide operating temperature range, low self discharge rate and long storage life, no memory effect and pollution, etc..
The drawback of lithium batteries is expensive, so it is not yet universal application, mainly used in handheld computers, PDAs, communication devices, cameras, satellites, missiles, torpedoes, equipment and so on. With the development of technology, process improvement and increase of production, the price of lithium will continue to decline, the application will be more common.
Non-rechargeable lithium batteries
Non-rechargeable lithium batteries have a variety of commonly used lithium - manganese dioxide batteries, lithium - thionyl chloride batteries, and lithium and other compounds battery. This article describes only the first two most commonly used.
1, lithium - manganese dioxide battery (Li MnO2)
Lithium - manganese dioxide battery is a lithium anode, manganese dioxide as cathode, and an organic electrolyte disposable batteries. The main characteristics of the battery is the battery voltage and rated voltage of 3V (alkaline batteries); termination of the discharge voltage of 2V; energy (see the examples above); discharge voltage is stable and reliable; have better storage properties (storage time of more than 3 years), low self discharge rate (self-discharge rate ≤ 2%); Operating temperature range -20 ° C ~ +60 ° C
The battery can be made into a different shape to meet different requirements, it has a rectangular, cylindrical and button-shaped (button). Cylindrical different diameter and height dimensions. Here are more familiar with a # (size code D), the main parameters of the 2 # (Size Code C) and # 5 (Size Code AA) batteries.
CR cylindrical lithium - manganese dioxide battery; five figures, the first two said that the diameter of the battery, after three height with a decimal. For example, CR14505, its diameter is 14mm, height is 50 5mm (this model is generic).
Here to point out that the different factories of the same type of battery its parameters may be some differences. In addition, the standard discharge current value is smaller, the actual discharge current can be larger than the standard discharge current, and continuous discharge and pulse discharge allows the discharge current is also different from the battery factory to provide relevant data. For example, the the Lixing power produced CR14505 given maximum continuous discharge current of 1000mA, the maximum pulse discharge current up to 2500mA.
Most camera using the lithium is lithium - manganese dioxide battery. Here the camera lithium - manganese dioxide battery included in Table 2 for reference.
Button (button) batteries are smaller, its diameter is 12 24 5mm height of 1 0mm. Some of the more commonly used button cell is shown in Table 3.
CR is a cylindrical lithium - manganese dioxide battery, the first two in the last four digits of the diameter size of the battery, the latter two with the height of the decimal point. For example, the diameter of the CR1220 12 5 mm (not including the number after the decimal point), its height is 2 0mm. This model representation is internationally accepted.
This button batteries commonly used in clocks, calculators, electronic organizers, cameras, hearing aids, electronic games, IC card, standby power, etc..
Lithium - thionyl chloride batteries (Li of SOCl2)
Lithium - thionyl chloride batteries is a maximum specific energy can be achieved 500Wh/kg or 1000Wh / L level. Its rated voltage is 3 6V to medium current discharge extremely flat 3 the 4V discharge characteristics (available at a flat 90% capacity within the discharge, to keep small change). The battery can be in the range of -40 ℃ ~ +85 ° C, but about 50% of the room temperature capacity at -40 ° C the capacity. The self-discharge rate of low self discharge rate (≤ 1%), the storage life of more than 10 years.
# 1 (size code D) nickel-cadmium battery # 1 lithium - thionyl chloride batteries than the energy for a comparison: 1 # nickel-cadmium battery rated voltage 2V 1 capacity 5000mAh; 1 # lithium - thionyl chloride of rated voltage capacity of 0.01 6V, 10000mAh, the latter is six times larger than the energy than the former!
Application Notes
The two lithium disposable batteries, non-rechargeable (charge is dangerous!); Can not short-circuit between the battery positive and negative; not be too large current discharge (more than the maximum discharge current discharge); battery to the termination of the discharge voltage from the electronic products removed in a timely manner; a dead battery is not squeezing, burning and demolition; not exceed the specified temperature range.
The lithium battery voltage is higher than ordinary batteries or nickel-cadmium batteries, make no mistake when used to avoid damage to the circuit. Familiar models of the CR, ER can know its type and rated voltage. Buy a new battery, certainly according to the original model to buy, otherwise it will affect the electronic product performance.
Rechargeable lithium batteries
A variety of rechargeable lithium-ion batteries, such as lithium - vanadium oxide batteries, lithium-ion batteries and abroad, the newly developed lithium - polymer battery. Here only on the first two, focusing on lithium-ion battery.
Rechargeable lithium-ion battery is currently the most widely used mobile phone batteries, but it is more "delicate" in use can not overcharge, over discharge (may damage the battery or scrapped). Therefore, the protection of components or the protection circuit to prevent costly damage to the battery in the battery.
The lithium-ion battery charge high, to ensure termination of the voltage accuracy within 1%, the major semiconductor devices Factory has developed a variety of lithium-ion battery charging IC, in order to ensure safe, reliable, fast charge.
The phone is very common part of the phone is a nickel-metal hydride battery, but the smart type phone lithium-ion battery. Proper use of lithium-ion battery to extend battery life is very important.
(1) lithium - vanadium oxide battery (Li-V6O13)
Lithium - vanadium oxide battery lithium anode, vanadium oxide cathode, the organic solvent of the inorganic salt composition of the electrolyte. It is characterized by charge. On the 2nd battery, for example, lithium - vanadium oxide battery and lithium - manganese dioxide batteries, and lithium - thionyl chloride batteries as shown in Table 5.
Table 5 shows, as lithium - vanadium oxide battery rated voltage of only 2.8V, and the rated capacity is also small compared with the other two lithium batteries, the specific energy is the smallest. Of these cylindrical cells, the main parameters shown in Table 6. From Table 6 we can see, the number of charge cycles (cycle life) is not long, so this rechargeable battery instead of lithium-ion battery.
(2) lithium-ion battery (Li-Ion)
Lithium ion batteries are currently the most widely used lithium batteries, according to the requirements of different electronic products can be made into a flat rectangular, cylindrical, rectangular and button, and by several batteries in series with the battery pack consisting of.
Lithium-ion battery rated voltage of 3.6V (some of 3.7V). Terminate the charging voltage when fully charged battery anode material: anode material is graphite 4.2V; anode material for coke 4.1V. The internal resistance of the anode material, coke anode of the internal resistance of slightly larger, the discharge curve is also slightly different, shown in Figure 1. Commonly referred to as a 4.1V lithium-ion battery 4.2V lithium-ion battery. Termination of lithium-ion battery discharge voltage of 2.5V to 2.75V (battery factory given operating voltage range or given to terminate the discharge voltage of each parameter is slightly different). Lower than the termination of the discharge voltage to continue to discharge called over-discharge, over-discharge the battery will be damage.
The lithium-ion batteries are not suitable for high current discharge is too large current discharge will reduce the discharge time (internal temperature will result in higher loss of energy). Battery manufacturing plant gives the maximum discharge current, in use should be less than the maximum discharge current.
The lithium-ion battery temperature, the factory gives the charging temperature range, the discharge temperature range Storage temperature range.
Lithium-ion battery charging requirements are high, it requires a sophisticated charging circuit to ensure the safety of Charging. Termination of the rated charge voltage accuracy tolerance is ± 1% of (for example, rechargeable 4.2V lithium ion battery, the tolerance is ± 0.042V), over-voltage charging lithium-ion battery can cause permanent damage. Lithium-ion battery charging current should be based on the recommendations of the battery manufacturing plant, and requires current limiting circuit in order to avoid over-current (overheating). Commonly charge rate of 0.25C ~ 1C (C is the capacity of the battery, such as C = 800mAh, 1C charge rate, charge current is 800mA). Often detected in the high current charging the battery temperature to prevent overheating damage the battery or an explosion.
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