Lithium iron phosphate batteries from Pacific Automotive Network will fail if left unused for a long period of time. During the life of lithium iron phosphate batteries, they are usually put on standby most of the time. being left aside for a long time, the battery performance will decrease. The general performance is as follows: internal resistance increases, voltage decreases, and discharge capacity decreases.
When lithium batteries are idle, due to the nature of the battery itself, phenomena such as self-discharge, passivation of positive and negative electrode materials and decomposition of the electrolyte occur. The unstable performance of the SEI negative electrode will cause the active material of the negative electrode to rapidly decrease and easily cause lithium metal precipitation. At the same time, differentDifferent components of the electrolyte have different effects on the attenuation of electrode materials. It is therefore particularly important that lithium batteries have good long-term storage performance.
The lithium-ion battery is a relatively complex electrochemical system. After long-term storage, the internal balance will gradually change. When accumulated to a certain extent, lithium batteries tend to undergo the following changes:
1. Physical Characteristics According to the actual evidence after long-term storage of the lithium battery, the physical characteristics of the battery (appearance, size, weight, etc.) will change Some changes, especially in the appearance characteristics. This changing trend is more obvious when the temperature and humidity of the storage environment are not good. In high humidity, the increasing importance of lithium batteries hasAfter long-term storage is significantly higher than that of batteries placed in low humidity conditions. For example, the steel housing of the battery tends to rust in high humidity conditions, resulting in a slight improvement in quality. Rust will not affect the internal condition of the battery, but will directly affect the shipping of the product and may have a negative impact on the corresponding electronic components.
2. Electrochemical characteristics ●Capacity, long-term storage The change in capacity of lithium battery is mainly reflected in two points:
One is the decrease in battery capacity, mainly caused by the self-degradation. -discharge ; the other is irreversible. The capacity increase mainly depends on the irreversible consumption reaction between the chemical systems inside the battery. Self-discharge is inevitable in all blithium-ion batteries.
●Internal resistance. For long-term storage of lithium batteries, the resistance tends to increase as the storage time increases. Exceeding a certain internal resistance will cause the internal battery to exceed the baseline and be discarded or degraded. Therefore, it is necessary to pay attention to the change in battery resistance during long-term storage.
●Discharge characteristics, The discharge characteristics of lithium-ion batteries show a decreasing trend after long-term storage. The low temperature performance of batteries stored for a long time is significantly reduced.
The lifespan of lithium batteries is affected by operating temperature and ambient humidity. High temperatures and humidity will accelerate the life of rechargeable lithium batteries.It is recommended to store rechargeable batteries in a dry, natural environment between 0°C and 20°C. If the lithium battery is not used for a long time, it should be charged to 50% ~ 80% capacity, removed from the instrument and stored in a dry and cool environment. The battery should be charged every 3 months to avoid long storage time and battery self-discharge. Too low, leading to irreversible loss of capacity. If a lithium battery emits an odor, generates heat, changes color, becomes deformed, or appears abnormal in any way during use, storage, or charging, immediately remove the battery from the device or charger and stop using it.
(Images/Text/Photos: Pacific Automotive Network Calling the Beast Q&A)
What is the best way to store cell phone lithium batteries if they don'tnot used for a long time?
Lithium-ion batteries must be fully charged before storage. It can be stored for more than six months at 20°C, which shows that lithium-ion batteries are suitable for low temperature storage. Someone once suggested that it was actually a good idea to keep rechargeable batteries in the refrigerator compartment. Lithium-ion batteries have a self-discharge phenomenon. Long-term storage will cause the battery to over-discharge, destroy the internal structure of the battery and shorten its service life. Therefore, lithium-ion batteries stored for a long time should be recharged every 3 to 6 months, that is, charged to a voltage of 3.8 to 3.9 V (the best storage voltage of lithium batteries is approximately 3.85 V).
Notes
When using lithium-ion batteries, pay attention to three points: WhenWhen using lithium-ion batteries, it should be noted that the battery will enter a sleep state after being left for a period of time, the capacity is lower than normal, and the use time is also shortened. However, lithium-ion batteries are easy to activate. After 3-5 normal charge and discharge cycles, the battery can be activated and restored to its normal capacity. Due to the characteristics of the lithium battery itself, it has almost no memory effect. Therefore, users do not need any special methods or equipment during the activation process of new lithium batteries. Not only is this true in theory, but in practice the “natural activation” method of loading using standard methods from the start is best.
Regarding the problem of "activation" of lithium-ion batteries, many opinions believe that timecharging time should be more than 12 hours and repeated three times to activate the battery. This claim that "the first three charges require more than 12 hours" is obviously a continuation of the claim regarding nickel batteries (such as nickel-cadmium and nickel-metal hydride). This statement can therefore be considered misinformation from the beginning. There is a very big difference in the charging and discharging characteristics of lithium ion batteries and nickel batteries. All serious formal technical information points out that overcharging and overdischarging will cause huge damage to lithium batteries, especially liquid lithium ion batteries. Therefore, it is best to charge according to standard time and methods, especially not to charge for more than 12 hours. Additionally, lithium-ion batteries or chargers automatically stopcharge once the battery is fully charged. There is no so-called “maintenance” charge that lasts more than 10 hours with nickel battery chargers. In other words, if your lithium-ion battery is fully charged and placed on the charger, it will charge in vain. And no one can guarantee that the characteristics of the battery charge and discharge protection circuit will never change and the quality is foolproof, so the battery will be on the verge of danger for a long time. This is another argument against a long charge.
On some machines, if you do not remove the charger after charging for more than a certain time, the system will not only stop charging, but also start a discharge-charge cycle. Perhaps the manufacturer of this approach has its own agenda, but it obviously hurts battery life. At the same time, long-term charging takes a long timeand must often be performed at night. Judging from the power grid situation, the voltage at night is relatively high and fluctuates significantly. As mentioned earlier, lithium-ion batteries are very delicate. Nickel-based electricity is much less resistant to charge and discharge fluctuations, leading to additional dangers.
In addition, another aspect that cannot be ignored is that lithium-ion batteries are also not suitable for over-discharge, and over-discharge is also very detrimental to the battery. This brings us to the next question. Since the number of charges and discharges is limited, the lithium battery should be exhausted as much as possible before recharging. However, the experimental table data on charge and discharge cycles of lithium-ion batteries is listed as follows:
Lifetime (10% DOD): >1000 times
< p>Lifespan (100%DOD):> 200times where DOD is the English abbreviation for depth of discharge. The table shows that the number of recharges is related to the depth of discharge. The lifespan at 10% DOD is much longer than at 100% DOD. Of course, if converted to actual charge relative total capacity: 10% * 1000 = 100, 100% * 200 = 200, the latter's full charge and discharge is even better. Under normal circumstances, you should reserve the remaining battery capacity accordingly. au The principle of charging is to recharge when the battery is exhausted. However, if it is not expected to last all day on the second day, of course you should start charging on time. carrying the charger to the office is another matter.When it is necessary to charge to meet upcoming important events that are expected to result in charged communication, even if the battery still has plenty of power remaining, charge- simply do it in advance, because there is no charge. actual loss of "1" Life per charge is only "0.x" times, and often this x will be very small.
The principle of recharging the remaining battery is not to go to extremes. A widely spread saying, like long-term charging, is "try to exhaust the machine's battery, and it is better to use automatic shutdown." This approach is actually only applied to nickel batteries. The goal is to avoid the memory effect. Unfortunately, it also spreads to lithium-ion batteries. There was an example of someone continuing to use the machine without charging it until it automatically turned off after a low battery warning appeared. As a result, the machine in this example was unresponsive during subsequent loading and startup and had to be sent to customer service for repair. This is actually due to the battery being too exhausted.charged and the voltage is too low, so that it does not have normal charging and power-on conditions. To summarize, the most important tips for charging and discharging lithium-ion batteries in use are: 1. Charge according to standard time and procedures, even for the first three times. 2. When the machine battery is too low, a prompt will appear; appears, charging should be started as soon as possible; 3. Lithium battery activation does not require special methods. The lithium battery will activate naturally during normal use of the machine. If you insist on using the popular "first three charges and 2 hour activation" method, it will actually not be effective.
Therefore, all practices of doing 12 hours of ultra-long charging and using lithium-ion batteries to automatically shut down are wrongs.
4. Pay attention to fire prevention when using lithium batteries
Many people may only be familiar with lithium-ion batteries in mobile phones. In fact, it is used in many household appliances. There is no doubt that the advantages of lithium-ion batteries, such as high efficiency and light weight, make them rapidly popularized and applied.
Lithium batteries have the advantage of being light, efficient and resistant to low temperatures (-40°C). A 0.3mm thick lithium battery, the size of a postage stamp, can be used continuously for more than 5 years. and is widely used in many high-end household appliances and mobile phones.
Lithium ion batteries are different from the water-soluble zinc chloride and potassium hydroxide electrolytes of manganese batteries and al dry batteriescalines currently in use. They use organic solvents. manganese dioxide, lead fluoride, sulfur chloride and other materials. Compared with the zinc chloride used in the negative electrodes of general batteries, the metal lithium sheet used in the negative electrode has a stronger ionization tendency and a larger voltage difference between the positive and negative electrodes, which improves the operating efficiency of lithium-ion batteries.
However, lithium-ion batteries often generate heat and burn during use. In mild cases, it affects the use of the host, and in severe cases, it may burn the host and cause a fire. There have been numerous house fires in Japan caused by the heat and burning of lithium-ion batteries.
So why do lithium-ion batteries heat up and burn? It turns out that when many materialsIf the contents of lithium-ion batteries come into contact with water, they can undergo violent chemical reactions and release a large amount of thermal energy, causing heating and burning. The manganese dioxide contained in the positive electrode of lithium batteries can generate heat when exposed to a small drop of water. When the sulfur chloride in lithium batteries comes into contact with water, it generates hydrochloric acid and sulfur dioxide and releases thermal energy. Several factors make lithium batteries a “fire” in life. Therefore, people should pay attention to waterproofing and waterproofing when using lithium batteries. . Humidity. After various hosts are out of service, lithium batteries should be removed and stored in a dry and low temperature place to prevent and avoid house fires caused by improperuse of lithium batteries.
Lithium batteries will permanently lose their capacity if stored for a long time
The picture shows the capacity which can be restored after 1 year storage of rechargeable batteries. . It can be seen that high temperature and full power are the two main causes of death of stored lithium batteries.
The four columns from left to right are:
1. the battery storage environment
2. The capacity of a lithium battery that can be restored after 1 year of storage when fully charged to 40%
3. can be restored to 100% storage after 1 year of storage
4. Nickel-metal hydride battery Capacity can be restored after 1 year of storage