Do you know lithium-ion batteries?
How Lithium-ion Batteries Work
Lithium-ion batteries are incredibly popular these days. You can find them in laptops, PDAs, cell phones and iPad. They’re so common because, pound for pound, they’re some of the most energetic rechargeable batteries available.
Lithium-ion batteries have also been in the news lately. That’s because these batteries have the ability to burst into flames occasionally. It’s not very common — just two or three battery packs per million have a problem — but when it happens, it’s extreme. In some situations, the failure rate can rise, and when that happens you end up with a worldwide battery recall that can cost manufacturers millions of dollars.
So the question is, what makes these batteries so energetic and so popular? How do they burst into flame? And is there anything you can do to prevent the problem or help your batteries last longer? In this article, we’ll answer these questions and more.
Lithium-ion batteries are popular because they have a number of important advantages over competing technologies:
- They’re generally much lighter than other types of rechargeable batteries of the same size. The electrodes of a lithium-ion battery are made of light weight lithium and carbon. Lithium is also a highly reactive element, meaning that a lot of energy can be stored in its atomic bonds. This translates into a very high energy density for lithium-ion batteries. Here is a way to get a perspective on the energy density. A typical lithium-ion battery can store 150 watt-hours of electricity in 1 kilogram of battery. A NiMH (nickel-metal hydride) battery pack can store perhaps 100 watt-hours per kilogram, although 60 to 70 watt-hours might be more typical. A lead-acid battery can store only 25 watt-hours per kilogram. Using lead-acid technology, it takes 6 kilograms to store the same amount of energy that a 1 kilogram lithium-ion battery can handle. That’s a huge difference.
- They hold their charge. A lithium-ion battery pack loses only about 5 percent of its charge per month, compared to a 20 percent loss per month for NiMH batteries.
- They have no memory effect, which means that you do not have to completely discharge them before recharging, as with some other battery chemistries.
- Lithium-ion batteries can handle hundreds of charge/discharge cycles.
That is not to say that lithium-ion batteries are flawless. They have a few disadvantages as well:
- They start degrading as soon as they leave the factory. They will only last two or three years from the date of manufacture whether you use them or not.
- They are extremely sensitive to high temperatures. Heat causes lithium-ion battery packs to degrade much faster than they normally would.
- If you completely discharge a lithium-ion battery, it is ruined.
- A lithium-ion battery pack must have an on-board computer to manage the battery. This makes them even more expensive than they already are.
- There is a small chance that, if a lithium-ion battery pack fails, it will burst into flame.
Many of these characteristics can be understood by looking at the chemistry inside a lithium-ion cell. We’ll look at this next.
What Kind of Lithium-ion Batteries We Use In All In One Solar LED Street Light
After years of development, the current type of lithium-ion batteries with lithium manganese acid, lithium iron phosphate, lithium, cobalt acid lithium titanate, three yuan, such as material for energy performance and cost reasons, rare metal manganese acid lithium, lithium titanate and cobalt acid lithium batteries gradually become a niche selection, while the lithium iron phosphate and ternary lithium battery get more extensive application.But what's the difference?
Ternary lithium battery
Ternary lithium batteries full name is "battery" ternary material, generally refers to using nickel cobalt manganese acid lithium (Li (NiCoMn) O2, sliding) lithium nickel or cobalt aluminate (NCA) ternary positive electrode material of lithium battery, nickel salt, manganese and cobalt salt salt as a proportion of three different components to different adjustment, so called "three yuan", contains many proportion of different types of batteries.
In terms of shape, it can be divided into soft-pack battery, cylindrical battery and square hard-shell battery.
Its nominal voltage can reach 3.6-3.8v (3.7V per cell), high energy density, high voltage platform, high vibration density, long range, large output power, poor high temperature stability, but excellent low temperature performance, high cost.
Lithium iron phosphate battery
Lithium iron phosphate battery USES lithium iron phosphate (LiFePO4) as the positive electrode material, and iron is used as the battery raw material. On the one hand, it has low cost, and on the other hand, it does not contain heavy metals, which causes little environmental pollution. The working voltage is 3.2V.
Lithium iron phosphate crystals in P - solid O key, so in zero voltage does not have leakage, when stored in high temperature conditions or overcharge when security is very high, can fast charge, high discharge power, no memory effect, high cycle life and disadvantages for the low temperature performance is poor, the anode material tap density is small, the energy density is low, the yield of the product and consistency is also in question.
Both types of batteries have different strengths
Under the condition of high temperature, the ternary lithium batteries ternary material can cause decomposition at 200 ℃, produce severe chemical reaction, release oxygen, and under high temperature is easy to occur the phenomenon of the combustion or explosion, so based on security considerations, China's ministry of industry in January, 2016, through the special post regulation will be temporarily limit the use of the ternary lithium battery in pure electric bus.
And phosphoric acid lithium battery decomposition temperature at 800 ℃, more is not easy to catch fire, security is relatively high.
Under the condition of low temperature (the temperature below - 10 ℃), phosphate lithium battery decay very fast, after less than 100 times charging and discharging circulation, battery capacity will fall to 20% of the initial capacity, the use of cold region and basic insulation;
Three yuan in the low temperature performance of lithium-ion batteries, under the condition of - 30 ℃ can keep the normal battery capacity, to meet the conditions of use of the northern cold region.
Under the experimental conditions, after 5,000 cycles of the lithium iron phosphate battery, the remaining capacity was 84%, and after 5,000 cycles of 1C (1C stands for the current intensity when the battery is fully discharged in one hour), the initial capacity of over 80% could still be maintained.
After 3900 cycles of ternary lithium battery, the remaining capacity is only 66%. After 2500 cycles of 1C, the initial capacity drops to 80%.
In comparison, the cycle life of lithium phosphate batteries is much longer than that of lithium ternary batteries.
In addition, the energy density of lithium iron phosphate battery is 120Wh/kg, which has basically reached the theoretical extreme, while the energy density of ternary battery is 180Wh/kg, which has a lot of Space for improvement in the future.