Marine lithium ion battery is a kind of secondary battery which is charged and discharged through the back and forth removal and embedding of lithium ions between the positive and negative electrodes of the battery in the process of charging and discharging. Lithium ion battery is mainly composed of positive electrode, negative electrode, electrolyte and diaphragm.
Marine lithium-ion batteries work mainly by moving lithium ions between the positive and negative terminals. In the process of charging and discharging, Li+ is embedded and disembedded back and forth between the two electrodes. During charging, Li+ is embedded from the positive electrode to the negative electrode through the electrolyte, and the negative electrode is in the rich state of lithium. The opposite is true when discharging.
Marine lithium ion battery has many remarkable characteristics, and its advantages are mainly shown as follows:
1. High voltage: the working voltage of the single battery is as high as 3.7-3.8V (lithium iron phosphate is 3.2V, which is 3 times that of Ni-Cd and Ni-MH batteries.
2, the specific energy: can achieve the actual specific energy of 555Wh/kg, that is, the material can reach more than 150mAh/g specific capacity (3-4 times that of Ni-Cd, 2-3 times that of Ni-MH, has been close to its theoretical value of about 88%.
3, long cycle life: generally can reach more than 500 times, even more than 1000 times, lithium iron phosphate can reach 8000 times. For low-current discharge appliances, the life of the battery will double the competitiveness of the appliance.
4, good safety performance: pollution-free, no memory effect. As the predecessor of Li-ion, lithium metal is easy to form dendrite and short circuit, which reduces its application field. Li-ion does not contain cadmium, lead, mercury and other elements that pollute the environment. Some processes (such as sintered Ni-Cd batteries, a big drawback is the "memory effect", which severely restricts the use of batteries, but Li-ion does not have this problem at all.
5, self-discharge is small: at room temperature, the self-discharge rate of fully charged Li-ion stored for 1 month is about 2%, which is much lower than the 25-30% of Ni-Cd and the 30-35% of Ni-MH.
6, fast charging: 1C charging 30 minutes capacity can reach more than 80% of the nominal capacity, iron phosphorus battery can reach 10 minutes to charge to 90% of the nominal capacity.
7, the working temperature: the working temperature is -25~45°C, with the improvement of electrolyte and anode, expected to widen to -40~70°C.
Lithium-ion batteries also have some shortcomings, mainly in the following aspects:
1, aging: different from other rechargeable batteries, the capacity of lithium-ion batteries will slowly decline, and the number of times, but also related to the temperature. This decline can be represented by a decrease in capacity or an increase in internal resistance. Because it is related to temperature, it is easier to reflect in electronic products with high working current. Replacing graphite with lithium titanate seems to extend life.
2. Recovery rate: about 1% of new products need to be recycled due to various reasons.
3. Intolerant of overcharging: when overcharging, excessive embedded lithium ions will be permanently fixed in the lattice and cannot be released again, which can lead to short battery life.
4. Intolerant overdischarge: when overdischarge, the electrode is inlaid with too much lithium ion, which can lead to lattice collapse and shorten the life.
In recent years, the application of lithium ion battery is more and more extensive. Lithium battery is widely used in energy storage power system such as water power, fire power, wind power and solar power station, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields. At present, lithium batteries have been gradually extended to electric bicycles, electric vehicles and other fields.