#1-Lithium Ion Battery Classification. According to Practical Performance, Electrolyte Material, Appearance, Positive Electrode Material and Negative Electrode Material, They Are Divided Into Different Types, as Follows:
①Practical performance: power type (short-term high power output) and energy type (long-distance running, high energy storage)
②Appearance: cylindrical, square (steel/aluminum shell), soft package (aluminum plastic film)
③According to the electrolyte material: liquid lithium ion battery (LIB) and polymer lithium ion battery (PLB).Liquid lithium-ion batteries use liquid electrolytes (currently power batteries are mostly of this type). Polymer lithium-ion batteries are replaced by solid polymer electrolytes. This polymer can be in a “dry state” or in a “colloid state”. Currently, most of the polymer gel electrolytes are used. Regarding solid-state batteries, in a strict sense it means that the electrodes and electrolyte are both solid.
④Positive electrode material: lithium iron phosphate battery (LFP), lithium cobalt oxide battery (LCO), lithium manganese oxide battery (LMO), (binary battery: lithium nickel manganate/lithium nickel cobalt oxide), (ternary: nickel cobalt Lithium manganese oxide battery (NCM), nickel-cobalt lithium aluminum oxide battery (NCA)).
18650 is a model of lithium ion battery, 18650 is the originator of lithium ion battery. Wherein 18 means that the diameter is 18mm, 65 means that the length is 65mm, and 0 means that the battery is cylindrical. 18650 batteries have two types, one is lithium-ion batteries and the other one is lithium iron phosphate batteries. The nominal voltage of lithium ion battery is 3.7V, the charge cut-off voltage is 4.2V, and the capacity is usually 1200mAh-3350mAh. The nominal voltage of lithium iron phosphate battery is 3.2V, the charge cut-off voltage is 3.6V, and the common capacity is 2200mAh-2600mAh. .
Lithium iron phosphate battery
Lithium iron phosphate (molecular formula LiFePO4, Lithium Iron Phosphate, also known as lithium iron phosphate, lithium iron phosphorus, or LFP for short) is a positive electrode material for lithium ion batteries, also known as lithium iron phosphorus batteries, featuring no cobalt and other valuables Elements, raw materials are low in price and phosphorus, lithium, and iron are abundant. Its working voltage is moderate (3.2V), large capacity (170mAh/g), high discharge power, fast charging and long cycle life, and high stability in high temperature and high heat environment.
#2-What Are the Advantages of Lithium Ion Battery?
①Lightweight: The weight energy density of lithium-ion batteries is currently generally 200-260wh/g; lead-acid batteries are generally 50-70wh/g, and nickel-hydrogen batteries are generally 40-70wh/kg. This means that with the same capacity, the other two batteries are 3 to 5 times heavier than lithium batteries. Therefore, in the light of energy storage devices, the volumetric capacity density of lithium batteries is usually about 1.5 times that of lead-acid batteries, and the energy density of nickel-metal hydride batteries is only 60-80% of that of lithium-ion batteries. Therefore, with the same capacity, lithium batteries The volume is also smaller.
②Fast charging: due to the lively performance of lithium-ion batteries, they move faster inside the battery, so the charging current is larger and the charging speed is faster. A lithium-ion battery can be fully charged in about 3 hours; while the charging speed of nickel-hydrogen batteries is very slow. , It takes about 1 day to fill up.
③No memory effect:Lithium batteries have no memory effect, and only need to pass 3-5 normal charge and discharge cycles to activate the battery and restore normal capacity.
#3-The Safety of Lithium Ion Battery
Lithium is one of the most active metal in the world. Due to its active chemical properties, when lithium metal is exposed to the air, it will react fiercely with oxygen, so it is prone to explosion and combustion. In addition, redox reactions are also generated inside the lithium battery during the charging and discharging process. The explosion and spontaneous combustion are mainly caused by the accumulation of the lithium battery after heating, and it is too late to diffuse and release. Simply put, a lithium battery will generate a lot of heat during the charge and discharge process, which will cause the internal temperature of the battery to rise and the temperature unevenness between the single cells, which will cause the performance of the battery to be unstable.
Unsafe behaviors of lithium-ion batteries (including battery overcharge and overdischarge, rapid charge and discharge, short circuit, mechanical abuse conditions, and high temperature thermal shock, etc.) easily trigger dangerous side reactions inside the battery to generate heat, directly destroying the negative and positive electrodes Passivation film on the surface.
There are many trigger causes for thermal runaway accidents of lithium-ion batteries. According to the characteristics of the trigger, they can be divided into three methods: mechanical abuse trigger, electrical abuse trigger, and thermal abuse trigger.
Mechanical abuse: Refers to needle sticks, squeezing, and heavy object impact caused by car collisions, etc.;
Electricity abuse: Generally caused by improper voltage management or malfunction of electrical components, including short circuit, overcharge and over discharge, etc.;
Heat abuse: caused by overheating caused by improper temperature management.
#4-Application of Lithium ion Battery
At this stage, most lithium iron phosphate (LFP) batteries are used in lithium battery energy storage systems.
Lithium iron phosphate batteries have many advantages, as follows:
①The life of the iron phosphate battery has been greatly improved. In the case of standard charging, the service life of the iron phosphate battery can reach more than seven years, and the cycle charge is more than 2,000 times.
③safety. The iron phosphate battery has excellent stability and will not bulge.
④Constant capacity. The characteristic of the lithium phosphate battery is that it can be used at any time! And it will never affect its storage capacity.
⑤Green and environmental protection. Lithium iron phosphate battery has environmental protection performance that other batteries do not have, because the battery does not contain heavy metals. It has been used in the field of electric bicycles or electric cars.
Ternary Lithium Battery refers to a lithium battery that uses lithium nickel cobalt manganate or lithium nickel cobalt aluminate as the positive electrode material, graphite as the negative electrode material, and lithium hexafluorophosphate as the electrolyte. Because its cathode material contains three metal elements, nickel, cobalt, and manganese/aluminum, it is named “ternary”. Ternary lithium batteries are mainly used in the field of power batteries, and their energy density and other indicators are slightly sacrificed to achieve higher safety.