With the popularity of various smart phones and tablets, more and more people find that various digital products, especially the power of the mobile phone itself, can no longer meet the needs of battery life in daily use, and the emergence of mobile power can be said to be in This problem has been solved to a certain extent.
A good power supply depends on the battery cell. The battery inside the mobile power supply is like the fuel tank and transmission system of a car. It is responsible for providing a steady stream of power for the entire mobile power supply, which directly determines whether the mobile power supply is good or bad. The circuit board of the mobile power supply can be regarded as a control system, which is mainly used for power distribution and conversion, and converts the 3.7V (or higher) voltage provided by the lithium battery cell into a standard 5V (or higher) voltage. Provide power for the device being charged.
The current mobile power batteries generally use lithium-ion batteries, but the performance is different, and it is completely invisible from the appearance, and the general specifications cannot reflect it. Let's start with the battery and explore the mysterious world of mobile power step by step.
According to the different electrolyte materials used, lithium-ion batteries can be divided into two categories: liquid lithium-ion batteries (LIB) and polymer lithium-ion batteries (LIP). The positive and negative electrode materials used by the two are the same. The positive electrode materials include lithium cobalt oxide, nickel cobalt manganese and lithium iron phosphate materials. The negative electrode is graphite, and the working principle of the battery is basically the same.
Learn more about mobile power:Best power bank reviews in 2022
Their main difference lies in the different electrolytes. Liquid lithium-ion batteries use liquid electrolytes, while polymer lithium-ion batteries use solid polymer electrolytes instead. This kind of polymer can be in "dry state" or "colloidal state". At present, most of them use polymer colloidal electrolytes.
- Lithium cobalt oxide (LiCoO2)
Lithium cobalt oxide is what is commonly known as a liquid lithium-ion battery, and its common forms are 18650 and square. The 18650 battery is a cylindrical battery with a diameter of 18 mm and a height of 65 mm (it looks like an enlarged version of the AA battery), which is widely used in notebook batteries. Due to the common use with notebook batteries, more than 60% of mobile power supplies on the market now use 18650 batteries.
At present, commercial lithium-ion batteries basically use layered lithium cobaltate as the positive electrode material. Its theoretical capacity is 274mAh/g, and its actual capacity is about 140mAh/g. It is also reported that the actual capacity has reached 155mAh/g.
This kind of positive electrode material has high working voltage (average working voltage is 3.7V), stable charging and discharging voltage, small size, high specific energy, good cycle performance, high electrical conductivity, simple production process and easy manufacture.
Main advantages: mature technology, wide range of applications, small size.
Main disadvantages: The cycle life is about 300 times, the safety performance is low, the overcharge resistance is poor, it is not suitable for high-rate charge and discharge, and it will pollute the environment after being discarded.
- Nickel cobalt manganese (LiNiCoMnO2)
Nickel-cobalt-manganese, also known as ternary material (LiNiCoMnO2), is a kind of polymer lithium-ion battery, and its common form is a square soft package shape. Note that lithium cobalt oxide can also be made into a square shape, but it is hard after forming, and it can be distinguished by pinching it with hands.
With the popularity of smart phones, ternary materials have developed rapidly in the past two years, and they are used in more and more fields. It uses nickel salt, cobalt salt, and manganese salt as raw materials, and the ratio of nickel, cobalt, and manganese can be adjusted according to actual needs.
Compared with lithium cobalt oxide batteries, batteries with ternary materials as positive electrodes are safer and have a longer service life than lithium cobalt oxide batteries, reaching a cycle life of 500 cycles.
Main advantages: diverse volume, wide range of use, not easy to explode, high safety factor.
Main disadvantages: high price, pollute the environment after being discarded, and weak high-current charging and discharging performance.
- Lithium iron phosphate (LiFePO4)
The scientific name of lithium iron phosphate is ferroelectric. The biggest difference from the previous two types of batteries is that iron is added to the positive electrode of the battery. Lithium iron has just started in recent years. It is a material with great potential. Its safety performance and cycle life are unmatched by other materials. These are also the most important technical indicators of power batteries. The charge-discharge cycle life is up to 2000 times, and the overcharge voltage of a single battery is 30V without burning or exploding when punctured.
The large-capacity battery pack made of lithium iron phosphate cathode material is easier to use in series to meet the needs of frequent charging and discharging of electric vehicles, and has the advantages of non-toxic, non-polluting, good safety performance, wide source of raw materials, cheap price, and long life. It is an ideal cathode material for a new generation of lithium-ion batteries.
At present, Ferroelectric is mainly used in large-capacity electric buses, signal base station energy storage, and large-scale UPS applications. Among them, mobile power supplies and AA batteries have just begun to test large-scale production. , lawn lights, electric tools are widely used.
Main advantages: 2000 cycle life, high current charge and discharge, small internal resistance and less heat generation, safe, environmentally friendly and non-toxic.
Main disadvantages: the price is expensive, the field of digital products has not yet been used on a large scale, and the awareness in the minds of consumers is low.