The difference between lithium polymer batteries and lithium ion batteries:
First of all, from a structural point of view, the full name of lithium polymer batteries should be lithium batteries -polymer ion. view, lithium polymer batteries In fact, it is also a type of lithium ion battery. But the biggest difference between the two is the electrolyte used inside. Lithium-ion batteries use liquid electrolytes, while lithium-ion polymer batteries use solid polymer electrolytes instead. This polymer can be solid or semi-solid (colloidal).
Second, in terms of appearance, most mobile power supplies currently on the market use cylindrical lithium-ion batteries (that is, 18650) or lithium-polymer batteries shaped like block. Therefore, when selecting a mobile power supply, if the outer packaging of the product does not specifically indicate thetype of battery cells used, you can just get a rough idea of the type of battery used inside the product by the thickness of the product. himself.
Lithium-ion batteries are improved products of lithium batteries. Due to the highly active chemical properties of lithium metal, early lithium batteries often burned when used. In order to suppress the active chemical properties of metallic lithium, people added cobalt, manganese and other metallic materials to the cathode material of lithium batteries, which greatly improved the safety factor of early lithium batteries.
Charging and discharging lithium-ion batteries can be done via two processes: intercalation and deintercalation. During discharge, lithium ions flow out of the cathode material and enter the electrolyte, like water in electrolyteyou. a sponge negative electrode material, this process is called deintercalation. In the state of charge, this process is reversed and is called integration. In the figure above, the left side shows the integration process of lithium batteries and the right side shows the disintegration process.
It can be said that after years of development, lithium-ion battery technology has become relatively mature, and mass production has made its manufacturing cost very low. Therefore, lithium-ion batteries have more price advantages than lithium-polymer batteries. This is why most laptops and other devices currently use this type of battery cell.
Since lithium ions using liquid electrolytes will suddenly increase their internal pressure when overcharged (overcharging), in order to avoid the explosion of the sealed metal case, this 18650 battery isusually equipped with a security system. Valve on the top When the internal pressure of the battery is too high, the safety valve on the top will automatically pop up to reduce the pressure. However, when the safety valve opens, the lithium ions escaping from the battery can still catch fire due to contact with oxygen in the air.
Therefore, for electronic products using this type of lithium-ion battery cells, there are very high requirements for their internal charge and discharge protection integrated circuits. However, with the years of development of lithium-ion batteries, both the design of the battery itself and the technical level of various protection integrated circuits have become very mature, provided that the battery can be used properly in daily life and avoid that it is not damaged. Pierced by hard objects, phenomenon, cellss 18650 battery packs are still very safe, otherwise most laptops on the market would not use this type of battery.
Compared to lithium-ion batteries using liquid electrolytes, lithium polymer batteries using solid polymer electrolytes are ultra-thin in shape, with a theoretical minimum thickness of up to 0.5 mm, and any arbitrary shape and area. It greatly improves the flexibility of the battery shape, so that it can be better transformed into a new generation of lithium batteries of any shape and capacity.
In addition, lithium polymer batteries using solid polymer electrolytes have a higher energy density than ordinary lithium-ion batteries, that is, in the same volume, batteries lithium polymer have the advantages of being lighter. weight and higher capacity.