What is the charging principle of lithium batteries?



Lithium-ion batteries are generally batteries that use lithium alloy metal oxide as the positive material, graphite as the negative material, and non-aqueous electrolyte. We usually use cell phones are almost all lithium batteries, the current market is more hot electric car power supply mostly belongs to the lithium iron phosphate battery. That lithium battery is how to charge and discharge?

First of all, let's understand the structure of lithium batteries, lithium batteries are generally composed of positive electrode, negative electrode, electrolyte and diaphragm, daily we commonly see cell phone lithium batteries for the square, electric car battery packs within the battery is generally round, and other shapes there are stacked and coiled type.

Common cell phone batteries on the four contacts, in addition to positive and negative, the remaining contacts are simply to detect (or monitor) the information of the cell phone battery.

Lithium battery positive electrode is generally lithium manganese or lithium cobaltate, lithium nickel cobalt manganese material, electric bicycles are commonly used lithium nickel cobalt manganese (commonly known as ternary) or ternary + a small amount of lithium manganese; the negative electrode is generally the active substance graphite, or graphite structure of the carbon, or similar to graphite structure, the positive electrode and the negative electrode between the diaphragm for a special molding of the polymer film, aperture to meet the good ionic throughput, at the same time, has the electronic insulating properties, which means that it can let the Lithium ions can pass freely, while electrons cannot pass.

Electrolyte plays a role in transporting charge between positive and negative electrodes, generally a solvent of carbonate with lithium hexafluorophosphate dissolved, and a gel electrolyte is used for polymer.

Lithium battery in charging, the positive electrode release lithium ions, lithium ions through the electrolyte through the diaphragm, the movement to the negative electrode, and the electrons of the abs combined together, at this time, the positive electrode occurs in the chemical reaction for the LiCoO2 = Li (1-x) CoO2 + xLi + + xe- (electrons), the negative electrode occurs in the chemical reaction for the 6C + xLi + + xe- = LixC6.

When the lithium battery is discharged, the lithium ions move in the opposite way, the lithium ions enter the electrolyte from the negative electrode, pass through the diaphragm and finally arrive at the positive electrode, while the electrons go from the negative electrode to the positive electrode by the external circuit (the direction of electron movement is opposite to the direction of the current), and combine with the lithium ions at the positive electrode, and the process enables the lithium battery to output electric energy to the outside.