Lithium batteries consist of positive electrode, negative electrode, electrolyte, and diaphragm. Lithium batteries mainly use lithium ion to remove and discharge lithium ions back and forth between the positive and negative electrodes of the battery. When charging the lithium battery, the lithium-ion is removed from the positive electrode of the battery. The lithium-ion that is removed is migrated to the negative electrode after the electrolyte, and it is embedded in the gap between the negative electrode material. The ion was removed and the migration returned to the positive electrode.
1.1 Basic Structure of Lithium Iron Phosphate Battery
Lithium iron phosphate (LIFEPO4, LFP) battery is a lithium battery based on LFP materials as a battery-positive electrode. This lithium battery is low in price and stable structure. It can maintain the stability of the structure during the repeated charging and discharge process, and the cycle is high.
LFP is an orderly olive structure and belongs to the PNMA space group. The crystal structure diagram is shown in Figure 1. It can be seen from Figure 1 that because the P atom (the light-colored shadow part in the figure) occupies the 4C position of the O atomic tetragon, the FE atom (the dark shadow part in the figure) occupies the 4C position of the eight -facial body, the li atom (the small particles in the figure in the figure (the small particles in the figure ) The 4A position occupied by the eight -facial body, thus forming a mesh structure of the three -dimensional space.
1.2 Basic Structure of Ternary Lithium Battery
Depending on the types of orthopedic materials, the ternary lithium battery can be divided into (linixco YMN1 -X -YO 2, NCM) batteries and lithium cobalt aluminum (NCA) batteries. Because the ternary lithium battery has good overall performance and high energy, it has a very wide application in passenger vehicle power batteries. The energy storage battery of the new energy power station is mainly used by NCM battles. Depending on the relative content of transition metal ions, the type of NCM battery can be divided into NCM111 (Li Ni1/3CO 1/3MN 1/3O 2), NCM424, NCM523, etc. Among them, NCM1111 is the most widely used. The positive material of the NCM battery is the α-Nafeo2 layer structure, which belongs to the R-3M space group. There is no α-Nafeo2 layer structure in the ideal state of the LI+/NI 2+ mixed row in the existence of the li+/ni 2+mixed row. In Figure 2, O2-lying in cubic stacked arrangement, li+and CO 3+ are alternately located between O 2-layers between O 2-layers Octobic position; Li +occupies a 3A position between the octagonal layer, and the transition metal ion occupies a 3B position to form a two -dimensional alternative layer and forms the MO6 octopus structure with O2 -to form the MO6 octopus structure.