Analysis of the advantages and disadvantages of ternary lithium batteries

Ternary lithium battery Ternary polymer lithium battery: A lithium battery using lithium nickel manganese manganate (Li (NiCoMn) O2) ternary cathode material as the positive electrode material, especially refers to the positive electrode is ternary, and the negative electrode is graphite ternary power lithium Ion battery. The other type of positive electrode is ternary, and the negative electrode is lithium titanate, which is usually called lithium titanate, which is not a ternary material in general. 1. Advantages of ternary lithium battery: The ternary lithium battery has high energy density and better cycle performance than normal lithium sulphate. At present, with the continuous improvement of the formula and the perfect structure, the nominal voltage of the battery has reached 3.7V, and the capacity has reached or exceeded the level of lithium sulphate batteries. The LiNi1/3Co1/3Mn1/3O2 cathode material has a single hexagonal a-NaFeO2 layered rock salt structure similar to LiCoO2, and the spatial point group is R3m. Lithium ions occupy position 3a of the (111) plane of the rock salt structure, transition metal ions occupy position 3b, and oxygen ions occupy position 6c. Each transition metal atom is surrounded by 6 oxygen atoms to form an MO6 octahedral structure, and lithium ions are inserted into transition metal atoms. Ni1/3Co1/3Mn1/3O layer formed with oxygen. Because the radius of divalent nickel ions (0.069nm) is close to the radius of lithium ions (0.076nm), a small amount of nickel ions may occupy the 3a position, leading to the occurrence of mixed cations, and this mixed occupancy makes the material The electrochemical performance becomes worse. Usually in XRD, the intensity ratio of the (003)/(104) peak and the splitting degree of the (006)/(012) and (018)/(110) peaks are used as indicators of the cation mixing and occupancy. In general, when the intensity ratio of (003)/(104) peak is higher than 1.2, and the (006)/(012) and (018)/(110) peaks are clearly split, the layered structure is distinct, and the electrochemical properties of the material Excellent performance. The unit cell parameters of LiNi1/3Co1/3Mn1/3O2 are au003d2.8622A, cu003d14.2278A. Nickel, cobalt, and manganese exist in the crystal lattice with valences +2, +3, and +4, respectively. At the same time, there are also a small amount of Ni3+ and Mn3+. In the process of charging and discharging, in addition to the electron transfer of Co3+/4+, there are also The electron transfer between Ni2+/3+ and Ni3+ also makes the material have a higher specific capacity. Mn4+ only serves as a structural substance and does not participate in redox reactions. Koyama et al. proposed two models describing the crystal structure of LiNi1sCou3Mnm3O2, namely a complex model with [v3xV3]R30°-type superstructure [Ninaco1sMn1] layer, and the unit cell parameter au003d4.904Acu003d13.884A. The lattice formation energy is -0.17eV and CoO2 The simple model of ordered stacking of NiO2 and MnO2 layers, the lattice formation energy is +0.06eV. Therefore, under suitable synthesis conditions, the first model can be formed. This crystal type can minimize the change in the volume of the crystal lattice and reduce the energy during the charge and discharge process, which is beneficial to the stability of the crystal lattice. The electrochemical performance and thermal stability of the ternary material LiNi1/3Co1/3Mn1/3O2 LiNi1/3Co1/3Mn1/3O2 as a lithium battery cathode material has a high lithium ion diffusion capacity and a theoretical capacity of 278mAh/g. During the charging process Among them, there are two platforms between 3.6V and 4.6V, one is around 3.8V and the other is around 4.5V, which is mainly attributed to the two electric pairs of Ni2+/Ni4+ and Co3+/Co4+, and the capacity can reach 250mAh /s is 91% of theoretical capacity. In the voltage range of 2.3V~4.6V, the discharge specific capacity is 190mAh/g, after 100 cycles, the reversible specific capacity is more than 190mAh/g. Electrical performance detection is carried out in the potential range of 2.8V～4.3V, 2.8V～4.4V and 2.8V～4.5V. The specific discharge capacity is 159mAh/g, 168mAh/g and 177mAh/g, and at different temperatures (55℃). , 75°C, 95°C) and different rates of charge and discharge, the material structure changes are small, has good stability, high temperature performance is good, but low temperature performance needs to be improved. The safety of lithium batteries has always been an important criterion for commercialization. The thermal effect of the electrolyte with the electrolyte in the charged state is the key to whether the cathode material is suitable for lithium batteries. The DSC detection result stated that the charged LiNi1gCo1gMn1/3O2 showed no peak at 250~350℃, LiCoO2 had two exothermic peaks at 160℃ and 210℃, and LiNiO2 had an exothermic peak at 210℃. Ternary materials also have some exothermic and endothermic reactions in this temperature range, but the reaction is much gentler. 2. Disadvantages of ternary lithium battery: ternary material power lithium battery mainly includes nickel diamond lithium aluminate battery, nickel diamond lithium manganate battery, etc. The high-temperature structure is unstable, resulting in poor high-temperature safety, and excessive pH is easy to make the monomer. Flatulence, which in turn causes malfunctions, is not low in cost under current conditions. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: What types of lithium batteries are important?