What is the reason for lithium batteries?

Аўтар: Iflowpower - Cyflenwr Gorsaf Bŵer Cludadwy

In terms of the most important carrier transmission and transport behavior, lithium battery is not suitable for fast charge. The localized carrier conduction and transport behavior of the lithium electrical system depends on the electrical conductivity of the positive and negative electrode materials and the electrical conductivity of the lithium ion diffusion coefficient and the organic electrolyte. Based on embedded reaction mechanism, lithium ions in positive electrode materials (ilivestone of one-dimensional olivat, two-dimensional passage of two-dimensional channels, spinel positive material of three-dimensional passage) and negative graphite negative material (layered structure) The rate constant of the coefficient of universal oxidation reactions in the secondary battery in the secondary battery is low.

Moreover, the ionic conductivity of the organic electrolyte is less than two orders of magnitude lower than the secondary battery electrolyte (strong acid or strong base) of the water system. The negative surface of lithium electricity has a layer of SEI membrane. In fact, the magnification performance of lithium electricity is largely received by lithium ions in the SEI membrane.

Since the polarization of the polarization of the powder electrode in the organic electrolyte should be much more serious, the negative safety hazard is caused by high magnification or low temperature conditions. Further, under the conditions of large rate charging, the lattice of the positive electrode material is easily destroyed, and the negative electrode stone ink sheet may also be damaged, and these factors will increase the attenuation of capacity, thus seriously affecting the life of the power lithium ion battery. Therefore, the essential characteristics of embedded reactions determine that the lithium ion battery is not suitable for high-magnification charging.

The results of the study have confirmed that the cycle life of the single battery in the fast charge mode will drop sharply, and the performance of the battery performance is significantly decayed in use. Of course, readers may say that the lithium titanate (LTO) battery is not a large rate charge and discharge? The magnification performance of lithium titanate can be explained from its crystal structure and ion diffusion coefficient. However, the energy density of the lithium titanate ion battery is very low, and its power type is based on sacrificing energy density, which results in a high cost of lithium titanate ($ / WH) cost, and the low price determines titanium.

Silver ion batteries are impossible to become the mainstream of lithium-electric development. In fact, the Japanese Toshiba SCIB battery has been downswilted in these years. At the electrical core level, it is possible to improve the magnification performance from a pole process and a battery design, such as a technique such as a relatively thin electrode, and a new pricing agent ratio.

More more, even manufacturers use the thermistors in the battery and thickening the extreme methods such as fluid. In fact, many domestic powered lithium-ion battery companies have high-magnification data of their LFP power lithium ion batteries at 30c or even 50C as a technical highlight. The author should point out that as a means of detecting, it is not very good, but what is changed inside the battery cells is the key.

Long-term high-rate charge, perhaps the positive and negative material structure has been destroyed, and the negative electrode has been paid for lithium, these problems use some of the in-situ test (such as SEM, XRD and neutron diffraction, etc.) clear. It is a pity that these in situ test methods have almost no report on domestic battery companies.

The author also reminds the reader to pay attention to the difference in lithium battery charging and discharge process, and the charging process is that lithium electricity is discharged at a higher magnification (external work) damage to the battery is not so serious, this is other Aquatic secondary battery. However, for the actual use of electric vehicles, the demand for high-magnification charging (fast charge) is undoubtedly more eager to discharge over large currents. The level of the rising to the battery pack will be more complex, and the charging voltage and charging current of different monomer batteries during the charging process are inconsistent, and the charging time of the power lithium-ion battery must exceed the monomer battery.

This means that although the conventional charging technology can also charge the monomer battery to half in 30 minutes, the battery pack will definitely exceed this time, which means that the advantages of rapid charging technologies are not ten. Obvious. In addition, during the use (discharge) of the lithium ion battery, the consumption of the capacity and the discharge time is not linear relationship but accelerate over time.

For example, a motor vehicle is full of driving mileage, then when it takes 100 kilometers normally, the power lithium-ion battery may have a capacity of 80%. When the battery capacity is 50%, the electric car may only Can drive 50 kilometers. .