1. In high-rate lithium batteries, the capacity of the thin positive electrode is lower than that of the thick positive electrode. When discharging at the same rate, the current density flowing through the positive electrode is different. Under the same rate, the current density flowing through the thin positive electrode battery is smaller. The polarization of the chemical reaction is relatively small, so the discharge effect is better than that of a thick positive electrode battery. Reducing the thickness of the positive electrode can effectively increase the discharge rate of the battery.
High rate battery
Under roughly the same discharge current density, the discharge utilization rate of the thin-positive battery is higher. This is because when the battery is discharged at a high rate, the reaction speed of the active material is very fast, and ions are required to be inserted and released from the material quickly. If the pole piece is thick, it lengthens the path of ion movement, increases the resistance of ion movement, and ultimately affects the performance of the battery capacity.
2. The effect of conductive agent content on high-rate lithium batteries
The content of the conductive agent in the positive electrode has a significant impact on the high-rate discharge performance of the battery. The content of the positive electrode conductive agent is a key factor affecting the high-rate discharge performance of lQ0C. The main reason why a normal battery cannot be discharged at a 1Q0C rate is that the content of the conductive agent in the normal positive electrode formulation is insufficient. When the high current discharges, the electrons cannot be transferred in time, and the internal polarization resistance increases rapidly, so that the voltage of the battery quickly drops to the discharge termination voltage.
3. The influence of anode materials on high-rate lithium batteries
Artificial graphite and MCMB, different types of anode materials have a greater impact on the high-rate discharge performance. The specific surface area of artificial graphite is much larger than that of MCMB, but the high-rate discharge performance is far inferior to MCMB.
The surface morphology of MCMB is similar to a spherical shape, which is conducive to the maximum accumulation of particles and the compaction of the pole pieces, so that the contact between the active material particles is better. The electronic conductivity is also better; the surface morphology of the artificial graphite is similar to the bar shape, and the active material particles will have less contact. Or there will be voids, which will cause the conductivity of the electrode to decrease, so the high current discharge performance is not as good as MCMB.
4. The impact of size on high-rate lithium batteries
The discharge performance of different types of batteries is different. The high-rate discharge performance of the same formula and different types of batteries is different. The battery area is large and the high-rate discharge performance is better. Therefore, the discharge capacity under the same rate is significantly larger.
5. The influence of electrolyte on high-rate lithium batteries
The high-rate discharge curves of the standard electrolyte and functional electrolyte of the battery can be seen: when the 100C rate discharge, the first discharge capacity of different electrolyte batteries is very small; when the 20.0C rate discharge, the first discharge capacity of the standard electrolyte battery is obviously inferior Functional electrolyte batteries cannot even be discharged normally. For polymer lithium-ion batteries, ordinary ternary electrolytes to achieve 100C high-rate discharge can meet the requirements. If higher discharge rates are required, the electrolyte should be optimized. Functional electrolyte has a significant improvement effect on the common voltage first drop and then rise problem of high-rate discharge. It indicates that the optimization of electrolyte functionalization should be strengthened when discharging at a higher rate.
Post time: Apr-19-2021