In the power lithium battery system, each parameter can characterize the different performance of the system. This article lists the lithium battery parameters.
1.Lithium battery cell
Lithium-ion battery cells are composed of positive and negative electrodes, electrodes, electrolytes, and separators, and are the basic structural units that make up battery modules and batteries. As an electrochemical power source, a battery naturally has characteristics such as voltage, internal resistance, capacity, energy, and power.
The cell voltage mainly depends on the type of the monomer positive and negative electrode materials. The general lithium cobaltate and ternary positive electrode combined with the graphite negative electrode can obtain a full charge voltage of about 4.2V, while the lithium iron phosphate battery can only reach a maximum of 3.6V. The voltage here should be precisely that the electric potential depends on the material properties, and the electric potential value is equal to the open circuit voltage of the battery after being left for a long enough time. The single-terminal voltage in the closed circuit is the voltage value that we detect with an external instrument, and its value is equal to the battery potential minus the battery internal resistance. The internal resistance of the battery is not constant, and it will be affected by various factors.
Lithium battery capacity, measurable capacity, is the maximum power that can be charged and discharged within the reasonable maximum and minimum voltage range of the battery. The capacity of the monomer is obviously affected by the degree of aging. Everyone knows that when the capacity decays to a limit value when the lithium battery is eliminated, it can be seen that the two have absolute correlation. Secondly, the capacity is also affected by the temperature. At low temperatures, the activity of the active substance decreases, and the ions that can be provided decrease, and the capacity inevitably decreases.
The power here should be specifically the specific power, which is the charge / discharge power capability of a single cell or the charge / discharge power capability of a unit mass or unit volume cell. Whether a lithium battery can be charged and discharged with high power is already determined when it is designed. Once the battery cell is produced, its reasonable maximum charge and discharge current has been determined. Except for adjusting the battery heat dissipation conditions, which can change its maximum charge and discharge power within a small range, there is little room for further adjustment.
6.Charge and discharge ratio
The current value corresponding to the charge-discharge rate is multiplied by the operating voltage, and the continuous power and peak power indicators of the lithium-ion battery can be obtained. The more detailed the definition of the charge-discharge rate index, the greater the guiding significance for use. In particular, lithium ion batteries used as power sources for electric vehicles need to specify continuous and pulse rate indicators under different temperature conditions to ensure that lithium batteries are used within a reasonable range.