【Research Background】Since commercialization in 1991, the lithium-filled lithium-free battery (LIBS) has occupied the dominant position of the storage market in the field of portable electronic equipment, electric vehicles and smart grids. However, the battery energy density obtained so far does not meet the growing energy storage demand, especially for remote electric vehicles over 500 kilometers of endless mileage. Although different types of batteries (high voltage Libs, Li-S battery and lithium metal batteries) have been widely studied, the energy density exceeds 300 WH kg-1 still challenging. In addition to the electrode material capacity, it is also necessary to consider other parameters of the battery, for example: the voltage difference between the area load density, the positive electrode and the negative electrode, the initial capacity, and the initial roaming efficiency.
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[Introduction to the results]
* Nearly, the Chinese Academy of Sciences Changchun Stress Ming army, Professor Yang-Kook Sun, Hanyang University, and Professor Abdullah Science and Technology Husam N. ALSHAREEF (common admission author) proposed a new experience model, which is considered In addition to the electrode capacity, a plurality of design parameters are considered, including area load density, voltage difference, initial capacity balancing, and initial cauling efficiency to estimate the energy density that can be realized. This method is used to predict the battery energy density and can achieve 300 WH kg-1 or more. At the same time, the model shows that the storage capacity of the electrode material is only one of the important factors affecting the energy density of the end battery. The model of this article breaks the model of the traditional estimation of battery energy density, providing a direct guide for designing higher energy density batteries. Related research results are published in ACS Energy Lett on ACS Energy Lett.
【core content】
I. Description of the model
In a conventional understanding, the energy density (e) of the lithium-ion battery can be determined by its electrode material to a large extent:
Among them, Q and M are the capacity and mass of the battery, and the variable u is the potential difference between the positive electrode and the negative electrode, which is related to the positive and substantially electron charges, however, electrons are in vacuum levels (Fermi) The level of level) is different from the actual situation. Further, although the voltage difference can be represented by the potential difference of Li in the two electrodes, the voltage difference varies with the battery charging state (SOC). Therefore, the average voltage difference (ΔU) is introduced to simplify the calculation of E, the variable Q represents the battery capacity, and the battery capacity can be calculated from Q = CPMP, where CP and MP represent the reversible specific capacity of the positive electrode and the total mass load, E The expression can be written:
Among them, constant K is represented as k = (MP + MN) / m. Therefore, the expression of E can be written:
K 's size is affected by many factors, such as electrode material properties (particle size, specific surface area), electrode preparation process (area load density, compact density), diaphragm, collective fluid, and packaging process. Therefore, the K value is a universal constant that can be used for different types of batteries, and it is difficult to calculate the K value directly. However, an empirical value can be obtained by the current actual energy density of the current LIBS.
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* After, the balance initial capacity (χ) between the positive and negative electrodes is introduced, where = cnmnεP / CPMPεN introduces it into formula 3:
When εn / εp = 1.1, this means that the reversible capacity of the negative electrode is 10% higher, which is currently required in most battery design.
Figure 1. Libs schematic and factors that affect its energy density. (A) Battery schematic and its parameters; (b) a method of implementing high energy density using a simple model. Recommend: LiFePO4 Battery Manufacturer Energy storage battery Manufacturer Integrated machine energy storage battery series Manufacturer Lead lithium battery Manufacturer Outdoor Backup Battery Manufacturer Portable outdoor power supply Manufacturer Power battery Manufacturer Powerwall LiFePO4 Battery Manufacturer Battery rack Manufacturers Telecom LiFePO4 Battery Manufacturer Wall mounted battery storage Manufacturer China Lifepo4 Battery
