Analyze the energy density and size specifications of lithium batteries

The relationship between energy density and lithium battery size The following is an actual lithium battery model to explain the relationship between battery energy density and size: lithium battery model: 523450A1000mAh lithium drill material battery thickness 5.2mm, battery width 34mm, battery height 50mm. Lithium battery first step: List the relevant fixed parameters lithium battery cathode gram capacity: 142mAh/g; cathode gram capacity: 330mAh/g; positive compaction density: 3.8g/cm3; negative compaction density: 1.55g/cm3; The proportion of positive electrode drilling lithium sulfate: 94% of negative electrode graphite powder. Diaphragm thickness: 0.016; tab width: 4mm; for a lithium battery system, some parameters are fixed, just plug it in when designing ! Step 2: Carrying out the battery design journey 1. The battery is small and one iron core, then the maximum iron core thickness: u003d battery thickness-shell thickness u003d 5.2-0.2*2 u003d 4.8mm (generally the thickness of the aluminum shell is 0.2-0.3 , Different places may be different, but it does not matter much) 2. Core height: remove the upper cover 1mm, lower cover 0.5mm, plastic gasket 1.5mm, reserve 1mm space, core heightu003d50-1-0.5 -1.5-1u003d46mm, that is, the diaphragm can be 44mm wide. Generally speaking, if we make an aluminum shell, we can choose a 20um diaphragm. If we process larger batteries, the separator may be thicker, ranging from 25um to 35um. 3. The width of the negative electrode. The negative electrode must be narrower than the separator. It can be 1mm or 2mm, depending on how you stay. Assuming it is 2mm, the width of the negative electrode is 42mm. (For some large-size batteries, please widen it by 3-4mm) 4. The negative electrode covers the positive electrode, so the positive electrode is narrower than the negative electrode, 1-3mm. Because it is a small battery, we choose 1mm and the width of the positive electrode 44-1u003du003d43mm 5. According to relevant experience, suppose the double-sided density of the positive electrode u003d 40.5mg/cm2, the capacity of the positive electrode is 140mAh/g, and the active The proportion of substances is 94%. The negative g capacity is 320mAh/g, and the active material ratio is 94%. Safety factor u003d 1.03 (high, 1.1) Then we can calculate: negative double-sided density u003d 40.5*140*94%/(320*94%)1.05u003d18.45mg/cm26, the cathode material can be pressed to 3.8g/cm3; The negative electrode is 1.6g/cm3; the aluminum foil is 12um, and the copper foil is 12um. 7. Then calculate the thickness of the positive and negative electrodes: the thickness of the positive plate is 40.5/3.8*10+16u003d119um, and the thickness of the negative plate is 18.45/1.6+10u003d127um; 8. Then, after winding, there are 2 layers, single layer Thicknessu003dpositive thickness+negative thickness+2 layer diaphragm thicknessu003d119+127+16*2u003d2789. It can be seen that the total number of rollersu003dcore thickness/(single layer thickness*2)u003d4.8*90%/(278 /1000)u003d15.5 turns (90% is the space reserved for the thickness of the battery, and the thickness value varies with the thickness of the material) 10. Calculate the size of the winding needle. Winding needle width u003d winding core width-winding core thickness-2u003d(34-0.20*2)-4.8)*92%u003d27mm 11.Calculation of the length of the positive electrode plate: the length of the positive electrode u003d (number of layers-2)* Double winding thickness + coil width + coil thickness + one layer of winding thickness + coil width)*(number of layers-1)/2+coil width-thickness/2u003d((16-2)*0..278*2+( 27+27+0.5+0.262))*(16-1)/2+27-5.2/2u003d505mm negative electrode length calculation: negative electrode u003d positive electrode length-needle width-tail scraper level-1012, tab Width and thickness, the battery is small, and the pole ear 0.1*4mm is basically enough. 13. The position of the electrode: au003d10Bu003dcoil width*2.7+3Cu003dD+4*2Du003dextreme ear width+(2~4)Eu003dneedle- C/214. Calculation capacity: design capacityu003dpositive mineral processing capacity*g capacity*active material ratiou003d*140mAh/g*7.516*94%u003d1052mAh 15. Nominal capacity: In general design, the design capacity is about the nominal capacity 1.05% 16. According to different situations, make corresponding adjustments to design the battery size. Generally, edit the formula on the computer, and you only need to enter the corresponding parameters for 2-5 minutes to get a process. 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: Power lithium battery packaging technology