Analysis of the four problems in the negative electrode of lithium batteries

The four problems of the negative electrode of lithium battery are analyzed. The output voltage of lithium battery is equal to the difference between its positive and negative voltage. Therefore, the de-embedded lithium voltage of the lithium battery determines the output voltage of the battery (at least half). The lower the negative operating voltage, the higher the operating voltage of the battery. 1. What is the importance of the negative electrode? What is the importance of the negative electrode in a lithium battery? The output voltage of a lithium battery is equal to the difference between its positive and negative voltages. Therefore, the de-embedded lithium voltage of the lithium battery determines the output voltage of the battery (at least half). The lower the negative operating voltage, the higher the operating voltage of the battery. The specific capacity of the battery is determined by the specific capacity of the positive electrode and the specific capacity of the negative electrode, and the specific capacity of the negative electrode determines at least half of the specific capacity of the battery. The actual available capacity of the battery is also related to the skew of the negative delithiation voltage channel. The flatter the lithium removal voltage channel is, the greater the effective capacity of the negative electrode and the greater the specific capacity of the battery. Assuming that the positive capacity is PmAh/g and the negative capacity is QmAh/g, then the theoretical capacity of battery x satisfies the following formula 2. Mass ratio concession between energy and voltage Strictly speaking, this concession does not include lithium. The working voltage of metallic lithium is 0V, the theoretical capacity is 3862mAh/g, and the actual capacity is determined by the utilization rate of the active material. Why go back? Generally speaking, a basic feature of current negative electrode candidate data (excluding metal lithium) is that the larger the capacity of the active electrode data, the higher the lithium removal voltage channel (may be a uniform value). For example, the uniform delithiation potential of graphitic carbon data is 0.15v, and the actual capacity is 350mAh/g. The lithium removal potential of the Sn negative electrode is uniform, 0.5v, and the theoretical capacity is 990mAh/g. The uniform lithium removal potential of the Si negative electrode is 0.45v, and the theoretical capacity is 4200mAh/g. The actual usable capacity of Sn and Si has not yet been determined, and is ultimately determined by the conditions of use. The energy density and specific characteristics of the battery are the product of the working voltage (positive and negative voltage difference) and the mass specific capacity (or volume specific capacity). When using Si or Sn to replace carbon-based data, whether the substantial increase in battery specific capacity can compensate for the drop in battery operating voltage is an important factor to consider. A simple example is given. Lithium iron phosphate has a working voltage of 3.45v and a capacity of 160mAh/g. 1g lithium iron phosphate matches graphite carbon (0.15v, 350mAh/g actual capacity) and 0.457g graphite carbon. The theoretical specific energy of the entire battery is (3.45-0.15)V*160mAh/1.457gu003d362.3mwh/g. 1g lithium iron phosphate is combined with Si negative electrode. The Si negative electrode is calculated at 0.45v and 4200mAh/g, and the specific energy of the entire battery after matching is (3.45-0.45)V*160mAh/1.038gu003d462mWh/g. It is worth noting that the increase in silicon anode capacity can compensate for the decrease in battery voltage caused by the increase in lithium removal voltage. Of course, this is a theoretical consideration, because the actual capacity of the Si anode may not reach the theoretical value. Assuming that the actual capacity of the Si negative electrode is p, it should meet the condition that the specific energy of the full battery is greater than 362.3mWh/g. Of course, the above equation is still a bit simplified, without considering the relationship between the Si negative voltage and the capacitance, but it can explain us The purpose of the current review. The calculation can get p at least 492.5mAh/g, in other words, the actual capacity of Si negative is greater than the capacity of 492.5mAh/g, in order to ensure that the quality of the battery is not bad (compared with the lithium iron phosphate/graphite carbon system). The development of large-capacity c-si composite cathode data can also learn from the above opinions. Roughly speaking, in practice, the dedicated capacity of the Si part of the c-si composite cathode should not be less than 492.5mAh/g, otherwise it is meaningless. 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: Application field of lithium iron phosphate power lithium ion battery