What are the important differences between lithium batteries and lead-acid batteries?

Lithium batteries are a type of batteries that use lithium metal or lithium alloy as the negative electrode material and use a non-aqueous electrolyte solution. Lithium batteries can be roughly divided into two categories: lithium metal batteries and lithium batteries. In 1912, the lithium metal battery was first proposed and studied by Gilbert N. Lewis. Due to the very active chemical properties of lithium metal, the production, storage and use of lithium metal have very high environmental requirements. Therefore, lithium batteries have not been used for a long time. With the development of science and technology, lithium batteries have now become the mainstream. Lead-acid battery: Lead-acid battery (VRLA) is a kind of storage battery whose electrode is mainly made of lead and its oxide, and the electrolyte is sulfuric acid solution. In the discharge state of a lead-acid battery, the important component of the positive electrode is lead dioxide, and the important component of the negative electrode is lead; in the charged state, the important components of the positive and negative electrodes are lead sulfate. The nominal voltage of a single-cell lead-acid battery is 2.0V, which can be discharged to 1.5V and can be charged to 2.4V; in applications, 6 single-cell lead-acid batteries are often connected in series to form a lead-acid battery with a nominal 12V , There are 24V, 36V, 48V and so on. From the perspective of battery safety protection, 18650 batteries are designed with safety valves, which can not only release excessive internal pressure, but also physically disconnect the battery from the external circuit, which is equivalent to physically isolating the battery to ensure The safety of other batteries in the battery pack. In addition, lithium battery packs are usually equipped with a BMS protection board, which can accurately control the state of each cell in the battery pack and directly solve the problem of overcharge and overdischarge from the root cause. Lithium battery BMS battery management system can provide full protection to the battery. The functions include: charge/discharge high and low temperature protection; single cell overcharge/overdischarge voltage protection; charge/discharge overcurrent protection; cell balance; short circuit protection; Charging reminders and so on. The electrolyte of the lithium battery pack is a mixed solution of lithium salt and organic solvent. Among them, the commercial lithium salt is lithium hexafluorophosphate. This material is prone to thermal decomposition at high temperatures and undergoes thermochemical reactions with trace amounts of water and organic solvents to reduce The thermal stability of the electrolyte. Power lithium batteries mainly use lithium iron phosphate. The PO bond in the lithium iron phosphate crystal is stable and difficult to decompose. Even at high temperatures or overcharge, it will not collapse and generate heat or form strong oxidizing substances in the same structure as lithium cobalt oxide. Good security. A report pointed out that in actual operation, a small part of samples were found to burn in acupuncture or short-circuit experiments, but there was no explosion. The safety of lithium battery packs has been greatly improved. In contrast, lead-acid batteries lack BMS system protection. Lead-acid batteries seem to be lackluster in terms of safety protection except for safety valves. BMS protection is almost non-existent. Many low-quality chargers cannot even be powered off after being fully charged. Safety protection is far from lithium batteries. Coupled with inferior chargers, your character is good if you don't have an accident. Spontaneous combustion and explosion of electric vehicles often occur, most of which are caused by battery charging and discharging. Experts explain that the charging time of lead-acid batteries is too long. After charging to the end, after the two poles are converted into effective substances, if you continue to charge, there will be a lot of Of hydrogen and oxygen gas. When the concentration of this mixed gas is 4% in the air, it is too late to escape. If the vent is blocked or there is too much gas, it will explode if it encounters an open flame, which may damage the battery in the slightest, and injure people and objects. That is, once a lead-acid battery is overcharged, it will increase the probability of explosion. However, the lead-acid batteries currently on the market do not have any overcharge protection, which makes charging, especially the lead-acid batteries at the end of charging, extremely dangerous. Finally, if the battery structure is damaged due to an accidental collision, lead-acid batteries seem to be safer than lithium batteries. However, in this level of accident, the battery material has already been exposed to the open environment, and there is no way to talk about explosion. From the above safety hazards related to lead-acid batteries and lithium iron phosphate batteries, it can be seen that the biggest safety hazard of lead-acid batteries lies in their constituent materials. The electrodes of lead-acid batteries are mainly made of lead and its oxides, and the electrolyte is a sulfuric acid solution. 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: What are the lithium battery packs and lithium battery pack production equipment?