As a manufacturer with deep experience in the customized lithium battery energy storage industry, SES Power has always been confident in the development of lithium ion batteries. The concept of safety first has always been the insistence of SES Power, but there are always customers or partners who have many questions about the safety performance of lithium-ion batteries and lead-acid batteries.

　　Let the senior engineers of SES Power answer your questions about the safety performance of the battery in detail:

　　Q. Is safety the most important thing for batteries?

　　A: Yes, without security, various functions cannot be accepted by people. In fact, lithium batteries can begin to be practical, but also because the safety has reached a level acceptable to the public.

　　The "lithium battery" we often say is not a very correct name, it should actually be a "lithium ion battery". The real lithium battery is only used in some special occasions. In principle, the lithium battery is still quite different from the lithium ion battery: the lithium ion battery is essentially the flow of lithium ions from a high concentration to a low concentration environment, thereby forming a current; lithium battery It uses metal lithium as the negative electrode, and the redox reaction occurs to form a current, which is the same as the general zinc-manganese dry battery.

　　The energy density of lithium batteries is much higher than that of lithium-ion batteries, but the number of cycles is low. However, lithium-ion batteries are very common in daily life, and lithium batteries are rarely seen. The core reason is that lithium-ion batteries are safe enough, but lithium batteries are very unsafe: metal lithium may react with water and oxygen, then heat up, and finally cause an explosion.

　　Lithium-ion batteries can be widely used because although its safety problems exist, the threat has been greatly reduced to an acceptable level. At the same time, the huge value of lithium-ion batteries is enough to cover the low cost of safety.

　　Q. Are lead-acid batteries safe?

　　A: If you evaluate lead-acid batteries according to the standard of lithium-ion batteries, then the conclusion is very simple: safe! For example, many lithium-ion batteries cannot pass the needle prick test, but lead-acid batteries can easily pass the test.

　　This is because the interior of lithium-ion batteries contains flammable electrolytes, to be precise, conductive salts and flammable solvents, including carbonates, ethers, esters, and the like. Once the battery is pierced and the positive and negative electrodes are directly connected, that is, a short circuit occurs, the battery is rapidly discharged, and the sharply increased heat will cause the solvent to be ignited, which may eventually cause an explosion.

　　Lead-acid batteries do not have this problem. Its electrolyte is sulfuric acid, which does not cause a sharp increase in heat, but leaks liquid. Although lead-acid batteries can pass the needle prick test, would we consider it safe?

　　Obviously not, sulfuric acid is highly corrosive, and during normal use, lead-acid batteries will release sulfur-containing gas, and a part of sulfuric acid will always be reduced to toxic sulfur dioxide. Simply put, a lead-acid battery can pass the toughest needle prick tests, but it still releases substances that are harmful to humans.

　　Therefore, the safety of lead-acid batteries is not as high as imagined. Safety is not just a dimension. Lithium-ion batteries will explode when punctured, and lead-acid batteries are corrosive when punctured. These are all unsafe factors, but the explosion has a greater visual impact.

　　Q. Can lithium-ion batteries be safe?

　　A: Yes.

　　The current lithium-ion batteries usually add flame retardants to prevent the electrolyte from burning due to short-circuit and other reasons, which solves the safety problem to a certain extent. Of course, there is a more direct way, using solid-state electrolytes, that is, to make solid-state lithium-ion batteries, to completely achieve non-combustibility and not explode.

　　The question is why are lithium-ion batteries in our minds very unsafe and prone to explosion? For example, the fire and explosion of mobile phones and electric vehicles, and even the accidents of some energy storage power stations. And of course the most common electric bikes. In terms of accident rate, electric bicycles are much higher than mobile phones and new energy vehicles, and most mobile phones and cars catch fire while charging, and people may not be on the scene, but electric bicycles often catch fire suddenly during use.

　　The reason for this is largely due to cost compression. Generally, the battery used in electric bicycles is 48V20Ah, and the energy is 960Wh, which is nearly 1 kWh. The production cost of lithium-ion batteries in formal enterprises can be compressed to about $0.1 per Wh. Such a battery of course also contains BMS, casing, wires, transportation costs, etc. If it is produced and sold by a regular manufacturer, the sales price should be around $200. However, there are many such batteries on the market for less than $100, which of course reduce the cost by reducing the quality.

　　Q. Since lithium-ion batteries are prone to explosion due to extreme control costs, why not replace them with cheaper lead-acid batteries?

　　A: Many people don't understand: Since lithium-ion batteries are too expensive, and some people cut corners, the safety performance of lithium-ion batteries has been greatly reduced. Isn't it a better choice to use lead-acid batteries?

　　It is not impossible, but industry standards and consumers are not willing. Take the 960wh battery mentioned above as an example. It is made of lead-acid battery and weighs about 20 kg, which is indeed very heavy. The weight of the lithium-ion battery is about 8 kg. The advantages of lightweight lithium-ion batteries are very obvious.

　　As for the automotive field, lead-acid batteries proved unsuitable for electric vehicles more than a hundred years ago. When Edison built electric vehicles, he still used iron-nickel batteries. At that time, the battery life exceeded 200 kilometers, but they were still eliminated by fuel vehicles. How can lead-acid batteries be used?

　　In fact, even some of the scenarios that are least afraid of weight are considering replacing the lithium-ion battery. For example, underwater ships, electric forklifts, etc., need to increase the counterweight, and lead-acid batteries are quite suitable. But now, these products have more and more functions, the weakness of lead-acid batteries that cannot be intelligent has been magnified, and lithium-ion batteries have begun to be taken seriously.

　　Of course, lead-acid batteries still have problems such as short lifespan, heavy metals, and not enough environmental protection. When lithium iron phosphate batteries in lithium-ion batteries appear, lead-acid batteries have completely entered a dangerous period. Because the advantages of lithium iron phosphate battery voltage, discharge curve, high cycle life, environmental protection and other advantages are almost fully aimed at the shortcomings of lead-acid batteries. Therefore, lithium iron phosphate batteries are called the perfect substitute for lead-acid batteries.

　　Q: What are the requirements and standards for the safety performance of lithium ions

　　A: According to SES Power's knowledge, the safety tests of lithium-ion batteries include UL, IEC and other common test methods. Although there are UL2054 standards for lithium-ion battery packs, they do not clearly stipulate the internal or external storage of medium and large battery energy storage systems. Safety standard between battery packs.

　　The International Fire Code and National Fire Protection Association (NFPA) Standard 855 set limits on the number of battery energy storage systems that can be installed in any space and require a one-meter separation between battery energy storage systems and from the exterior walls of buildings.

　　As a company that has been customizing lithium-ion battery pack products for nearly 20 years, SES Power believes that safety is the first priority of lithium-ion batteries from the perspective of lithium-ion batteries, and we cannot sacrifice safety performance to meet other performance. From our 12V100Ah, 12V200Ah, 24V100Ah, 24V200Ah, 36V100Ah, 48V50Ah, 48V100Ah, etc. using square aluminum-shell lithium iron phosphate cells, to 12V30Ah, 12V50Ah car starting batteries using high-performance rate lithium battery A123 (the maximum peak current can reach 1500A). Frankly speaking, many customers are very concerned about cost performance, but SES Power insists that safety performance cannot be reduced to reduce costs. We usually use the price advantage of echelon batteries to make SES Power's customized lithium-ion battery packs based on guaranteed performance, to meet the needs of customers who are discerning enough about price.

　　Finally, SES Power summarizes: the safety of lithium-ion batteries is not as low as expected, and the safety of lead-acid batteries is not as high as expected. As for the unsafe problem of lithium-ion batteries, on the one hand, it is technology, which can be improved, and on the other hand, it is a question of cost control, which depends on the concept. The substitution of lithium-ion batteries for lead-acid batteries is mainly dominated by the market and regulations.