Hello everyone, I'm Xiao Li. There are two major pain points in the battery of today's trams, which have not been able to be solved well, resulting in many people buying trams either with poor battery life or with relatively large safety risks. Many trams burn out during the charging process, and they can't be controlled when they burn. But these two major pain points of the tram may soon be solved, and the solid-state battery with higher energy density and safer is coming, and it is the final king.
- Disadvantages of traditional lithium-ion batteries
There are two main types of lithium-ion batteries used in trams today, one is lithium iron phosphate battery and the other is ternary lithium battery. Among them, it is generally recognized that lithium iron phosphate batteries are safer than ternary lithium batteries, but its energy density is not as high as ternary lithium batteries. Speaking of which, I have to talk to you about the energy density of lithium-ion batteries. Whether it is a ternary lithium battery or a lithium iron phosphate battery, it uses lithium ions to swim between the positive and negative electrodes to store and release electric energy. Lithium-ion batteries on the market use graphite as the negative electrode, and the lithium ions pass through the separator inside the battery to embed and remove graphite to form the process of storing and discharging. So why use graphite as a negative electrode?
In fact, it is also possible not to use graphite as the negative electrode, and the direct use of lithium metal can directly fill the energy density of the battery, which makes the battery have the highest energy density, but the lowest safety factor. This kind of battery is very prone to short-circuit explosion, and the main reason for short-circuit explosion is that there is a short-circuit phenomenon inside the battery. The inside of the battery is divided into a positive electrode, an electrolyte and a negative electrode, and there is a separator inside the electrolyte between the positive and negative electrodes, which is used to penetrate lithium ions back and forth without short circuiting. However, lithium ions will form lithium dendrites in the process of embedding and coming out of the negative electrode, and lithium dendrites are like tree branches, which will be used more and more after formation, and finally pierce the separator and cause a short circuit.
Although the use of lithium metal can fill the lithium content, the lithium metal will react with the electrolyte to form lithium dendrites faster, and the use of graphite can greatly delay the formation of lithium dendrites, and under normal circumstances, the battery can be used until the end of its service life without short circuit. However, after using graphite, because there is no lithium element in graphite, all energy density is relatively low, and if you want to have a longer battery life, you can only think of other ways. Solid-state batteries are the ultimate solution to the problem that lithium dendrites are easy to puncture the separator, but the imagination is beautiful, the reality is skinny, and the development of solid-state batteries has not been breakthrough.
- Advantages of solid-state batteries
Although the power batteries we see now are all piece by piece, they are actually not solid inside, and there is an electrolyte inside. A real solid-state battery does not contain an electrolyte, and it is all hard electrolyte, so that the so-called lithium dendrites have no way to penetrate the electrolyte and cause a short circuit. Because the solid electrolyte is more difficult to burn, even if it is short-circuited, it must be burned slowly, like burning gas when cooking at home must be more violent than burning carbon, right? Coal gas explodes without moving, who has ever seen a carbon explosion? All solid-state batteries are safer. In this way, the use of lithium metal as the negative electrode can solve the problem of low energy density. However, the difficulty of solid-state batteries lies in the selection of electrolytes, and there is no way to solve the problem of what kind of electrolyte is used.
However, even now everyone is vigorously developing solid-state batteries, but they are still only made in laboratories, and it is very difficult to mass produce them in reality, just like laboratories can use nuclear fusion to produce energy, but they cannot be commercialized. However, many companies have announced that they will be able to mass-produce solid-state batteries by 2030, and the newly released Zhiji L6 also claims that there will be a model equipped with a solid-state battery version in the future. GAC Aion's Haobo brand also announced the release of "all-solid-state" batteries on April 12, and it may not be long before ordinary people can use models equipped with solid-state batteries.
In general, compared with solid-state batteries, the current battery has low energy density and is easy to spontaneously combust, which is really weak, and the solid-state battery is the last king in the future, what do you think?