Everyone knows that electric car has many advantages, but also many disadvantages. For example, safety issues, battery life issues, and charging issues, so is there a solution?
In fact, many companies have been working hard to study and have many results. For example, aluminum ion battery , sodium ion battery and solid-state battery studied by domestic companies. Especially solid-state batteries, theoretically, both battery life and safety have been greatly improved. Under the same quality, the battery life is at least twice that of liquid lithium batteries.
What is a solid state battery?
In fact, solid-state batteries are not a new thing. Battery-related companies have been researched many years ago. For example, BYD , Guoxuan Hi-Tech , CATL , etc. have already had many related patented technologies.
Lithium batteries can be divided into four categories according to the content of liquid electrolytes, liquid, semi-solid state, quasi-solid state and all-solid state. Among them, semi-solid state, quasi-solid state and all-solid state are solid state batteries. Depending on the electrolyte material, solid-state batteries can be divided into three electrolytes: polymer, oxide, , and sulfide. According to the different positive and negative electrode materials, solid-state batteries can be divided into solid-state lithium-ion battery and solid-state lithium metal battery.
solid-state batteries have the following characteristics:
1 and conductivity is high, and the general commercial electrolyte conductivity range is 3×10-3~2×10-2S/cm. Although the conductivity of solid electrolytes is not as good as that of liquid lithium batteries, it is completely enough.
2, good stability, solid electrolyte is non-flammable, high temperature resistant, corrosion-free, and non-volatile, eliminating safety hazards such as electrolyte leakage and electrode short circuit in traditional lithium-ion batteries.
3. The voltage is high, and the solid electrolyte can reach 5V. High voltage means that the single cell can be connected in series inside the single cell, thus making the single cell larger.
4, high lithium ion migration number, and the ion migration number reaches 1 is the ideal state.
Is the solid-state battery really that good?
is not the case. The poor conductivity of leads to high internal resistance, which directly affects the energy density and power density of the battery, and therefore affects the fast charging performance of the battery. However, the problem of low conductivity can be improved by doping liquid electrolytes. However, due to the extremely active characteristics of lithium metal, new interface problems and stability problems will arise. Therefore, the negative electrode material cannot be directly used with lithium metal, but instead of graphite by doping graphite silicon and silicon instead of graphite, looking for a material system that not only improves energy density but maintains stability and security.
So what is the prospect?
With the improvement of solid-state battery technology, the liquid electrolyte content gradually decreases, the negative electrode is gradually replaced with metal lithium sheets, the energy density is expected to reach 500Wh/kg, and the working temperature range is more than three times. The production process is expected to be simplified, which can achieve lower costs than traditional lithium batteries. If the material is good enough, the battery cycle life can be infinitely improved. And it is safe enough, so you no longer have to worry about safety issues such as fire and explosion.
However, there are also many technical problems that need to be solved. , such as , conductivity is low, interface , impedance is large, and the positive and negative electrode materials cannot meet expectations. Also, the initial cost is relatively high, the price is 2-3 times that of the power battery of car and , and family cars cannot be promoted on a large scale.
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