Perhaps it was the time for the fire, and the epoch-making solid-state battery suddenly became popular, and it was popular among various new energy vehicle companies! First, Li Bin personally drove the NIO ET7 equipped with a 150-degree semi-solid-state battery, and drove 1,044 kilometers without charging halfway. Later, Liu Tao, CEO of Zhiji, announced that the Zhiji L6 will be equipped with a "quasi-900V ultra-fast charging solid-state battery", which can easily achieve a range of 1,000 kilometers, which is a production car. It seems that overnight, the once unattainable solid-state battery is about to "fly into the homes of ordinary people".
However, some people soon raised doubts: whether it is NIO's 150-degree battery pack or Zhiji LS6's ultra-fast charging solid-state battery, it is not a real solid-state battery, but a semi-solid-state battery. In particular, Zhiji seems to have deliberately concealed the word "half" in the propaganda materials, which is suspected of exaggeration. So what is the difference between this solid-state battery and a semi-solid-state battery? Is the semi-solid-state battery really so unbearable?
Of course not, even semi-solid-state batteries have left liquid lithium-ion batteries far behind in terms of performance, while all-solid-state batteries have gone to the next level. If semi-solid-state batteries and solid-state batteries are successfully popularized, the range and safety of pure electric vehicles will be greatly increased. When a pure electric car only needs to be charged for 20~30 minutes and the range reaches 1000 kilometers, it seems that there is really no need for people to drive a petrol car anymore. Bottom line: The mass production of solid-state batteries means that the end of fuel vehicles is coming.
Believe me to say this, it will definitely attract many netizens' questions, after all, it is too convenient to refuel fuel vehicles, and the tram is not only troublesome to charge, but also spontaneously combusted, which dissuaded many people. But if you know about the benefits of solid-state batteries, it makes sense. The current pure electric new energy vehicles are not very popular, and the biggest root cause is still two: one is the short battery life, and the other is the unsafe battery.
A pure electric car with a price of 20~300,000 yuan can write a nominal CLTC range of 600~700 kilometers, but it is not the case when it actually runs. The endurance of 500 kilometers at low speed in urban areas is good, and 400 kilometers at high speed is thank good. If in the winter in the north, you can run more than 300 kilometers at a high-speed speed of 120 per hour, then you must definitely give a big praise! The reason why it is so collapsed is because the lithium-ion batteries used in the car now belong to liquid batteries, and they are born with shortcomings.
Liquid lithium-ion batteries are composed of a positive electrode, a negative electrode, and a liquid electrolyte. Charging and discharging are achieved by the movement of lithium ions in the electrolyte. When charging, the battery cathode loses electrons, resulting in the formation of lithium ions, which escape from the lattice of the cathode material and then move through the electrolyte to the battery anode and embed in the anode material. The discharge process is reversed, where lithium ions are deintercalated from the anode material and returned to the positive electrode through the electrolyte.
Between the positive and negative electrodes, a separator is also added, which is an important component of liquid lithium batteries. If there is no diaphragm, the positive electrode and the negative electrode will easily contact each other, forming a short circuit, and then it will directly start a fire and play is over. Not only does the diaphragm avoid contact between the positive and negative electrodes, but it also has many tiny pores for lithium ions to pass through. In this way, a liquid lithium battery cell is made. A large number of battery cells are stacked and packaged, and a piece of automotive power battery is formed.
However, there are a number of disadvantages to doing this out of a liquid battery. For example, the electrochemical interval of the liquid electrolyte is relatively narrow, which limits the selection of cathode and anode materials, and it is impossible to use high energy density cathodes and cathodes, such as lithium-rich manganese-based, spinel lithium nickel manganese oxide, etc., and also cannot match the high energy density lithium metal anodes.
The energy density of lithium batteries is high or not, to a large extent, depends on the selection of positive and negative electrode material systems, and the use of electrolyte seriously limits the upper limit of energy density of liquid batteries, and the direct consequence is that the cruising range is not high.
In addition, liquid batteries also have a big disadvantage of thermal runaway. During the charging and discharging process of the battery, some lithium ions cannot be smoothly embedded in the anode material, and will be deposited on the surface of the anode to form lithium dendrites. If the lithium dendrites grow severely, they will puncture the fragile separator, causing a short circuit in the positive and negative electrode contact, and generating a large amount of heat in a short time. Under the action of high temperature, the SEI film, separator, electrolyte and cathode material formed on the surface of the cathode of the battery will decompose one after another, generating heat and oxygen, which further increases the temperature and causes thermal runaway.
The terrible thing is that the liquid electrolyte is generally flammable, when the temperature rises to the combustion conditions of the electrolyte, the battery will catch fire, the combustion will be very violent, produce a large amount of gas, and even explode, leaving a relatively short time for the people in the car to escape. The general fire extinguisher cannot extinguish the fire of the liquid lithium battery at all, and can only wait for the accumulated energy to be released, at which time the vehicle has basically burned out completely.
It's not just short circuits that can cause thermal runaway, when the battery is overcharged, exposed to external heat, or subjected to a mechanical crash. Thermal runaway has led to a large number of spontaneous combustion incidents of new energy vehicles, as well as deflagration in the event of a traffic accident and a violent impact, which has seriously affected the public's perception and desire to buy new energy vehicles.
In order to improve the safety of the battery, the liquid lithium battery also needs to leave enough margin in the design and take a lot of protective measures, which further reduces its low energy density. The energy density of liquid batteries is theoretically difficult to exceed 300Wh/kg, and it is not easy to achieve 200Wh/kg.
It is precisely in order to solve these problems of liquid batteries that solid-state batteries were born! Solid-state batteries, as the name suggests, use solid-state electrolytes instead of liquid electrolytes. The solid-state electrolyte can use polymers, sulfides or oxides, which can also play a role in allowing lithium ions to pass through, but the solid-state material has low chemical activity, high temperature resistance and is not easy to decompose, and it is not easy to burn, and at the same time has quite good mechanical strength, which can inhibit the formation of lithium dendrites, and it is difficult to puncture the solid material even if the dendrites are formed, avoiding the risk of short circuit, so that the requirements for the separator are greatly reduced.
In this case, the solid-state lithium battery can be assured to boldly use the high energy density of the positive and negative electrode material system, easily break through the upper limit of energy density, reaching hundreds of Wh/kg is a piece of cake, Li Bin test drive with the battery is 360Wh/kg, the future of 500Wh/kg solid-state battery will not be surprising. In addition, due to the characteristics of not easy to short circuit, high temperature resistance and non-flammability, solid-state batteries can save a lot of safety measures, further improve energy density, and greatly reduce the risk of thermal runaway, and it is not impossible to achieve zero spontaneous combustion!
Then some netizens will ask: Since the solid-state battery technology is so good, why not use it from the beginning? Why do the vast majority of electric vehicles still use liquid batteries? I have to say that the solid-state battery is not perfect, it also has shortcomings, and the biggest shortcoming is that it is too expensive! The solid-state battery uses a large number of new materials, the cost is very high, the manufacturing process is not mature, the investment in research and development and equipment and facilities is relatively large, and various factors make the price remain high, which is not at all affordable for family cars.
In addition to this, solid-state batteries have some technical drawbacks. Since the electrolyte is solid, a solid contact surface is formed between the electrode and the positive electrode, and it is difficult to achieve perfect contact without gaps, resulting in a decrease in the effective contact area and an increase in impedance. After multiple charge-discharge cycles, due to continuous expansion and contraction, the gap in the solid interface will become larger and larger, which will cause serious attenuation of power. In addition, the overall conductivity of solid electrolytes is lower than that of liquid electrolytes.
Therefore, all-solid-state batteries are not as good as many people imagine, due to the above-mentioned shortcomings, even now, all-solid-state batteries want to be popularized, it is very difficult. It is precisely in order to solve the problem of all-solid-state batteries and accelerate the speed of technology update and iteration that semi-solid-state batteries come into play.
The so-called semi-solid-state battery does not completely abandon the liquid electrolyte, but still adds a part. These liquids can fill the gap between the solid electrolyte and the positive and negative electrodes, creating good contact, eliminating solid interface problems and improving conductivity. Some semi-solid-state batteries, known as "jelly" batteries, use in-situ curing technology to form a polymer gel network in the electrolyte, which resembles jelly.
The semi-solid electrolyte also has a certain strength, which can avoid short circuits caused by lithium dendrites, and although it is not as good as the all-solid state in terms of energy density and safety, it is much better than the traditional liquid battery. In addition, the structure of semi-solid-state batteries is actually similar to that of liquid batteries, which can be compatible with existing liquid battery production lines, and the process is relatively mature, which can effectively reduce costs. In this way, it is easier for semi-solid-state batteries to be mass-produced and installed in vehicles.
Even so, the price of semi-solid-state batteries at this stage is much higher than that of liquid batteries. The 150-degree semi-solid used by Li Bin during the test drive, he himself admitted that it cost more than 300,000 yuan, which was enough to buy a luxury fuel car. However, with the continuous progress of technology and production processes, as well as the growth of production, the rapid decline in the cost of semi-solid-state batteries is predictable. At this point, semi-solid-state batteries have obvious advantages over all-solid-state batteries, and they are easier to enter the homes of ordinary people.
Whether it is semi-solid or all-solid, as long as it can be popularized, it will greatly increase the endurance and charging speed of pure electric vehicles, charging for half an hour to run 1000 kilometers will no longer be a dream, enough for the vast majority of people to run long distances, and then considering that the battery safety will also be greatly improved, car owners will no longer have worries. In the face of such a challenge, fuel vehicles will be deprived of the last advantage, which is really powerless. Now, do you believe that the end of the gasoline car is coming?