Text/Peach Lee
The development of the new energy vehicle field has made great achievements so far, and its penetration rate in the automobile market is also constantly improving, especially pure electric vehicles, which has become a mainstream trend in the current automobile market, but the battery as a power source for electric vehicles has encountered obstacles on the way to development, first of all, the rise of raw materials, followed by the difficulty of battery technology to have a breakthrough. As one of the cores of electric vehicles, the progress of battery technology is related to the future development of electric vehicles, so major car manufacturers have to start looking for a new way out of battery development, and solid-state batteries have become a new hope for electric vehicles.
First of all, let's talk about the current situation of lithium-ion batteries, the current new energy electric vehicles generally use lithium-ion batteries as power batteries, after a long period of research and testing, lithium-ion batteries are considered to be the most outstanding comprehensive performance, the most mature technology of a choice, but even so, he also has a lot of deficiencies.
The energy density of the battery is related to the endurance performance of the electric vehicle, and improving the endurance of the electric vehicle is the best way to make it compete with the fuel vehicle. Although the energy density of lithium-ion batteries is basically a ceiling-level existence in all current battery types, the current energy density of lithium-ion batteries has reached more than 250Wh/kg, but it is still difficult to surpass fuel vehicles.
The energy density of lithium-ion batteries can theoretically reach up to 350Wh/kg, but the pursuit of higher energy density will lead to the safety of the battery being affected. Lithium-ion batteries use liquid electrolyte, once the battery has an internal short circuit, thermal runaway, or electrolyte leakage, etc., may cause the combustion of the electrolyte, and then cause the battery fire and other safety accidents, which is also the reason why some people talk about electrochromic change. In addition, because the liquid electrolyte is easy to form and grow a solid interfacial membrane during charging and discharging, the life of the battery also has greater limitations.
So what is a solid-state battery? Traditional lithium battery by the positive electrode, negative electrode, diaphragm, electrolyte, structural parts and other parts, with the help of lithium ions in the positive and negative poles between the shuttle back and forth to complete the battery charge and discharge, solid state battery structure and principle does not change much, mainly all the materials inside it use solid materials, only contains very little or no liquid, and according to whether there is a small amount of liquid electrolyte inside the battery can be divided into solid state batteries and all solid state batteries.
Don't underestimate the change in this step, it can bring about a leap in performance. You know, the speed of lithium ion movement means that the charge and discharge electric speed is fast, and now the fast charge lithium battery is known as 20-30 minutes fast charge 30% of the power to 80% of the charge, and the solid-state battery can basically be fully charged within ten minutes, after all, one is swimming in the water, one is running on the road, and the solid-state battery is naturally more efficient than the lithium-ion battery.
In addition, the use of solid medium avoids the leakage and combustion risk of the electrolyte (the solid electrolyte will decompose under certain conditions, but it is relatively more difficult to decompose), and even after the physical impact and destruction test, the battery still does not smoke, does not fire, does not explode, and the safety performance is greatly improved.
Although it has great advantages, but the solid-state battery is not perfect, not to mention its expensive cost, solid-state batteries still have many technical problems, such as solid-state electrolyte kinetic ion conductivity is much lower than the liquid electrolyte, resulting in lithium ions between the positive and negative electrodes between the patency of the reduced.
In addition, the contact area between the solid electrolyte and the positive and negative electrodes is small and the compactness is worse, so the interfacial impedance is higher, which will affect the transmission of lithium ions between the interfaces. The volume change of the electrode material during charging and discharging will further aggravate the separation of the interface and the deterioration of the cycle performance.
Write at the end:
All-solid-state batteries are indeed a very good direction in principle, but combined with the current stage of industry research results, combined with comprehensive considerations such as cost, output, and reliability, there is still a long way to go to be widely used in the existing business environment, but as more and more car companies invest in it, I believe that the distance of this section of the road will gradually shorten.