In the past few years, we have heard about new battery products, there should be a lot, right?
News about new battery products is available every year, such as solid-state batteries, semi-solid-state batteries, sodium batteries, and so on. While we are looking forward to it, there is no news of mass production of these products. Well, it doesn't hurt to add one more lithium-ion battery today.
What is an aluminum-ion battery? Can it sit on an equal footing with lithium batteries?
Aluminum-ion batteries have not risen, what are aluminum-sulfur batteries?
The first proposed aluminum-ion battery should be the aluminum-air battery mentioned by the United Kingdom and Japan, which is the early Development Plan of Japan in 2030. Aluminum air battery as the name suggests is to 99% of the aluminum as the negative electrode, oxygen as the positive electrode, the biggest advantage of the product is the high energy density, the theoretical energy density up to 8100WH / kg, compared with the current energy density of only about 400WH / kg lithium-ion batteries, aluminum air batteries have obvious advantages.
The disadvantage is that the power density is low, only 50-299W/kg, which means that the discharge speed of the aluminum-air battery will be very slow, and the conversion to the electric vehicle can only be at a low speed. In the era of new energy, such products are definitely not good on the car. Another loading scheme is to keep the lithium battery and equipped with an aluminum-air battery as an auxiliary, which will be started when the lithium battery is exhausted, which is really redundant, so there is no following.
The aluminum element is one of the rich metal elements in the earth's crust, and it is cheap and safe, so it is an ideal anode material in the preparation of batteries. The great challenge faced by the cathode material of the aluminum-ion battery is to obtain a higher working efficiency of the cathode material and realize the reversible ion embedding and shedding. AlCl3 / [EMIm] Cl is the most commonly used liquid electrolyte for aluminum-based batteries, has been applied in aluminum ion batteries, based on this electrolyte, compatible cathode materials include carbon material graphene, carbon nanotubes, expanded graphite and metal compounds of sulfides, selenides, phosphides and the like.
At present, there are already experiments on graphite materials, graphene films, and the sulfur element mentioned above is the cathode material used by Japanese companies. The composition of the aluminum-sulfur battery is roughly as follows: the use of aluminum anode, ionic liquid or deep eutectic solvent-based electrolyte and carbon-sulfur composite positive electrode.
Why use carbon-sulfur composite cathode, in fact, is a bit similar to the logic of lithium sulfur. Composites have excellent electrochemical properties and exhibit good cycling properties in a variety of organic electrolytes. The micropores of about 1 nm present in the activated carbon material can effectively fix the sulfur and the polysulfides generated during the reaction, preventing its shuttle and causing capacity attenuation.
Therefore, through the pore size structure of the sulfur-carbon composite cathode to change the problem of sulfides in the electrolyte, the next problem is how to increase the load of sulfur (it is also the current problem of lithium-sulfur batteries, which need to adjust the positive aperture and be compatible with different electrolytes/liquids).
The capacity of this soft battery starts at about 950 mAhg-1 and is reduced to 200 mAhg-1 after 100 cycles at a room temperature of 0.025 degrees Celsius. This means that the current recycling capacity of aluminum batteries is not as good as the lithium battery products on the market. In addition, the open circuit voltage of this aluminum-sulfur battery soft pack battery cell is about 0.9V; while the open circuit voltage of the lithium battery is about 4.1-4.2V after full charge, and the open circuit voltage after discharge is about 3.0V (the larger the open circuit voltage, the better).
Aluminum batteries, why can not be commercialized?
In summary, aluminum-sulfur batteries are the second new battery product based on aluminum elements after aluminum-air batteries. The current advantages of this battery are that the energy density of aluminum-sulfur batteries is large, the cell capacity is larger, because aluminum batteries do not use nickel and cobalt, so it is not easy to explode, more secure, and the reserves of aluminum are very rich and the cost is lower.
Similarly, the disadvantages of aluminum-sulfur (aluminum-ion) batteries are also obvious, including:
1. Can not accept high-current charging at one time, resulting in reduced charging efficiency;
2. Poor cycle capacity, can not be comparable to the current stage of lithium batteries;
3. Sulfur, as a non-conductive substance, has very poor conductivity, which is not conducive to the high magnification performance of the battery;
4. Sulfur in the process of charging and discharging, the expansion and reduction of the volume is very large, which may lead to battery damage.
Therefore, whether it is aluminum-sulfur or aluminum-ion batteries, the commercial landing may be for a long time, but in theory, the characteristics of lithium batteries with large energy density may give priority to commercial landing in the field of energy storage. But we have already realized last year that sodium batteries may be the next outlet for the energy storage industry? Sodium battery products represented by the Ningde era will achieve the basic industrial chain as soon as 2023.
We may wish to look forward to the possibility of aluminum batteries landing in the passenger car market, is still an aluminum air (aluminum ion) battery, by changing the aluminum battery formula, the structure to increase the maximum allowable discharge power, relatively complex, and the previous 99% aluminum + oxygen structure may be difficult to make progress, can only pursue other efficient cathode materials, but the proportion of aluminum should be as large as possible (to maintain a low-cost advantage).
In this way, we may usher in aluminum battery products with a battery life of easily breaking through 1000km. But then again, how long has lithium battery developed today, aluminum batteries may take the corresponding time to complete the final landing; take sodium batteries as an example, the basic industrial chain is expected to take 2 years to improve, and then product iteration, performance upgrades to get better products.
summary
The technological innovation of battery products is relatively slow, and in recent years, new battery products and higher mileage have emerged in recent years, but they still have not alleviated the fundamental anxiety of 21 electric vehicles.
In theory, aluminum batteries have higher energy density and lower prices than batteries, and if they can achieve commercialization, they will bring qualitative improvement to the electric vehicle industry. At the end of last year, there was an aluminum-ion solid-state battery product that can solve all the pain points of lithium batteries, which is expected to land this year as planned, but this product cannot withstand scrutiny, but it provides a good development idea.
As for aluminum batteries, sodium batteries or solid-state (semi-solid-state) batteries, who can land on the ground first? No conclusive conclusions can be made at this time.