1. Sodium ions perform better at low temperatures. Can it really reach 160wh/kg now?
It can be achieved in theory. But no parameters are given for cycle life. The current cycle stability is not good. Electric vehicles on the market require 2,000 times, but current research can only allow 1,000 times. 160wh/kg. It can quickly charge 80% of the battery in 15 minutes, which is theoretically no problem. The low temperature situation is better because there is no composition and parameters of the material, so be suspicious. Sodium batteries are larger than lithium batteries, their dynamic performance is relatively poor, and the movement of sodium ions will be slower. Sodium ions are also affected by low temperatures. Generally speaking, the low-temperature performance of sodium ions is worse than that of lithium, but I don’t know if CATL has adopted new technologies.
2. What are the main factors affecting cycle life? How much room for improvement is there in the cycle life indicator, and when can it be estimated that it will be able to meet the cycle life of an energy storage battery?
Structural stability of positive and negative electrode materials. The reversible drag-intercalation of sodium ions makes the cathode material an economical material that can change. Some materials are relatively stable, so they can maintain cycle life. The circulation of sodium ions is not as good as others, mainly because the volume is too large, which causes greater damage to the material structure. In terms of long life, it can reach 1,000 times. But this problem can be solved through technology in the future. Can make the material more stable. In the next 3-5 years, the total number of cycles can be 3,000-4,000 times without any problem.
3. If both the positive and negative electrode materials are replaced, and sodium ions replace lithium, how much will the cost drop compared to now?
At present, sodium ions have not yet been mass-produced. They are mainly still in laboratories, and the material cost is higher than the current industrial lithium.
However, after mass production, the entire production process is equal to that of lithium batteries, and the entire cost can be reduced by about 50%. However, the positive and negative electrode materials have not yet been determined, so it is impossible to estimate. The negative electrode has a slight advantage over lithium. The biggest advantage is still in the positive electrode, because the relative performance of manganese is more stable in terms of metal ions in the positive electrode. A system based on sodium manganese oxide and adding some elements such as nickel or cobalt iron is not too expensive. However, lithium batteries are all made of high nickel, which requires no less cobalt and nickel, and the cost is much higher than manganese. However, if lithium manganese oxide is used, the performance will be poor if there is too much manganese. But manganese can be used as a large amount of stabilizing element in sodium, without using nickel and cobalt. Using manganese as the main metal element combined with sodium carbonate, after mass production, the production cost will be significantly reduced compared to current lithium batteries.
4. Comparing the current domestic lithium-ion battery companies, from a technical perspective, are there any companies that are leading?
Among mainstream companies, CATL’s company has a team to make sodium-ion batteries. Their R&D team is relatively large, and their layout is more long-term. They have existing sodium-ion batteries and have released news. Therefore, their technology is relatively advanced, and many universities are now doing research and development. For example, the Chinese Academy of Sciences has incubated Zhongke Haina, which specializes in sodium-ion batteries. Shanghai Jiao Tong University incubated Sodium Innovative Energy in Shaoxing, which mainly produces energy storage batteries and is also a start-up sodium-ion battery company. These two are specialized in the research and development and industry of sodium-ion batteries, not lithium batteries. The main business of CATL is other things, except for some research and development on sodium.
However, current sodium-ion batteries are not yet mature. Although CATL stated that they will be mass-produced in the next year, their products should only be in the laboratory stage.
5. Zhongke Haina has developed a sodium battery with an energy density of about 145wh/kg and a cycle life of more than 4,500 times. What do you think?
The cycle life depends on the conditions. Generally speaking, 2,000 cycles is very good, but if the charge and discharge are within the range of 80%, it can reach 3,000-4,000 times. The cycle life depends on the charging cut-off voltage. Because the cut-off voltage increases by 0.1 volt, its cycle life will decrease a lot. The positive electrode material of Zhongkehaina is also based on layered materials, based on the sodium manganese oxygen system, which is doped with elements such as copper, iron, and cobalt. The negative electrode is also made of hard carbon. The electrolyte should also be sodium hexafluorophosphate.
6. What specific measures does the country have in industrial policy?
The national level is very supportive, but there are no concrete measures yet. The State Grid and the Ministry of Science and Technology have laid out many sodium battery projects and invested funds to encourage scientific research institutions and enterprises to apply. The State Grid has invested in research and development for applications where energy storage is difficult, including wind power and solar energy storage stations, and the demand for sodium ions. There are currently no others, but policies will be rolled out gradually.
7. What is the difference between sodium battery manufacturing equipment and lithium battery?
The material manufacturing equipment is almost the same. Just change the raw materials. The ternary materials of lithium batteries or lithium cobalt oxide are controlled by engineering electricity and solid-phase methods. The raw materials input into the cathode material production line are mainly lithium carbonate, nickel oxide, acid benzene or metal salts plus lithium carbonate or lithium hydroxide. The metal salts in sodium batteries remain unchanged, that is, lithium carbonate or lithium hydroxide is replaced by sodium carbonate and sodium hydroxide, but the entire synthesis process is the same. For cathode manufacturers, they can basically use the current lithium battery cathode production equipment, but some adjustments must be made to the specific production parameters and conditions. But the equipment is basically the same. The difference in graphite won’t be too big either. The electrolyte is basically similar, that is, the dissolved lithium hexafluorophosphate is replaced by sodium hexafluorophosphate, but it is not much different from the entire lithium battery production line.
8. If sodium ions can be used as solid-state batteries, how much can the energy density be increased? Will the price/performance ratio be higher?
Sodium-ion solid-state batteries have little advantage. On the one hand, its technological maturity is currently relatively low. The main problem is that the solid electrolyte of sodium batteries does not have a particularly good solid state. Moreover, solid-state batteries are not very mature now, which is also a barrier that solid-state batteries need to break through. Or replace the electrolyte with a solid electrolyte. But solid electrolytes have not been particularly good so far. Currently, the most commonly used positive and negative electrode materials are layered materials or hard disk materials. However, the volume ratio of sodium ions is large and it is not easy to migrate in solids. Its ionic conductivity is relatively poor in electrolytes. Therefore, if you want to make a solid-state sodium battery, you must first find one with a relatively high ion mobility. It will take 5-10 years to develop a product with better performance.
9. If a good electrolyte is found for sodium batteries, how much can the energy density be increased?
If it cannot reach 200wh/kg, its improvement in liquid sodium-ion batteries will be very limited. If done well, it may reach 150-180wh/kg.
The electrolyte accounts for more than 20% of the weight of the battery. If it is all made into a solid state and done well, it can be made very thin and the entire energy density can be optimized. However, the solid electrolyte cannot be made very thin because there is a risk of short circuit. If it is made thick, the energy density will be reduced. Today’s sodium batteries are not very mature, so the performance of solid-state batteries is still far lower than that of liquid sodium-ion batteries. The capacity of the positive and negative electrodes can produce 90%-100% of the energy in the liquid state, but only 60%-70% may be used in the solid state. Because it involves the migration of ions in the solid, the electrolyte can penetrate into the positive and negative electrodes, and all particles of the positive and negative electrode materials can come into contact with the electrolyte. But in a solid, there must be an ion transmission channel. However, in the positive and negative electrodes, the particles may not be able to touch the positive and negative electrodes of the electrolyte. The utilization rate of the positive and negative electrodes will be compromised, and the increase in energy density will also be reduced. Will be limited.
10. Are there any plans to develop sodium-ion batteries abroad? What is their progress?
The United States and Europe now have some research projects, including the United States, which has also set up some research and development projects for sodium-ion batteries. However, the research and development progress of sodium-ion batteries in the United States is still lagging behind that of my country and South Korea. China and South Korea are now ahead of the United States and South Korea. European.
There are several start-up companies in the United States that also want to industrialize sodium-ion batteries, but their scale and technology are not as good as those of related domestic companies. South Korea’s LG, Samsung and SKI are also making plans, and their progress is similar to China’s.
11. When sodium ion technology matures, what proportion will it account for in the total installed battery capacity?
The technical advantages of sodium ions are reflected in mass manufacturers, but the disadvantage is that the energy density is weaker than that of lithium-ion batteries. Its applications are mainly focused on energy storage and electric tools that do not require high energy density, such as low-speed electric vehicles and electric buses. Therefore, if the technology matures in sodium, its market share in the energy storage field can exceed 50%. However, in terms of power batteries, it is difficult for sodium-ion batteries to occupy a relatively high market share, up to 20%.
12. Which one can develop faster and more maturely, sodium-ion batteries or fuel cells?
From the perspective of technological maturity, I am more optimistic about sodium-ion batteries, because the process is very similar to lithium-ion batteries, and lithium-ion batteries are already very mature, so the process of promoting mass production of sodium-ion batteries will be very fast, in 2-3 years. Related industrial chains can be established.
However, it is still relatively long-term for fuel cells to be mass-produced and applied. Fuel cells are the ultimate goal to solve energy problems. The last thing is the reaction of hydrogen and oxygen, which is very clean and has high energy density. But the current bottleneck is the storage and release of hydrogen, as well as the problem of precious metals in the catalysts in fuel cells. It is difficult to reduce the cost of precious metals, and it is difficult to find alternative thin catalyst technologies. Therefore, these two technical bottlenecks are difficult to overcome in the short term. It may take 3/50 years for fuel cells to really mature and the cost of hydrogen production to come down.
13. If China can provide sodium ion raw materials completely independently, does it not need to import large-scale materials like lithium materials?
As raw materials for sodium ions, China has sufficient mineral resources.
14. Will sodium-ion and lithium-ion fuel cells coexist?
The odds are high. Because each technology has its characteristics and application scenarios. Lithium batteries, fuel cells, and sodium batteries have different technologies and targeted scenarios, so the possibility of coexistence is very high. Including lead-acid batteries will not withdraw from the market. The current mass production and application of lead-acid batteries are growing every year, but the growth is not as fast as that of lithium batteries.
15. Where is lead-acid used on a large scale now?
Energy storage power stations and start-stop batteries for fuel vehicles, these two aspects. Because its technology is mature, it also does a good job in industrial recycling, such as battery recycling. Although lead is toxic and polluting, if recycling is done well, pollution can be avoided. This recycling technology is an advantage that current lithium batteries do not yet have. However, after a large number of power lithium batteries are retired, battery recycling is also a big problem.