The energy density requirement promotes the upgrading of batteries, and puts higher requirements on materials such as positive and negative electrodes. However, when the materials are gradually maturing, the application has been delayed, mainly because various materials are combined into batteries, and the system Problems such as compatibility and safety have not been well resolved. The current level of technology is gradually maturing and the equipment is modernized. The focus of these issues is on how to use the appropriate electrolyte.
In the high nickel system, there are two main requirements for the electrolyte. One is the use of new additives, and the other is the formulation of the electrolyte.
New additives: For high nickel systems, it is necessary to solve the problems of gas production on the surface of the positive electrode, film formation stability and safety of the negative electrode. New additives can solve the problems encountered in high nickel. We believe that the ability to develop new additives is The electrolyte company will benefit significantly.
Electrolyte formula: The electrolyte formulation has a long development cycle and high cost. It is currently one of the highest barriers for battery companies. As the industry division of labor expands, the focus of development will be tilted toward electrolyte manufacturers, electrolyte manufacturers in formulation development and additives. The research and development advantages are even greater.
Power battery is about to enter the high nickel era as a whole
1. Policy orientation - increased battery energy density requirements
With the subsidy policy for new energy vehicles entering 2018, the country began to shift the subsidy focus to improving the performance of new energy vehicles. From the cruising range, the subsidy threshold has increased from 100KM in 2017 to 150KM now, the maximum subsidy mileage. It has also risen from the original 250KM to the current 400KM; from the energy density point of view, the threshold has also increased from the previous 90Wh/kg to the current 105Wh/kg, and the highest subsidy factor has also increased from 1.1 times to 1.2 times now. At the same time, the corresponding highest-grade energy density increased from 120Wh/kg to 160Wh/kg.
For the gradual improvement of the corresponding policy requirements, various products related to new energy vehicles are also facing an upgrade problem. As the country's energy density requirements for power batteries are getting higher and higher, the high-nickel-based cathode materials are coming. The more popular the market.
2. Market orientation - more in line with the future market demand for passenger cars
The market for power lithium batteries is mainly based on ternary and lithium iron phosphate. Compared with lithium iron phosphate batteries, ternary lithium batteries have unique advantages in terms of energy density, and the market share has increased from 23% in 2015 to 48 in 2017. %, the proportion of ternary in passenger cars in January-April 2018 is as high as 89%. Compared with low-nickel ternary materials, the use of high-nickel ternary materials can significantly increase battery energy density. At the same time, due to the continuous price of cobalt Going higher, the price of cobalt sulphate has risen from 1300,500 yuan/ton at the end of 16 to the current 465,000 yuan/ton, an increase of 256.32%, which has accelerated the development and use of high-nickel ternary materials to some extent.
The development of high-nickel ternary is not only a policy requirement, but also a demand for battery upgrades. High-nickel ternary batteries have a very large advantage in energy density, and are currently the most mature application materials for high-energy density industrialization. The low content can alleviate the dependence of the power battery on cobalt to a certain extent, so the development of high nickel power battery is the trend of the whole industry.
Why is the power battery high nickel? Why should we pay attention to the electrolyte?
The increasing proportion of nickel in the cathode material and the use of silicon-carbon anodes have brought new problems to the development and production of electrolytes. If the electrolyte cannot be upgraded with the battery materials, the high-nickel ternary system is difficult to achieve. Original design.
The four major problems encountered in the current high nickel system:
1) Gas production: The nickel content in the positive electrode material increases. Since the tetravalent nickel ion in the high nickel has high catalytic activity, it catalyzes the oxidative decomposition of the electrolyte and affects the battery performance. 1) Therefore, an additive is required to inhibit nickel to electrolysis. Catalytic decomposition of liquid;
2) Destroy the negative SEI film: During the cycle of the high nickel system, there will be manganese, cobalt and other transition metals dissolved, which will destroy the negative SEI film, which needs to improve the dissolution of the excessive metal and enhance the stability of the SEI film through additives;
3) Silicon-based anode additive: Due to the high expansion characteristics of the silicon-based anode, the SEI membrane is destroyed, and the particles themselves are also pulverized. For recycling and safety performance, additives and special treatment are required;
4) Safety: For the high-nickel system, there is a more important point in the safety of the battery. It is necessary to add additives such as overcharge and flame retardant to improve the safety of the battery.
The technical requirements and complexity of electrolytes in high-nickel systems are significantly improved compared to conventional electrolytes. Solving these problems requires various additives to be realized, and the role of additives in high-nickel systems is becoming more and more prominent. In addition, compatibility between various additives, solvents and additives, positive and negative systems and additives must be considered, which also makes the development of high nickel electrolytes difficult.
What should we focus on for high nickel electrolytes?
Electrolyte is one of the most important raw materials affecting battery performance, and it is highly valued in battery companies. Positive and negative electrodes and separators are more like a standardized material for battery companies, and electrolytes are used in battery companies. The use is more diversified and complicated. The main reason is that the electrolyte has a great relationship with the design of the battery, the production process, and the production environment. Any change may cause changes in the use of the electrolyte.
Battery upgrades, higher requirements for materials such as positive and negative electrodes, but when the materials are gradually maturing, the application has been delayed, mainly due to the compatibility and safety of various materials when assembled into batteries. The problems have not been solved very well. Now that the process level is gradually maturing and the equipment is modernized, the focus of these issues is on how to use the appropriate electrolyte. Take the current consumption of lithium cobalt oxide battery materials as an example. The voltage rises by 0.5V, and the requirements for material changes such as the negative electrode and the diaphragm are not improved, and accompanied by the improvement and improvement of the electrolyte. Therefore, the battery upgrade is the most important for the battery company to upgrade the electrolyte.
In the high nickel system, there are two main requirements for the electrolyte. One is the use of new additives, and the other is the formulation of the electrolyte.
1, new additives
Additive characteristics: Additives can be directly added to the base electrolyte, the amount is very small, the addition amount generally does not exceed 5% of the electrolyte mass or volume fraction, and the operation process is simple, does not change the battery production process, and compensates for some of the electrolyte itself. Insufficient, it can significantly improve the conductivity of the electrolyte and its compatibility with the positive and negative electrodes, thereby further improving the battery's discharge capacity, service life and other electrochemical properties.
New additives are one of the most active research topics in today's electrochemical and battery academia and industry, as all battery upgrades, including high energy density (high nickel) or high voltage direction, require the support of new additives.
Taking the current mature high-voltage additives as an example, increasing the voltage can increase the energy density of the battery, but it also brings many problems. The solution to these problems is to find a more stable (non-oxidizing) electrolyte or to seek a positive electrode/ Methods such as stabilization of the electrolyte interface, without exception, are achieved by selecting additives.
The same is true for high-nickel systems. We need to solve the problems of gas production on the surface of the positive electrode, film formation stability and safety of the negative electrode. The final solution is similar to high voltage, which is targeted by additives. Problems encountered with nickel. Companies with the ability to develop new additives will benefit significantly.
Taking LDY269 developed by Xinzhoubang as an example, the high and low temperature performance and impedance are better than VC. The traditional positive electrode protection additive is PS, and RPS also has some applications. Compared with traditional PS, RPS and other positive electrode protection additives, The LDY196 developed by Xinzhoubang is better on high voltage and high nickel anodes.
2, electrolyte formula
The electrolyte formulation has a long development cycle and high cost. The electrolyte formulation is currently one of the highest barriers for battery companies. Therefore, the electrolyte formulation has become the core competitiveness of battery companies. There are three main paths for electrolyte formulation development. Provided for electrolyte manufacturers, independent development and joint development of battery companies.
Insufficient formula of electrolyte manufacturer: Focus on electrolyte production and R&D, cooperate with battery companies in the industry, familiar with various system formulas, and independently develop new additives, with obvious comprehensive advantages. The shortcoming is the actual production and application of batteries. Lack of.
Battery manufacturers' advantages and disadvantages: Battery companies are familiar with their own production processes and electrolytes, but the scope is relatively narrow, which is not conducive to the development of new systems.
Cooperative development: The cooperation between battery manufacturers and electrolyte companies can play a complementary role, with low development cost and high efficiency.
Future cooperation and development will be the main direction. As the industry division of labor expands, the focus of development will be tilted toward electrolyte manufacturers. Electrolyte manufacturers have greater advantages in formulation development and additive research and development, and professional electrolytes have more and more discourse rights. Strong. Under the trend of battery upgrade, the electrolyte formulation of high-nickel system will be more complicated. After the high-nickelization of the battery, the value and added value of the electrolyte will be greatly improved, no less than the positive electrode from 523 to 811. The span of high nickel electrolyte is significantly higher than that of ordinary electrolyte, and it also brings higher profit elasticity. Taking the electrolyte price as an example, the price of ternary 532 electrolyte is about 50,000/ton, and ternary 622 is 60,000 / ton, and the price advantage of the complex 811 high nickel system will be more obvious.
In the development of new system electrolytes such as high nickel, it is impossible to accomplish it overnight. It requires years of technical accumulation and cooperation between upstream and downstream. The additives and formulas will also become the source of the electrolyte company's continued advantage.
