On March 4, 2020, GM's "EV? At the "Week" event, GM and its partner LG Chem launched a new battery product Ultium.
▲ General new battery pack
The core of this product is not the battery pack technology blown by the outside world. The key point is that the battery core of Ultium battery will adopt NCMA quaternary lithium battery newly developed by LG Chemical.
The technical principle of this battery is that a small amount of aluminum is doped into NCM ternary lithium cathode material, so that the nickel ternary cathode material with high activity can maintain a relatively stable state while maintaining a high energy density.
It can be considered that NCMA quaternary lithium battery has solved many intractable diseases faced by ternary lithium battery.
Compared with NCM/NCA ternary cathode material, NCMA quaternary cathode material has a stable H2-H3 irreversible phase transition voltage (indicating that the microcracks of cathode material increase to an unrecoverable state, which causes the change of internal parameters of the battery), and there are fewer microcracks in the material, and the dissolution of transition metals in the cathode material is not obvious. At the same time, the exothermic peak temperature of NCMA cathode material is also high and its thermal stability is strong.
It is worth noting that cobalt, the most expensive element in NCMA quaternary cathode materials, ranges from NCA/NCM? 20% of 622 is reduced to 5%, and the cost is further reduced. According to figures released by LG and GM, the mass production cost of NCMA quaternary battery is 100 USD (about RMB 694). Previously, LG Chemical NCM? The mass production cost of 622 is about 148 USD (about 1027 RMB).
NCMA quaternary lithium battery has realized the characteristics of high energy density, high stability and low cost that NCA/NCM ternary lithium battery can not achieve at the same time. For power battery products, mass production of NCMA will set off a wave of technical route upgrading.
In this wave, the products provided by upstream miners and midstream material suppliers to the downstream must be rapidly iterated, and the technical route of power battery enterprises must also make new choices, while new energy automobile factories need to adapt models for new battery technologies, and the whole new energy industry chain will be greatly affected.
1. What is the technical principle of decrypting NCMA batteries? Has become an effective solution for high energy density battery.
NCMA quaternary lithium battery is not a brand-new power battery technology.
From the perspective of material composition, this technology is based on the mixture of two mainstream ternary lithium battery systems NCM and NCA.
From the point of view of battery structure, it does not change the main structure of the battery like solid state battery, lithium sulfur battery and lithium air battery.
However, this technology has the potential to lead ternary lithium batteries to the next stage.
▲ What is the cooperation between GM and LG?
Essentially, the so-called NCMA quaternary lithium battery is a battery system using NCMA quaternary cathode material.
The principle is that a small amount of transition metal aluminum is doped into the original NCM ternary cathode material to form a quaternary cathode, so as to ensure that the cathode is enriched with nickel without affecting the stability and cycle life of the battery.
In this transformation process, Li[Ni-Co-Mn]O2 cathode material system of NCM ternary system is transformed into Li[Ni-Co-Mn-Al]O2 (the chemical composition of cathode material has changed).
The strength of Al-O chemical bond formed by the addition of transition metal Al is much stronger than that of Ni(Co, Mn)-O chemical bond, which chemically enhances the stability of the positive electrode, and further makes the irreversible phase change voltage of NCMA quaternary battery remain stable after many cycles, while Li element is not easy to release oxygen in the process of positive electrode deintercalation, which reduces the dissolution of transition metal and improves the stability of crystal structure.
However, the stable crystal structure reduces the formation of microcracks in the cathode material during the charge-discharge cycle and inhibits the rising speed of cathode impedance.
At the same time, some studies show that the peak temperature of exothermic reaction of NCMA cathode material is 205 degrees Celsius, which is higher than 202 degrees Celsius of NCA cathode material and 200 degrees Celsius of NCM cathode material, which means that the thermal stability of NCMA cathode material is more excellent.
This characteristic is very important for the current positive high nickel route of power batteries.
With the market demand for the cruising range of electric vehicles from less than 300 kilometers in the early days to 600+ kilometers today, the energy density of ternary lithium batteries is constantly pushing up, and the high nickel route is constantly clear.
▲ What is the model of the new battery? 3 The battery life will be close to 600 kilometers.
NCM/NCA at this stage? In 8 1 1 ternary lithium battery, the molar ratio of nickel as the positive active material has exceeded 80%, which is called 8-series ternary lithium battery.
After the 8-series ternary lithium battery, the 9-series ternary lithium battery with more than 90% nickel content is ready to go. According to the report of Hi-Tech Lithium Battery, Meg, a well-known lithium battery material supplier, has completed the research and development and mass production of ternary precursor materials such as Ni90, Ni92 and Ni95 with nickel molar ratios of 90%, 92% and 95% respectively.
However, behind the seemingly bright technical prospects, hidden worries are constantly emerging.
The results show that with the enrichment of nickel as the cathode material of ternary lithium battery, the capacity retention and thermal stability of the battery decrease.
When the nickel content in the cathode of NCM ternary lithium battery exceeds 60% and that of NCA ternary lithium battery exceeds 80%, after a certain number of cycles, the microcracks in the cathode material of the battery increase obviously, the electrode impedance increases, and the cathode begins to precipitate a large amount of oxygen into the battery cell.
This phenomenon directly leads to the rapid decline of the capacity of high-nickel ternary lithium battery and the increase of potential safety hazards. In recent years, the spontaneous combustion accidents of electric vehicles are mostly related to the safety hazards of power batteries.
Whether improving the shape of the battery pack or adjusting the battery management system is only a drop in the bucket to alleviate this situation. At such a node, the power battery industry began to explore more promising power battery solutions from materials.
NCMA quaternary lithium battery is a technical scheme born in this process, and its stable physical and chemical structure can support the high nickel route of future power batteries.
At the same time, the mixing of relatively cheap aluminum greatly reduces the content of expensive cobalt in the positive electrode of power battery, which is also very effective for reducing the cost of power battery.
No matter the technical route or the market level, the future prospect of NCMA quaternary lithium battery is very broad. It can be considered that the quaternary lithium battery is the most revolutionary battery technology before the birth of all-solid-state batteries, which will open a new wave of technology for power batteries. In this wave, GM and LG, which took the lead in taking out the finished products of quaternary lithium batteries, are undoubtedly one step ahead.
Secondly, Korean battery experts proved three advantages of NCMA battery.
At present, Un-Hyuck, a lithium battery expert at Hanyang University in Korea? Gold has proved the excellent performance of NCMA quaternary lithium battery in high nickel technical route through experiments.
201April 2, 9 Un-Hyuck? Kim's team published a paper in the journal of American Chemical Society (ACS) entitled "Quaternary layered nickel-rich NCMA anode for lithium ion batteries".
In this paper, the properties of NCM, NCA and NCMA cathode materials with nickel content of about 90% were compared from five aspects: capacity attenuation, H2-H3 irreversible phase transition voltage change, microcrack of cathode particles, oxygen evolution during lithium ion deintercalation and thermal stability.
The capacity of 1 and NCMA quaternary lithium batteries did not decrease obviously.
To prevent mistakes in the experiment, Un-Hyuck? Team Jin conducted a control test on the 2032 battery.
▲ Comparative experimental data of battery capacity attenuation
Under the experimental conditions of 30℃ and 0. 1C, these batteries were placed between 2.7V and 4.3V for initial charge-discharge test.
The first discharge capacity of NCM90 battery with 90% nickel content is 229mAh/g, and the first discharge capacities of NCA89 and NCMA89 batteries with 89% nickel content are 225mAh/g and 228mAh/g respectively.
It can be found that the initial discharge capacities of the three kinds of high-nickel batteries are very close, but after 100 cycles, the discharge capacity of NCMA89 battery drops to 90.6%, while that of NCM90 and NCA89 battery drops to 87.7% and 83.7% respectively.
At the same temperature and voltage, increase the discharge rate to 0.5C, and then test the same (brand-new) battery.
After 100 cycles, the discharge capacities of NCMA89, NCM90 and NCA89 decreased to 87. 1%, 82.3% and 73.3% respectively.
In order to be closer to the actual situation, Un-Hyuck? Team Jin put the battery at 25℃, 1C and 3.0V-4.2V, and conducted 1000 charge and discharge experiments.
Results The initial capacity of NCMA89 battery was maintained at 84.5%, while the capacity of NCM90 battery and NCA89 battery decreased to 68.0% and 60.2% respectively.
It can be seen that the stability of NCMA quaternary lithium battery in high nickel route is far better than that of NCM and NCA ternary lithium battery, and the closer it is to practical use, the more obvious this advantage is.
2. The structure of 2.NCMA quaternary lithium battery is more stable.
The decrease of battery capacity is mainly reflected in the irreversible phase transition of H2-H3 and microcracks in cathode materials.
▲ The H2-H3 irreversible phase transition of three batteries.
The so-called H2-H3 irreversible phase transition is mainly used to reflect the change of positive electrode lattice and the reversibility (redox peak) of lithium ion intercalation and deintercalation process.
The process of H 1-H2 is usually reversible, but once H3 phase appears on the electrode, it is irreversible, and the ability of lithium ion intercalation and deintercalation will be lost. When the voltage exceeds a certain value or the discharge rate reaches a certain rate, H3 phase will appear.
Therefore, the consideration of battery performance will be reflected in the changes of voltage value and redox peak when H3 irreversible phase transition occurs.
After 100 charge and discharge cycles, the batteries of NCMA89, NCA89 and NCM90 are Un-Hyuck? Kim's team found that only the voltage of the H2-H3 irreversible phase transition of NCMA89 was almost maintained in the initial state, while the voltage of the H2-H3 irreversible phase transition of NCM90 and NCA89 batteries decreased in different degrees, and the redox peak decreased.
That is to say, in many cycles, batteries made of NCA and NCM cathode materials are more prone to H3 phase, and the reversibility decreases.
As far as microcracks of cathode materials are concerned, different materials have different properties, but the appearance of microcracks will affect the impedance of the electrode. Once the impedance increases, it will affect the current charging and discharging of the battery.
▲ Micro-cracks of three kinds of battery cathode materials, the upper and lower rows of pictures from left to right are NCA89 battery, NCM90 battery and NCMA89 battery respectively.
As mentioned above, it is difficult for NCMA89 electrode to undergo irreversible phase transition from H2 to H3, and it has strong mechanical stability. An he? The experiment of Kim's team also proves this point. After many cycles of charge and discharge, the microcracks of the cathode material of NCMA89 battery are obviously less than those of NCM90 and NCA89 batteries.
In addition, the oxygen released in the process of lithium ion deintercalation will also dissolve the transition metal, which will lead to the structural instability of the cathode material.
An he? Kim's team calculated the oxygen vacancy energies of NCMA89, NCM90 and NCA89 batteries by density functional theory (DFT), and found that the oxygen vacancy energies of the three batteries were 0.80eV, 0.72eV and 0.87eV, respectively.
From this value, it can be seen that NCA89 battery with stable Al-O chemical bond is the most difficult to release oxygen, and NCMA89 battery is relatively stable, and NCM90 battery needs the least energy to release oxygen, which is the most likely to lead to the change of cathode material structure.
3. The thermal stability of 3.NCMA cathode material is stronger.
Considering that the thermal stability of electrode materials is also very important for the safety of batteries, Un-Hyuck? Kim's team also used differential scanning calorimetry (DSC) to measure the peak temperature of exothermic reaction of cathode materials.
The measurement results show that the peak temperature of the exothermic reaction of NCA89 battery anode is 202°C, and the calorific value is 1753J/g, while the peak temperature displayed by the cathode of NCM90 battery is 200°C? The calorific value is1561j/g. In contrast, the peak temperature of cathode exothermic reaction of NCMA89 battery is 205°C, and the calorific value is only1384 j/g. The thermal stability of NCMA quaternary lithium battery is obviously better than the other two types of batteries.
The capacity decrease, H2-H3 irreversible phase transition, microcrack of cathode material, oxygen release during lithium ion deintercalation and thermal stability after multiple charge and discharge cycles were comprehensively tested. Jin's team finally proved the excellent performance of NCMA cathode material in high nickel route.
Third, the short-term mass production cost of NCMA cathode materials is higher? But the long-term cost is better.
However, the current NCMA quaternary lithium battery is not completely without shortcomings. First of all, the preparation process of cathode material, the core of NCMA quaternary lithium battery, is more complicated than that of NCM and NCA batteries.
An he? Kim's team published a paper in Materialstoday on March 20 19, entitled "Redesigning the composition and structure of high-energy nickel-rich cathode for the next generation lithium battery".
▲Un-Hyuck？ Papers published by Kim's team
The preparation steps of NCMA cathode materials mentioned in this paper can be roughly divided into six stages:
1. Spherical NC NCM[Ni? 0.893? Co？ 0.054? Mn？ 0.053? ](OH)2 precursor is used to prepare [Ni? 0.98? Co？ 0.02? ](OH)2 was added to the batch reactor.
2. In the inert gas (nitrogen) environment, a certain amount of deionized water, sodium hydroxide solution and ammonia hydroxide solution are continuously added into the batch reactor, and at the same time, a certain amount of sodium hydroxide solution and a sufficient amount of ammonia hydroxide solution (chelating agent) are introduced into the reactor.
3. During the synthesis process, the initially formed [Ni0.98Co0.02](OH)2 particles gradually became spherical.
4. In order to construct NC-NCM structure, quantitative nickel sulfate solution, cobalt sulfate solution and manganese sulfate solution (Ni: Co: Mn = 80: 9: 1 1, molar ratio) were introduced into the reactor to prepare [Ni? 0.80? Co？ 0.09? Mn？ 0. 1 1](OH)2, and finally [Ni? 0.893? Co？ 0.054? Mn？ 0.053? ](OH)2 powder.
5. Filter the powder, wash it, and dry it at 1 10℃ under vacuum.
6. To prepare Li? [Ni? 0.886? Co？ 0.049? Mn？ 0.050? Al. 0.0 15? ]? o？ 2. Precursor ([Ni? 0.893? Co？ 0.054? Mn？ 0.053? ] (Oh) 2) And LiOH? 2? O and Al(OH)3? 3H2O, and calcined in pure oxygen at 730℃ for 65438 00 hours.
If the NCM cathode material is prepared, the step of adding aluminum in step 6 can be omitted; However, if the NCA cathode material is prepared, step 4 can be omitted.
Therefore, the production process of NCMA cathode materials is more complicated than that of NCM and NCA cathode materials, and its short-term production cost is bound to be higher.
At the same time, it is necessary to strictly control the amount of aluminum. Too much or too little material will affect the energy density of the battery and weaken its stability. The introduction of this technology undoubtedly puts forward stricter requirements for the production process.
However, in the long run, the introduction of aluminum reduces the use of cobalt. Take Ultium battery that LG Chem and GM cooperated as an example, the cobalt content in the battery decreased by 70%.
This situation can reduce the production cost of power batteries. It is understood that the average import price of cobalt hydrometallurgical intermediates from 2065438 to July 2009 was 19707 USD/ton (about137,000 yuan/ton), while the price of good bauxite was about 1200 yuan/ton.
The complexity of the production process may temporarily delay the market occupation of NCMA batteries, but the long-term interests will still drive power battery factories and car companies to use NCMA quaternary lithium batteries.
Fourth, NCMA battery 202 1 year mass production? Material suppliers, battery factories and automobile manufacturers have made their plans.
At present, although NCMA is still in the early stage of industrialization, many companies have entered this field for layout. From the company's attributes, it can be divided into three types of players: lithium battery material suppliers, power battery enterprises and automobile manufacturers.
1, lithium battery material supplier
According to public information, lithium battery material supply giant Cosmo? AM & ampt, GEM has taken the lead in this field.
Cosmo？ AM & ampt is the main supplier of cathode materials for NCMA quaternary lithium batteries of LG Chem. According to the company, NCMA high nickel cathode material is being studied, in which the nickel content reaches 92% and the cathode energy density is 228 mAh/g.
The company expects to realize mass production of quaternary cathode materials in 20021year, and will first verify with LG Chemical after mass production. However, the company has also reached a cooperation with Samsung SDI in cathode materials, so it is likely to supply NCMA cathode materials to Samsung SDI.
In response to investors' questions, Meg also revealed that the company has completed the research and development and mass production of quaternary cathode materials, and is carrying out ton-level certification with customers.
In addition, the enterprise survey shows that Linnaeus New Energy, an American new energy materials startup, applied for a four-yuan patent for cathode materials in China, which was publicized on February 5, 20 19.
2. Power battery enterprises
At present, the power battery companies deploying NCMA quaternary lithium batteries are mainly battery companies in China and South Korea.
Among domestic power battery enterprises, Guo Xuan Hi-Tech and Honeycomb Energy take the lead in laying out quaternary lithium batteries.
Honeycomb Energy released NCMA quaternary lithium battery products at the press conference in July, 20 19. It is understood that this product was established in the hive in March 20 18, and has been developed for 16 months.
▲ Honeycomb Energy Conference
However, at present, Honeycomb Energy does not have the mass production capacity of quaternary lithium batteries. Yang Hongxin, general manager of Honeycomb Energy, said that the company will complete the production capacity layout of NCMA quaternary cathode materials in the fourth quarter of 20 19, with an initial production capacity of100t/year. By 202 1, Honeycomb Energy will officially mass-produce NCMA quaternary lithium batteries.
Guo Xuan Hi-Tech is not high-profile. According to the enterprise survey information, in 20 16, Guo Xuan Hi-Tech applied for two patents for the preparation of quaternary lithium batteries, and the two patents were authorized for invention on 20 18 and 20 19 respectively.
However, Guo Xuan Hi-Tech has few technical routes, and applied for the patents for the preparation of NCAT (Nickel Cobalt Aluminum Titanium) and NCMT (Nickel Cobalt Magnesium Titanium) cathode materials.
Contemporary Ampere Technology Co., Ltd. has not announced that it will develop NCMA batteries, but considering that Meg is one of its suppliers of cathode materials, Contemporary Ampere Technology Co., Ltd. may also secretly develop NCMA batteries.
Among Korean battery companies, LG Chem is the first to announce that it will cooperate with General Motors to mass-produce NCMA quaternary lithium batteries and apply them to Ultium batteries. Lg Chem said that the energy density of this battery will reach 200mAh/g (whether it is the energy density of the battery is not disclosed).
3. Automobile factory
At present, only one automobile manufacturer has made it clear that it will use NCMA quaternary lithium battery. The company opened "electric car?" Week "announced a project to develop batteries in cooperation with LG Chem. The core of this project is NCMA battery and Ultium battery pack technology.
It is understood that GM will use the battery on its latest electric vehicle platform to provide 50kWh-200kWh battery packs for different models, and the cost of battery packs will be reduced to 65,438+000 USD/kWh (about 693 RMB/kWh).
▲ GM's new electric vehicle platform
If the plan goes smoothly, GM will launch 20 electric vehicles in the next three years, and reach the sales volume of 6.5438+0.0000 electric vehicles in 2025.
Once GM realizes the successful transformation of electrification with NCMA batteries, major car companies will follow suit, and the number of car companies deploying NCMA quaternary lithium batteries will increase significantly.
The entry of lithium battery material suppliers, power battery enterprises and automobile manufacturers means that NCMA quaternary lithium battery scheme may become one of the alternatives for future power batteries.
If it is successfully commercialized on a large scale, the product will have an impact on upstream mines, midstream power battery enterprises and downstream vehicle manufacturers.
For the upstream mining industry, the demand for cobalt ore is greatly reduced, and the once high cobalt price may be greatly reduced.
For power battery enterprises, a new round of technical iteration will bring benefits to head power battery enterprises. Enterprises that are laid out first will be able to seize the opportunity, while enterprises that are laid out later may face backwardness or elimination.
For automobile manufacturers, the cost of NCMA quaternary lithium battery is greatly reduced due to the reduction of cobalt consumption, and the cost pressure of automobile enterprises to produce electric vehicles is reduced. Moreover, NCMA battery has better cycle life and stability, and the reliability of electric vehicle products will be improved.
Conclusion: Is the era of quaternary batteries coming?
The quaternary lithium battery that GM cooperates with LG is likely to set off a round of industrial transformation of power batteries. Compared with NCM/NCA ternary lithium battery products, quaternary lithium battery has longer cycle life, excellent safety and lower cost. For car companies and battery factories, these advantages mean that quaternary lithium batteries are an irresistible choice.
However, before mass production, the fate of the quaternary lithium battery has not been determined. There are many subsequent development routes for ternary lithium batteries, and the new technology has changed in production technology and materials.
From the material point of view, lithium nickel manganate "cobalt-free" battery, lithium sulfur battery and lithium air battery are all potential competitors of quaternary lithium batteries, and these battery products have no small performance advantages compared with the current ternary lithium batteries.
It can only be said that the quaternary lithium battery is a substitute for the ternary lithium battery which is close to mass production at present, and the follow-up situation needs to wait and see.
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.