Around this time last year, I wrote a series of articles to discuss the choice of power lithium battery technology routes, which included a detailed comparison of the advantages and disadvantages of lithium batteries, fuel cell lithium batteries, and supercapacitors.
The final result was that lithium batteries easily won.
Those who believe that Japan's fuel cell lithium batteries represent the future are actually still thinking in the era of gasoline cars, only now they've replaced gas stations with hydrogen refueling stations.
As for supercapacitors, they have irreplaceable advantages in specific fields—such as energy recovery in rail transit, energy recovery in tower cranes, and kinetic energy recovery devices for automobiles; however, in the field of electric vehicles, due to issues of energy density and cost, they cannot become a viable technology route for the future.
Therefore, there is no doubt that lithium batteries will be the real protagonist in the upcoming electric vehicle revolution, and will be the unshakable path for the next ten or even twenty years.
Moreover, once lithium-ion batteries have undergone more than a decade of development and the entire industry chain has formed a stable, complete, and mature supporting system (the supporting industry is a huge moat; once the entire industry chain matures, the investment may be in the trillions, which is an obstacle that any other new technology route can hardly overcome), the technology route of lithium-ion batteries will be even more difficult to shake.
Therefore, lithium batteries are undoubtedly the champion in this competition.
However, there are several other technical routes within lithium battery technology, including lithium cobalt oxide, lithium titanate, lithium manganese oxide, lithium iron phosphate, ternary lithium batteries, and so on. People may be more concerned about which of these technical routes has more advantages.
To clarify this issue, I will conduct a series of in-depth discussions in this article. Please feel free to leave comments below to point out any shortcomings.
Preliminary selection
First, let's talk about lithium cobalt oxide: its cycle performance is too poor, and it uses a large amount of the extremely rare metal cobalt. Its shortcomings are too obvious, and its only fate is to be phased out.
Then there's lithium titanate: it has a high charging rate and a long lifespan; but it also has a significant drawback—its energy density is too low, leading to excessively high costs.
Its characteristics are similar to those of supercapacitors, and this fatal flaw has prevented it from becoming the mainstream of power lithium batteries, thus preventing it from standing out in the initial selection.
Thirdly, let's talk about lithium manganese oxide: it has low cost and high charging rate; however, it has poor high-temperature performance and poor cycle life.
Therefore, lithium manganese oxide is rarely used directly as a power lithium battery. Instead, other materials are added to form modified batteries, such as nickel and cobalt, to form nickel-cobalt-manganese batteries, thereby achieving a balance of various performance characteristics.
However, after these improvements, it is no longer a simple lithium manganese oxide battery, but has become a type of ternary battery.
This argument suggests that lithium manganese oxide should also be phased out.
Among the many technologies for lithium batteries, the competition between lithium iron phosphate and ternary lithium batteries is the most intense.
Lithium iron phosphate (LFP) offers high safety and long lifespan, but suffers from low energy density, poor low-temperature performance, and inconsistent performance.
Ternary batteries have high energy density, good consistency, good low-temperature performance, and low cost, but poor safety performance and shorter cycle life than lithium iron phosphate batteries.
Currently, the most mature lithium iron phosphate industry chain is in my country, and we have mastered many core technologies in related fields; while ternary batteries are represented by Japan and South Korea, and are more mature.
Therefore, the competition between these two technological approaches has a stronger sense of my country versus Japan and South Korea.
Over the past year, I have continued to think about this issue diligently every day, reading a large number of articles in related fields, reading numerous interviews with technical experts in related fields, and reflecting on the advantages and disadvantages of the two power lithium battery technology routes.
Today, I finally believe I have a clearer understanding and have decided to finish this article that I've been putting off for over a year. Okay, enough rambling, let the final showdown begin!
finals
The performance of power lithium batteries can be evaluated from the following seven dimensions:
1. Safety
2. Energy density
3. Cycle life
4. Cost
5. Charging rate
6. Consistency of individual battery cells
7. Low temperature performance
As a qualified technical approach, it cannot have too many obvious shortcomings in any of the above aspects. Only by achieving a balance in all aspects can it be a feasible approach.
1. Safety
In this respect, lithium iron phosphate batteries have a distinct advantage: they only decompose when the temperature reaches above 480°C and can pass severe tests such as needle penetration and fire.
Ternary batteries, represented by nickel-cobalt-aluminum batteries, decompose and release gas at 180°C, and the reaction is more violent.
The outcome was swift: lithium iron phosphate batteries won.
2. Energy density
Due to the materials used in lithium iron phosphate batteries, the discharge platform voltage is lower, only 3.2V; and the compaction density is very low, only about 2.2~2.5. These factors result in a low theoretical energy density of lithium iron phosphate batteries, only 178Wh/kg.
BYD, a leading manufacturer of lithium iron phosphate batteries, has already achieved an energy density of 147Wh/kg for its single cells. Wang Wenfeng, head of BYD's battery division, claimed that they would achieve 160Wh/kg for lithium iron phosphate batteries in 2018.
This is already a remarkable achievement, but it is close to the theoretical upper limit of the energy density of this battery route, and it will be difficult to make significant improvements in the future.
In contrast, the current energy density of nickel-cobalt-aluminum (NCA) ternary batteries (used by TSLA) is 245Wh/kg for the 18650 battery, while the energy density of the 20700 battery to be used in the Model 3 in the future needs to be above 300Wh/kg.
Many domestic manufacturers have chosen the nickel-cobalt-manganese (NCM) ternary lithium battery technology route, which has a theoretical energy density of up to 280Wh/kg. The lithium batteries used in DJI drones are of this type, and currently 80% of drone lithium batteries are supplied by manufacturers in Guangdong.
I looked at the parameters, and the energy density of nickel-cobalt-manganese lithium batteries that have been mass-produced can reach 190Wh/kg. This is still far from the theoretical upper limit, and there is still a lot of room for improvement.
In the near future, under ideal conditions, the energy density can reach over 230Wh/kg, and the overall energy density of the battery pack can still reach over 200Wh/kg, which is about 40% higher than that of lithium iron phosphate.
In addition, lithium iron phosphate has a lower compaction density, which results in a larger volume for the same battery capacity.
After comparing and calculating the battery packs of BYD e6 and TSLAmodels, it was concluded that, for the same battery capacity, lithium iron phosphate batteries are 48% larger in volume than nickel-cobalt-aluminum ternary batteries.
When we evaluate energy density and safety together, we find that these two indicators are natural enemies. In fact, we can understand from the simplest physics and chemistry that the higher the energy density, the more unstable and less safe it is.
3. Cycle life
When evaluating performance in this area, the information I encountered gave me a headache.
Taking lithium iron phosphate as an example, some articles say that its lifespan is 2,000 cycles, while Wang Chuanfu said that his lithium iron phosphate battery can reach more than 4,000 cycles, and some articles even say that the full lifespan can reach 20,000 cycles.
The huge discrepancies in the data made me dizzy, and I had to carefully distinguish them repeatedly to gain a correct understanding; later I found that the above statements were all "correct", they were just different evaluation criteria.
The claim that the battery life is only 2000 cycles refers to repeated charging and discharging at a 1C charging rate. The battery life is considered to end when the battery capacity drops below 80% of the rated capacity (this is an extremely rigorous charge and discharge test; a 1C rate means that the battery can be fully charged in 1 hour).
The 4,000 times mentioned by Wang Chuanfu is more likely the result of actual testing based on a large number of e6 vehicles already on the road under normal usage conditions.
The so-called 20,000 times is the result under the entire usage cycle.
Because a battery capacity below 80% of its rated capacity does not mean that the battery is completely unusable. After all, it still has 80% capacity. At this point, the battery can be removed and reused in a tiered manner as an energy storage power station. Under reasonable current, temperature and usage conditions, it can achieve 20,000 charge-discharge cycles.
However, regardless of the circumstances, lithium iron phosphate batteries have a significantly longer lifespan than ternary lithium batteries.
When a ternary lithium battery is charged and discharged at a 1C rate, after about 800 charge-discharge cycles, its actual capacity is already lower than 80% of the rated capacity. From this perspective, lithium iron phosphate batteries have a lifespan that is even three times that of ternary lithium batteries.
However, this is not the case in actual use. Due to the difficulty in controlling the consistency of lithium iron phosphate batteries, the overall lifespan of lithium iron phosphate battery packs is shorter, and it is not as exaggerated as the lifespan of ternary batteries being three times that of lithium iron phosphate batteries.
However, in terms of cycle life, lithium iron phosphate wins.
4. Cost
Some people believe that lithium iron phosphate does not use rare metals in its cathode material, while ternary batteries use more expensive metals such as cobalt and nickel. Therefore, they naturally assume that lithium iron phosphate is cheaper. This is actually a misconception.
The discharge voltage of lithium iron phosphate is 3.2V, while the discharge voltage plateau of ternary lithium batteries is 3.8V. A higher discharge voltage means a higher battery capacity, which means that with the same material consumption, ternary lithium batteries have a larger capacity.
Or vice versa: for batteries of the same capacity, ternary lithium batteries consume fewer raw materials.
Especially after the price of lithium carbonate, an essential component of lithium batteries, soared from 40,000 yuan last year to 150,000 yuan currently, the cost problem of lithium iron phosphate batteries, which consume more lithium carbonate materials, has become prominent. According to data from Li Zhen, chairman of Guoxuan High-tech, the current cost of Guoxuan High-tech's ternary batteries is actually 10-15% lower than that of lithium iron phosphate batteries.
Ternary batteries are now moving towards a technology route of high aluminum and high nickel, and low cobalt, which reduces the consumption of expensive rare metals.
Global cobalt production reached 98,000 tons last year, with 40% used in lithium batteries, indicating a relatively small consumption volume. Furthermore, cobalt resources remain in a state of oversupply, and the current price of 200,000 yuan per ton is at a historically low level.
The booming lithium battery industry last year did not lead to a surge in cobalt resource prices. Multiple factors have resulted in the current cost of lithium iron phosphate batteries being higher than that of ternary lithium batteries.
However, we should view the cost comparison between the two in a dynamic way. We should recognize that before the price of lithium carbonate surged, the cost of lithium iron phosphate was slightly lower than that of ternary batteries.
Conversely, if cobalt resources are in short supply next year and experience a price surge similar to that of lithium carbonate, which is four or even five times higher, then the cost of ternary batteries will also rise accordingly.
In summary, the costs of the two technical routes are roughly the same, and at any given point in time, the cost is greatly influenced by the price of upstream raw materials.
In the long run, I believe that the price of 150,000 yuan/ton for lithium carbonate is not sustainable, because lithium is not a scarce resource. The production cost of lithium carbonate per ton for many domestic manufacturers such as Tianqi Lithium and Ganfeng Lithium is between 29,000 and 35,000 yuan, while Lanke Lithium, a subsidiary of Salt Lake Group, claims that the cost is only 19,000 yuan/ton.
The lithium carbonate industry is currently a highly profitable industry, with a cost of 30,000 yuan and a price of 150,000 yuan, a fivefold increase.
The lure of huge profits naturally led to a frenzied expansion of production. Companies across the entire industry chain were multiplying their output, with Lanke Lithium expanding its output by tens of times. Although demand would continue to rise, the expansion of production was even more frenzied.
When the prices of upstream raw materials change in the near future, it remains to be seen whether the cost of lithium carbonate or ternary lithium will be higher.
In this category, it's a tie.
5. Charging rate
To sum it up, lithium iron phosphate batteries have a significant lead in charging rate.
In fact, when discussing battery life two years ago, we were already able to conclude that lithium iron phosphate batteries have a significantly better lifespan than ternary lithium batteries at high charging rates.
The American company A123 (now a subsidiary of Wanxiang) even produced a lithium iron phosphate battery with a 25C charging rate in the laboratory (25C charging rate means that the battery can be fully charged in 60÷25=2.4 minutes).
In terms of charge/discharge rate, lithium iron phosphate (LiFePO4) is significantly superior.
6. Consistency of individual battery cells
TSLAmodels battery packs using nickel-cobalt-aluminum ternary lithium batteries contain 7,000 small cells connected in series and parallel. If there is a problem with the consistency of the cells, the consequences will be disastrous, because there is a "barrel principle" in series batteries, where the worst-performing cell affects the overall performance of the battery pack.
However, the 2014 Qin hybrid vehicle, which uses lithium iron phosphate batteries, has encountered a major problem. The battery is rated at 13 kWh, but after more than a year of use, many owners have reported that it can only charge up to 8 kWh, indicating significant degradation.
Didn't I say earlier that lithium iron phosphate batteries have a longer lifespan? How come this phenomenon is occurring? This is actually a problem of consistency between individual battery cells.
In fact, most of the batteries used in BYD's 2014 "Qin" electric vehicles are probably fine individually, and can be restored to their original performance after being returned to the factory for equalization. However, problems only arise when the batteries are assembled into a pack.
In fact, there are solutions to the battery consistency problem. There are two main solutions: one is to upgrade the process and improve the automation level and control precision of the factory.
Another point is to increase the capacity of individual battery cells. The 2014 Qin used 27AH battery cells, while the BYD K9 used 270AH battery cells. Compared to the Qin, the K9 had far fewer problems and even no battery consistency issues.
Finally, there's the improvement of the battery management system (BMS), an area where we are indeed lagging behind Europe, America, and Japan.
Compared to the 2014 Qin, the 2015 Qin uses a brand-new battery management system, with a controller added to each battery cell for better operation and eight extra batteries (meaning the actual capacity is greater than the nominal capacity).
Many issues regarding battery consistency have been resolved, but in any case, lithium iron phosphate batteries lag behind ternary lithium batteries in terms of consistency. In this round: Ternary lithium wins.
7. Low temperature performance
The conclusion is clear: lithium iron phosphate has poor low-temperature performance, while ternary lithium phosphate is superior.
In winter, the driving range of electric vehicles decreases, but the problem is more severe for lithium iron phosphate batteries. But exactly how much does the range decrease?
We still need to present clear data. Take the new BYD e6 with a range of 400 kilometers as an example. After entering winter, car owners have reported that the range can only reach 60% of the original range, which is 240 kilometers.
However, this cannot be entirely blamed on the battery. Based on the simple principle of thermal expansion and contraction, we know that the tire pressure of a car will decrease in winter, and low tire pressure is an important reason for the shortened driving range. When the car owner pays attention to the tire pressure and driving style, the driving range can be restored to 70% to 75% of the nominal range, reaching nearly 300 kilometers, which is 100 kilometers less than the nominal 400 kilometers.
The question is, where did that 100-kilometer range go? The answer lies in the air conditioning.
Traditional gasoline vehicles have an energy conversion efficiency of less than 30%, with the remaining 70% of energy being dissipated as waste heat. In winter, turning on the car's heater does not require additional gasoline consumption; it simply blows the waste heat emitted by the engine into the passenger compartment.
However, electric vehicle motors have an energy conversion efficiency of 90% and do not generate additional waste heat. If air conditioning is needed in winter, the energy stored in the battery will be consumed. Therefore, the reduction in driving range cannot be entirely blamed on the poor low-temperature performance of lithium iron phosphate batteries.
The BAIC EV200, which uses ternary lithium batteries, also experiences a significant reduction in range in winter. Moreover, due to the lower overall battery capacity, the original range of only 200 kilometers is reduced to only 140 kilometers after a 30% reduction, causing drivers to complain bitterly.
There are many ways to deal with winter for lithium iron phosphate batteries, such as material nano-sizing and carbon coating. Another simple and effective method is to install a heating device on the battery pack.
Overall, the impact of low temperature on the overall performance of lithium iron phosphate battery packs is less than 10%. Furthermore, since ternary lithium batteries are also affected by low temperatures to some extent, the actual performance difference between the two at low temperatures is even smaller.
However, regardless of the circumstances, low-temperature performance is a weakness of lithium iron phosphate batteries, and ternary lithium batteries win this round!
The above seven analyses cover almost all aspects of the new energy indicators of power lithium batteries. In the seven battles, ternary lithium and lithium iron phosphate batteries fought fiercely and painfully, with each side winning and losing, and also drawing.
So, after these seven matches, can I, as the judge, give a final conclusion? Or can you, the readers and viewers, offer your own judgment? Who is the undisputed champion?
As the judge, after so much analysis and discussion, I can only regretfully tell you that I cannot draw a conclusion on who is better. Therefore, this competition has no champion, or rather, everyone is a champion.
resolution
Some people might be angry upon hearing this result. After reading 7,000 words and wasting so much of everyone's time and effort, all I got was a draw. Am I asking for a beating?! But wait, let's continue reading.
While I cannot give a simple conclusion or directly say which is better or worse, a clear answer will emerge when considering the specific application environment. This is because certain application environments will highlight the advantages of one aspect while masking the disadvantages of others.
1. Energy storage application scenarios
Need I say more? Lithium iron phosphate has achieved an overwhelming victory in this application scenario.
Energy storage power stations often have thousands or even tens of thousands of kilowatts of batteries stacked together. If ternary lithium batteries are used, it is equivalent to stacking tons of bombs together.
The long lifespan of lithium iron phosphate also meets the application requirements of energy storage. Energy storage power stations are often built in suburban areas, where land and space are not a problem, thus masking the disadvantage of low energy density of lithium iron phosphate.
Especially for energy storage power stations used for grid frequency regulation, high-rate charging and discharging are frequently required, and the charging rate of lithium iron phosphate (LFP) batteries meets this demand. In energy storage applications, the disadvantages of LFP batteries are no longer disadvantages, but rather their advantages are quite prominent.
Therefore, when we consider this application scenario, lithium iron phosphate is the undisputed champion.
2. Drone batteries
Need I say more? Have you ever seen a drone that uses lithium iron phosphate batteries?
Undoubtedly, this is another extreme application scenario, in which ternary lithium batteries occupy 100% of the market share.
The inherent disadvantage of lithium iron phosphate batteries in terms of energy density means that they can never be used in drones.
In the field of lithium batteries for drones, ternary lithium batteries are the clear winner.
3. Electric buses and electric commercial vehicles
These vehicles are heavy and spacious, and have low sensitivity to weight. Buses and coaches, due to their large number of passengers, have high safety requirements.
These vehicles operate for long periods and have high requirements for battery life. These characteristics perfectly leverage the advantages of lithium iron phosphate and mask its disadvantages.
Therefore, BYD, a leader in lithium iron phosphate technology, was the first to dare to apply its pure electric vehicles to buses, electric forklifts, and electric trucks. This was based on their confidence in the safety, high charge-discharge rate, and long lifespan of lithium iron phosphate batteries.
Recently, the government suspended the catalog application for buses using ternary lithium batteries. This, to some extent, indicates that ternary lithium batteries have no future application in this field. In the fields of electric buses and commercial vehicles, lithium iron phosphate batteries have won out.
4. Plug-in hybrid electric vehicles
There is actually very little controversy in this field. Although most plug-in electric vehicles now use lithium iron phosphate batteries, BYD itself is preparing to abandon this technology.
Starting with the Qin Tang 100, BYD's plug-in hybrid vehicles will fully switch to nickel-cobalt-manganese ternary batteries. I believe the core reason behind this shift is the consistency issue of small lithium iron phosphate cells.
In this field, Sanyuan wins.
5. Pure electric passenger vehicles
This is another fiercely contested battleground. First of all, the lithium iron phosphate batteries used in pure electric passenger vehicles are large cells, with each cell having a capacity of up to 0.82 kWh, which is ten times larger than the cells used in plug-in hybrid electric vehicles.
Taking the Qin EV300 as an example, the entire car has only 58 batteries, which is a tiny fraction compared to the 7,000 batteries in the Model S.
Since there are few individual battery cells, it is cost-effective to install a control unit on each cell, thereby maximizing the solution to the consistency problem. Furthermore, the consistency problem of large individual battery cells is not so prominent.
However, this does not mean that lithium iron phosphate has won in the pure electric passenger vehicle sector; the situation is far more complex than that.
Because lithium iron phosphate batteries have a low density, they are heavier for the same capacity, resulting in heavier pure electric vehicles and higher energy consumption. Compared to the BAIC EV200's 14 kWh per 100 kilometers, the BYD e5's energy consumption is slightly higher, around 16 kWh per 100 kilometers.
In addition, passenger cars travel an average of 46 kilometers per day, which is much shorter than buses (230 kilometers per day) and taxis (400 kilometers per day). This makes it difficult for lithium iron phosphate batteries to fully utilize their long lifespan, while the shorter lifespan of ternary lithium batteries is not as fatal.
Another point is safety. Private passenger cars do not have the same stringent safety requirements as buses, but that does not mean that safety can be ignored. The reason why the ternary lithium battery pack of the TSLA models weighs as much as 900kg is because additional protective devices are needed to protect the battery pack.
In summary, the two battery approaches are in a stalemate in the pure electric passenger vehicle market.
Since everyone can feel the average energy consumption per 100 kilometers in daily life, and reducing energy consumption is a national requirement and direction, the two technical routes may coexist in the pure electric vehicle field for a long time, with ternary lithium batteries having a slight advantage.
Summarizing the five major application scenarios above, we can understand that lithium iron phosphate batteries and ternary lithium batteries have different advantages in their respective specific fields: lithium iron phosphate batteries are suitable for energy storage and commercial vehicles; ternary lithium batteries are suitable for plug-in hybrid vehicles, passenger cars, drones, and other fields.
Since my country's new energy vehicles first took off in the commercial vehicle sector, lithium iron phosphate batteries were used more in previous years; however, with the deepening of the electric vehicle revolution and the explosive growth in passenger vehicle sales, the proportion of ternary lithium batteries will gradually increase.
However, the two will coexist for a long time, and leading domestic battery companies will inevitably choose a two-pronged strategy (producing both ternary lithium batteries and lithium iron phosphate batteries).
