Lithium battery is the future of mankind, but where is the future of lithium battery?

Those who think Japan's fuel cells represent the future are stuck in the era of petrol-powered cars, replacing petrol stations with refuelling stations.

As for ultra capacitors, they have irreplaceable advantages in specific fields, such as energy recovery of rail transit, energy recovery of tower crane, and kinetic energy recovery device of automobile. In the field of power vehicles, due to energy density and cost, it cannot be a feasible technology route in the future.

Therefore, there is no doubt that in the upcoming electric vehicle revolution, lithium battery will be the real protagonist, is the next 10 years or even 20 years of unshakable line.

And, once the lithium power battery after 10 years of development, the whole industry chain from top to bottom to form stable, complete and mature after matching (industrial supporting is huge moat, mature, the whole industry chain may need trillions of investment, this is any other new technical route insuperable barrier), lithium power battery technology is more difficult to shake.

So lithium batteries are the undisputed champion in the ring.

But there are a variety of technical routes within the lithium battery technology route, roughly lithium cobalt acid, lithium titanate, lithium manganese acid, lithium ferrite, ternary battery and so on, friends may be more concerned about which of these technical routes is more advantageous.

In order to clarify this issue, the author will carry out a series of in-depth discussion in this paper, the shortcomings of the friends after the comments are not hesitate to correct.

primary

lithium cobalt oxide: poor recycling performance, and the use of a large number of extremely rare cobalt metal, the shortcomings are too obvious, its fate only out.

Then lithium titanate: high charging rate, long life; However, there is a distinct disadvantage -- too low energy density, resulting in high cost.

Its characteristics are similar to those of ultra capacitors, but this fatal flaw also prevents it from becoming the mainstream of power batteries, so it cannot stand out in the primary election.

Third, lithium manganate: low cost, high charging rate; But the high temperature performance is bad, the circulation is not good.

Therefore, lithium manganate is rarely directly selected as a power battery, but other materials are added to form modified batteries, such as nickel and cobalt to become nickel-cobalt-manganese batteries, so as to achieve the balance of various performance.

But after these improvements, it is no longer a simple lithium manganate battery, but a kind of ternary battery.

The result of this discussion shows that lithium manganate should also be eliminated.

Of all the technical routes for lithium batteries, lithium iron phosphate v ternary battery are the most closely related.

Lithium iron phosphate has high safety and long life, but low energy density, poor low-temperature performance and poor consistency.

Ternary battery has high energy density, good consistency, good low temperature performance, low cost, but poor safety performance, cycle life is not as good as lithium iron battery.

At present, the most mature industrial chain of lithium iron phosphate is in China, and we have many core technologies in related fields. The ternary battery is represented by Japan and South Korea, and more mature.

So the two technological routes of the confrontation is more of a China vs Japan and South Korea.

In the past year, I continued to think about this problem day by day, reading a lot of articles in related fields, reading numerous interviews with technical experts in related fields, and thinking about the pros and cons of the two power lithium battery technology routes.

Finally today, I think I have a clearer understanding, determined to complete this article dragged for more than a year of the manuscript, ok, no more nonsense to say, the finals of the formal start!

The final

There are roughly seven dimensions to evaluate the performance of power batteries:

1. Security

2. Energy density

3. Cycle life

4, cost,

5. Charging ratio

6, the battery monomer consistency

7. Low temperature performance

As a qualified technical route, there should not be too obvious shortcomings in any of the above aspects. Only a balanced approach in all aspects can be a feasible route.

1. Security

The lithium iron phosphate battery has a distinct advantage: the temperature is above 480 ° to decompose, can pass the needle, fire and other severe test.

Represented by aluminum nickel and cobalt ternary cell, then in the 180 ° will decompose and release the gas, and more violent reaction.

The result was a swift victory for iron-lithium batteries.

2. Energy density

Due to the material of lithium iron phosphate battery, the voltage of discharge platform is lower, only 3.2v. And the compaction density is very low, only about 2.2~2.5, which leads to the low theoretical energy density of lithium iron phosphate battery, only 178wh/kg.

BYD, the leading manufacturer of lithium iron phosphate (002594), has achieved 147wh/kg of the energy density of the cell, and wang wenfeng, the boss of BYD's battery business division, has declared that it will achieve 160wh/kg of lithium iron phosphate in 2018.

This is quite an achievement, but it is close to the theoretical upper limit of the energy density of this battery line, and it is difficult to make further improvement in the future.

On the contrary, nickel-cobalt-aluminum (NCA) ternable battery (adopted by Tesla), the current 18650 battery energy density is 245wh/kg, and the 20700 battery used on the model3 in the future should achieve the energy density above 300wh/kg.

Many domestic manufacturers choose nickel-cobalt-manganese (NCM) ternary lithium battery technology route. Its theoretical energy density line is 280wh/kg. The lithium battery used in dji uav is this kind of lithium battery.

I have looked at the parameters. After large-scale production, the energy density of nickel-cobalt-manganese lithium battery can reach the level of 190wh/kg, which is far from the upper limit of theoretical density, and there is still a lot of room for improvement.

In the near future, the ideal energy density can be more than 230wh/kg, and the overall energy density of the battery pack can still be more than 200wh/kg, about 40% higher than lithium iron phosphate.

In addition, lithium iron phosphate has a low compaction density, which results in a larger volume of lithium iron phosphate for the same battery capacity.

After comparing and calculating BYD e6 battery pack and Tesla models battery pack, it is concluded that the volume of lithium iron phosphate is 48% larger than that of nickel-cobalt-aluminum ternary battery under the same battery capacity.

If we put the two parameters of energy density and safety together, we can find that the two indicators of energy density and safety are a pair of natural enemies. In fact, we can know from the simplest knowledge of physics and chemistry that the higher the energy density is, the more unstable and insecure it is.

3. Cycle life

When evaluating this aspect of performance, the information I am exposed to gives me a headache.

Take lithium iron phosphate as an example. Some articles say that its life is 2000 times. Wang chuanfu says that his lithium iron battery life can reach more than 4000 times.

Such a big gap in data makes me dizzy, need to repeatedly carefully screening to have a correct cognition; Later, I found that the above statements are "good", but they have different evaluation criteria.

If the battery life is only 2000 times, it will be charged and discharged repeatedly according to the 1C charging ratio, and the battery life will be considered to be terminated when the battery capacity is below 80% of the nominal capacity (this is an extremely rigorous charging-discharging test, and the 1C rate means that the battery is fully charged in an hour).

Mr Wang's 4,000 are more likely to be measured under normal conditions, based on a large number of e6 operations already on the road.

In the end, the so-called 20,000 times is the result under the full use cycle.

Because the battery capacity is lower than 80% of the standard, it does not mean that the battery cannot be used completely. After all, there is still 80% of the capacity. At this time, the battery can be taken down and used as a cascade for energy storage power station.

In any case, the life of lithium iron phosphate is significantly longer than that of a ternary battery.

Ternary battery in 1C charge and discharge rate, repeated charge and discharge about 800 times, the actual capacity has been lower than the 80% of the nominal capacity, from this point of view, iron lithium battery is even three times the life of ternary battery.

However, this is not the case in practical use. Because the consistency of lithium iron phosphate battery is difficult to control, the overall life of the battery pack of lithium iron phosphate battery is shorter, which is not as exaggerated as the life of three times of a ternary battery.

But anyway, in terms of cycle life, iron lithium wins out.

4, cost,

Some people think that lithium iron phosphate does not use rare metals in the positive electrode materials, while the ternary battery USES cobalt, nickel and other more valuable metals, so it is reasonable to think that the cost of lithium iron phosphate is lower, which is actually a misunderstanding.

The discharge voltage of lithium iron phosphate is 3.2v, and the discharge voltage platform of ternary battery is 3.8v. Higher discharge voltage means higher battery capacity, which means the capacity of ternary battery is larger under the same material consumption.

Or the reverse is also true: ternary batteries consume less raw material for the same capacity.

Especially when lithium battery is necessary since last 4 Wan Yuanbiao lithium carbonate price to go up to the current 150000 yuan, lithium carbonate material consumption more lithium iron batteries cost problem is apparent, according to the porch tech centers (002074, shares) chairman lee 'data, the current Chinese xuan high-tech ternary batteries but lithium iron batteries that are lower than the cost of 10 ~ 15%.

Ternary batteries are now high in aluminum, high in nickel and low in cobalt, reducing the consumption of expensive rare metals.

Of the 98,000 tonnes of cobalt produced worldwide last year, 40 per cent was used in lithium batteries, not a huge amount. Moreover, cobalt resources are still in a state of oversupply, and the current price of 200,000 yuan/ton is at a historically low level.

Last year's boom in the lithium battery industry did not lead to a surge in cobalt resources, a variety of factors lead to the current cost of lithium iron batteries than ternary batteries.

But look at the cost comparison in a dynamic way, recognizing that lithium iron phosphate cost slightly less than a ternary battery before the lithium carbonate boom.

On the other hand, if demand for cobalt outweighs supply next year by a factor of four or even five, as with lithium carbonate, the cost of ternary batteries will rise.

In short, the cost of the two technical routes is no different, to a specific point in time, and the price of upstream raw materials have a great relationship.

In the long run, I think the price of lithium carbonate 150000 / ton is not sustainable, because lithium is not scarce resources, domestic sky LiYe (002466, shares), Jiangxi feng LiYe (002460, shares) many manufacturers such as lithium carbonate production cost per ton is about 29000-35000 yuan between, and the salt lake shares (000792, shares), a subsidiary of blue division LiYe claims costs only 19000 yuan/ton.

At present, lithium carbonate industry is a profiteering industry. The cost of 30,000 yuan and the price of 150,000 yuan have increased fivefold.

The huge profit temptation is naturally the crazy expansion of production. Companies in the whole industrial chain are multiplying the expansion of production capacity, and the expansion of lankethithium is even more than ten times. Although the demand will continue to grow, the expansion of production capacity is even more crazy.

When the price of upstream raw materials changes in the near future, it is unclear whether the cost of lithium carbonate or ternary is higher or lower.

This term, they're even.

5. Charging ratio

To conclude, lithium iron phosphate leads the pack by a wide margin.

In fact, the year before last in the elaboration of battery life has been able to draw a conclusion: lithium iron phosphate battery in the high charging rate, life is significantly better than the three battery.

American company a123 (now a wanxiang subsidiary) has even built a lithium iron phosphate battery in the lab that can be charged at a 25C rate.

Charge - discharge ratio, iron - lithium significantly out.

6, the battery monomer consistency

There are 7,000 small batteries in series and parallel in the tesla models battery pack using the nickel-cobalt-aluminum ternary. If there is a problem with the battery consistency, the consequences will be disastrous, because the series battery has a barrel principle, and the one with the worst performance will affect the overall performance of the battery pack.

However, the problem of using lithium iron phosphate in the 2014 model qin hybrid electric vehicle caused a lot of troubles. The battery of 13kwh was calibrated, and after more than a year of use, many car owners reported that they could only charge the battery of 8kwh, which had a severe attenuation.

Didn't I say lithium iron phosphate has a longer life? How can such a phenomenon, this is actually the battery monomer consistency problem.

In fact, most of the batteries used by byd's 2014 "qin" electric car may not have any problem when taken out individually. The battery can also restore its original performance after returning to the factory for balance, but the problem arises when the battery is put into a group.

In fact, there are two ways to solve the battery consistency problem. One is to upgrade the process, improve the level of factory automation and control accuracy.

In 2014, Qin used 27AH battery, while BYD K9 used 270ah battery. Compared with Qin, K9 has fewer problems or even no battery consistency.

Finally, we are behind Europe, America and Japan in improving battery management systems (BMS).

Compared with the model of Qin in 2014, Qin launched in 2015, because of the use of a new battery management system, in each section of the battery has been equipped with a controller to facilitate better control and additional 8 batteries (that is, the actual capacity is greater than the nominal).

Battery consistency has been addressed a lot, but in any case, lithium iron phosphate lags behind ternary batteries in terms of consistency. This game: three wins.

7. Low temperature performance

The conclusion is clear: lithium iron phosphate low temperature performance, ternary better.

Electric cars have shorter range in the winter, but the problem is worse with lithium iron phosphate batteries. But by how much?

Still need to come up with clear data to speak, for example, the new BYD e6 with a range of 400 kilometers, after entering the winter, the car owners have reported that the range can only achieve the original 60%, namely 240 kilometers.

But this can't blame the battery, all based on the simple principle of heat bilges cold shrink, we know that after entering the winter, car tire pressure decreases, and the child down is the most important reason lead to shorten life, after the owner pay attention to the tire pressure, as well as footwork, life can be restored to the nominal 70% ~ 75%, nearly 300 km range, less than the nominal 400 kilometers, 100 kilometers.

The question is where is the 100-kilometer range? The answer lies in air conditioning.

Traditional fuel car energy conversion efficiency is less than 30%, the remaining 70% of the energy in the form of waste heat distributed, into the winter, the car turned on the warm air does not need additional consumption of gasoline, just need to send the waste heat emitted by the engine to the cab.

But the electric car's electric motor energy conversion efficiency reached 90 percent, and there is no additional waste heat, if you want to turn on the air conditioning in winter, only extra consumption of energy in the battery. So the reduction in range is not entirely to blame for the low temperature performance of lithium iron phosphate.

Baic ev200, which USES a three-yuan battery, was also significantly reduced in winter. Moreover, due to the lower overall battery capacity, its original range was only 200 kilometers. After a 30% discount, it was only 140 kilometers left.

There are also a number of ways to prepare lithium iron phosphate batteries for the winter, such as nano-materials and carbon cladding, and a simpler and more efficient way to do this is to heat the battery pack.

Taken together, the effect of low temperature on the overall performance of lithium iron phosphate battery pack

But anyway, low temperature performance becomes a short board of lithium iron phosphate, this game three yuan win!

The analysis from the above seven aspects almost covers all aspects of the new energy index of power batteries. In the seven match ups, Sanyuan and iron-lithium were fiercely fought and bitterly contested, with winners and losers or even scores.

So after these 7 matches, can I, the referee, give the final conclusion? Or do you readers and viewers give your own inner judgment? Who is the deserving champion?

As a referee, after so much analysis and discussion, I can only tell you regretfully that I can't come to a better conclusion, so there are no champions or both champions in this game.

The resolution

Hear this result some people may want to be angry, ocean ocean asperses 7000 words, waste everyone so many time and affection, read here unexpectedly only got draw conclusion, I this isn't to beat? ! Wait, let's keep watching.

Although I cannot give a simple conclusion and directly tell who is better and who is worse, I can give a clear answer based on the specific application environment, because some specific application environment will highlight the advantages in one aspect and overshadow the disadvantages in some aspects.

1. Energy storage application situation

You bet! The application scenario for lithium iron phosphate won in a landslide.

Thousands of kilowatts or even tens of thousands of kilowatts of batteries are often stacked in a power storage station. If ternary batteries are used, it is equivalent to stacking tons of bombs together.

The long life of lithium iron phosphate is also in line with the application demand of energy storage. Energy storage power stations are often constructed in suburban areas, so land and space are not a problem, overshadowing the disadvantage of low energy density of lithium iron phosphate.

Especially, as an energy storage power station with frequency modulation of power grid, it often needs to charge and discharge at a high rate, and the charging rate of iron lithium also meets this demand. In the scenario of energy storage application, the disadvantage of lithium iron phosphate is no longer the disadvantage, but the advantage is very prominent.

So when we think about this application scenario, lithium iron phosphate is the undisputed champion.

2. Uav battery

Needless to say, have you ever seen a drone with iron-lithium batteries?

No doubt this is another extreme application scenario, where ternary lithium batteries account for 100% of the market share.

The inherent disadvantage of energy density means that iron-lithium batteries can never be used in drones.

In the field of uav lithium battery, ternary battery wins.

3. Electric bus and electric commercial vehicle

These cars from the heavy, large space, low sensitivity to weight, buses, buses due to the large number of passengers, high safety requirements;

These cars have long operation time and high requirements for battery life, which exactly play the advantages of lithium iron phosphate and overshadow the disadvantages of lithium iron phosphate.

Therefore, BYD, a leader in lithium iron phosphate technology, takes the lead in applying pure electric vehicles to buses, electric forklifts and electric trucks. Is with the lithium iron battery safety, high charge and release rate, long - life confidence.

Some time ago, the state suspended the catalog declaration of three-yuan battery bus. In fact, to some extent, it declared that three-yuan battery had no application in this field. In the future, electric bus and commercial vehicle field, lithium iron phosphate won.

4. Plug-in hybrid cars

The controversy in this area is small. Although lithium iron phosphate is the main driver of current electric cars, byd itself is ready to abandon this technical route.

Starting with the Qin-tang 100, BYD's plug-in hybrids will be fully converted to nickel-cobalt-manganese ternary batteries. I think the core reason behind this shift lies in the consistency of the small lithium iron phosphate battery.

In this field, three wins.

5, pure electric passenger cars

This is another battleground. First, the lithium iron phosphate used in electric passenger cars is a large monomer, each with a capacity of up to 0.82 KWH, ten times larger than the monomer used in plug-in hybrids.

The ev300, for example, has just 58 batteries, which is a fraction of the models' 7,000 batteries.

Because there are fewer cells, it pays to put a control unit on each one, thus minimizing the problem of consistency, which is less of a problem for large cells.

But that doesn't mean lithium iron phosphate wins in the all-electric passenger car business, which is far more complicated.

Due to the low density of lithium iron phosphate and its greater weight under the same capacity, the pure electric vehicle using lithium iron phosphate battery is self-significant and has high energy consumption. Compared with the 14kwh power consumption of baic ev200km, byd e500km power consumption is higher at about 16kwh.

In addition, the average daily mileage of passenger cars is 46 kilometers, which is much shorter than the average daily mileage of buses, which is 230 kilometers, and the average daily mileage of taxis, which is 400 kilometers. As a result, the long life of lithium iron phosphate cannot be brought into play.

In terms of safety, private passenger cars are not as strict as buses in terms of safety. However, this does not mean that safety can be ignored. The reason why the ternary battery pack of Tesla models weighs 900kg is that additional protection devices are needed to protect the battery pack.

In short, in a pure electric passenger car, the two battery lines are in a state of stalemate.

Since the average power consumption of 100 kilometers can be felt by everyone in daily life, and the reduction of energy consumption is the requirement and direction of the country, the two technical routes may coexist in the field of pure electric power for a long time, and ternary power is slightly superior.

To sum up the above five application scenarios, we can know that iron-lithium battery and ternary battery have different advantages in their specific fields: iron-lithium is suitable for energy storage and commercial vehicles; Ternary is suitable for plug-in hybrid vehicles, passenger vehicles, unmanned aerial vehicles and other fields.

Because our country new energy vehicle takes the lead in the commercial vehicle domain erupts, in previous years USES the iron lithium battery some more; With the deepening of the electric car revolution, passenger car sales explosion, the proportion of ternary batteries will gradually increase.

However, the two will coexist for a long time, and the leading battery companies in China will definitely choose the strategy of walking on two legs (producing both ternary battery and iron-lithium battery).

The page contains the contents of the machine translation.