Let’s compare Ternary material with LiFePo4 in 7 points:
2。 Energy density
3。 Cycle Life
5, charge rate
6, the consistency of battery cells
7. Low temperature performance
This aspect of lithium iron phosphate battery has a distinct advantage: in temperature of more than 4800C ,battery will be decomposed, through acupuncture, fire and other harsh tests.
The ternary cells, represented by nickel-cobalt-aluminum(NCM), are decomposed and released in the 1800C and react more violently.
The result of this inning is swift, lithium iron battery wins.
Lithium iron phosphate battery discharge platform voltage is lower, only 3.2V; and compaction density is very low, only 2.2 ~ 2.5 or so, which leads to the theoretical energy density of lithium iron phosphate battery is not high, only 178wh/kg.
BYD, the leading manufacturer of lithium iron phosphate battery, has now put the energy density of single cell to 147wh/kg.
The 18650 battery energy density is 245wh/kg, and the 20700 batteries used in Tesla Model 3 will have to be 300wh/kg above the energy density in the future.
Many domestic producers choose Ni-co-MN (NCM) ternary lithium battery technology line, its theoretical energy density is 280wh/kg, the DJI unmanned aerial Vehicle is using NCM battery, the current 80% of the UAV lithium battery supplied by the manufacturers in Guangdong。
In addition, lithium iron phosphate has a lower compaction density, which leads to a larger size of lithium phosphate under the same battery capacity.
To evaluate the energy density and security of these two parameters together, we can find that the energy density and security of these two indicators are a pair of natural enemies, in fact, through the simplest physics and chemical knowledge, we can know that the higher the energy density, the more unstable it, the more unsafe.
When evaluating the performance of this aspect, I got a headache.
Taking Lithium iron phosphate as an example, some articles said that the life expectancy is 2000 times, some would said that lithium battery life can reach more than 4,000 times, and even there are articles that the total cycle life can reach 20,000 times.
The discrepancy between such data makes me dizzy, and needs to be carefully screened to have a correct understanding, and later found that the above statements are "good", but they are using different criteria for evaluation.
Said the life only 2000 times, is according to 1C charge/discharge magnification repeatedly flushes, the battery capacity under the calibration capacity 80% is believed that the life terminates (this is an extremely rigorous charge and discharge test, the 1C rate means 1 hours fills the battery.
4,000 times, is more likely to be under normal conditions, according to a large number of already on-road vehicles operations measured results.
The last so-called 20,000 times is the result of the full use cycle.
Because the battery capacity is lower than the calibrated 80% does not mean that the battery is completely useless, after all, there are 80% of capacity, at this time the battery can be taken down echelon use, as a storage power station, reasonable current reasonable temperature reasonable use of the environment can be achieved 20,000 times the repeated charge and discharge。
However, the lifetime of lithium iron phosphate is significantly longer than that of ternary batteries.
Ternary battery in 1C charge/discharge rate, repeated charging/discharging about 800 times, the actual capacity has been lower than the rated capacity of 80%.
But the actual use is not so, due to the consistency of lithium iron phosphate battery is difficult to control, so that the overall life of lithium-ion battery packs a little shorter, and there is no life expectancy can reach 3 times more than the ternary battery
But anyway, the cycle life of this one, lithium iron wins。
Some people think that lithium iron phosphate cathode materials do not use rare metals, and ternary batteries to use cobalt, nickel and other more valuable metals, so it is taken for granted that the cost of lithium iron phosphate is lower, which is actually a misunderstanding of the understanding。
Discharge voltage of lithium iron phosphate 3。2V, ternary battery discharge voltage platform in 3。7V, higher discharge voltage means higher battery capacity, which means that the capacity of the ternary battery is even larger in the case of equal material consumption.
Or vice versa: the same capacity of batteries, the ternary battery consumes less raw materials。
The three-cell battery is now heading for the technical route of high alumina, nickel and low cobalt, which reduces the consumption of expensive precious metals.
But we have to look at the cost of the two in a dynamic way, and realize that the cost of lithium phosphate is slightly lower than the ternary battery before the price of lithium carbonate soars.
In a word, the cost of the two technology routes is not the same as the same, specific to a certain point in time, and upstream raw material prices have a great relationship。
This one, the two are tied.
Let's start with the conclusion that lithium iron phosphate is a big lead in the charge/discharge rate。
American A123 Inc. (now a universal subsidiary) even made a 25C rechargeable lithium iron phosphate battery in the lab (25C charge means 60÷25=2。4 minutes to fill the battery)。
In terms of charge and discharge rate , lithium iron has won a large victory.
In the battery pack of the Tesla Model S with nickel-cobalt-aluminum ternary, there are 7000 small batteries in series and parallel, and if there is a problem with the consistency of the battery, the consequence is disastrous because the battery has a cask principle and the worst performance of the battery affects the overall performance of the battery pack.
However, the use of lithium iron Phosphate 2014 Qin Hybrid train has been a problem, the calibration of 13kwh battery, the use of more than a year after a lot of car owners in the reflection can only charge in 8kwh of electricity, attenuation。
I am saying that lithium phosphate iron has a longer lifespan, How can this phenomenon appear, this is in fact the problem of the consistency of the single cell。
In fact, BYD 2014 "Qin" electric vehicles battery, most single cell doesn’t have problems, problem comes out when cells grouped.
In fact, the problem of battery consistency is not a dead problem, there are two ways to deal with it, one is to upgrade the production process, improve the level of factory automation and control accuracy.Another is to enlarge the cell capacity, 2014 Qin uses 27AH battery cell, and BYD K9 is using 270ah capacity of single battery cell, compared to the Qin, K9 the problem of a lot less ,even there is no battery consistency problem.Finally, improve the battery management system (BMS), which we do lag behind in Europe and America.
Compared to the 2014 Qin, the 2015 launch of the Qin due to the use of a new battery management system, in each section of the battery installed on the controller to facilitate better control and extra 8 batteries (that is, the actual capacity of the nominal).
The problem of battery consistency has been solved a lot, but in any case, in terms of consistency, lithium phosphate is lagging behind a ternary battery. This inning: ternary win。
This conclusion is very clear: lithium iron phosphate low temperature performance, ternary better。
The above 7 aspects of the analysis, almost covering the power battery new energy indicators in all aspects, in seven games, ternary and lithium iron fierce fight, the pain of competition, each other, there is a tie.
So after the 7 games, can I give the final verdict? Or do you readers or viewers give your own inner judgment? Who is the worthy champion?
As a referee, can only regret to tell you that I can not say who better conclusion, so this field DA no champions or are champions.
Hear this result some people may want to be angry, eloquent 7000 words, wasting everyone so much time and feelings, read here unexpectedly only got draw conclusion, I this is not owe beat?! Wait, we'll see.
Although I can not give a simple conclusion, directly say who gifted who inferior, but the combination of specific application environment, there will be a clear answer, because some specific application environment, will highlight some aspect of a bit, shielding some aspects of the disadvantage.
1. Storage and Energy application situation
That's a word! The application scenario of lithium iron phosphate was overwhelmingly victorious。
The energy-storage power plant is stacked on thousands watts, and if you use a ternary battery, it is equivalent to piling tons of bombs together.
The long life of lithium iron phosphate is also in line with the application demand of energy storage, the power plant tends to be in the suburb construction, the land as well as the space is not a problem, obscuring the low power density disadvantage of lithium iron phosphate.
In particular, as a power grid FM energy storage power station, often need large-scale charge, lithium iron charge/discharge rare also meet this demand。 Under the scenario of energy storage application, the disadvantage of lithium iron phosphate is no longer a disadvantage, but the advantage is very prominent。
So, when we consider this scenario, lithium iron phosphate is the undisputed champion。
2. UAV Battery
Does this mean that you've seen drones using lithium-iron batteries?
There is no doubt that this is the extreme of another application scenario, in which lithium-ion batteries account for 100% of the market share.
The natural disadvantage of energy density, it is determined that lithium iron batteries can never be used in unmanned aerial machines.
UAV Lithium battery field, triple battery。
3, Electric bus and electric commercial vehicle
These vehicles from the major, large space, low sensitivity to the weight of buses, buses due to the large number of passengers, high security requirements;
These vehicles operate long hours and require high battery life, and these features just give the advantage of lithium phosphate, obscuring phosphorus
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