Aug 23, 2019 Pageview：122
1. Lithium iron phosphate battery: it refers to the lithium ion battery with lithium iron phosphate as the positive electrode material. The anode materials of lithium ion battery mainly include lithium cobalt acid, lithium manganese acid, lithium nickel acid, ternary materials, lithium iron phosphate and so on. At present, lithium cobalt oxide is the anode material used in most lithium ion batteries.
2. Ternary polymer lithium battery: it refers to the lithium battery with lithium nickel-cobalt-manganese ternary positive electrode materials for positive electrode materials. There are many kinds of positive electrode materials for lithium ion batteries, mainly including lithium cobalt acid, lithium manganese acid, lithium nickel acid, ternary materials and lithium iron phosphate.
3. Reflect the different materials, USES and processes of the two.
A battery is a device for converting and storing energy by means of a reaction that converts chemical or physical energy into electrical energy.
A battery is a kind of chemical power supply. It is composed of two electrochemically active electrodes of different components, which are respectively composed of positive and negative electrodes. The two electrodes are immersed in an electrolyte that can provide media conduction.
The material system of lithium iron phosphate battery is different from that of ternary battery. Lithium iron phosphate is a 3.2v voltage platform with a cycle life of more than 2000 times. Ternary battery is a 3.6v voltage platform. The high-temperature performance of iron-lithium battery is good, and the low-temperature performance of ternary battery is good. In terms of safety, iron lithium is better. Some discharge data, can consult.
Although domestic subsidies for new energy vehicles have begun to decline, consumers are also embracing the popularity of new energy vehicles due to the increasingly rich infrastructure and a growing variety of alternative models. In addition to being an alternative solution to the problem of being unable to buy fuel powered vehicles in restricted areas, new energy vehicles also have many unique advantages. Quiet driving environment, clean energy type and low car costs, even including the start of the instant output of large torque, can let many around the fuel car driving friends envy.
As the source of power for electric vehicles, the battery is naturally one of the most important parts. Battery life, charge-discharge and other USES of electric vehicles are also closely related to the performance of the battery. At present, the domestic power battery is mainly divided into two factions, according to the different anode materials are divided into lithium iron phosphate pie and ternary materials pie. Although both of them are secondary batteries and can be used for charging and discharging repeatedly, due to the difference in materials, the performance reflected in the final use level is quite different.
To figure out which battery is better, we should first have a simple understanding of the difference between the two.
The so-called lithium iron phosphate battery refers to the lithium ion battery with lithium iron phosphate as the positive electrode material. This type of battery is characterized by the absence of precious metals (such as cobalt). Without precious metals, the raw material cost of a lithium iron phosphate battery can be compressed very cheaply. In practical use, lithium iron phosphate battery has the advantages of high temperature resistance, strong safety and stability, low price and better cycle performance.
The ternary lithium battery is a lithium battery which USES lithium nickel-cobalt manganate as the positive electrode material and graphite as the negative electrode material. Unlike the lithium iron phosphate, the ternary lithium battery has a high voltage platform, which means that at the same volume or weight, the ternary lithium battery has more specific energy and more specific power. In addition, ternary lithium batteries also have great advantages in high power charging, low temperature resistance and other aspects.
I always believe that there is no good or bad technology, but suitable for different products or environment. There is no such thing as a better or worse battery. Just to put it into context, ternary lithium batteries are better suited to today's and tomorrow's electric cars than lithium iron phosphate batteries.
China has a vast territory and a complex climate. The temperature variation is very rich from the three northeastern provinces in the north to the hainan islands in the south. In Beijing, for example, as the main electric car market, Beijing summer high temperature around 40 ℃, while winter is basic about 16 ℃ below zero, even lower. Such a temperature range is obviously suitable for low-temperature performance of better ternary lithium batteries. The high-temperature performance of lithium iron phosphate battery in Beijing in the winter will appear a little weak.
"Relative capacity of 25 ℃" refers to the different temperature conditions to devolve electricity capacity and 25 ℃ when the ratio of discharge capacity. This value can accurately reflect the attenuation of battery life at different temperatures. The closer to 100%, the better the battery performance.
Can see from the above, 25 ℃ as a benchmark in normal temperature, two types of cells in 55 ℃ high temperature lowering electricity and room temperature 25 ℃ to devolve electricity, almost no difference between the discharge capacity. But at 20 ℃ below zero, the ternary lithium battery and lithium iron phosphate battery has obvious advantages compared.
Higher energy density
According to the data provided by bick battery, the leading enterprise of 18650 cylindrical battery with terna-materials in China, the energy density of its 18650 battery has reached 232Wh/kg, which will be further increased to 293Wh/kg in the future. By contrast, the energy density of domestic mainstream lithium iron phosphate battery is only about 150Wh/kg at present. According to the analysis of domestic battery industry experts, the hope that the energy density of lithium iron phosphate battery can reach 300Wh/kg in the next few years is very slim.
Unlike the bulky electric bus, for the home electric car, space is always the first. The lithium iron phosphate battery with lower energy density will take up less space in the car, and because of its heavier mass, its battery life will be greatly affected when it is used. Relatively high energy density ternary lithium battery solves the weight problem and saves space for the family car at the same time.
Higher charging efficiency
In addition to battery life, charging is also an important link in the actual use of electric vehicles, and ternary lithium battery has a great advantage over lithium iron phosphate battery in charging efficiency.
At present, the common charging method in the market is constant current and constant voltage charging. In general, constant current charging is adopted at the beginning of charging. At this time, the current is larger and the charging efficiency is relatively higher. After the voltage reaches a certain value, the current is reduced to a constant voltage charge, which can make the battery charge more full. In this process, the ratio of constant current charging capacity to the total battery capacity is called constant current ratio. It is a key measure of a battery's charging efficiency during charging. Generally, a larger percentage indicates that the charge in the constant current stage is higher, which also proves that the charging efficiency of the battery is higher.
As can be seen from the table, when the ternary lithium battery and lithium iron phosphate battery are charged below 10C, there is no obvious difference in constant current ratio. When the multiple rate is charged above 10C, the constant current ratio and charging efficiency of lithium iron phosphate battery decrease rapidly.
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