The competition in the electric vehicle market has always been a
battlefield without smoke, just like a crowd of heroes vying for victory in the
Central Plains. Those who win occupy the market, and those who lose are
eliminated by the market. In this competition, battery energy density is a key
technology. In ternary lithium batteries, the current mainstream cathode
materials are NCM or NCA. How to improve their energy density has become a hot
topic in recent years. Nowadays, the 811 battery stands out, with a single cell
even exceeding 300Wh/kg? What is energy density? What impact does it have on new
energy vehicles? Energy density refers to the energy that can be released per
unit mass, and the unit is expressed in Wh/kg. The concept of 300Wh/kg means
that 1kg of lithium battery can release 300Wh of energy.
If this is not intuitive yet, 300Wh is equivalent to 0.3kWh, which is 0.3
kilowatt hours of electricity. It can light up the 30W light bulb at home for 10
hours and charge the mobile phone 30 times. The energy contained in a lithium
battery pack in a vehicle can reach 100kWh or even higher. Higher energy density
can obviously effectively reduce the weight and size of the battery pack. This
can not only improve acceleration performance, but also reduce power consumption
per 100 kilometers. That is to say, when the volume of the battery compartment
remains unchanged, the energy density is higher and the energy of the battery
pack is higher. What is the current energy density of lithium batteries?
Currently, mainstream lithium batteries mostly use ternary lithium batteries.
According to the different proportions of nickel, cobalt, and manganese,
nickel-cobalt-manganese ternary lithium batteries can be subdivided into type
111 and type 523. , 622 type and 811 type, etc. Nowadays, 523 and 622 type are
the main ones, with a single energy density of 200Wh/kg. The 811 battery broke
through 300Wh/kg in one fell swoop, which is equivalent to a 50% increase in
energy density. This is equivalent to a battery compartment of the same size,
which can carry more lithium batteries or significantly reduce the quality of
lithium batteries.
What exactly is an 811 battery? NCM811 is a ternary lithium battery with a
cathode material of nickel, cobalt and manganese and a content ratio of
80%:10%:10%. It is currently the lithium battery with the highest energy density
and highest technical content. Due to the high technical barriers to NCA
batteries and Japanese companies monopolizing the NCA material market, most
Chinese battery manufacturers choose the NCM route due to multiple factors.
Why develop 811 battery?
First, the main purpose is to increase energy density. The nickel component
can increase the activity of the material and increase the energy density. So go
the high nickel route. The cobalt component is also an active substance, which
can stabilize the layered structure of the material, thereby increasing the
discharge capacity of the material. The manganese component plays a supporting
role in the material and provides stability during the charge and discharge
process.
Second, it must be cost, because the cost of cobalt has been rising.
Reducing the cobalt content can reduce production costs. After using 811
batteries, the general cost can be reduced by 8%. Taking Model 3 as an example,
the 2170 battery cell it uses reduces the cobalt content required in the cathode
material to less than 10%, which is lower than the cobalt content in the
next-generation NCM811 batteries produced by other battery manufacturers. This
breakthrough reduced Tesla's demand for cobalt by 59%. While increasing the
energy density, it also reduces the manufacturing cost of 2170 battery
cells.
Third, it is mainly policy guidance. National policies continue to use
power battery energy density as a key indicator to guide the development of the
new energy vehicle industry, and at the same time directly link new energy
subsidies to power battery energy density. In addition, according to the "Medium
and Long-term Development Plan for the Automotive Industry", by 2020, the energy
density of a power battery cell will reach more than 300Wh/kg, and it will
strive to achieve 350Wh/kg and the cost will be reduced to less than 1 yuan/Wh.
Therefore, under these three pressures, the development of 811 is unstoppable.
What are the risks of 811 batteries? At the same time, we cannot ignore the
possible hidden dangers of 811 batteries. As the nickel content increases, the
stability of the cathode material decreases.
The main manifestations are capacity loss due to cyclic charge and
discharge and accelerated attenuation of capacity in high temperature
environments. On the one hand, this means that the service life of the 811
battery is reduced, and on the other hand, the risk of spontaneous combustion
caused by thermal runaway increases. Which models now use this kind of battery?
The new BMW X1 PHEV model is a plug-in hybrid model, not a pure electric model.
BMW Brilliance X1 is also the first model to be officially equipped with 811
batteries. To know how much NCM811 has improved it, it is enough to see the
improvement in its cruising range. The energy density of the battery core is as
high as 280Wh/kg, the power capacity of the new model has increased from 14.7KWh
to 24KWh, and the pure electric cruising range has also increased from 60
kilometers to 110 kilometers.
For a plug-in hybrid model, this is already a qualitative leap. The pure
electric range of 100km allows most usage scenarios to be driven by pure
electricity. At the same time, the greater the energy of the battery pack, the
greater the discharge power, and the opportunity for the engine to intervene.
Just less. For details, please refer to the BMW X1 plug-in hybrid long-range
version, which is priced at 393,800 yuan. GAC AionS is GAC's initiative model
this year. Its cruising range has exceeded 500km. Under NEDC operating
conditions, the cruising range has reached 510km. Many reasons for this are that
the Aions has increased power. Under the same battery compartment
specifications, 811 batteries The energy density is higher, and the battery
system energy density reaches 180Wh/kg. The battery pack energy is 58.8kWh. This
enables it to break through the 500km endurance mark. For details, please refer
to the price after subsidy of 139,800-205,800 yuan. GAC New Energy AionS is
officially launched. The NIO ES6 is NIO's second model and was released at the
end of last year. The car is equipped with an 84kWh liquid-cooled
constant-temperature battery system. The ES6 also uses CATL's NCM811 battery.
The system energy density reaches 170Wh/kg, and the cruising range reaches 510
kilometers under NEDC operating conditions.
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