Electric vehicle companies get
together to engage in CTC technology, what is the difference?
Among the new energy vehicles in
the head, Tesla explained the CTC technology as early as the 2020 Battery Day
event, believing that this technology can save 370 body parts and
reduce the body weight by 10%, while the other head Part of the player BYD also
released this year CTB technology (essentially still CTC technology).
The leading player in the power
battery industry, CATL, is also actively developing CTC technology. Cai
Jianyong, the former general manager of Huawei\’s smart car solution BU
intelligent vehicle control field, joined CATL and will fully promote the CTC
battery-chassis integration business.
The domestic new car company
Leapmotor also officially announced its CTC technology in April, which can
increase the battery life of its first sedan C01 to more than 700 kilometers.
In addition, Nezha, Volkswagen,
Volvo, and other car companies will make efforts in CTC technical methods, and
Nezha Auto has made it clear that this product will be launched next year.
Judging from the actions of these
car companies, CTC technology has undoubtedly become one of the hottest
topics in the power battery field this year.
With the development of new
energy vehicles, the development of power batteries has reached the ceiling,
and a solution is urgently needed. From the perspective of chemical
materials, the ceiling of ternary lithium batteries is gradually emerging,
while solid-state batteries still have a long way to go before mass production.
Under this circumstance, new energy
vehicle industry giants such as Tesla and BYD and power battery giants such as
CATL have begun to make layouts at the level of battery packaging technology.
Judging from the actions of many
car companies and battery companies, the current leading car companies in the
new energy vehicle field have joined the CTC army. In the foreseeable future,
this technology may become the main power battery packaging technology.
So, what are the main
difficulties of CTC technology? What are the main technical paths? What
are the main paths adopted by the car companies that have been released so far?
01. It is also difficult to
redesign the body structure of the integrated battery
First of all, let\’s briefly
understand the CTC technology, its full name is Cell to Chassis, that is,
the cell to the chassis. Literally understood, it is to place the
battery directly into the vehicle chassis, which is different from the previous
design of the separation of the chassis and the battery pack.
The reason for this is
mainly to increase the energy density of the battery by improving space
utilization. After integrating the cells directly into the chassis,
a lot of materials can be saved, and the volume of the battery cells that can
be installed is correspondingly expanded. By adding more cells, car companies
can increase the volumetric energy density to achieve longer battery life
On the other hand, the cost of
the power battery is also reduced due to the saving of more materials.
From the above description, CTC
technology does have many advantages, but the fact that there is no mass
production at present also shows that this technology still has certain
On the whole, there are multiple
core technical points in CTC technology.
First, Cell to Chassis means that
the traditional vehicle chassis structure needs to be changed.
A body engineer told the car that
to save costs, most car companies will directly take the battery pack
from the supplier, and then design the body structure according to the battery
The body, battery pack, and
chassis form a sandwich structure, and the battery pack is located
between the body and the chassis, that is to say, the battery pack is always
under the protection of the body structure and will not be directly subjected
to external impacts.
The CTC technology integrates the
cells directly into the vehicle chassis, and the battery pack becomes a part of
the chassis. The inner bottom plate of the compartment serves as the upper
cover of the traditional battery pack, and the cells and the lower tray are
stuffed into the body, making the battery pack also become One of the stress
structures of the body.
This makes the traditional mode
of designing the body and battery pack separately no longer applicable.
The body designer must take the layout of the chassis cells into consideration
when designing the body from the very beginning, which is a big deal for most
body designers. \’s tests.
On the other hand, CTC technology
also has a certain impact on the flexibility of body design. Large-scale
car companies, they will design a general car platform, which can be extended
to various models. The changes are operations such as lengthening and
However, after the CTC technology
is adopted, when the body structure changes, the battery structure of the
chassis will also change, which will eventually lead to an increase in the
More importantly, after the
battery cell and the chassis are integrated, the cost and technical difficulty
of maintenance will also increase.
From this point of view, one
of the most critical technologies of CTC is the design of the body structure.
Then let\’s turn our attention to
the battery pack itself. A very important element of CTC technology is to
completely cancel the module and pack and directly integrate the battery into
This also means that the battery
cells need to be directly laid in the vehicle chassis, and without the
protection of the module and the PACK structure, the cells need to be insulated
In addition to some necessary
designs for cells, battery thermal management and other aspects also need to be
The cells and the cells are
directly arranged together, which means that once a cell is thermally out of
control, it is easy to conduct to adjacent cells, resulting in a thermal runaway
of the entire battery.
When designing, it is necessary
to consider where the water-cooling plate is placed and how to design the
pressure relief valve. These issues are directly related to the safety of the
vehicle and passengers, so the design in this aspect must not be sloppy. The
BMS design of the entire battery pack is also very important.
Overall, if you want to use CTC
technology, it will have a certain impact on the structural design of the body
and the design of the battery pack. These main difficulties have become the
most critical aspects of CTC technology.
02. Divided into two ways, both
have reached the eve of mass production
At present, CTC technology is
still relatively new, and only a few car companies have displayed their own
solutions and products, and most car companies have not yet exhibited products.
Judging from the products that
have been released, there are two main forms of CTC technology. One is the
method currently adopted by many car companies – integrating the battery
directly into the vehicle chassis.
This method is a bit close to the
development idea in the field of smartphones: from the beginning, the
battery is detachable and the battery is integrated.
Specifically, car companies
directly cancel the upper plate structure of the battery pack, or use the inner
bottom plate of the vehicle as to the upper plate structure of the battery pack,
and then arrange the cells on the tray, and combine the tray and the inner
bottom plate of the body to form New body structure.
The seat of the vehicle can be
directly installed above the battery pack to further expand the space structure
of the body, and more cells can be added to the battery layout, thereby
improving the battery life.
So, how does this approach deal
with technical challenges? In this regard, the strategies of different car
companies are different. In terms of body structure, Tesla has changed the body
structure by adopting the front and rear integrated die-casting technology. The
front and rear two large pieces can be directly spliced into the
vehicle chassis, which can pre-empt the space of the chassis in advance. Keep
it ready for cell integration.
And BYD also adopts the
brand-new model platform e3.0, although it is not clear how BYD does it,
the body structure will also be adjusted on the new model platform.
In terms of heat dissipation,
most of the water-cooling plates are still used to dissipate heat. In Tesla\’s
solution, the water-cooling plate is placed directly above the battery cells,
which is convenient to block the heat of the battery cells from being uploaded
to the cockpit, and the pressure relief of the battery pack. The valve is under
the battery cell, which further ensures the safety of the battery
pack. Low-density glue is used between the cells to reduce the risk of
heat conduction between them.
In the zero-run solution, a
water-cooling plate and a thermal insulation layer are used under the
battery core, and a thermal insulation layer is also used on the top of the
battery core to prevent heat from rising to the interior of the cockpit.
The other is the skateboard
chassis, which covers CTC technology, wire control technology, etc., completely
decouples the driving system and steering system of the vehicle chassis from
the passenger compartment of the vehicle, and the chassis and body are directly
Che Dongxing has previously
watched the skateboard chassis designed by Yopao Technology. Through the remote
control device, the vehicle chassis can freely complete a series of
instructions for forwarding and backward, and even automatic parking.
This design method is similar to
the non-load-bearing structure in the era of fuel vehicles, where the chassis
and body are separated. But the difference is that this skateboard chassis
is more powerful and can be said to be the soul of the vehicle.
As long as the chassis and the
body reach a consensus communication agreement, various models can be
manufactured based on the skateboard chassis.
Thanks to the previous experience
in non-load-bearing body structure design, it does not require much effort to
redesign the body after adopting the skateboard floor, and can almost copy the
previous non-load-bearing body design scheme.
The battery pack structure and
heat dissipation are particularly critical to the skateboard chassis. Lucid CEO
and CTO Peter Rawlinson have explained how to protect and dissipate heat from
the skateboard chassis. He believes that the combination of the battery
pack with the body shell of the vehicle can increase the structural rigidity of
the car, make the car more convenient to operate, stabilize the central structure
of the collision buffer zone at the rear of the car, absorb energy, protect
passengers from collisions, and also protect Battery.
In Lucid\’s solution, the cells
are basically installed upside-down, the battery is cooled downwards, and there
is an additional layer of coolant.
However, this technology has not
yet achieved mass production. The head companies Rivian and Lucid are currently
in the stage of ramping up their production capacity and have not been able to
complete large-scale delivery. In addition, other skateboard chassis
companies have not achieved mass production.
On the whole, the direct
integration of batteries into the chassis has become a common choice among car
companies. Therefore, the number of car companies currently making
efforts in CTC technology has also increased significantly.
Tesla, BYD, and Leapmotor have
released their own CTC solutions. Volkswagen and Volvo have also proposed CTC
solutions in 2021, which will be put into mass production in the future, and
Nezha Motors is also at its battery sharing meeting and Said that it will launch
CTC technology next year.
In terms of battery companies,
CATL proposed to develop CTC technology as early as August 2020. At present, it
has also welcomed the participation of Huawei car BU executives, and its
mass-produced products should also be unveiled soon.
In addition, other power battery
companies such as Honeycomb Energy have also accelerated the layout in this
At present, CTC technology may
really become an important breakthrough point in battery technology, which is
very important for alleviating battery life anxiety and improving battery
03. The three auto companies have
released their main strategies that are similar
Although many car companies have
announced their own CTC plans, at this stage, only Tesla, BYD and Leapmotor
have released products, and there are already many product maps.
From the perspective of product
design, these three car companies all chose the first form above and directly
adopted the CTC technology. However, in terms of design details, there are
some differences in the strategies of the three companies.
The following mainly compares the
schemes of Tesla, BYD, and Leapmotor from three aspects: structure, cell
integration, and manufacturing process.
Structurally, Tesla may be the
company that has made the most radical changes. According to the pictures
from Tesla\’s Berlin factory and Texas factory, its CTC technology has
completely opened up the connection between the battery pack and the carriage.
There is a beam above the battery
pack, the front seats are directly mounted on the beam, and the fixed structure
of the rear row has nothing to do with the battery pack.
In this way, the downforce of the
two front seats is directly borne by the battery pack, and the force of the
foot positions of the front and rear passengers is also directly borne by the
The plans of BYD and Leaprun are
relatively close. The pictures displayed by Leapmotor at the press
conference show that its CTC solution still retains the skeleton ring beam
structure on the body of the original vehicle chassis.
The upper plate of the battery
pack is directly welded to the structural beam of the chassis, which is
equivalent to both the bottom plate of the carriage and the upper plate
structure of the battery. The vehicle seats are mounted directly to
the structural beams of the body. The battery pack is only responsible for
the foot space of the front and rear passengers.
Judging from the exposed
pictures, the designs of BYD and Leapmotor are very similar. They also combine
the bottom plate of the carriage and the upper plate structure of the battery
into one, and the design of the seat is also similar.
Although Tesla, BYD, and Leapmotor
have slightly different plans, there is no good or bad between them.
In these solutions, the passengers
in the car are only separated from the battery cell by the upper plate
structure of the battery. Therefore, the three-car companies need to make a
buffer design to avoid direct pressure on the battery cell when the car owner
vigorously steps on the bottom plate, reducing unnecessary trouble.
On the other hand, it is also
very necessary to add thermal insulation material above the battery cells, to avoid thermal runaway and heat transfer to the passenger compartment for
the first time.
In addition to the body
structure, cell integration is also a very critical point, which is also
the biggest difference between the three car companies.
Let’s start with Tesla. Tesla’s
batteries are already very clear. Whether it’s the pictures shown at the Berlin
factory or the pictures shown at the Texas factory, its CTC technology is
closely connected to the 4680 batteries.
Tesla mainly arranges and
combines 4680 cells on the chassis. There are no modules inside. At first
glance, it is full of dense 4680 cells. According to the pictures shown by
Tesla, there are about 34 columns in one column, divided into 24 columns in
total, with a water cooling plate in the middle for heat dissipation.
From this point of view, Tesla
has truly implemented Cell to Chassis.
At present, BYD has not exposed
the internal pictures of the CTC battery, but according to the previous design
of the dolphin battery pack, it can be guessed that its approach is similar to
that of Tesla, and the blade battery is directly integrated into the chassis.
Unlike Tesla\’s cylindrical
battery, BYD\’s blade battery is longer, almost traversing the body, and the
module has been canceled in the CTP era. At present, the blade battery will likely be directly integrated into the chassis.
The zero-run approach is slightly
different. From the structural diagram, Leapmotor\’s CTC adopts the method
of integrating modules into the chassis and adopts 7 large modules, which saves
a limited number of parts and does not achieve the best space utilization.
So from this point of view,
ZeroRun’s strategy is more like MTC than CTC.
However, this is also inseparable
from the fact that Leapmotor did not participate in the development of
batteries. BYD has been using its own batteries. Tesla has also been actively
producing 4680 batteries recently. The advantage of self-producing batteries is
that these two companies are in When developing CTCs, you can develop them
in advance according to your own cell standards.
For Leapmotor, there is currently
no ability to produce batteries by itself, and the main thing is to buy
batteries from suppliers, and it is more efficient and convenient to directly
From the manufacturing process
point of view, Tesla has innovated the manufacturing process and adopted the
front and rear integrated die-casting technology, which complements the CTC
technology and can manufacture the body more efficiently. Without much change,
it is also possible that one-piece die-casting technology will be introduced in
On the whole, Tesla and BYD\’s CTC
are more thorough in terms of structure and overall design, while Leapmotor
cannot integrate cells, and there is still a lot of room
But these three car companies
have already taken a critical step, and I believe that more car companies will
join these ranks in the future.
04. Conclusion: battery
technology innovation is imminent
In the current field of new energy
vehicles, the power battery is still a very important component and even
determines the lower limit of an electric vehicle. But at present, its
development has encountered a certain bottleneck, and it has never been able to
make further breakthroughs.
Car companies and battery
vehicles mainly look for solutions from two aspects. One is to start from the
chemical system, develop new chemical systems, and develop solid-state
batteries, but the progress is not obvious.
Another method is to pack more
cells into a unit volume by improving the packaging process. On this path,
car companies and battery companies have launched CTP technology, that is, cell
to Pack, which cancels battery modules; at this stage, CTC technology has been
But this is not enough for the
current battery industry. In the case that the price of raw materials continues
to skyrocket, it is also necessary to promote the innovation of battery