Bitauto Original In the context of the second- and third-wheel wave and the increasingly mature new energy market, more and more car companies have begun to enter the pure electric MPV market. SAIC Motor is focusing on medium and large families. MPV Roewe's iMAX8 EV has started pre-sales some time ago and has now entered the countdown stage for launch, with the market popularity also being very high. But in the eyes of users, no matter how high the demand for a pure electric vehicle is, the battery life and safety must be the focus of attention. So, can the SAIC Rubik's Cube battery equipped with Roewe iMAX8 EV be called "reliable"? Why is it said to be "winning" all the way? Let's talk.
Basic information on SAIC Rubik's Cube battery
Battery pack size: length, width and height are 1690mm*1300mm*110/125/135mm
Arrangement method: 96 strings, 100 strings, 104 strings, 108strings
Density system: low (sodium ion, lithium iron phosphate, M3P), medium (5 series, 6 series, high nickel three Yuan), high (silicon carbon anode, semi-solid)
Energy density: low (44/51/64/70kWh), medium (64/77/90/100kWh), high (115/135 /150kWh）
In fact, when MG MULAN was released recently, it highlighted SAIC Nebula’s exclusive pure electric platform and “ultra-thin flat screen” Rubik’s Cube battery. They will be a powerful weapon for SAIC to compete in the electric vehicle market in the next few years. The English name of the Rubik's Cube battery is also called ONE PACK. As the name suggests, it is the standardization of battery packs. It is the basis for a large-scale universal battery replacement model. From the basic information, it is easy to see that a major feature of the Rubik's Cube battery is modularity. The length and width of the battery pack are fixed. The dimensions are unified through the ONE PACK platform design and a separate patented battery replacement structure. All battery packs can be quickly replaced and interchanged on the same quick-change device.
At the same time, because the length and width of the battery pack are fixed, after the energy density and grouping rate reach the limit, the only way to increase the capacity is to increase the thickness. So“Cube ” battery provides three different battery module thicknesses for different battery capacities, 110mm, 125mm, 13 5mm. The thicker the battery, the more cells it can accommodate. (Note, this is the key point. Other battery packs mainly increase the capacity by increasing the horizontal area, and the thickness is generally not easy to change. Why can the Rubik's Cube battery do this? )
RoeweiMAX8 EV uses a battery pack with a thickness of 125mm. The energy density of the battery pack reaches 195Wh/kg and the battery capacity is 90kWh, CLTC has a cruising range of 550-570km, and 30-80% fast charging only takes 30 minutes. In terms of power, it is equipped with a high-performance front-drive motor with a maximum power of 180kW and a maximum torque of 350N·m, which is comparable to mainstream fuel vehicles The power level of the 2.0T engine. With such power and endurance performance, it is foreseeable that Roewe's iMAX8 EV will also be competitive among mainstream medium and large pure electric MPVs, and it will not be difficult for most people to satisfy most people's weekend self-driving trips in the suburbs. .
The killer feature of Rubik's Cube batteries - lying cells
There are currently three common battery technology solutions: CTP (Cell To Pack) technology represented by CATL, and CTB (Cell To Body) technology, and CTC (Cell to Chassis) technology represented by zero running. However, in order to realize the foundation of CTC and CTB, it is also necessary to complete the CTP technology first. Regardless of BYD Blade Battery, Great Wall Motors " Dayu Battery ", or GAC " Magazine Battery ", Essentially they all belong to CTP technology.
Previously, there were two main routes for CTP technology: one was to cancel modules, such as BYD blade batteries; the other was to integrate small modules into large modules. This solution is represented by CATL. . But now there is a third technical route, which is SAIC's "Magic Cube Battery" which is famous for its ultra-thin flat screen.
The biggest advantage of the Rubik's Cube battery that can achieve "free thickness" is the lying type battery cell. Previously, almost all electric vehicle battery components on the market used a vertical cell layout internally. Placing the cells "lying" would bring huge problems to the structural design and development. Because the structural adhesive will expand with the battery core and the pressure plate will deform accordingly, it will face harsh stress conditions and need to match the ultra-long life cycle of the battery core, which poses a huge challenge to the performance of the structural adhesive.
It is said that CATL has also discussed the layout of lying battery cells before, but due to too many challenges in structure and cooling, it is still at the conceptual level. SAIC Rubik's Cube Battery has also developed and tested more than a thousand structural adhesive solutions. After 20,000 hours of reliability verification, it finally determined the structural adhesive formula to achieve a flat battery cell.
The overall structure of the lying cell battery pack is still based on the design concept of CTP. The two sides of the cell are separated by expansion sheets and aerogel, and the front and rear are separated by cooling plates and structural plates. The top of the cell There is a special pressure plate and a tray-like device at the bottom.
As can be seen from the figure, after the battery core changes from an upright layout to a flat layout, the number and amount of materials placed on the side to alleviate expansion and insulate (mainly expansion compensation sheets and aerogels) will be reduced, and the overall The thickness of the package is as low as 110mm, which increases the vehicle space and increases the energy density. Zhu Jun, deputy chief engineer of SAIC and general manager of Geneng, believes that the biggest feature of lying-type batteries is the ultra-high level of integration, which greatly improves the space utilization of battery packs.
But there is a question here. The energy density and volume of the battery core are fixed. Why is the integration level higher when placed lying down than when placed upright, and the energy density of the battery pack is higher? As can be seen from the figure below, in traditional vertical batteries, only the green part accommodates electrochemical materials, and the rest of the space is used for structural parts and other components, while the horizontal battery mainly utilizes the horizontal space.
According to SAIC, the horizontal structure design will make full use of the horizontal space. The Rubik's Cube battery uses NCM523 cells but can achieve the energy density of NCM811 cells. CTPThe group efficiency reaches 79.6%. Everyone should know that the monomer energy density of NCM523 is only 200Wh/kg, while the monomer energy density of NCM811 is as high as 300Wh/kg span>, this is that the monomer energy density gap is evened out by a higher integration system Pack.
In addition, the lying layout can also extend the battery life. The traditional vertical battery cell method places the battery core in an iron cage with a rigid frame. As the battery core ages and expands, the stress conditions will deteriorate sharply, and the battery core can only bear greater pressure in a limited space. Tight force. The lying cell structure adopts a flexible constraint method and is combined with a special cell pressure plate, which can adapt to the expansion of the cell, greatly reducing the force on the cell, thereby increasing the cycle life of the cell. It is said that the longest battery pack is the 64kWh battery pack, with a lifespan of 12 years and 1 million kilometers.
Where is the battery of Roewe iMAX8 EV ahead?
It solves the problem of energy density of traditional CTP batteries, and returns to the safety level, but it is still the lying-type battery cells that make the difference. At present, domestic car companies mainly make plans around iron lithium. The cells are erected and a certain thickness of insulation material is added, and the heat dissipation is placed in the middle. The bottom of the cells is cooled through a long water-cooling plate similar to Tesla battery packs. However, the contact area between battery cells is large. Once the battery core experiences thermal runaway, heat will continue to accumulate and ignite the entire battery pack, causing a chain reaction.
The lying cells of the Rubik's Cube battery can reduce the effective contact area between the cells and reduce the heat transfer channel through a unique lying arrangement design; the airgel flame retardant material can effectively achieve physical heat isolation to ensure Thermal runaway of a single cell will not affect the surrounding adjacent cells, and will only burn the upper and lower cells at most.
At the same time, there is also a 7*24-hour remote monitoring system that can detect thermal runaway in advance. The advance cooling system can remotely monitor thermal runaway and turn on maximum power heat dissipation during the brewing period; automatic pressure relief and explosion-proof valve Through active pressure relief, the pressure in the battery pack is released to cool down the overheated gas and prevent gas injection.
According to the official acupuncture experiment on the Rubik's Cube battery, after the steel needle penetrated the battery pack and triggered thermal runaway, the punctured battery pack smoked, but there was no fire, explosion, or heat spread. Double needles are used at the same time to prevent open flames from coming out of the bag for a long time. The protection level can also reach the IP68/IP69K level, making it easy to achieve full-area waterproofing.
According to the 2020 National Battery Safety Standard GB 38031-2020 "Safety Requirements for Power Batteries for Electric Vehicles": After the battery cells heat out of control, the battery system becomes thermally out of control. The protection time is 5 minutes. The manufacturer stated that the Rubik's Cube battery has L0 level thermal runaway prevention technology.
In addition, with the support of CTP, high voltage, ultra-thin substrate and other technologies and the lying battery solution, the thickness of the Roewe iMAX8 EV battery pack is only 125mm< /span>, from the overall effect, while not occupying the space in the car and ensuring the passability of the chassis, it can also reduce the height of the floor as much as possible, making the RoeweiMAX8 EV has an interior height of 1020mm and an ultra-low threshold of 395mm for its class. For MPV models, it is convenient for passengers to get in and out of the car. The language is quite useful.
Editor's comment: At present, SAIC's Rubik's Cube battery has not yet entered the stage of large-scale practical use, but from a technical point of view, it is innovative and compatible, supporting both charging and battery swapping. Once SAIC's electric ecosystem matures, for example If there are enough power swap stations, the Rubik's Cube battery will become the RoeweiMAX8 The biggest advantage of EV in competing with other medium and large pure electric MPV is that after all, NIO’s battery swapping model is still in line with the travel style of high-end life circles, but the current home market can only swap batteries. MPV It seems that the model has not appeared yet, so please wait for the actual car experience.
Finally, according to Bitauto App data, Roewe iMAX8 ranks 5MPV popularity list >, if you want to know more information, please check Bitauto App.