Xpeng Motors’ battery technology route shifts from cylindrical to soft pack

Introduction: Xiaopeng Motors and I are a new car company with a lot of fate. When the founders first started, they were named Juzi Auto. There are many stories and energy, and after several years of development, some detours have been taken. In terms of battery systems, there is a route from cylindrical cells to square shells and soft packs. I want to divide it into two parts. The first part is mainly for the transformation of G3, and the second part is mainly for the selection of high and low matching of P7.

Drivers of the EE architecture of various OEMs

Xpeng Motors’ battery technology route shifts from cylindrical to soft pack

Figure 1 Xiaopeng’s G3 battery technology roadmap

01 Early cylindrical dynamic systems

The battery technology of Xiaopeng Motors was initially positioned to learn, imitate and improve from Tesla’s module design and process technology. The essential problem is that Tesla has relied on a lot of hard work to have a very stable supplier of battery cells. In the construction of the super factory, people and technology are used to pay. For Xiaopeng Motors, it can be referenced, compared, transformed and optimized at the design level, mainly by integrating key technologies such as liquid cooling tubes and fuses, distributing the fire protection requirements of components, and putting in the requirements for flame retardancy. Real-world manufacturing requires a Pack supplier. In terms of cell selection, it is now divided into BAK’s NCM and Delangen’s NCA, and there is also a Linkage Tianyi (Panasonic’s domestic counterpart) for NCA.

Remarks: There is a model in the announcement database that uses Penghui Energy

Table 1 Configuration of the power system in the recommended catalog

The strategy for battery constituencies has several problems here:

1) The characteristics of the three batteries are different, especially the safety design, whether it is effective enough on batteries with different characteristics, it takes a lot of effort. This choice can be regarded as a defensive strategy. The actual selection ratio of all cylindrical batteries is as shown in the figure below. The stability of the integrated process and the SOC accuracy and protection limits of the BMS are relatively high. The real volume is running, and there will be pressure immediately.

Figure 2 Selection ratio of BAK and Linkage Tianyi

2) The power is not enough to use the original 18650 cells, which is a big challenge. Even with Panasonic’s NCA, the largest expansion is only 50.5kWh. It’s very troublesome. Therefore, in this matter, Xiaopeng made a strategic decision to switch from the original technical route of cylindrical cells to standard modules compatible with square shells and soft packs. We can read the patents made by Xiaopeng Motors in the early days, most of which are related to the process routes of cylindrical cells.

Table 2 G3 version comparison

02 Technical route of square shell and soft package

In terms of mileage and powertrain configuration, Xiaopeng Motors has taken a relatively special technical route in terms of powertrain, which is inconsistent with the technical route of most traditional car companies. Therefore, while the cost of power batteries has dropped significantly, this dividend has not been enjoyed. In fact, switching from the early module design of tesla in 18650 to a long module similar to Model 3 requires a great challenge. As shown in the figure below, the G3 car was originally designed around a low Pack similar to Model X, so after switching to a square shell, in order to use the space as much as possible, I also tried to stack modules in the front row. And in order to have a better one, a strategic soft package supplier has also been introduced on the standard module, and dual supply has been realized on both G3 and P7. The main factors forcing decision-makers here are cost, energy density (subsidy factor) and battery energy (representing the mileage of the vehicle and the competitiveness of its corresponding models).

Figure 3 Comparison of battery systems for G3 in 2019 and 2020

On the P7, the cell was switched from 148mm to 220mm, but in order to take into account the design of the car, the height of the cell was reduced from 103mm to 84.5mm, which is the design target specification of PPE.

Figure 4 Schematic diagram of the battery patent of P7

Summary: I think Xiaopeng Motors has been under a lot of pressure for a period of time with its technological shift. It was very uncomfortable for the owner to hold the flag at that time, but after the switch, the overall competitiveness of the G3 has kept up with the overall progress in 2020. The rhythm of the rhythm, sometimes the road must be selected, and the P7 can reduce the energy consumption, and the design dividend brought by the battery system change is indispensable.

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