The adoption of new material systems, the fine-tuning of lithium battery structures, and the improvement of manufacturing capabilities are the three areas where R&D engineers can “dance long and hard”. In the following, we will explain the two dimensions of monomer and system. –Monoblock energy density, mainly based on breakthroughs in chemical systems

1. Increase the size of the battery

Battery manufacturers can increase the size of the original battery to achieve the effect of power expansion. We are most familiar with the example: the first to use Panasonic 18650 battery well-known electric car company Tesla will change the new 21700 battery.

But “fattening” or “growing” the cells is only a symptom, not a cure. The bottom of the barrel solution is to find the key technology to improve energy density from the positive and negative electrode materials and electrolyte composition of the battery cells.

2. Change in chemical system

As mentioned earlier, the energy density of the battery is limited by the positive and negative electrodes of the battery. As the current energy density of the negative electrode material is much higher than that of the positive electrode, it is necessary to upgrade the positive electrode material to increase the energy density.

High nickel cathode

Ternary materials generally refer to the large family of lithium nickel cobalt manganese oxide, we can change the performance of the battery by changing the ratio of the three elements: nickel, cobalt and manganese.

In the diagram silicon-carbon anode

The specific capacity of silicon-based anode materials can reach 4200mAh/g, much higher than the theoretical specific capacity of 372mAh/g for graphite anodes, making them a strong alternative to graphite anodes. Currently, the use of silicon-carbon composites to increase the energy density of batteries is one of the industry’s recognised directions for the development of anode materials for lithium-ion batteries. The Model 3 released by Tesla uses silicon-carbon anode.

In the future, if you want to go one step further – breaking through the 350Wh/kg barrier for a single cell – your industry peers may need to look at a lithium metal cathode type battery system, but this also means a whole battery production process change and refinement. As can be seen in several typical ternary materials, the proportion of nickel is getting higher and the proportion of cobalt is getting lower. The higher the nickel content, the higher the specific capacity of the cell. In addition, due to the scarcity of cobalt resources, increasing the proportion of nickel will reduce the amount of cobalt used.

3. System energy density: improving the efficiency of battery pack formation

Battery pack formation is a test of the battery “siege lions” on the ability of the single-cell and module array, need to take safety as the premise, the maximum use of every inch of space.

There are several ways to slim down a battery pack.

Optimizing the layout

The internal arrangement of the system can be optimized in terms of external dimensions, making the internal arrangement of the battery pack components more compact and efficient.

Topology optimization

We use simulation calculations to achieve weight reduction while ensuring rigidity and structural reliability. This technology enables topology optimization and shape optimization and ultimately helps to achieve a lighter battery box.

Material selection

We can choose low-density materials, for example, the upper cover of the battery pack has been gradually changed from the traditional sheet metal cover to a composite cover, which can reduce the weight by about 35%. For the lower box of the battery pack, there has been a gradual change from the traditional sheet-metal solution to an aluminum profile solution, with a weight reduction of about 40%, which has a significant effect on the lightweight.

Integrated vehicle design

The integrated design of the whole vehicle and the structural design of the whole vehicle is considered as a whole, and structural parts are shared and common as far as possible, such as the anti-collision design, to achieve the ultimate in lightweight. The battery is a very all-round product, you want to improve the performance of one aspect, you may sacrifice the performance of other aspects, this is the basis of understanding battery design and development. Power batteries are vehicle-specific, so energy density is not the only measure of battery quality.