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How to Improve the Energy Density of Batteries Lithium?

Jan 05 , 2022

The adoption of new material systems, the fine-tuning of the batteries lithium structure, and the improvement of manufacturing capabilities are the three main stages for R&D engineers to show their abilities. We will explain the two dimensions of monomer and system in the following part.

Ⅰ. The energy density of lithium battery cells mainly depends on the breakthrough of the chemical system

1. Increase the size of the electrical batteries: Electrical batteries manufacturers can increase the size of the original battery to achieve the effect of capacity expansion. The most familiar example is that Tesla, a well-known electric car company that was the first to use 18650 batteries and will replace the new 21700 batteries.

However, the "fat" or "growth" of the battery cell is only a temporary cure, not a permanent cure. The method of drawing salaries from the bottom of the kettle is to find the key technology to increase the energy density from the positive and negative materials that constitute the battery cell and the composition of the electrolyte.

2. Changes in the chemical system of lithium batteries: As mentioned earlier, the energy density of electrical batteries is restricted by the positive and negative electrodes of the battery. At present, the energy density of negative electrode material is much higher than that of the positive electrode, so it is necessary to continuously upgrade the positive electrode material to improve the energy density.

(1) High nickel cathode: Ternary materials generally refer to the large family of nickel cobalt lithium manganate oxides. We can change the performance of electrical batteries by changing the ratio of the three elements of nickel, cobalt, and manganese.

(2) Silicon-carbon anode in the figure: The specific capacity of silicon-based anode materials can reach 4200mAh/g, which is much higher than the theoretical specific capacity of graphite anodes of 372mAh/g, so it has become a powerful substitute for graphite anodes.

(3) At present, the use of silicon-carbon composite materials to improve electrical batteries' energy density has become one of the industry's recognized development directions for lithium battery anode materials. The Model 3 released by Tesla uses a silicon carbon anode.

3. In the future, if you want to further break through the 350wh / kg mark of single cell, peers in the industry may need to focus on the lithium metal negative electrical batteries system, but this also means the change and improvement of the whole battery manufacturing process. It can be seen from several typical ternary materials that the proportion of nickel is higher and higher, and the proportion of cobalt is lower and 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 use of cobalt.

Ⅱ. Energy density of batteries lithium system: improve the group efficiency of battery packs

1. The group test of electrical batteries packs is the ability of electrical batteries "siege lions" to arrange troops for single cells and modules. It is necessary to make maximum use of every inch of space on the premise of safety.

2. The "slimming" of electrical batteries pack mainly includes the following ways:

(1) Optimize the layout structure: in terms of overall dimensions, the internal layout of the system can be optimized to make the layout of internal parts of the electrical battery pack more compact and efficient.

(2) Topology optimization: we realize weight reduction design on the premise of ensuring stiffness, strength, and structural reliability through simulation calculation. Through this technology, topology optimization and morphology optimization can be realized, and finally, help to realize the lightweight of the battery box.

(3) Material selection: we can choose low-density materials. For example, the electrical batteries pack upper cover has gradually changed from the traditional sheet metal upper cover to the composite upper cover, which can reduce the weight by about 35%. For the lower box of the battery pack, it has gradually changed from the traditional sheet metal scheme to the aluminum profile scheme, reducing the weight by about 40%, and the lightweight effect is obvious.

(4) Integrated design of the whole vehicle: the integrated design of the whole vehicle and the structural design of the whole vehicle shall be fully considered, and the structural parts shall be shared and shared as much as possible, like anti-collision design, to achieve the ultimate lightweight.

The electrical batteries are very comprehensive products. If you want to improve one aspect of performance, you may sacrifice other aspects of performance. This is the basis for understanding battery design and development. Power electrical batteries are dedicated to vehicles, so energy density is not the only measure of battery quality.