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Development trends of power batteries for new energy vehicles

Published Time:

2023-06-26

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With the vigorous promotion of the major project of new energy vehicles during the Eleventh Five-Year Plan period, China has gradually established the overall development route of "three verticals and three horizontals" for new energy vehicles. Among them, the "three verticals" refer to hybrid vehicles, pure electric vehicles, and fuel cell vehicles, and the "three horizontals" refer to multi-energy powertrain control systems, motors and their control systems, and batteries and their management systems. The proposal of "three verticals and three horizontals" provides a clear development path for China's new energy vehicles to achieve the "overtaking on a curve" strategy.

In the "three verticals and three horizontals" route, the battery and its management system is not only the core of new energy vehicles, but also a new field that has never been involved in traditional automotive systems. On the one hand, the power battery is the core component that determines the cruising range and charging time of new energy vehicles; on the other hand, the power battery and its management system are the biggest risk points in the safe use of new energy vehicles; in addition, the power battery is also the component system with the largest cost proportion in new energy vehicles, and its service life will directly affect the whole life cycle cost of new energy vehicles. Therefore, it is no exaggeration to say that the power battery and its management system are the core factors determining whether new energy vehicles can be popularized.

Existing new energy vehicle power batteries mainly use lithium battery systems, including two major categories: ternary lithium batteries and lithium iron phosphate batteries. Ternary lithium batteries have higher energy density, and under the same volume and weight, they can provide new energy vehicles with longer cruising range and better performance. Lithium iron phosphate batteries have lower energy density than ternary lithium batteries, but they have higher safety and lower cost. With the development of battery packaging technology, lithium iron phosphate battery packs can also provide product solutions that meet the cruising range expected by most consumers. New energy vehicle manufacturers generally use ternary lithium batteries in long-range/high-performance electric vehicles to ensure better power performance and longer cruising range, while using lithium iron phosphate batteries in basic versions to reduce costs and achieve a high-low product mix.

In the next stage, in order to further improve the safety and higher energy density of power batteries, solid-state and semi-solid-state batteries will become the development direction of the next generation of products. By changing the liquid electrolyte to solid-state/semi-solid-state, lithium dendrites can be suppressed, and the risk of combustion and explosion can be reduced. Moreover, the solid-state electrolyte will not leak, will not undergo side reactions at high temperatures, and will not puncture the diaphragm due to lithium dendrites under high current, leading to short circuits, nor will it burn due to gas generation. At the same time, solid-state batteries can use metallic lithium directly as the negative electrode, significantly reducing the total amount of negative electrode material and thus improving the energy density. Of course, solid-state batteries have problems such as large interface impedance and high manufacturing cost, so further research is needed before large-scale application.

On the other hand, sodium-ion batteries are also attracting attention as a low-cost alternative to lithium-ion batteries. Due to the abundant reserves and wide sources of sodium, the material cost is lower than that of lithium-ion batteries, and sodium-ion batteries are also better than lithium-ion batteries in low-temperature performance and charging rate. However, the energy density of sodium-ion batteries is only 100-150 kW/kg, which is far lower than that of ternary lithium batteries, and is also significantly inferior to lithium iron phosphate batteries. Through nearly ten years of development, China's lithium-ion battery industry for new energy vehicles has formed a complete upstream and downstream industrial chain. Although the material cost of lithium-ion batteries is higher than that of sodium-ion batteries, the manufacturing cost is more advantageous. With the return of the soaring lithium price in the previous stage to normal levels, the cost advantage of sodium-ion batteries is no longer obvious. Therefore, lithium-ion batteries will still be in a dominant position in the field of new energy vehicles, while sodium-ion batteries may be more likely to replace traditional batteries in fields such as energy storage and electric bicycles. (Toutiao)