Lithium battery performance requirements -Lithium - Ion Battery Equipment

Lithium battery performance requirements and development process -Lithium - Ion Battery Equipment

Today, I would like to briefly share with you what the specific requirements for the performance of the power lithium battery are and what kind of development and testing process should be followed.

1. Depot's demand for battery performance

In fact, the basic requirements for batteries include: energy density (cruising range), safety, fast charging, cost, life, and size compatibility.

1. Energy density

According to my country's automotive power lithium battery technology roadmap plan, by 2020, the system-level energy density should reach 250Wh/kg, the cost should be reduced to less than 1 yuan, and the cruising range should be more than 400km. There are not many mature material systems to choose from. It is basically confirmed to use high Ni ternary materials and silicon-based anode materials or corresponding high voltage materials.

The actual goals of mainstream battery companies at home and abroad are as follows:

The improvement of cell energy density, the lightweight and compact design of Pack, and the improvement of system energy utilization efficiency have contributed greatly to the improvement of cruising range and cost reduction.

2. Cell safety performance

The rapid increase in cell energy density corresponds to new cell safety challenges, and the market urgently requires large-scale product launch. In addition, investment in system security design should be strengthened, and product integration and application security should be realized through multi-level and multi-dimensional design from a system perspective.

3. Fast charging feature

The comprehensive charging facilities and battery technology progress believe that 30-45min fast charging will be the mainstream technical requirement, and 10-15min fast charging will be partially researched and applied. The power exchange mode mainly appears in the operation of taxis, and the current level is 3-5min quick change.

4. Battery cost and size compatible

Material technology progress and scale, standardization, reduction of vehicle energy consumption, and cascade utilization promote battery cost reduction. Standardization minimizes development costs and is also an important foundation for cascade utilization. In the future, the vehicle company will define the module specifications (such as VDA or the new national standard electric vehicle power battery product size specifications), and arrange them within the module specifications, which is conducive to cross-platform applications and facilitates recycling and cascade utilization. With the optimization requirements of the vehicle layout, the skateboard battery pack is arranged on the battery chassis, and the requirements for the Z-direction are getting higher and higher.

5. Longevity

The battery life should be guaranteed: 10 years or 160,000 km, life target: 10 years, 240,000km, with the increase of vehicle cruising range, the cycle life of the battery will be relaxed accordingly.

2. The development process of the power lithium battery by the car factory

Taking BAIC as an example, the overall vehicle development process is as follows:

In BAIC's vehicle EVDP process, the development and verification process of each level of subsystems must precede the parent system to ensure the reliability of the product development process. The above is the development process based on the simultaneous development of battery systems and cells. According to the actual development situation, the battery products with high maturity will be preferentially selected.

SAIC has divided it into four stages: pre-screening - battery confirmation and evaluation - unit confirmation and evaluation - system verification. There are strict testing procedures and controls at each stage.

1. Selection of cell type

From the perspective of positive and negative materials, cells currently include NCM (111, 523, 622, 811), LCO, LFP, LMO, LTO, etc. Car companies need to filter from the dimensions of energy density, power characteristics, cycle life and safety. In addition, from the shape of the battery package, it can be divided into cylindrical, soft package (lamination and winding), square (lamination, winding, parallel winding). The important characteristics of each type of cell are summarized as follows:(Lithium - Ion Battery Equipment)

2. Battery test and evaluation system

Three horizontal and four vertical evaluation system. Three horizontals: three major product dimensions with batteries as the core components, battery modules, and battery systems, and different test evaluations are carried out according to different development stages; four verticals: approval test, calibration test, extension test, and virtual verification Four Large-scale test type, nearly 158 verification items, including 33 system thermal safety, electrical safety and mechanical safety. 



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