In response to the new energy vehicle market, ADI provides two secrets to break through the bottleneck of battery production efficiency

The demand for electric vehicles is growing, and the demand for batteries is naturally rising. However, battery production is time-consuming, thus forming a supply bottleneck, and its cost is high, accounting for up to 40% of the cost of EVs. At present, whether it is small-volume and small-capacity or large-volume and large-capacity batteries widely used in electric vehicles, they need to go through two processes before leaving the factory: formation and capacity separation. The formation process is the process of turning a battery from ineffective to effective, which simply means activating the battery. After formation, the capacity separation is to determine the capacity size. These two steps determine the performance indicators of lithium-ion batteries, and the consistency of lithium-ion batteries directly affects the range of electric vehicles.

Therefore, battery formation and testing are particularly challenging in the battery completion stage, as their costs account for 20% to 30% of the battery cost. For battery manufacturers and instrumentation providers, expanding EV production scale and improving efficiency are the keys to seizing this opportunity in the electric vehicle market. How to reduce the time and cost of battery formation and testing? In a recent speech, automotive technology experts from ADI, a semiconductor solution provider in the industry, mentioned two secrets of ADI to break through battery production efficiency.

ADI Innovation Delivers Measurable Results to Battery Formation and Test Equipment Manufacturers

ADI's current integrated precision solution AD8452 for battery testing and formation integrates analog front-end, controller and PWM, which can improve the system accuracy and efficiency of lithium-ion battery formation and grading. Compared with traditional technologies, the new AD8452 can provide 50% more channels in the same space, thereby expanding capacity and increasing battery production. At the same time, the switching technology used by AD8452 can recover the energy of the battery during discharge, with an accuracy of up to 10 times that of traditional switching solutions. Higher accuracy means that more cells can be placed in the battery pack, which helps to extend the battery life of applications such as electric vehicles.

In addition, the AD8452 also has better detection and monitoring functions, which can effectively prevent overcharging and undercharging behaviors that may cause battery failure, thereby improving the safety of the manufacturing process. The AD8452 can save up to 50% of the bill of materials (BoM) cost for the charge/discharge board and about 20% of the system cost. The device has a matching system simulation demonstration board, which can reduce R&D engineering costs and shorten time to market for test equipment manufacturers.

However, batteries used in vehicles or for electrical energy storage have much higher capacities, typically several hundred Ah. This is achieved by either a large number of small battery cells or a few high-capacity batteries. For example, a certain model of electric car uses about 6,800 18650 lithium-ion battery cells and weighs 450 kg. For this reason, battery production needs to be made faster, more efficient, and more precisely controlled to meet the market's price requirements.

The typical lithium-ion battery manufacturing process is shown in the figure below. The battery formation and testing in the end-of-line conditioning step not only have a great impact on battery life and quality, but also are the bottlenecks of the battery production process. With current technology, formation must be completed at the battery cell level, which may take hours or even days, depending on the battery chemistry. A 0.1 C (C is the battery capacity) current is usually used during formation, so a complete charge and discharge cycle will take 20 hours, and a typical test sequence includes multiple charge and discharge cycles.

Lithium-ion battery manufacturing process

In order to produce batteries faster and at a lower cost, the system uses hundreds or thousands of channels in the formation and test stages, and its tester topology depends on the total energy capacity of the system. Formation and electrical testing have strict accuracy specifications, with current and voltage controlled within ±0.05%. The high current in the tester will cause a significant temperature rise, increasing the difficulty of maintaining high measurement accuracy and repeatability over time. ADI's precision integrated analog front-end, controller, and PWM product series for battery testing and formation systems can simplify system design through control loop design, reduced calibration time, reduced ripple, and current equalization control. It has a system accuracy of better than 0.05% and an energy efficiency of more than 90%, which helps to solve the bottleneck problem of rechargeable battery manufacturing and contribute to the popularization of environmental protection technologies.

Typical lithium-ion battery charge and discharge curve