A rigorous approach to quality control and testing is critical in the battery energy storage supply chain. Chi Zhang and George Touloupas of the Clean Energy Association (CEA) have analyzed and discussed common manufacturing defects in battery storage systems and how quality assurance systems can detect them.
It was shown that an effective inspection regime is the key to quality assurance in the production of battery storage systems. The U.S. Clean Energy Association (CEA) has been focusing on energy storage services since 2015 when the energy storage industry was in its relatively early stages. The association predicts that energy storage systems are a key enabler of the renewable energy transition in countries around the world and a valuable asset for grid operators.
The last eight years have seen the expansion of battery capacity from under 100 Ah to over 300 Ah today. Energy storage systems have transformed from containerized storage systems to today's highly integrated, energy-intensive modular cabinets; and large liquid-cooled battery storage systems.
Battery suppliers are also offering specialized batteries for battery storage systems as opposed to the earlier use of electric vehicle batteries in grid-scale battery storage systems. One has also witnessed the transition from battery energy storage systems using nickel, cobalt, and manganese (NCM) lithium ternary batteries supplied mainly by Korean and Japanese battery manufacturers to lithium ferrous phosphate (LFP) batteries supplied exclusively by Chinese manufacturers. In addition, other energy storage technologies that have yet to achieve significant breakthroughs, such as liquid flow batteries, are also looking to capture a piece of the lithium-ion battery market.
Rapid Changes in the Battery Energy Storage Industry
Overall, the battery energy storage industry is very different from what it was a few years ago, facing significant challenges that are exacerbated by high growth rates. Lithium-ion batteries have inherent limitations, and improper use can lead to excessive degradation or result in uncontrollable thermal runaway.
Manufacturing defects and electrical, thermal, or mechanical abuse can lead to thermal runaway in batteries. In the best-case scenario, fire protection systems will prevent a battery fire from spreading and causing damage to a portion of the energy storage system. The worst-case scenario could result in a total burnout of the energy storage system, leading to extended downtime. In addition, the complexity of the parts of the energy storage system creates additional points of failure that can lead to battery abuse and thermal runaway. A battery fire is a nightmare that battery storage system owners or operators would like to avoid, as it can lead to significant reputational and financial losses, as well as long-term disruptions to business operations.
The Clean Energy Association (CEA) has been working to effectively identify manufacturing risks associated with all aspects of battery energy storage systems through its quality assurance services. This work includes identifying risks between energy storage units, battery modules, racks, and battery storage systems.
Quality Assurance Inspections
Since 2018, a team of Clean Energy Association (CEA) engineers has been conducting quality assurance inspections on 26GWh lithium-ion battery energy storage projects deployed globally. Quality assurance checks are conducted before the batteries are produced at the factory; reviewed during production through monitoring; and tested after production through pre-shipment inspection and factory acceptance. In a survey of 52 factories around the world by the U.S. Clean Energy Association (CEA), there were more than 1,300 questions indicating deviations from production standard best practices, process deviations, or product specifications.
Most focus on battery quality, but little attention is paid to integration issues, as batteries will be integrated into modules, racks, and containers. System-level issues account for 47 percent of all issues, while battery cell issues account for 30 percent and module issues for 23 percent. Complex manufacturing processes and sensitivity to the stability of quality control systems make the battery the most risk-prone component of a battery energy storage system. However, battery energy storage systems also contain many other components, so most of the risk comes from other components. A large number of system-level problems are due to inadequate quality control of the manual integration process, the complexity of the battery energy storage system, and the vulnerability of the energy storage system to potential problems with upstream components. As the final step in the battery energy storage system manufacturing process, system integration can magnify potential problems at the subsystem level and is susceptible to quality and performance risks at the interfaces between subsystems.
