Electric vehicles (EVs), which claim to be more environmentally friendly, must rely on huge batteries to store power, but these batteries also have environmental issues that need to be focused on. How to use more advanced battery management and monitoring technology to improve the operating efficiency of these batteries and recycle old batteries has become an important topic for the EV industry. This article will show you the challenges faced by EV batteries, the characteristics of the Battery Management/Monitoring System (BMS) introduced by ADI, as well as how to improve EV battery utilization.
EV battery technology away from cobalt dependence
As EVs (and electrification technologies) become more popular with consumers and ecosystem participants, there is growing concern about ethics and sustainability throughout value chain operations and processes. From the mining practice of minerals to the second life of batteries, ecosystem participants hope to pay more attention to sustainable development by applying more ethical standards throughout the life cycle of batteries.
Today, most lithium-ion batteries use cobalt as a basis for cathode materials, which will determine the storage capacity of lithium-ion batteries. Cobalt cathode batteries have a longer-range than other chemical elements, making charge measurement and management easier. However, cobalt mining has long been controversial.
Since about 70% of the world's cobalt is mined in the Democratic Republic of the Congo (DRC), cobalt mining in that country also involves child labor, unsafe mining conditions, the mistreatment of miners, and other illegal issues. As electrification ecosystems require a balance between social and environmental sustainability, there is growing interest in reduced-cobalt battery chemical materials (NMC and NCA) and cobalt-free battery chemical materials (e.g. lithium iron phosphate (LFP)).
LFP batteries are not only manufactured and verified, but have been used in the industry for more than 10 years, and are fully supported and preferred by leading OEMs. However, cobalt-based chemical materials have a higher energy density of 10%-20%, resulting in a longer range for a single charge. However, this high performance is accompanied by a high risk – lower cobalt flash point and a higher risk of battery fire than LFP. In addition, LFP batteries are lower cost to produce and more efficient in dealing with safety hazards such as punctures or thermal runaway. The LFP's high power characteristics also make it charge faster.
EV manufacturers expect today’s battery technology to be used in high-cost, high-performance (high-end) vehicles and LFP batteries in low-end vehicles. These low-end vehicles do not use cobalt, which reduces costs, and are therefore sold at lower prices. Although LFP batteries are cheaper and safer to use than cobalt, their discharge curve are flatter, making it difficult to measure battery power accurately.
EV battery recycling and reuse
According to the World Economic Forum, 2.3 million EVs were sold in 2020, a fourfold increase over the sales of EVs five years ago. Consumer demand, the development of EV battery charging infrastructure, city and countries enacting regulations conducive to electrification have all contributed to this dramatic transformation. Although EVs are boasted of as green alternatives to combustion engines and fossil fuels, it has a fatal weakness in what happens to all these half-ton EV batteries when they are no longer able to store enough power to drive the vehicle.
Electric vehicle battery recycling is now a very common option, but the process can only recover some raw materials (e.g. cobalt and lithium), not all of them. However, EV battery recycling is costly, unregulated, and lacks a clearly defined supply chain.
Batteries are the heart of EVs and account for about 30% of the total cost of EVs. However, battery technology is about to be significantly improved. Major advances in battery chemistry and electronics can reduce costs, realize efficient battery reuse and second life, and promote battery recycling in EVs, thus providing cost advantages for promoting the popularity of EVs.
Effective battery health monitoring during the first life of a battery and any subsequent life cycle will help build trust between the seller and the buyer of the battery. Based on this trust, OEMs can use batteries as assets to compensate for some initial battery investment and potentially pass the value of its savings to consumers.
Battery second life to regenerate batteries
More than 10 million EVs are already driving on the road. It is estimated that 10 million EVs will be sold annually by 2025. Given that the average useful life of EV batteries is about 10 years, the total number of EV batteries discarded each year by 2035 will be 1.3-1.5 times the mass of the Great Pyramid of Giza (5.8 million tons).
Battery reuse is the process of identifying batteries in a battery that retain available power, disassembling the pack, and reassembling these viable cells. This alternative recycling approach is emerging in the form of "battery second life”. Replacement is required when the automobile lithium-ion battery charging capacity drops to 70-80% of the original capacity (usually after 8 to 10 years) and the automobile can no longer be effectively powered. The increasing number of these batteries that are no longer in use creates new market opportunities – the "second-life battery sector”.
Since battery pack costs account for more than 30% of EV sticker prices, obvious economic and environmental incentives can motivate battery manufacturers, automobile manufacturers, regulators, and even insurance companies to actively nurture a secondary market. The most direct way to do so is through the application of energy storage systems (ESS), which allow batteries that remain usable in old batteries to be reused in renewable power grids to store excess power generated by wind, solar, hydroelectric, or geothermal power plants. EV batteries can also be disassembled into smaller battery modules for less demanding uses, such as power tools, forklifts, or electric scooters.
The emerging second life battery market is not accessible in terms of technology, quality control, and realization. For example, EV batteries today use electrical harnesses to monitor battery charging. These harnesses (and other harnesses) must be completely removed before the batteries can be redeployed, adding cost and design complexity. Considering end-of-life disassembly in product design will be a trend in which designers can use wireless BMS (wBMS) technology to extend hardwired battery monitoring systems (BMS). wBMS not only reduces the size, weight, and material cost of electric vehicles, but also allows for safer and more scalable robotic disassembly and assembly processes for batteries.
BMS solution improves battery utilization
ADI provides industry-leading technology for accurate battery state-of-charge (SOC) measurement. ADI battery management systems (BMS) solutions can accurately and efficiently manage LFP battery state of charge requirements and release potential cost and safety characteristics advantages of LFP batteries for the industry, thus greatly reducing the burden on automobile manufacturers. In addition, LFP batteries provide higher power density, longer life cycle, and lower operating costs over a wider range of temperatures, and therefore are well suited for battery second-life scenarios such as energy storage applications.
Ultimately, LFP batteries will reduce price barriers to EVs and drive consumers to purchase EVs. Currently, battery costs account for 51% of EV sticker pricing. In addition, moving away from heavy cobalt dependence will drive the industry to build more ethical supply chains, and the advantages of LFP batteries will ultimately help to achieve more environmentally sustainable battery ecosystems and improve efficiency in the battery second life applications.
It is estimated that battery cascade utilization can extend battery life by 6 to 30 years. However, this period ultimately depends on battery usage during the first application. If the wBMS technology is able to collect battery data without contact throughout the battery life cycle, this important data can be consolidated into the cloud and tied back to the battery secure identity.
The seller can use this data to generate state-of-health history records, including how many times the battery has been fully/partially charged and discharged, whether the EV has had an accident, and record vehicle maintenance records before determining that the battery has been used in a second life. In addition, this sophisticated health monitoring can be applied where data collection is logically impossible, including the storage and transportation of new batteries or second life of batteries.
After use and reuse, all batteries are eventually decomposed and recycled. The wBMS technology allows for the mass characterization of inventory information contactless and facilitates rapid decision making for reuse or recycling. Once reuse or recycling is decided, the buyer and seller can establish a normalized trust basis by using state-of-health data and fairly assess the value of batteries before reaching a sales price. The industry could even develop a rating criterion to differentiate between less-used AAA-rated batteries and poorly maintained batteries.
Conclusion
EVs are growing rapidly, and batteries will play a key role in promoting environmentally friendly transportation. The automotive industry is currently developing a number of environmentally and socially relevant initiatives, including removing cobalt from battery chemicals and reducing emissions from the production of automotive materials such as aluminum and plastics, all to achieve zero-carbon automobiles.
Changes in battery and BMS design thinking will improve the overall service life of batteries and play an important role in creating new market channels that are environmentally sustainable and economically feasible. Therefore, more environmentally friendly EVs will emerge in the near future, and EV batteries will be revived in second life applications to continue playing a role in future automobiles, ESS, or other applications.