Sometimes we techies need to step out of our labs and offices and take our ideas to the average consumer. I want to tackle something the public knows little about: the value proposition of a battery pack.
This explanation is more about philosophy; I am not trying to achieve a technical description, but a layman’s understanding. Many people are skeptical of electrified vehicles (EVs)—and specifically the battery pack, because it is the most expensive part of the auto. If we can help the industry build an explanation that is more accessible to society, the industry (and the world) will benefit.
The primary component of a battery pack system is an electrochemical cell—it’s all about the chemistry. The cell is a combination of chemicals that permit the storage of energy in the form of chemical compounds. These cells require mechanical support via packaging in the form of frames and fasteners. They also need electrical circuits for proper charging and discharging that require control software. This includes both low-voltage communications and charge control, along with the high voltage and discharge control.
Transportation application manufacturers are very respectful of the SAE International Standards Steering Committee priority list: 1) Safety, 2) Performance, 3) Life, and 4) Cost. There is a clear focus on the ultimate safety of battery systems for EVs. After safety, the most important factors are energy and power dependent on application requirements. Clearly, an EV is sensitive to volume and mass considerations, as vehicle design is limited by physical space and weight. Life and cost play key roles in the calculation of the value proposition.
Automotive manufacturers work very hard to design vehicles to match a particular demographic group that will buy EVs. These consumers have various driving behaviors, from mild (the grandma that drives like a turtle to the grocery store twice a week) to severe (the daily long-haul commuter who speeds through traffic). The combination of Father Time (calendar life) along with the behavior of the driver (which the industry calls duty cycle/usage life) determines the rate at which the battery pack system deteriorates in energy-storage capacity. In the auto industry, we typically express this “life expectancy” in mileage (usage life) or months of service (calendar life). These criteria are typically the matrix we use in warranty policy and enforcement. These factors hold true in all forms of EVs, which we call xEV and include plug-in hybrids, regular hybrids, and pure electrics.
At this point in time, the requirements for repurposing are not well defined (in most cases). There are so many applications being considered for repurposed batteries that there is a plethora of requirements to be documented. Many of these are electrical requirements similar to those from the National Electric Code from the U.S. government. Although the SAE International battery standards committees do not write for governmental rulemaking, the standards they create are largely adopted and enforced as guidelines for good practice.
Most of these applications have a more narrow range of performance than an automotive application, as the requirements for power and energy for repurposed products are defined within a fairly narrow band. Consequently, the repurposed product design is typically not as stringent as an automotive application. Safety is still the No. 1 consideration, but power and energy are achieved by proper series/parallel cell configurations, as volume and process are significantly less important in most repurposed products. For example, a power application may have more cells in series to achieve higher voltages and an energy application may have more cells in parallel to provide additional capacity. Since the repurposed application is probably stationary, the need for energy/power density is less severe than in automotive usage.
Most secondary applications for repurposed EV batteries are for energy-storage systems, including renewable energy storage, load leveling, and frequency regulation. These can be applied to grid applications including everything from “behind the meter” application for residential use (low kW·h) to micro-grid applications (kW·h to MW·h) and even large utility suppliers (MW·h to GW·h). The definitions of each are just too broad a topic to try to cover here. Suffice it to say these applications cover from tiny to enormous in the marketplace.
In China, Amperex Technology Ltd. is working directly with one major OEM on repurposed batteries from automobiles with installations in Asia, North America, and Europe. These installations are simple solar renewable energy generation stored in repurposed battery systems.
The recycler is the end of one food chain…and the creator of a new one. The point at which the recycler receives the battery pack is when it has the least value from an application standpoint. The value proposition is to convert spent product back to raw materials for reuse. For example, in today’s lead-acid world, 99% of battery products are recyclable. About the only thing that isn’t recycled are fastener features in the terminal area. Battery packs represent a different opportunity in that we are recycling large systems that can include steel and aluminum frames, plastic dielectric materials, high- and low-voltage wiring systems, and a whole variety of fasteners. And, of course, there are the cells, which have the highest value of all within the pack. The reason for the value is the metals within the cell structure. As an example, the lithium cells usually have both copper and aluminum current collectors, and the active materials may contain additional exotic metals that carry a high price tag.
Battery pack systems may have up to a 10-year life in an auto. Some systems could even have a 10-plus year life in a secondary application as an ESS (energy-storage device). Clearly, none of us knows what the time-value of money will be over a 10- to 20-year period. And the value of these battery pack systems is dependent upon the energy storage and recovery of energy during the total useful life of the systems.
We also do not know the exact application usage profiles to calculate true value. Today, valuation is merely an estimate based on best knowledge. New technologies focused predominately on lithium cathode/anode and electrolyte systems will play a key role, as we know that every battery manufacturer on the planet is running to the finish line to improve energy, power, and life span while reducing cost.
It is my hope that some young genius will emerge from the toils of university life to create the next energy-storage invention that will achieve the goals of the energy-storage revolution.
Robert "Bob" Galyen, President of Business Development of NA/EU, Amperex Technology Ltd., and Chief Technical Officer, Contemporary Amperex Technology Co., Ltd., wrote this article for Automotive Engineering. He serves as the SAE International Battery Standards Steering Committee Chairman. View an Automotive Engineering magazine video-interview of Galyen at https://www.youtube.com/watch?v=pwXWV1qYNX4.