In 1959, Volvo invented the three-point seatbelt, and famously made it available for the rest of the automotive industry to use. They estimate it has saved over 1 million lives. But seatbelts with shoulder harnesses were not enough. And so, additional safety improvements and innovations were made, such as airbags, crumple zones, anti-lock brakes, electronic stability control, lane departure detection, forward collision warning, adaptive cruise control and others. When a new safety innovation came along, it was piled into the mix with all the others. And yet, even with the innovation of airbags and other safety additions, we still dutifully buckle-up every time we get into the car. The result? Well, thanks to the industry’s continuous safety innovations, it is far safer to drive 75 mph today than it was to drive a fraction of that speed in the early 20th century.
When it comes to lithium-ion batteries for electric vehicles, however, the discussion goes differently with some safety-technology companies promoting their solution as a silver bullet that will obviate the need for other safety considerations.
Safety features in lithium-ion battery packs will take the same wholistic approach that mechanical safety has taken in the auto industry. It is this philosophy, and how it will play out in the industry, that I will be breaking down within this article and the next few in this newsletter. First a few overarching themes will be covered, and then individual solutions, testing, and other safety strategies. But expect maximum safety to be achieved by bundling a variety of innovations into a wholistic, safe battery pack.
Several factors will determine the mix of safety features that are included in a lithium-ion battery pack.
- Cost: Though cost will always play a role, it is not a critical factor. However, given two equal choices, the lower cost will almost always win. And for devices that are less sophisticated, low cost solutions will fulfill that role.
- Energy density: Several integral companies are currently developing very high energy density batteries--Ampruis, Cuberg, Sepion, GDI, Advano, LeydenJar and Ionblox to name a few. Energy density will continue to go up, and the more energy that is put into a smaller box, the more safety design features will be needed to keep it under control. On the other hand, lithium iron phosphate and sodium ion will require fewer features.
- Space and weight: Depending on the size of the device, space and weight can be major considerations, which will drive those that take up less space and weight to the forefront.
- Complexity: Simplicity will win. However, battery packs will tolerate a certain amount of complexity, especially those that are made in large numbers, or for which safety is paramount.
- Cost of failure: At the high end, you have satellites, manned space missions, hospitals, mining vehicles, marine and other critical environments, where failure can result in the loss of many dollars or lives. On the lower cost end, you have small consumer devices, power tools, and micro-mobility. But these are increasing as the number of devices increases, and they are more often carried into critical environments like urban buildings.
- Performance: Safety features that inhibit performance will in most cases be a no-go. At the end of the day, the battery's job is to power the device, and no one will sacrifice that.
In a nutshell, cost, energy density, space & weight, complexity, cost of failure, and performance are the top considerations that will trade of in safe battery pack design. In reference to the car analogy, most of the safety devices that were implemented added cost, some weight, and certainly complexity. And yet they are all used today, almost ubiquitously, but rarely did they inhibit the performance of the car.
In summary, if a safety feature works without inhibiting the performance of the device, and is not too expensive, heavy, or complex, it will likely be used. The venture capitalists, OEMs and others who are investing in this area should focus most heavily on 1) whether the innovation works and 2) how strong the advantage it creates is. The rest will work out. Still skeptical? Just think about how complex and expensive anti-lock brakes, electronic stability control and airbags are. And then try to go buy a car without them.