Batteries are the biggest problem facing the adoption of electric power on far broader scales than are presently feasible. Electric cars require large batteries to achieve a useful range of operation, and the weight of batteries required to power a passenger plane are currently prohibitive. Battery size and weight also restrict the design and manufacture of a whole range of products, including cell phones and computers. Also, they are always included as an add-on to the basic product rather than an integral part of it.
This problem exists partially because suitable electrical storage materials have not been available, or developed, but also partially because battery manufacturers have a vested interest in selling as many “AA” and “AAA” batteries as they can. It has made them a fortune, and continues to do so. They are understandably somewhat reluctant to invest in technology that might make their sacred financial cows obsolete.
However, a great deal of progress has been made in recent years. Battery design for cars, cell phones, computers, and many other devices have improved significantly, but the barrier of weight, size and storage capacity is still a limiting factor. Tesla car batteries are still huge and heavy, but are getting smaller and more efficient. Rolls Royce has produced a small, single-seat, test plane that has achieved world records in speed, climb rate and endurance but, in all cases, the battery is an add-on to the basic design and construction. Design processes, in all cases, have to allow for battery space and weight.
Enter engineers from the Chalmers University of Technology and KTH Royal Institute of Technology, both located in Sweden.
These scientists have made, what is called a massless, structural battery that is 10 times better than previous attempts at the same concept. It performs well in structural and energy storage tests.
You may well ask, what’s a massless structural battery, and why is it such a big deal? First of all, I think the term “massless” is confusing, and I will leave it out of the following description. It can’t possibly be massless, although I understand what the term is intended to portray.
The term structural battery refers to an energy storage device that can also bear weight as part of a structure. An example might be that the material from which the body-shell of your car, or the fuselage of your jet, is made can also store electricity. Another example might be that the materials used to make the walls of your house can not only hold up the roof, but can store the electricity the house needs to operate. In other words, an integral part of the design rather than an add-on.
The main initial use case will be for electric cars and electric bicycles, where batteries take up space and don’t contribute to the actual structure. These vehicles currently designed to carry the mass of the batteries. What if the frame of the vehicle could hold energy?
To make the new structural battery, the scientists layered a buffer glass “fabric” between a positive and negative electrode, then packed it with a space-age polymer electrolyte, and cured it in the oven. What results is a tough, flat battery cell that conducts well and holds up to tensile tests in all directions.
According to the Swedish scientists’ press release, “The battery has an energy density of 24 Wh/kg, meaning approximately 20 percent capacity compared to comparable lithium-ion batteries currently available. But since the weight of the vehicles can be greatly reduced, less energy will be required to drive an electric car, for example, and lower energy density also results in increased safety. And with a stiffness of 25 GPa, the structural battery can really compete with many other commonly used construction materials.”
The scientists say the next step is to improve the performance even more, replacing aluminum foil in the electrode with carbon fiber material and thinning out the separator. This could result in a battery that produces 75 Wh/kg of energy and 75 GPa of stiffness, setting more records for structural batteries and also greatly reducing their weight.
Flying in electric passenger airliners just became a whole lot closer to reality, not to mention a development that can cut your house electric bill significantly, and contribute to the elimination of fossil fuel usage. Hurrah for the Swedish scientists.