Battery 'Sponge' Made from Foam-Like Copper
The humble battery is crucial for technologies ranging from consumer electronics to electric vehicles. But for all of its necessity, it still has major limits. Batteries still take too long to charge, are full of toxic chemicals and typically last just a
few hundred cycles. After that, it’s the landfill.
Battery Company wants to change that by building a battery that has a
three-dimensional internal structure, allowing them to suck up energy faster and extend their lifetimes. The design is the brainchild of Amy
Prieto, a chemistry professor at Colorado State University.
Ordinary batteries are made in layers: the part that
provides positive charge, called a cathode, the negatively charged part, called
the anode, and the electrolyte between them which is usually an acid. The
electrolyte allows electrons to move between the cathode and anode. The layers
are either flat, as in a phone battery, or rolled up, as in a AAA for the
The problem is that this design only allows electrons — the current — to
move from the side of the anode in contact with the electrolyte to the cathode. That provides fewer pathways for the electrons to move, and limits how many can do so, like cramming a crowd of people into a room and only opening the doors on one side. As a result the battery takes a while to charge and loses
Prieto’s design does something different: the cathode and
anode are like a sponge, with lots of holes. So instead of a solid block, the
battery has loads of surface area inside. That allows the electrons to move
more easily because they have more points of contact. In the room analogy, it's like opening up the exit doors on all four sides, allowing the people to leave faster.
The Prieto batteries are made with copper. The copper, which
takes on a foam-like structure, is then coated with the negative electrode
material. That in turn is coated with the electrolyte, which is a solid instead
of a liquid. The leftover space is filled with the cathode, which is initially
a kind of slurry that then hardens into place.
The chemicals used are non-toxic — one component is citric
acid as opposed to stronger ones such as the sulfuric acid used in car