Lithium-ion batteries have powered electronic devices since 1991. Tesla has successfully used them for cars and storage of renewable energy. They are expensive and dangerous.
The search for new green battery technology has not yet found any viable alternatives to lithium batteries. But developments over the past year show promise.
Any battery has two terminals, marked positive and negative. Within some kind of case, they have two electrodes separated by an electrolyte.
One electrode, the cathode, connects to the positive terminal. The other, the anode, connects to the negative terminal. The electrolyte allows the electrical charge to flow between the electrodes.
A collector conducts the charge to a load outside the battery. The load is whatever the battery operates, such as flashlight, a laptop computer, or a car engine.
So far, all commercial batteries use a liquid electrolyte. Anyone who has ever seen a “dry cell” battery that has gotten wet knows how corrosive and disgusting the electrolyte becomes once it leaches out. Several research teams have completed tests of safer solid-state electrolytes.
Flashlights, portable radios, and other devices have long used dry cell batteries. Eventually, standard dry cell batteries become completely discharged and can only be discarded.
Rechargeable batteries allow a current from outside the battery to reverse the flow of electrons. Instead of negative to positive, it goes positive to negative until the anode has a fresh supply of electrons.
Lithium-ion batteries are not the only rechargeable batteries, but they have become the most common and versatile.
The search for alternatives to lithium batteries
Lithium is a relatively rare element that must be extracted from brine. Other industries besides batteries rely on it, but its use in batteries has greatly increased demand for it, and therefore cost.
Lithium batteries don’t last very long between charges. But perhaps their most serious disadvantage comes from their tendency to overheat and catch fire.
Elemental lithium is unstable. It took scientists years to find safe compounds. Unfortunately, elemental lithium can escape and form dendrites between the anode and cathode. They cause a short circuit that destroys the battery.
For two main reasons, the search for alternatives to lithium-ion batteries has not yet produced a breakthrough:
- Many teams are researching many different alternatives. Any one of them might improve on lithium batteries in one way, but not be as good in another. All the research into new alternatives to lithium-ion batteries has produced many batteries that are better in one way or another, but nothing definitively better.
- Scaling up research to put innovations into production takes time and money. It may take hundreds of millions of dollars. Corporations that have that kind of money don’t invest it over a long enough time frame. Independent research labs that have plenty of time can’t raise money on that scale.
Tesla invested about $5 billion in its Gigafactory. Researchers working on alternatives to lithium wouldn’t have that much if they pooled their resources into one fund.
Fortunately, we don’t need a single new green battery technology. What works for powering electronic devices does not also necessarily have to work for cars or grid storage.
None of the articles I have read indicate any of this new battery technology provides a possible alternative to lithium batteries in electronic devices. But several technologies are potential game changers in electric vehicles and/or grid storage.
New battery technology for electric vehicles
Even if new technologies improve on existing ones, they will be more expensive at first and will face competition from entrenched products. It will help development of solid-state batteries if they can be integrated into the manufacturing capacity for lithium-ion batteries.
In principle, solid-state technology is suitable for both grid storage and electric vehicle batteries. High-end electric cars seem the quickest path to commercial success for any new battery technology.
John B. Goodenough introduced the cobalt-oxide cathode used in lithium-ion batteries for more than 25 years. His team at the University of Texas at Austin has worked out a new battery chemistry.
It uses sodium ions instead of lithium. Sodium, being much more common than lithium, will make sodium batteries less expensive than lithium batteries. Perhaps more important, his team made the electrolyte from annealed sheets of fiberglass instead of some kind of liquid. It can’t explode.
Goodenough’s is not the only team working on a solid-state battery. Scientists at Argonne National Laboratory near Chicago and the Lawrence Berkeley National Laboratory devised a solid-state electrolyte for a magnesium-ion battery. Magnesium’s advantages over lithium include higher energy density.
Available liquid electrolytes proved too corrosive, so the team decided to explore a solid electrolyte. Instead of glass, they used magnesium scandium selenide spinel. So far, the lab hasn’t yet produced a prototype battery. A Swiss team is also working on a battery using magnesium, sodium, and a solid electrolyte.
It will take at least ten years for solid state batteries to come on the market.
Although these solid-state batteries will most likely find their first commercial application in electric vehicles, developers also have their eye on grid storage.
New battery technology for grid storage
The following technologies will not be suitable for electric vehicles, but they show great promise for grid storage. The difficulty in finding commercially viable alternatives to lithium batteries is evident near Toronto.
The Canadian company Deltro has built two warehouse-sized lithium-ion batteries there. In spring 2018, they will become part of Canada’s electric grid, the first utility-scale energy storage project in the country.
Tesla has already installed utility-scale battery storage for wind energy in Australia. Any new green battery technology will have to compete with an established one.
Hydrogen fuel cells have long been seen as the leading alternative to lithium. They were invented in the 1830s, but the best minds have not been able to find a way to produce them economically.
Pumped hydroelectric storage is currently the least expensive storage technology. It costs about $100 per kWh, but it only works in certain geographic locations. Tesla claims it can make lithium batteries for only $5 more than that.
Researchers at MIT have announced a sulfur-based flow battery they estimate can cost as little as $20 per kWh. Anode, cathode, and electrolyte are all liquid in a flow battery. In this one, the anode is sulfur in water and the cathode is an aerated salt solution.
Sulfur, a waste material from tar sands refineries, is cheap and abundant. The existing stockpile already amounts to 4 million cubic meters. So the active materials in a sulfur-based battery cost only $1/kWh, less than those of nearly any other rechargeable battery. The new battery is 500 to 1,000 times as dense as pumped hydro systems. It still requires lithium ions to carry the charge.
Vanadium flow batteries have been around long enough that some companies are close to bringing them to market as an alternative to lithium batteries for grid storage. They currently cost three to five times as much as pumped hydro, however.
Other grid storage alternatives to lithium batteries
Stanford engineers have created a battery with electrodes made of aluminum and graphite, both much more common than lithium. The electrolyte consists mostly of urea, which comes from urine and is already a common ingredient in fertilizer. Using urea reduced the cost two orders of magnitude compared to the first electrolyte they tried.
The battery charges quickly and can be charged and recharged thousands of times. It has a 99.7% Coulombic efficiency, which implies it will have a long lifecycle. So it is less expensive, more efficient, and longer-lasting than lithium-ion batteries, but it has only half the energy density.
Researchers at Oregon State University have announced development of a hydronium-ion battery, which contains no metal at all. Hydronium is an altered water, H3O+. It is the first non-metallic ion proved useful for batteries. It uses a diluted sulfuric acid for the electrolyte, an abundant and renewable substance.
These innovations hardly represent all new green battery technology of the past year. Scientists have also made breakthroughs in flexible batteries, such as wearable batteries printed on fabric and implantable medical technology.
Lithium battery schematic. Public domain from Wikimedia Commons
Lithium energy storage system. Some rights reserved by Portland General Electric
BMW charging port. Public domain from Wikimedia Commons
Vanadium flow battery. Photo by UniEnergy Technologies. Public domain from Wikimedia Commons