Even with plenty of 2015 left, it is a safe bet that the Tesla Powerwall launch in May will be energy storage’s biggest moment this year. The announcement of a $3,500 residential storage system got the world talking about batteries, and not all in a positive light.
Skeptics have pointed out that Tesla did nothing to change the fundamental economics of battery manufacturing, and that long-term price reductions might be difficult to achieve given potential constraints on raw materials. But while it is true that Tesla is banking on economies of scale, rather than technology breakthroughs, to achieve its gigawatt-level storage ambitions, it is also the case that battery research is growing apace.
In fact, since Tesla’s announcement barely a week has gone by without news of some new potential breakthrough. Here are eight of the top developments to emerge from labs worldwide over the last quarter.
1. Aqueous solar flow: Ohio State University researchers unveiled a "solar air" battery in 2014, but this June they went one step further and integrated their lithium-iodine (Li-I) technology with a solar cell to boost its efficiency. “The charging voltage reduction translates to energy savings of close to 20 percent compared to conventional Li-I batteries,” said the team. “This concept also serves as a guiding design that can be extended to other metal-redox flow battery systems.”
2. Battery anodes from reed leaves: Chinese and German scientists announced in June that reed leaves might hold the key to better silicon anodes for lithium-ion (Li-ion) batteries. Silicon beats carbon as a Li-ion anode, they say, but current manufacturing methods are complicated, expensive and energy-intensive. With the calcination and magnesiothermic reduction of leaves, though, you get anodes with “a remarkable Li-ion storage performance.”
3. A new Li-ion battery: July saw a team of South Korean scientists unveiling a new high-performance Li-ion battery that is stable at high temperatures. The battery is made from pumpkin-shaped molecules of a substance called cucurbituril, arranged in a honeycomb-like structure, and can operate at temperatures of almost 100ºC with no thermal runaway and “hardly any change in conductivity.”
4. Doubling the capacity of Li-ion: In June it emerged that experts at Samsung Electronics had developed a way of coating silicon cathodes with high-crystal graphene to almost double the capacity of Li-ion batteries. Business Korea pointed out that this breakthrough could benefit mobile phones and electric vehicles, and said the technology may need two or three years for commercialization.
5. Copying photosynthesis for storage: Scientists at the University of California, Los Angeles have been inspired by photosynthesis in creating a solar cell design that allows energy to be stored for weeks. The cells are made of plastic and use polymers and nano-scale fullerenes arranged in a manner that has been described as “small bundles of uncooked spaghetti with precisely placed meatballs.”
6. High-capacity batteries from wood pulp: A team from KTH Royal Institute of Technology in Sweden and Stanford University in the U.S. has produced “an elastic, foam-like battery material that can withstand shock and stress,” according to a press release in May. The nanocellulose-based material is made from tree fibers and can pack a surface area equivalent to the size of a football pitch into a single cubic decimeter. It could be used in electric car bodies and even clothing, the team said.
7. Calcium batteries to beat Li-ion: research being carried out in France and Spain aims to create advanced calcium batteries that could give Li-ion a run for its money, according to reports in June. The Advanced Calcium Batteries project aims to come up with rechargeable calcium cells that could be used in the same way as Li-ion but without any of the supply-chain concerns associated with lithium.
8. Melanin as a storage material: Melanin, the skin pigment, is being tested for its potential in energy storage, said news reports in May. The work is being carried out by River Road Research and the Rochester Institute of Technology in the U.S. on the back of a $35,000 grant from the Department of Environmental Conservation. Initial results hint at the possibility of cheaper, safer batteries with lower environmental impact.