The best and most innovative ideas for new batteries

Machine learning finds new compounds  

One particular reason to innovate has been to find a way to move past lithium-ion batteries. Especially when it comes to electric cars and devices that use lithium-ion batteries. These batteries, containing liquid electrolytes, are very common.

But this type of battery has serious deficiencies, like its comparatively low efficiency and the potential for the liquid electrolytes to explode and cause fires. 

Looking for a safer, sustainable, and more stable approach, an international team of researchers recently uncovered the mechanics of a class of compounds called argyrodites, named after a silver-containing mineral, that have the potential to be used as electrolytes in solid-state batteries and converters in thermoelectric energy. 

Built from stable crystalline frameworks comprised of two elements that are held in place and a third one that’s free to move about the chemical structure, the argyrodite compounds can include silver, germanium, sulfur and other elements. Their advantage lies in the framework being quite flexible, which enables a range of possible combinations. 

For the recent study, the researchers utilized neutrons and x-rays, bouncing these fast-moving particles off atoms in a compound made of made of silver, tin and selenium. This allowed the scientists to reveal the molecular behavior of the compound in real-time. The data was then analyzed using machine learning and a computational model that relied on quantum mechanical simulations.

The study’s findings, published in the journal Nature, could result in a range of new energy storage possibilities — from creating battery walls for households to electric vehicles that charge exceedingly fast. 

As the study’s co-author, Duke University’s associate professor of mechanic engineering and materials science Olivier Delaire pointed out in a press release, "This study serves to benchmark our machine learning approach that has enabled tremendous advances in our ability to simulate these materials in only a couple of years,” adding “I believe this will allow us to quickly simulate new compounds virtually to find the best recipes these compounds have to offer."

Using nano materials

Another promising approach to replacing lithium-ion batteries has been explored by researchers at the Australian RMIT University, who employed the nano material MXene in a quest to create recyclable cell phone batteries that would have a lifetime up to three times longer than today’s tech.

The batteries created with this material could last up to nine years, utilizing high-frequency sound waves to dispose of the rust that builds up and affects battery performance. 

MXene has similarities to graphene and offers high electrical conductivity. As Leslie Yeo, professor of chemical engineering at RMIT University, and lead senior researcher, explained in a press release, “Unlike graphene, MXenes are highly tailorable and open up a whole range of possible technological applications in the future.”

One caveat with the use of MXene, however, is that it can easily rust, thus hampering electrical conductivity, which would make it unusable. 

Interesting Engineering reached out to professor Yeo for further comments on how his team devised a way to get around this MXene limitation by using sound waves. 

Professor Yeo explained that the primary motivation for finding alternatives to lithium lies in its relative scarcity as well as “the environmental and geopolitical considerations” that are associated with lithium extraction.

“MXenes have a number of desirable attributes that make them promising candidates for electrode materials, conductive additives and other components (e.g., protective layers) in batteries, not least its very high reversible capacity and cycling stability, as well as very high electrical conductivity,” he explained, adding that, “the diversity of its compositional as well as surface chemistry, which allows for tenability, and its hydrophilicity, are also key characteristics of the material that make it very attractive, as is its relatively low cost.”

The professor also delved into the specific technique devised by his team to remove rust from MXene-based batteries, pointing out that their research is still at an early stage. The researchers have been able to remove oxide layers from the MXenes by exposing them to high frequency vibration, although more testing needs to be carried out to find the most practical implementation of this method.

While he wasn’t ready to say exactly how consumer devices would utilize this approach to revive batteries, professor Yeo shared that, on the industrial recycling scale, the process would involve “throughput through massive parallelisation of the chipscale technology (utilise lots of the chips we use to generate the vibration given that the cost of each chip can be very low by exploiting the economies-of-scale associated with wafer-scale mass nanofabrication).”

Seaweed to the rescue 

One of the most unexpected areas for improving lithium-ion batteries comes courtesy of researchers from Scotland, who aim to make use of abundantly-available seaweed. The team from the Scottish company Marine Biopolymers and the University of Glasgow’s School of Chemistry are exploring the possibility of using tailored alginates, a material that can be found in brown seaweed, to replace a key ingredient in batteries and achieve a much-longer lifespan.

Graphite or carbon electrodes are a standard component of lithium-ion batteries, but have limitations in the amount of charge that can be stored, as well as with lifespan.

One alternative to graphite could be silicon, which can augment the charging capacity tenfold. But silicon has its own Achilles heel — because it expands and contracts with every cycle of the battery, it ultimately cracks. The team behind the new approach proposes using the alginate in a silicon battery, to aid in the electrode’s elasticity and energy-storing capacity. 

The team has so far been able to create and successfully test a prototype as large as a watch battery. They are now working on developing a larger battery that utilizes the seaweed alginates, with the goal of creating batteries to power a host of products for consumers and industry, including electric vehicles. 

Professor Duncan Gregory, chair of inorganic materials at the University of Glasgow’s School of Chemistry, sees this work as having a potentially large environmental impact. He shared in a recent interview that advancements in battery technology are a key part of the transition away from fossil fuels.

In fact, the future of electric vehicles and renewable energy production depends on batteries that can store more energy in smaller volumes and with much-extended lifespans. Gregory also stated that ‘’we need to find more sustainable production methods and ways to use naturally occurring materials as part of battery manufacturing.”

Improving sustainability

One of the major goals in going beyond the lithium-ion battery paradigm is developing technology that is more sustainable. One UK-based company, AMTE Power, is betting on sodium as an alternative to lithium.

While conventional lithium-ion batteries use lithium and cobalt, AMTE's cells use sodium instead. This offers huge potential advantages, as sodium is widely available and can be extracted using minimal energy. Because they lack heavy metals, sodium batteries are also much easier to recycle and safer to dispose of.

While AMTE have been struggling financially, they are not the only ones taking a fresh look at sodium batteries. Researchers at the University of Texas at Austin have developed a material for use in sodium-based batteries that can recharge as fast as a traditional lithium-ion battery and has the potential for a higher energy output than current lithium-ion batteries. 

Other companies, like the French otonohm, are improving sustainability in other ways, by using software instead of hardware. Its switched Battery Management System (BMS) allows manufacturers to remove the charger, converter and/or inverter on a drivechain or powerchain.

By paring down the battery, and monitoring the state of charge of each cell, Otonohm’s BMS offers big improvements in efficiency, battery lifespan, and reliability.

The company claims its system will work with almost any type of battery, extending battery lifetimes by almost 30% and providing 20 per cent more available energy over conventional batteries.