Flower Power: Lav­ender Oil Fuels Bat­ter­ies for the Future

A ground­break­ing sodi­um-sul­fur bat­tery with improved energy per­form­ance and longer lifespan? The secret ingredi­ent grows in our gar­dens: lav­ender. By com­bin­ing lav­ender oil with sul­fur, Dr. Paolo Gius­to’s team has cre­ated a unique mater­i­al that solves a per­sist­ent fail­ure prob­lem – poly­sulf­ide shut­tling. This research marks an import­ant step toward devel­op­ing more power­ful and sus­tain­able bat­ter­ies for the next-gen­er­a­tion large-scale energy stor­age systems.

Little did Aless­andro Volta ima­gine to what extent his inven­tion, the bat­tery, would trans­form our lives. It has been a long jour­ney from his ini­tial stack of met­al discs to the pock­et-sized power­houses in our port­able devices and the large grids sup­ply­ing factor­ies. Today, sci­ent­ists are explor­ing altern­at­ives to the tra­di­tion­al lith­i­um-based bat­ter­ies which cause sig­ni­fic­ant pol­lu­tion at every stage – from the extrac­tion of crit­ic­al com­pon­ents to the energy-intens­ive man­u­fac­tur­ing and dis­pos­al of tox­ic waste. Dr. Paolo Giusto’s team at the Max Planck Insti­tute of Col­loids and Inter­faces is work­ing on sodi­um-sul­fur bat­ter­ies, a prom­ising option made from read­ily avail­able ele­ments and using few­er haz­ard­ous chemicals.

But these emer­ging green­er bat­ter­ies do not come without their chal­lenges. The most sub­stan­tial is poly­sulf­ide shut­tling, or the form­a­tion of com­pounds that inter­fere with the mech­an­ism at the heart of how bat­ter­ies work. Poly­sulf­ides are unwanted byproducts that clog the bat­tery and, when dif­fus­ing, can lead it to com­plete fail­ure. Giusto and his research team added an unex­pec­ted yet game-chan­ging ingredi­ent to the syn­thes­is pot: lav­ender oil.

Dr. Evgeny Sen­okos com­bined lin­alool from lav­ender oil with sul­fur and heated the mix­ture to cre­ate a new mater­i­al that acts like a con­fine­ment cage for sul­fur and poly­sulf­ides. Its nan­o­pores (about a hun­dred thou­sand times smal­ler than a human hair) trap the poly­sulf­ides but allow the pas­sage of smal­ler sodi­um ions, ensur­ing a con­tinu­ous trans­fer of elec­trons. ​“Lav­ender oil proved to be the ideal addi­tion thanks to its thermal cross-link­ing and con­dens­a­tion. In easi­er words, as the tem­per­at­ure inside the bat­tery rises, its car­bon molecules bind more tightly, and as the water evap­or­ates, the res­ult­ing nanoc­age becomes stronger and dens­er. This con­tinu­ous lay­er of car­bon traps the sul­fur, pre­vent­ing its escape. And we get a bat­tery that lasts longer and stores more energy,” explains Sen­okos. Determ­ined to make an impact on green energy, he will soon lead his own group in the pur­suit of viable lith­i­um alternatives.

After under­go­ing 1,500 lab tests over three months, the lav­ender-tweaked bat­tery still retained more than 80% of its ori­gin­al capacity.

“If we look at nature with a cre­at­ive eye, it offers solu­tions to many chal­lenges of the energy trans­ition. I am con­fid­ent that our res­ults will soon find their way out of the lab into real-world applic­a­tions,” asserts Giusto. Once prop­erly scaled up, the innov­at­ive bat­ter­ies could power indus­tri­al grids, store energy from renew­able sources, and back up essen­tial infra­struc­ture. ​“It’s intriguing to shape future bat­ter­ies with some­thing that many of us grow in our gar­dens,” Giusto adds, as the pun­gent scent of sul­fur in his lab gives way to lav­ender, remin­is­cent of the fields in his nat­ive Rivi­era dei Fiori, Italy that have inspired this work.

The future of green bat­ter­ies may not be rosy yet, but it is cer­tainly lavender-tinted.