The convenience of batteries versus the guilt of adding to e-waste has played on many consciousnesses. But good news in the form of groundbreaking research comes from Friedrich Schiller University in Jena, Germany.
Scientists at the University of Jena, along with colleagues at Boston University and Wayne State University (WSU), have found a way to at least double the lifespan of lithium batteries commonly used in portable electronic devices and electric vehicles, whose market is growing. military and aerospace applications.
A press release from Friedrich Schiller University clarifies the issues. “The energy density of traditional lithium-ion batteries is approaching a saturation point which will no longer be able to meet the requirements of the future, for example in electric vehicles. Lithium metal batteries can provide double the energy per unit weight compared to lithium ion batteries. The biggest challenge, hampering its application, is the formation of lithium dendrites, small needle-like structures, similar to stalagmites in a trickle cave, on the metallic lithium anode. These dendrites often continue to grow until they pierce the separator membrane, causing the battery to short and ultimately destroy it.
Experts have been working for years on a more sustainable approach to the problem and are now taking the development of a two-dimensional membrane one step further that prevents nucleation of dendrites. The Encyclopaedia Britannica explains nucleation as “the initial process which occurs in the formation of a crystal from a solution, liquid or vapor, in which a small number of ions, atoms or solid, forming a site where additional particles are deposited as the crystal grows. Or, in this case, the growth of crystal dendrites.
The press release sheds more light on this fascinating process: “During the charge transfer process, lithium ions move back and forth between the anode and the cathode. Every time they pick up an electron, they drop an atom of lithium and these atoms build up on the anode. A crystalline surface forms, which grows in three dimensions where atoms accumulate, creating dendrites. The pores of the separator membrane influence the nucleation of dendrites. If the transport of ions is more homogeneous, nucleation of dendrites can be avoided.
Professor Andrey Turchanin from the University of Jena explains: “This is why we applied an extremely thin two-dimensional carbon membrane to the separator, with pores having a diameter of less than one nanometer. These tiny openings are smaller than the critical size of the nucleus and thus prevent nucleation which leads to the formation of dendrites. Instead of forming dendritic structures, lithium deposits on the anode in the form of a smooth film. There is no risk of damaging the separator membrane and the functionality of the battery is not affected.
“To test our method, we recharged the test batteries fitted with our hybrid separation membrane over and over again,” explains Dr Antony George of the University of Jena. “Even after hundreds of charge and discharge cycles, we couldn’t detect any dendritic growth. “
“The key innovation here is the stabilization of the electrode / electrolyte interface with an ultra-thin membrane that does not alter the current battery manufacturing process,” explains Associate Professor Leela Mohana Reddy Arava of the WSU.
Confident of wide applications for their research, the team filed a patent for their method. While battery efficiency will be a huge benefit, the potential for reducing the burden on the environment is even more exciting.