In what is being termed a breakthrough, researchers at the Indian Institute of Science (IISc.) and their collaborators have discovered how next-generation solid-state batteries fail and devised a novel strategy to make these batteries last longer and charge faster.
Solid-state batteries are poised to replace the lithium-ion batteries found in almost every portable electronic device. But on repeated or excessive use, they develop thin filaments called ‘dendrites’ which can short-circuit the batteries and render them useless.
In a new study published in Nature Materials, the researchers have identified the root cause of this dendrite formation – the appearance of microscopic voids in one of the electrodes early on. They also show that adding a thin layer of certain metals to the electrolyte surface significantly delays dendrite formation, extending the battery’s life and enabling it to be charged faster, an IISc release explained.
Vikalp Raj, PhD student of Naga Phani Aetukuri, Assistant Professor in the Solid State and Structural Chemistry Unit (SSCU) and corresponding author of the study, artificially induced dendrite formation by repeatedly charging hundreds of battery cells, slicing out thin sections of the lithium-electrolyte interface, and peering at them under a scanning electron microscope. “When they looked closely at these sections, the team realised that something was happening long before the dendrites formed – microscopic voids were developing in the lithium anode during discharge. The team also computed that the currents concentrated at the edges of these microscopic voids were about 10,000 times larger than the average currents across the battery cell, which was likely creating stress on the solid electrolyte and accelerating the dendrite formation,” said the release.
The researchers introduced an ultrathin layer of a refractory metal – a metal that is resistant to heat and wear – between the lithium anode and solid electrolyte, which shields the solid electrolyte from the stress and redistributes the current to an extent, the release quoted the researchers as explaining.
The team collaborated with researchers at Carnegie Mellon University in the US, who carried out computational analysis which clearly showed that the refractory metal layer indeed delayed the growth of microscopic lithium voids.
The researchers say that the findings are a critical step forward in realising practical and commercial solid-state batteries.