BY MARIA BURKE
Researchers at Stanford University, US, have created an ultrathin silver coating for solid electrolytes, which makes them five times more resistant to cracking, promising breakthroughs in the safety and longevity of next-generation lithium metal batteries.
Using solid electrolytes in a rechargeable lithium battery should make them safer, faster to charge and hold more energy than the lithium-ion batteries commercially available today. However, they can form microscopic cracks which grow during use until the battery fails.
‘The solid electrolyte that we and others are working on improving [consisting of lithium, lanthanum, zirconium and oxygen (LLZO)] is a kind of ceramic that allows the lithium-ions to shuttle back and forth easily, but it’s brittle,’ says senior author Wendy Gu. ‘A real-world solid-state battery is made of layers of stacked cathode-electrolyte-anode sheets. Manufacturing these without even the tiniest imperfections would be nearly impossible and very expensive. We decided a protective surface may be more realistic, and just a little bit of silver seems to do a pretty good job.’
While other researchers have investigated metallic silver coatings on LLZO, this research uses a dissolved form of silver (Ag+) deposited as a 3nm-thick layer. After heating the samples to 300°C, the team used a specialised probe inside a scanning electron microscope to measure the force required to fracture the surface. The silver-treated electrolyte required almost five times more mechanical pressure to crack than the untreated material (Nat. Mater., 2026, DOI: 10.1038/s41563-025-02465-7).
The researchers say that, during heating, the silver atoms diffuse into the electrolyte’s surface, exchanging places with much smaller lithium atoms to a depth of 20-50nm. The silver remains positively charged, which they suggest could be the key to preventing crack formation. Where imperfections already exist, the presence of some positive silver ions also appears to prevent lithium from growing destructive branches inside the electrolyte.
The authors report a very thorough and interesting fundamental study, says Alex Rettie of University College, London, UK. ‘[They] create compressive strain at the interface… in a clever way: annealing a thin Ag layer to incorporate Ag in the bulk and microstructure which improved the surface hardness and lithium plating capability markedly. However, the conditions under which these metrics were measured were very generous, ie on very small areas of an ultra-clean, carefully prepared samples. The improvement was modest when measured in a larger-scale (still small) electrochemical cell. [More] work is needed to demonstrate this as a promising approach on the cell level.’
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