ÌÇÐÄvlogÊÓƵ

DALLAS (ÌÇÐÄvlogÊÓƵ) – An ÌÇÐÄvlogÊÓƵ team has found a way to make lithium metal batteries last longer, with higher energy density, than existing renewable batteries by making them more stable. 

Lithium metal batteries hold the potential to be a great option for electric vehicles, portable electronics, and large-scale energy storage – they’re lighter, can hold more energy and make batteries last longer than is currently possible.

But when these batteries charge and discharge, they can grow tiny, sharp structures called dendrites. Dendrites can poke through parts of the battery and cause it to short-circuit, which could eventually lead to overheating or even fires. And lithium metal batteries don’t last as long over as many cycles. 

Same high energy, longer life batteries 

An innovation that ÌÇÐÄvlogÊÓƵ mechanical engineer Donghai Wang and his team created – called a dual-passivation polymer coating – keeps these unwanted side reactions from happening. It helps lithium move smoothly during charging and discharging and dramatically extends battery life, a study published in the journal Nature Energy reports. 

“Our coated lithium metal battery cells kept 80% of their capacity over 600 cycles, which is a major step toward making this technology practical for everyday use,” said Wang, the Brown Foundation Chair of Mechanical Engineering at ÌÇÐÄvlogÊÓƵ Lyle. His research focuses on the design and synthesis of nanostructured functional materials and energy storage technologies like Li-ion batteries and also beyond Li-ion technology.     

Wang added that the dual-passivation polymer coating “not only improves battery performance, but also offers a scalable and potentially cost-effective approach for commercial applications.”

ÌÇÐÄvlogÊÓƵ mechanical engineer Donghai Wang’s team developed coated lithium metal cells that retained 80% capacity over 600 cycles—“a major step toward making this technology practical for everyday use,” he said.

How it works

Every battery has two ends: a positive terminal (cathode) and a negative terminal (anode). A chemical reaction that is continually happening between these terminals generates the electricity that powers the battery.

Between the cathode and anode lies the electrolyte, a substance that enables ions to move back and forth between the two terminals, allowing the battery to function.

The problem is that lithium metal is very reactive, which means it easily reacts with other materials inside a battery. This high volatility causes lithium ions to deposit unevenly on the anode during charging, leading to the growth of sharp, needle-like dendrites. Instead of forming a smooth layer, the lithium clumps into these spikes, which can eventually pierce parts of the battery and cause it to short-circuit or even catch fire.

To help control this, a layer called the Solid Electrolyte Interphase (SEI) forms on the surface of the lithium metal. The SEI acts like a protective skin — it allows lithium ions to pass through but blocks unwanted reactions. 

Yet, when lithium grows unevenly into dendrites, the SEI breaks and reforms over and over, often becoming weaker or less effective each time. This makes it even harder to stop dendrites from growing, creating a cycle that worsens over time.

Wang’s dual-passivation polymer coating does two things to fix these issues.

“First, the polymer itself reacts spontaneously with the lithium to form a stable outer layer rich in lithium fluoride, which is very tough and helps block harmful reactions with the electrolytes,” Wang said. “Second, the coating also changes how lithium ions interact with the electrolyte components by removing certain anions from the way they’re surrounded.”

This change helps to make the inner layer of the SEI form in a more controlled way to delay dendrites from forming. 

An illustration of a dual-passivation polymer coating that boosts lithium battery anode stability by forming a lithium fluoride (LiF)-rich layer and improving lithium-ion interactions with the electrolyte.

Ongoing studies are being explored to see if this strategy can be used for other types of batteries, which could broaden its impact in energy storage technologies.