A team at The Hong Kong University of Science and Technology (HKUST) has created a new battery design that could make future energy storage both lighter and longer-lasting. Their anode-free lithium metal battery reached an energy density of 467 Wh/kg (212 Wh/lb) in a pouch cell, bringing its performance closer to that of current commercial batteries.
The full coin cell retained 90 percent of its capacity after 200 charge-discharge cycles. The results come from a strategy that modifies critical battery interfaces to improve lithium deposition and stabilize the internal layers that govern battery performance.
Led by Professor Shao Minhua, the research team developed the approach to address persistent problems that limit the lifespan and energy density of anode-free lithium batteries.
Anode-free design faces lithium deposition problems
Lithium metal is a promising battery material because it has a high specific capacity and a low reduction potential. Anode-free batteries use a bare copper current collector instead of a separate anode to store lithium, reducing inactive material and simplifying manufacturing.
However, conventional copper surfaces do not readily attract lithium. This can cause lithium to deposit unevenly during charging, encouraging the growth of dendrites, which are needle-like structures that can damage battery components and create safety risks.
Another problem is the solid electrolyte interphase (SEI), a layer that forms naturally on the electrode surface. When this layer becomes unstable, it can interfere with lithium-ion movement and shorten the battery’s life.
Silver-based additive reshapes battery interfaces
To solve these problems, the researchers added an AMI additive with silver ions and anions. This additive starts several processes after the battery is put together, helping to change the copper surface and control how lithium is deposited.
The silver-modified surface improves lithiophilicity, making it easier for lithium to deposit more evenly. It also anchors anion-derived species that help build a more stable SEI.
The resulting interface has an organic-rich inner layer and an inorganic-rich outer layer. This arrangement is designed to support lithium-ion transport while limiting the conditions that encourage dendrite growth.
Quasi-solid gel strengthens the protective layer
The released anions also start a reaction in the electrolyte that forms a quasi-solid gel inside the organic inner and inorganic outer SEI layers. This keeps the electrode and electrolyte in close contact, stabilizing the interface over many charge and discharge cycles.
These changes help lithium plate and strip more reversibly, so the battery wears less over time. The researchers also say this combined method can make batteries safer by stopping dendrites from forming.
Integrated strategy could advance future batteries
Shao, who is the corresponding author and head of HKUST’s Department of Chemical and Biological Engineering, explained that this approach combines several functions into a single process.
“The key is not simply adding a silver salt or a polymerization initiator. Our AMI releases multiple functions through a controlled process after cell assembly, allowing us to modify the current collector, build an anion-derived solvation structure, and form a robust organic-inner/inorganic-outer SEI in one integrated process,” he added.
“This makes lithium plating and stripping highly reversible in an anode-free, quasi-solid-state configuration, laying a stronger foundation for the development of next-generation batteries.”
The study was published in the journal Nature Communications.