Researchers at The Hong Kong University of Science and Technology (HKUST) report that a silver-containing additive helped an anode-free lithium battery retain 90% of its capacity after 200 charge-discharge cycles in a full coin cell.
The team, led by Professor Shao Minhua, also reported an energy density of 467 watt-hours per kilogram, equivalent to approximately 212 Wh/lb, in a pouch cell. That energy-density measurement concerns a different cell format from the coin cell used for the capacity-retention result. The reported performance figures have not been independently verified.
The researchers describe an approach that modifies several battery interfaces after assembly. They say it changes how lithium deposits on the copper current collector, helps stabilize the protective electrode layer and triggers the formation of a quasi-solid gel in the electrolyte.
Why anode-free batteries need stable interfaces
anode-free lithium batteries use a bare copper current collector instead of a separate anode at assembly. The researchers describe this design as a way to reduce inactive material and simplify manufacturing, while identifying control of lithium deposition as a central challenge.
In the team’s explanation, conventional copper surfaces have a limited affinity for lithium. Uneven deposition during charging can encourage dendrites: needle-like lithium structures that can damage internal components and create safety risks. Making lithium deposit more uniformly is therefore one of the aims of the interface treatment.
The researchers also identify instability in the solid electrolyte interphase, or SEI, as a problem. This protective layer forms on the electrode surface. They say an unstable SEI can hinder lithium-ion movement and contribute to declining battery performance as charging and discharging continue.
How the silver-containing additive works
The team used an additive it calls AMI, containing silver ions and anions. The researchers say its components perform several functions through a controlled sequence after cell assembly, linking changes to the current collector with changes in the electrolyte and electrode interface.
According to the team, silver modifies the copper surface to increase its affinity for lithium, a property known as lithiophilicity. The modified surface also helps anchor species derived from the anions, which the researchers associate with the formation of a more stable SEI.
They describe the resulting protective interface as having an organic-rich inner layer and an inorganic-rich outer layer. The proposed arrangement is intended to support lithium-ion transport while limiting conditions that encourage dendrite growth.
The researchers also say the released anions initiate a reaction in the electrolyte that produces a quasi-solid gel. They link that gel to closer contact between the electrode and electrolyte and to improved interface stability during repeated cycling.
Together, these processes are intended to make lithium plating and stripping more reversible. The team also identifies suppression of dendrites as a potential safety benefit, rather than treating capacity retention alone as evidence of safety.
Several functions in one process
Shao described the approach as an integrated treatment, with the additive coordinating several changes rather than serving only one purpose.
“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,” Shao said.
“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.”
