Researchers from the Hong Kong University of Science and Technology (HKUST) have developed an additive based on silver ions that improves the stability and energy density of lithium-metal batteries without a lithium anode. The work was published in the journal Nature Communications.
Lithium-metal batteries are considered promising for the next generation of batteries owing to their high theoretical specific capacity (the amount of energy a material can store per unit mass) and low reduction potential. In so-called anode-free cells, a copper current collector - the part on which lithium is deposited - is used instead of a lithium anode. This simplifies production and increases energy density. However, ordinary copper interacts poorly with lithium, which leads to uneven deposition of the metal and the growth of dendrites - filamentary crystals that can short-circuit the electrodes and shorten service life. In addition, the natural film at the electrolyte-electrode interface (the solid electrolyte interphase, SEI) is unstable, which limits battery life.
To solve these problems, the team led by Professor Shao Minhua added an AMI additive consisting of silver ions and anions (negatively charged ions) to the electrolyte. The additive performs several functions: it improves the wettability of copper by lithium, suppresses dendrite formation, promotes the formation of a stable SEI film with an organic-rich inner layer and an inorganic outer layer, and also triggers polymerization of the electrolyte, turning it into a quasi-solid gel. Such a gel improves contact between components and accelerates lithium-ion transport.
In tests, a pouch cell with this additive showed a specific energy of 467 Wh/kg - comparable to commercial samples. A full coin cell retained 90% of its capacity after 200 charge-discharge cycles. These results demonstrate that the approach could form the basis of lighter and more durable batteries, although mass production is still a long way off.
"The key is not simply adding a silver salt or a polymerization initiator," Shao Minhua explains. "Our AMI additive releases several functions in a controlled process after cell assembly, allowing the current collector to be modified, an anion-based solvation structure to be created and a robust SEI film to be formed in one integrated process." According to him, this makes lithium deposition and dissolution highly reversible in an anode-free quasi-solid configuration, which lays the foundation for the next generation of batteries.
The study involved members of Shao's laboratory: postdocs Yunyi Chen (first author) and Siqi Lu, former postdoc Xitan Qian, 2026 PhD graduate Yuxiang Lui, and graduate students Yican Qiu, Siyu Zhou and Xinyi Lan.