CHINESE researchers have solved a long-standing hurdle for all‑solid‑state lithium batteries by creating a self‑adaptive interphase that maintains intimate contact between the lithium metal anode and a solid electrolyte without the need for external pressure — a decisive step toward commercialization.

All‑solid‑state lithium batteries are widely regarded as the “grail” of next‑generation energy storage because they promise higher energy density and improved safety. But they have faced a persistent practical problem: the solid electrolyte and lithium metal electrode tend to develop tiny pores and cracks at their interface, breaking contact during cycling. Existing solutions have relied on bulky external fixtures to apply constant pressure, making devices impractically large and heavy.

The new work, published in Nature Sustainability, was conducted by teams from the Institute of Physics of the Chinese Academy of Sciences (CAS), the Ningbo Institute of Materials Technology and Engineering (CAS), and Huazhong University of Science and Technology.

The researchers found that introducing iodide ions into a sulfide solid electrolyte leads to the spontaneous formation of an iodine‑rich interphase at the electrode interface during battery operation. Under the cell’s electric field, iodide ions migrate to the interface and create a layer that actively attracts lithium ions, filling gaps and pores in a self‑healing manner and thereby preserving tight contact between electrode and electrolyte without external compression.

Prototype cells built with this approach exhibited stable, high performance over hundreds of charge-discharge cycles under standard testing conditions, significantly outperforming comparable existing solid‑state batteries.

Huang Xuejie of the CAS Institute of Physics, a corresponding author of the paper, said the technology could enable future cells with energy densities above 500 Wh/kg and potentially at least double the battery life of consumer electronic devices. The breakthrough is expected to accelerate development of high‑energy‑density all‑solid‑state batteries for demanding applications such as humanoid robots, electric aviation, and electric vehicles, offering safer and more efficient energy solutions, Huang added.

Wang Chunsheng, a solid‑state battery expert at the University of Maryland, commented that the study fundamentally addresses a key bottleneck that had hindered commercialization and represents a decisive step toward application.(Xinhua)