Thin activated‑carbon shell boosts sodium‑anode formation efficiency nearly fourfold, accelerating commercialization

A research team at Germany’s Federal Institute for Materials Research and Testing unveiled a core–shell anode architecture that sharply reduces capacity loss during the formation step of sodium‑ion cells. The approach applies a thin layer of activated carbon over a porous hard‑carbon core so sodium ions can still access storage sites while electrolyte molecules are kept out of the pore network. Laboratory results show the first‑cycle usable fraction climbs from roughly 18% without the coating to about 82% with it, a near fourfold improvement that directly addresses early formation inefficiency. That improvement has immediate manufacturing implications: higher initial availability of charge means less material left unusable after formation, shorter or less intensive formation protocols, and potentially higher production yields. Mechanistically the coating suppresses parasitic electrolyte decomposition that otherwise occupies pore volume and builds up unstable interphases, preserving sites intended for sodium insertion. Because sodium electrolytes are inherently less flammable than many lithium formulations, the coating’s manufacturability gains combine with safety advantages to broaden viable deployment scenarios—including urban stationary storage and rapid battery‑swap operations where fire risk is a limiting factor. The work dovetails with parallel industrial activity and testing initiatives in China and the United States that are pushing sodium cells toward both grid and mobility roles. Critical next steps include demonstrating long‑term cycle retention, compatibility with high‑throughput electrode processing, and consistent performance in larger cell formats. Expanded battery testing infrastructure should reveal real‑world tradeoffs in energy density, rate capability and lifecycle cost that lab cells cannot. If these follow‑on validations succeed, the materials tweak could shorten the path from prototype to commercial packs and strengthen a supply chain less reliant on constrained critical minerals. The net effect would be to make lower‑cost, safer sodium‑based options more practical for utilities and vehicle makers, altering procurement and deployment timelines across multiple markets.