Dense integration of chlorocatechols crosslinked polyphenylene sulfide solid-state separator for Li metal-free batteries

• Hydrothermal process introduces a chlorocatechol cross-linker on the PPS powder • Dense PPS-based solid-state separator is fabricated using the dry electrode process • Dense integration and chlorocatechol contribute to the homogenous Li deposition • PPS based Li metal-free pouch cells delivered high energy density of 448 Wh kg-1 • Ensure cycle stability with presence of Cu powder contamination on the CuSn anode Dry electrode film fabrication technology, known for its environmental friendliness and low energy consumption, is recognized as an effective industrial approach for producing highly dense solid-state electrolytes and pore-free separators. It holds promise for applying thin lithium metal and Li metal-free anodes in ultra-high energy density Li-ions batteries. However, the films produced by this method suffer from issues such as poor toughness, low strength, uneven thickness, and difficulties in rewinding, which limit its widespread adoption in the large-scale manufacturing of lithium batteries. In this study, we propose a hydrothermal process to introduce a chlorocatechol-based cross-linker onto the surface of highly crystalline polyphenylene sulfide (PPS) powder. By employing the dry electrode process, a PPS-based solid-state separator (PPS-SSS) is fabricated, featuring a thin profile (18±2 μm), a smoother surface, and a denser structure, significantly enhancing its mechanical properties. Moreover, the dense integration structure and chlorocatechol groups contribute to a higher Li + transference number and more effectively inhibit the growth of Li dendrites. Li metal-free batteries, constructed with this separator, a Sn-plated Cu 10 μm foil anode, and a thick high-nickel cathode dry electrode, exhibit high discharge areal and specific capacities (5 mAh cm −2 and 200 mAh g −1 , respectively) and pouch battery device energy density exceeding 440 Wh kg −1 . Impressively, even in the presence of Cu or Fe powder contamination on the CuSn foil anode or cathode, this separator can still achieve uniform electric field distribution and lithium deposition, demonstrating good cycle stability.