Precise compressive strain regulation to activate the electrocatalytic activity of FeOOH enabling ultrastable lithium-sulfur batteries

Precisely regulating the degree of lattice strain is an effective strategy to activate the electrocatalytic activity of crystalline materials, but the accompanying variations in phase compositions and chemical components hinder the real unravelling of the catalytic activity enhancement mechanism. Herein, the mechanism of lattice strain degree modulating the adsorption/catalytic conversion performance of crystalline electrocatalysts for sulfur species is investigated single-variedly and quantitatively on the atomic scale. An appropriate (4.2 %) lattice compressive strain reasonably reduces the d-band center of Fe atoms, making the strained FeOOH nanorods possess a moderate adsorbability that can effectively immobilize lithium polysulfides (LiPSs), which is conducive to the desorption and following conversion of LiPSs, and at the same time prominently narrows the energy gap between the d-band center of Fe atom and the p-band center of O atom, promoting the electron transfer between the strained FeOOH nanorods and sulfur species, which markedly accelerates the interconversion of LiPSs and reduces the decomposition energy barriers of Li2S. The batteries with FeOOH electrocatalysts containing 4.2 % lattice compressive strain exhibit a supereminent long-term cycling stability with an average capacity decaying as low as 0.013 % per cycle during 3000 cycles at 2.0 C. Even at an electrolyte/sulfur ratio of 4.6 μL mg−1, the batteries with a sulfur loading of 9.17 mg cm−2 sustain a remarkable areal capacity of 7.17 mAh cm−2 over 70 cycles at 0.2 C. This research illuminates the principle of catalytic activity enhancement of catalysts regulated by lattice strain degree in Li-S electrochemistry, delivering a novel insight into the rational design and construction of superior sulfur electrocatalysts.