Energy storage mechanism of monocrystalline layered FePS3 and FePSe3 as active materials for Mg batteries and pseudocapacitors

• Published in: Journal of alloys and compounds Vol. 883; p. 160822
• Main Authors: Wang, Mengqiao, Han, Jonghyun, Liu, Wei, Kamiko, Masao, Yagi, Shunsuke
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25-11-2021; Elsevier BV
• Subjects: Aluminum chloride; Current density; Energy storage; Intercalation; Intercalation/deintercalation; Interlayers; Layered structure; Phosphorous trichalcogenide; Pseudocapacitor; Tetrahydrofuran; Phosphorous trichalcogenide; Layered structure; Intercalation/deintercalation; Pseudocapacitor
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.160822

•Mg2+ ions can be intercalated/deintercalated into/out of layered FePS3 reversibly.•Both Faradaic and non-Faradaic processes contribute to energy storage.•FePS3 behaves a high specific capacity (232.7 mAh g–1) at 0.2 A g–1.•FePS3 retains layered structure after cycles irrespective of the (de)intercalation.
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We report the reversible intercalation of Mg2+ ions into monocrystalline layered FePS3 in a tetrahydrofuran electrolyte containing 0.8 M PhMgCl and 0.4 M AlCl3. Mg2+ ions were not intercalated into FePSe3 because of the lower interlayer spacings (FePS3: 1.24 Å, FePSe3, 1.00 Å). The contribution of the non-Faradaic (double layer formation) and Faradaic (electrochemical intercalation/deintercalation, adsorption/desorption) processes toward the energy storage mechanism of FePS3 and FePSe3 were quantified. The maximum specific capacity displayed by FePS3 was 232.7 mAh g–1 at a current density of 0.2 A g–1, which was higher than that of FePSe3 (153.1 mAh g–1). Even at high current density (2 A g–1), FePS3 exhibited a specific capacity of 100.7 mAh g–1 after 450 cycles; the specific capacity of the less robust FePSe3 was just 26.3 mAh g–1.