In situ fabrication of ultrathin few-layered WSe2 anchored on N, P dual-doped carbon by bioreactor for half/full sodium/potassium-ion batteries with ultralong cycling lifespan

Abstract Sodium/potassium-ion batteries (SIBs/PIBs) with high electrochemical performance are promising but there still remain daunting challenges to explore an anode material with appealing cycling stability and rate capability. In addition, the utilization of waste biomass arouses tremendous researches in energy storage applications. Herein, we elaborately coupling ultrathin few-layered WSe2 nanosheets with N, P-doped biochar by utilizing waste chlorella as adsorbent and reactor. It displays a prominent long-term cycling property (265 mAh g−1 at 1 A g−1 up to 1500 cycles) in SIBs, which is the best long-cycle performance ever reported for WSe2. Paired with Na3V2(PO4)3 cathode, full SIBs also exhibit superior capacity of 210 mAh g−1 at 0.5 A g−1 for 120 cycles. Notably, we also report WSe2-based anode material in PIBs, which delivers a high capacity of 333 mAh g−1 at 0.1 A g−1 for 100 cycles and superior cycling lifespan (155 mAh g−1 at 1 A g−1 up to 5300 cycles) as well as excellent rate properties. Additionally, the mechanism of the repeated process of sodiation/desodiation is revealed, by the deep characterization, such as ex-situ XRD/Raman, galvanostatic intermittent titration technique and CV measurements.