No abstract

No abstract

A novel O3-NaMn 0.42 Fe 0.42 Ni 0.17 O 2 cathode material for sodium-ion batteries is synthesized, for the first time, by a co-precipitation method followed by solid-state reaction. The effect of Ni 2+ , Cu 2+ and Ca 2+ substitution for Mn 4+ and Fe 3+ on the structural stability, rate capability and cycling performance of the cathode material are examined. Chemical titration results and powder Xray diffraction patterns indicate that the substitution of Ni 2+ , Cu 2+ and Ca 2+ for Fe 3+ and Mn 4+ can inhibit the reaction of Na + ions in the structure of O3-NaMn 0.33 Fe 0.33 Ni 0.21 Cu 0.08 Ca 0.04 O 2 with air. The Ni 2+ , Cu 2+ and Ca 2+substituted O3-NaMn 0.33 Fe 0.33 Ni 0.21 Cu 0.08 Ca 0.04 O 2 cathode material show a higher capacity and better cycling stability than that of O3-NaMn 0.42 Fe 0.42 Ni 0.17 O 2, indicating that a small amount of Ni 2+ , Cu 2+ and Ca 2+ substitution can improve the structure/air stability and the electrochemical performance. When O3-NaMn 0.33 Fe 0.33 Ni 0.21 Cu 0.08 Ca 0.04 O 2 cathode material is combined with the hard carbon anode, a full cell gives 220 Wh kg À1 energy density and 100% capacity retention after 56 charge/discharge cycles at 0.5C. The O3-NaMn 0.33 Fe 0.33 Ni 0.21 Cu 0.08 Ca 0.04 O 2 can be thought of as a potential cathode active material to encourage progress toward sodium-ion battery commercialization due to the high industrial applicability of the synthesis process and good electrochemical performance. Prime Novelty StatementA novel O3-NaMn 0.42 Fe 0.42 Ni 0.17 O 2 cathode material for sod um on batter es is synthesized for the first time by a co-precipitation method with subsequent solid-state reaction. The substitution of Ni 2+ , Cu 2+ and Ca 2+ for Fe 3+ and Mn 4+ improves the air stability and electrochemical performance of O3-NaMn 0.33 Fe 0.33 Ni 0.21 Cu 0.08 Ca 0.04 O 2 cathode material. When O3-NaMn 0.33 Fe 0.33 Ni 0.21 Cu 0.08 Ca 0.04 O 2 cathode material couples with the hard carbon anode, a full cell gives an energy density of 220 Wh kg À1 and the capacity retention of 100% after 56 charge/discharge cycles.

In this study, the resting eggs of aquatic creatures living in freshwater (Daphnia, Cladocera, Crustacean) ecosystems were used as a novel biosorbent extractant for synchronous preconcentration of trace Cd(II), Co(II), Cu(II), Mn(II), and Ni(II) previous to measurement by flame atomic absorpiton spectrometry (FAAS). Using column procedures, optimization studies were conducted to realize the effective adsorption of the analyte ions such as the solution pH, amount of the biosorbent, volume of the sample, interfering ions, etc. A high preconcentration factor of 67 and low relative standard deflection of ≤4.1% (n=8) were obtained. The invention constrains based on the 3 s/b criterion were 2.4 for Cd(II), 41.4 for Co(II), 4.2 for Cu(II), 3.0 for Mn(II), and 9.6 μg L(-1) for Ni(II). The accuracy of the method was verified by analysis of a certified standard reference material. The used procedure was applied to the definition of the analytes in diverse environmental samples with convincing results. Consequently, the resting eggs of Daphnia can be used as a biosorbent for preconcentration and biosorption studies.