Doping modification of electrode materials is a sought-after strategy to improve their electrochemical performance in the secondary batteries field. Herein,polyanion（BO3）^3-doped Li3V2（PO4）3 cathode materials were...Doping modification of electrode materials is a sought-after strategy to improve their electrochemical performance in the secondary batteries field. Herein,polyanion（BO3）^3-doped Li3V2（PO4）3 cathode materials were successfully synthesized via a wet coordination method. The effects of（BO3）^3- doping content on crystal structure, morphology and electrochemical performance were explored by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS）. All the asprepared samples have the same monoclinic structure;among them, Li3V2（PO4）（2.75）（BO3）（0.15） sample has relatively uniform and optimized particle size. In addition, this sample has the highest discharge capacity and the best cycling stability, with an initial discharge capacity of 120.4mAh·g^-1, and after 30 cycles at a rate of 0.1C, the discharge capacity still remains 119.3 mAh·g^-1. It is confirmed that moderate polyanion（BO3）^3- doping can rearrange the electronic structure of the bulk Li3V2（PO4）3,lower the charge transfer resistance and further improve the electrochemical behaviors.展开更多
Inorganic speciation of dissolved rare earth elements （REEs） were calculated for Chaohu Lake and Longganhu Lake by using the program MINTEQ 2.30. The result shows that REE-Carbonate complexes, which account for more...Inorganic speciation of dissolved rare earth elements （REEs） were calculated for Chaohu Lake and Longganhu Lake by using the program MINTEQ 2.30. The result shows that REE-Carbonate complexes, which account for more than 93% of total REE are the dominate and typically species in solution. Moreover, carbonator complexes （LnCO3^＋ ） were predicted to be the dominant species when pH between 7.2 and 8.0 and bicarbonate complexes （Ln （CO3）2^-） were predicted to be the dominant species when pH 〉 8.0. The free ion specie （i .e., Ln^3＋ ） increases in these waters with pH decreasing and accounts for about 5.03 %. The percentage of REE-phosphate complexes account for 1.61% of the dissolved REEs. REE-phosphate for light REEs complexes are supersaturated in Chaohu Lake and Longganhu Lake. Furthermore, LnPO4 for heavy REEs are supersaturated in west of Chaohu Lake in high water period. PO4^3- is responsible for limiting the dissolved REEs concentrations. REE-sulfate, REE-chloride, REE-fluoride and REE-hydroxide complexes, are negligible and generally account for less than 1% of the total dissolved REEs.展开更多
基金financially supported by the National Key Research and Development Program of China(No.2016YFB0100500)the Beijing Co-construction Project(No.20150939014)
文摘Doping modification of electrode materials is a sought-after strategy to improve their electrochemical performance in the secondary batteries field. Herein,polyanion（BO3）^3-doped Li3V2（PO4）3 cathode materials were successfully synthesized via a wet coordination method. The effects of（BO3）^3- doping content on crystal structure, morphology and electrochemical performance were explored by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS）. All the asprepared samples have the same monoclinic structure;among them, Li3V2（PO4）（2.75）（BO3）（0.15） sample has relatively uniform and optimized particle size. In addition, this sample has the highest discharge capacity and the best cycling stability, with an initial discharge capacity of 120.4mAh·g^-1, and after 30 cycles at a rate of 0.1C, the discharge capacity still remains 119.3 mAh·g^-1. It is confirmed that moderate polyanion（BO3）^3- doping can rearrange the electronic structure of the bulk Li3V2（PO4）3,lower the charge transfer resistance and further improve the electrochemical behaviors.
文摘Inorganic speciation of dissolved rare earth elements （REEs） were calculated for Chaohu Lake and Longganhu Lake by using the program MINTEQ 2.30. The result shows that REE-Carbonate complexes, which account for more than 93% of total REE are the dominate and typically species in solution. Moreover, carbonator complexes （LnCO3^＋ ） were predicted to be the dominant species when pH between 7.2 and 8.0 and bicarbonate complexes （Ln （CO3）2^-） were predicted to be the dominant species when pH 〉 8.0. The free ion specie （i .e., Ln^3＋ ） increases in these waters with pH decreasing and accounts for about 5.03 %. The percentage of REE-phosphate complexes account for 1.61% of the dissolved REEs. REE-phosphate for light REEs complexes are supersaturated in Chaohu Lake and Longganhu Lake. Furthermore, LnPO4 for heavy REEs are supersaturated in west of Chaohu Lake in high water period. PO4^3- is responsible for limiting the dissolved REEs concentrations. REE-sulfate, REE-chloride, REE-fluoride and REE-hydroxide complexes, are negligible and generally account for less than 1% of the total dissolved REEs.
