[ Manuscript received October 8, 2003, in revised form March 2, 2004]Corrosion behaviors of X70 steel were studied by means of electrochemical experiments and morphology observation. First, through potentiodynamic pol...[ Manuscript received October 8, 2003, in revised form March 2, 2004]Corrosion behaviors of X70 steel were studied by means of electrochemical experiments and morphology observation. First, through potentiodynamic polarization in solution of various Cl- ions concentration, it was found that Epit began to appear in solution of Cl- concentration above 0.1 mol/L, and there was a critical point of Cl- concentration between 0.05 mol/L and 0.1 mol/L, below which the extent of pitting and general corrosion were trivial, while in solution of Cl- concentration above 0.1 mol/L, general and pitting corrosion became greater as the increasing of Cl- concentration. All of them were confirmed by the SEM observations after anodic polarization. Second, via the potentiodynamic polarization curves of X70 steel in 0.5 mol/L Cl- solution with 0, 0.05, 0.5 and 1 mol/L SO42-ions, it was found SO42- ions were able to inhibit corrosion aroused from Cl- ions, accordingly a model was set up to describe the process. In addition, to further explore the inhibited effect of SO42- ions, EIS was used in solutions of different Cl- and SO42- concentrations, the results revealed that the electrochemical resistance has a relation with the [SO42-]/[Cl-], that was, the bigger the value of [SO42-]/[CI-], the greater the electrochemical resistance.展开更多
Despite the high energy density of lithium-rich(Li-rich)cathodes,their implementation is hampered by the unsatisfied rate capacity and poor cycling performance accompanied with substantial voltage decay.To address the...Despite the high energy density of lithium-rich(Li-rich)cathodes,their implementation is hampered by the unsatisfied rate capacity and poor cycling performance accompanied with substantial voltage decay.To address these issues,the hierarchical yolk-shell structured Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)cathodes(YK-LMNCO)was proposed and synthesized through a facile glycerol assisted solvothermal approach and the following lithiation process.Benefitting from the shortened lithium diffusion lengths and the enhanced tolerance to the large volume variation upon lithium ions intercalation/de-intercalation,the unique structure reciprocates an initial coulombic efficiency of 85.8%,an outstanding capacity retention rate of 89.1%after cycling at 2.0 C for 200 cycles with a minor voltage drop,and a capacity retention rate of 93.8%after cycling at 10.0 C for 500 cycles,85.2%for 1,000 cycles.When assembled with graphite as anode,the YK-LMNCO//graphite full cell shows a remarkable capacity retention rate of 87.2%after cycling at 5.0 C for 50 cycles.Our facile strategy for constructing the yolk-shell structured Li-rich cathodes with high capacity and voltage stability sheds light on synthesizing other lithium storage materials.展开更多
文摘[ Manuscript received October 8, 2003, in revised form March 2, 2004]Corrosion behaviors of X70 steel were studied by means of electrochemical experiments and morphology observation. First, through potentiodynamic polarization in solution of various Cl- ions concentration, it was found that Epit began to appear in solution of Cl- concentration above 0.1 mol/L, and there was a critical point of Cl- concentration between 0.05 mol/L and 0.1 mol/L, below which the extent of pitting and general corrosion were trivial, while in solution of Cl- concentration above 0.1 mol/L, general and pitting corrosion became greater as the increasing of Cl- concentration. All of them were confirmed by the SEM observations after anodic polarization. Second, via the potentiodynamic polarization curves of X70 steel in 0.5 mol/L Cl- solution with 0, 0.05, 0.5 and 1 mol/L SO42-ions, it was found SO42- ions were able to inhibit corrosion aroused from Cl- ions, accordingly a model was set up to describe the process. In addition, to further explore the inhibited effect of SO42- ions, EIS was used in solutions of different Cl- and SO42- concentrations, the results revealed that the electrochemical resistance has a relation with the [SO42-]/[Cl-], that was, the bigger the value of [SO42-]/[CI-], the greater the electrochemical resistance.
基金The authors acknowledge the financial support from Natural Science Foundation of Guangdong Province(No.2018A030313721)the National Key Research and Development Program of China(No.2018YFB0703500)the National Natural Science Foundation of China(No.91963113).
文摘Despite the high energy density of lithium-rich(Li-rich)cathodes,their implementation is hampered by the unsatisfied rate capacity and poor cycling performance accompanied with substantial voltage decay.To address these issues,the hierarchical yolk-shell structured Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)cathodes(YK-LMNCO)was proposed and synthesized through a facile glycerol assisted solvothermal approach and the following lithiation process.Benefitting from the shortened lithium diffusion lengths and the enhanced tolerance to the large volume variation upon lithium ions intercalation/de-intercalation,the unique structure reciprocates an initial coulombic efficiency of 85.8%,an outstanding capacity retention rate of 89.1%after cycling at 2.0 C for 200 cycles with a minor voltage drop,and a capacity retention rate of 93.8%after cycling at 10.0 C for 500 cycles,85.2%for 1,000 cycles.When assembled with graphite as anode,the YK-LMNCO//graphite full cell shows a remarkable capacity retention rate of 87.2%after cycling at 5.0 C for 50 cycles.Our facile strategy for constructing the yolk-shell structured Li-rich cathodes with high capacity and voltage stability sheds light on synthesizing other lithium storage materials.
