Nano-Li_(2)Mn_(0.5)Fe_(0.5)SiO_(4)/C cathode material is synthesized by a hydrothermal route and phosphorus substitution is applied to improve structural stability and electrochemical properties.At low substitution co...Nano-Li_(2)Mn_(0.5)Fe_(0.5)SiO_(4)/C cathode material is synthesized by a hydrothermal route and phosphorus substitution is applied to improve structural stability and electrochemical properties.At low substitution content,P element completely enters into the lattice,forms[PO_(4)]tetrahedrons and partially replaces[SiO_(4)]tetrahedrons,which is confirmed by X-ray diffraction and X-ray photoelectron spectroscope measurements.Phosphorus substitution helps to suppress the change of coordination number of Mn and stabilize the material structure to some extent,obtaining better electrochemical performance in the early cycle.With the increase of P content,parts of P element exist in Li_(3)PO_(4)which distributes uniformly and co-exists with active substance.Electrochemical tests prove that existing Li_(3)PO_(4)has positive impacts on cycle and rate performance,and the lithium ion diffusion coefficient increases by about 14 times than pristine sample.Under the synergistic effects of phosphate substation and proper Li_(3)PO_(4),Li_(2)Mn_(0.5)Fe_(0.5)SiO_(4)/C shows enhanced electrochemical performances.展开更多
In this paper,a low-cost and environmental-friendly leaching agent citric acid(C_(6)H_(8)O_(7))was used to treat the sediment of Dianchi Lake(SDL)to synthesize lithium silicate(Li_(4)SiO_(4))based CO_(2)sorbent.The re...In this paper,a low-cost and environmental-friendly leaching agent citric acid(C_(6)H_(8)O_(7))was used to treat the sediment of Dianchi Lake(SDL)to synthesize lithium silicate(Li_(4)SiO_(4))based CO_(2)sorbent.The results were compared with that treated with strong acid.Moreover,the effects of preparation conditions,sorption conditions and desorption conditions on the CO_(2)sorption performance of prepared Li_(4)SiO_(4)were systematically studied.Under optimal conditions,the Li_(4)SiO_(4)sorbent was successfully synthesized and its CO_(2)sorption capacity reached 31.37%(mass),which is much higher than that synthesized from SDL treated with strong acid.It is speculated that the presence of some elements after C_(6)H_(8)O_(7)treatment may promote the sorption of synthetic Li_(4)SiO_(4)to CO_(2).In addition,after doping with K_(2)CO_(3),the CO_(2)uptake increases from the original 12.02%and 22.12%to 23.96%and 32.41%(mass)under the 20%and 50%CO_(2)partial pressure,respectively.More importantly,after doping K_(2)CO_(3),the synthesized Li_(4)SiO_(4)has a high cyclic stability under the low CO_(2)partial pressure.展开更多
基金This work was supported by the National Natural Science Foundation of China(No.51372136)the NSFC-Guangdong united fund(U1401246).
文摘Nano-Li_(2)Mn_(0.5)Fe_(0.5)SiO_(4)/C cathode material is synthesized by a hydrothermal route and phosphorus substitution is applied to improve structural stability and electrochemical properties.At low substitution content,P element completely enters into the lattice,forms[PO_(4)]tetrahedrons and partially replaces[SiO_(4)]tetrahedrons,which is confirmed by X-ray diffraction and X-ray photoelectron spectroscope measurements.Phosphorus substitution helps to suppress the change of coordination number of Mn and stabilize the material structure to some extent,obtaining better electrochemical performance in the early cycle.With the increase of P content,parts of P element exist in Li_(3)PO_(4)which distributes uniformly and co-exists with active substance.Electrochemical tests prove that existing Li_(3)PO_(4)has positive impacts on cycle and rate performance,and the lithium ion diffusion coefficient increases by about 14 times than pristine sample.Under the synergistic effects of phosphate substation and proper Li_(3)PO_(4),Li_(2)Mn_(0.5)Fe_(0.5)SiO_(4)/C shows enhanced electrochemical performances.
基金the financial support from National Natural Science Foundation of China(21868015,51802135)the Applied Basic Research Programs of Yunnan Province(140520210057)+1 种基金Taif University Researchers Supporting Project number(TURSP-2020/163)Taif University,Taif,Saudi Arabia。
文摘In this paper,a low-cost and environmental-friendly leaching agent citric acid(C_(6)H_(8)O_(7))was used to treat the sediment of Dianchi Lake(SDL)to synthesize lithium silicate(Li_(4)SiO_(4))based CO_(2)sorbent.The results were compared with that treated with strong acid.Moreover,the effects of preparation conditions,sorption conditions and desorption conditions on the CO_(2)sorption performance of prepared Li_(4)SiO_(4)were systematically studied.Under optimal conditions,the Li_(4)SiO_(4)sorbent was successfully synthesized and its CO_(2)sorption capacity reached 31.37%(mass),which is much higher than that synthesized from SDL treated with strong acid.It is speculated that the presence of some elements after C_(6)H_(8)O_(7)treatment may promote the sorption of synthetic Li_(4)SiO_(4)to CO_(2).In addition,after doping with K_(2)CO_(3),the CO_(2)uptake increases from the original 12.02%and 22.12%to 23.96%and 32.41%(mass)under the 20%and 50%CO_(2)partial pressure,respectively.More importantly,after doping K_(2)CO_(3),the synthesized Li_(4)SiO_(4)has a high cyclic stability under the low CO_(2)partial pressure.
