Study On Preparation Nickel And Cobalt Doping Lithium Manganate/Reduced Graphene Oxide And Electrochemical Performance

The lithium manganate?LiMn₂O₄?/reduced graphene oxide composite and N i and Co doping lithium manganate/reduced graphene oxide composite were synthesised by hydro-thermal method with graphene oxide?GO?as supporter.The characterization of materials by means of all kinds of instruments,and the composite materials were measured as cathode material of lithium ions batteries?LIBs?.First of all,LiMn₂O₄/reduced graphene oxide?LMG?was prepared by hydro-thermal method from following calcinations.The LMG material was characterized with X-ray diffractometer?XRD?,Raman spectrometer,X-ray photoelectron spectroscopy?XPS?,transmission electron microscope?TEM?and energy dispersive X-ray spectroscopy?EDX?,and was tested in electrochemistryfield as a cathode in LIBs.It gained that the first discharge specific capacity was 137 mAh/g and kept 110 mAh/g after 150 charge/discharge cycles at current rate of 0.5 C.The rate capability of LMG was better than that of pure LiMn₂O₄ and LMG via physical method?PM-LMG?.These all proved that the existence of graphene in LMG improved the cation electrochemical performance in LIBs.Secondly,because of unsatisfactory cycle performance,we synthesized N i doping LMG composite?LMNG?.The LMNG material was characterized with XRD,Raman spectrometer,XPS,TEM and EDX,and was tested in electrochemistry field as a cathode in LIBs.We can know that the N i element uniformlydisperse in LMNG materials through EDX mapping image.The resule showed that LMNG material capacitydecreased owing to N i adulteration,but it increased cycling stability.The specific capacity kept 87% after 150 charge/discharge cycles at a current rate of 0.5 C.It is a strong evidence that doping can improve the electrode cycle performance.Because the LMNG capacity decreased and the promotion of cycle performance was not satisfied,we synthesized N i and Co doping LMG composite?LMNCG?.The LMNG material was characterized with XRD,Raman spectrometer,XPS and TEM,and was tested in electrochemistry field as a cathode in LIBs.The experiment result showed that the promotion of cycle performance of LMNCG was obvious.The specific capacity kept 95% after 200 charge/discharge cycles at current rate of 0.5 C.The rate capabilityperformance of LMNCG was also improved.