Comparative Study about Differently Structured Transitional Metal Molybdates as Negative Electrodes for LIBs

Abstract

The nanostructuredmaterials represent the center of fundamental advances to design new eraelectrodes for high energy density batteries. Especially, one-dimensionalnanomaterials are recognized as a solution due to their large surface area,short diffusion distance and high volume accommodation ability. In this sense,first in literature a comparative study has been done to examine theelectrochemical performances of differently fabricated transition metal oxide molybdatepowders: lithium storage capabilities of nickel-cobalt-molybdate composite iscompared to that of the cobalt oxide decorated nickel molybdate powders. Tomeasure the effect of cobalt atom, bare nickel molybdate powders have been alsofabricated and tested. The lithiation mechanism of these electrodes arediscussed based on the cyclic voltammetry curvatures and the SEI layerformation on the electrodes and the electrode/electrolyte stability uponcycling are analyzed following the electrochemical impedance spectroscopy testresults (after 1st,2nd and 4th cycles). The outcome of characterizations revealthat the addition of cobalt changes the powder morphology and improves theelectrochemical performance of the electrode. Among three samples, the cobalt oxidedecorated nickel molybdate performs higher retention and rate performance sincethe top layer promotes more stable electrode/electrolyte interface providing acapacity of 290 mAh/g after 100 cycles. The rate performance of the sample isalso found promising, the electrode delivers 200 mAh/g even at 400mA/g rate.

Keywords

• metal molybdates
• lithium ion batteries
• hydrothermal method
• anode