Research On Cathode Materials And Battery Systems Of Rechargeable Magnesium Battery

Rechargeable magnesium battery,as a kind of ideal green energy conversion device,has attracted much attention across the word.Now,the study of rechargeable magnesium battery just beagn.The study mainly focuses on the development of stable electrolytes,and high-capacity or high-voltage cathode materials which can realize reversible magnesium ions intercalation/de-intercalation.In this paper,four types of sulfur/Ketjen black?S/KB?composites with different sulfur contents were prepared via two facile processes including ball-milling and high temperature heat-treatment of the sublimed sulfur and conductive carbon black.The microstructure and electrochemical performance of the as-prepared composites were investigated systematically by X-ray diffraction?XRD?,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?and so forth.From the characteristic results,it was found that sulfur in S/KB composite?60 wt%S?was well dispersed on nano-scale and embedded inside nano-pores of the Ketjen black,leading to the best electrochemical performance among those parallel composites.The initial discharge capacity of S/KB composite?60 wt%S?was up to 466.3 mAh·g^-11 and about 165 mAh·g^-1 was retained after 6 cycles.Moreover,MoO₂ hollow microspheres with unique morphology were synthesized via two-step hydrothermal reactions.A new kind of hybrid battery was assembled with MoO₂ hollow microspheres cathode,metal magnesium anode,and dual-salt electrolyte containing both Mg²⁺and Li⁺cations.This type of battery can not only avoid metallic dendrite formation,but also possess high cathode capacity,which is still choke point for the development of rechargeable Mg battery.It is found that the unique morphology of MoO₂ hollow microspheres material plays a vital role in its electrochemical performance.The initial discharge capacity of the material turns out to be 217.2 mAh g^-1 with a coulombic efficiency of near 88%.And then,the efficiency approaches 100%in the following cycles.On the contrary,the commercial solid MoO₂ particles in the size of 1¹0?m show an initial discharge capacity less than 50 mAh g^-1,which is much inferior.Inductively coupled plasma mass spectrometry?ICP-MS?analysis reveals that both Mg²⁺and Li⁺take part in the intercalation/de-intercalation reactions happened in the cathode.Finally,the electrochemical behavior of differernt current collectors in the 2^nd generation of electrolyte was examined.A new kind mould battery with Inconel C-276 as current collector has been developed.