Toward 5V Spinel Oxides

Despitealimitedmarketshare to 10% ofthe global Li-Ion battery market, LiMn204, with its advantages of safety and low cost, is a candidate to be used in positive electrode mixed with other oxides for larger scale commercialization such as automotive application. 

We have optimized the electrochemical performances of high-voltage spinel oxides and selected the LiNio.4Mni 6O4 and LiNio sMni 5O4 compositions for future developments. Note that we have also regarded, as many authors, single and multiple substitutions of Co, Cu, Cr, and Ti for Ni and Mn. Such compounds did not have any particular advantage, possibly except the chromium-doped materials, already reported by Rojo et alP However, we believe that the presence of chromium is not justified 

Ab initio calculation methods predicted that the current solvents for the electrolytes used in Li-ion batteries often have oxidation stability to 5.5 V vs. Li /Li (propylene carbonate, ethylene carbonate, dimethyl carbonate). In practice, the potential limits are far below as illustrated by the work of Kanamura et For instance, the stability of PC-based electrolyte varied from 5 V (calculation) to 4.2 V vs. Li /Li (experiment). The origin of this difference may be multiple catalytic effect of the insertion materials, traces of water in the electrochemical system, influence of Li salts. In some cases, the decomposition of the electrolyte is accompanied by the formation of a solid film on the surface of the positive electrode.  

In the literature, the solutions explored usually consist in coating the active material by electro-inactive inorganic species (AI2O3, AIPO4, Ti02, Zr02). It is probable that the protective layer 

Another approach to obtain good cyclability and low selfdischarge may consist in the replacement of conventional liquid carbonates with new fluorinated solvents. Due to the inductive 

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