Structural, microstructural and electrochemical studies of layered Lix(Ni0.33Mn0.33Co0.33)1-xO2 as cathode materials for rechargeable lithium ion batteries.

MARTINA GAMBA; MARIELA GISELA ORTIZ; SILVIA GRACIELA REAL; GUSTAVO SUAREZ

São Paulo

Congreso; 7th International Congress on Ceramics; 2018

University of São Paulo (Polytechnic School)

Layered oxide cathode materials Lix(Ni0.33Mn0.33Co0.33)1-xO2(x = 0, 0.07, 0.143 and 0.175) have been prepared by solid state reactions from astoichiometric mixture of Li2CO3, NiO, Co2O3and MnO2. Starting materials were well mixed in a non-liquid state inan agate ball milling tank at 800 rpm for 270 min. The milled powder was heatedat 10 ºC/min heating rate under air atmosphere first up to 400 ºC for 4 h andthen up to 800 ºC for 12 h. The obtained materials were left at roomtemperature and ground using an agate mortar up to smaller than mesh #325. The phase purity and crystalline structure ofmaterials were determined by X-ray diffraction analysis and Rietveldrefinements studies. Surface morphology and elemental analysis were carried outusing scanning electron microscopy. Particle diameters were measured by lightscattering experiments. Electrochemical performances were evaluated using cellsthat were assembled in an argon-filled glove box. For the positive electrodes, thesynthesized material, Super P conductive carbon black and poly(vinylidene fluoride)(80:10:10 wt.%) were mixed in n-methylpirrolidone and the obtained paste was spreadover an aluminum film. Lithium metal was used as counter and referenceelectrodes, while the electrolyte was composed of a 1:1 volume ratio ofethylene carbonate (EC) and dimethyl carbonate (DMC) with 1 M LiPF6.The electrochemical behavior of the prepared electrodes was studied by cyclicvoltammetry and charge-discharge curves. The materials showed a well redox performance at electrode?electrolyticinterface. The capacity of the materials increasedfrom 90 mAhg-1 for non-rich lithium ion material (x = 0) to 174 mAhg-1for the highest content of lithium (x = 0.175) at 0.1 C, showing both wellcycling stability at ambient temperature, between 2-4.6 V. Theseproperties allow concluding that these cathode materials can be considered as suitablepositive electrodes for the development of rechargeable lithium ion batteries.