Structural, electrochemical and thermal stability investigations on LiNi\(_{0.5−x}\)Al\(_{2x}\)Mn\(_{1.5−x}\)O\(_4\) \((0 \leq 2x \leq 1)\) as 5 V cathode materials

https://www.sciencedirect.com/science/article/pii/S0378775312009779

Std E-lyte, Thermal testing, RAMAN, FTIR, CV, GCPL, SEM

  • The XRD patterns show that impurity(LiAlO2) arises when \(2x \geq 0.6\).
  • The FTIR and Raman spectra indicate that the introduction of Al in the LiNi0.5Mn1.5O4 increases the disordering degree of Ni/Mn ions, changing the spinel structure from P4332 to Fd3¯m.
  • Cyclic voltammetry tests show that the voltage step between Ni2+/Ni3+ and Ni3+/Ni4+ have a sudden leap at 2x = 0.075, responding to the structural difference of the spinels.
  • At room temperature the LiNi0.45Al0.10Mn1.45O4 presents the best cycle performance with the capacity retention of 95.4% after 500 cycles at 1C rate, and the best rate capability with the discharge capacity of 119 mAh/g at 10C rate, which is about 93.7% of its capacity at 0.5C
  • The thermal properties of the spinels have been tested by C80 calorimeter and the results show that introduction of Al in LiNi0.5Mn1.5O4 can effectively suppress the exothermic reaction below 225 °C, thus improve the safety of the high voltage cathode material.

Exp: Thermopolymerization from nitrates (and Mn acetate). Sintering: 900C 15h, 700C 48h. LP30 E-lyte 8:1:1 lnmo:acetylene black, PVDF and NMP AM loading: 4.5-5mg

Stability testing: 20mg cathode materials + 50mg E-lyte, Sealed SS tube. 0.2C/min, 30-300C. Same method as Thermal stability of LiPF_6-based electrolyte and effect of contact with various delithiated cathodes of Li-ion batteries

Cyclic voltammetry: Scan rate: 0.05mV/s

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