کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1606977 | 1516230 | 2016 | 7 صفحه PDF | دانلود رایگان |
• Kinetics of the lithium insertion by ac-impedance spectroscopy of Li7MnN4.
• Promoting effect of the crystallite size on the Li kinetics in Li7MnN4.
• Experimental evaluation of activation energy for lithium transition metal nitrides.
The kinetics of the electrochemical lithium insertion reaction in the as-prepared Li7MnN4 has been investigated using ac impedance spectroscopy as a function of cycles and temperature. The results are compared and discussed with that obtained for an optimized Li7MnN4 sample obtained by ball-milling. From this comparison, a promoting effect of a lower crystallite size on the electrochemical kinetics is evidenced. For the first time an experimental evaluation of the activation energy for Li diffusion in the as-prepared and the ball-milled Li7MnN4 is obtained. The lower activation energy obtained for the ball-milled nitride, Ea = 0.28 eV against Ea = 0.42 eV for the pristine material is responsible of the better rate capability and significant improvement of the electrochemical behaviour especially in terms of cycling properties: at high rate of 5C, a remarkable and stable capacity of 120 mAh g−1 is obtained over 50 cycles which competes very well with the LTO anode material.
Journal: Journal of Alloys and Compounds - Volume 663, 5 April 2016, Pages 624–630