能源材料-8

能源æ...

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Unformatted text preview: (Energy Materials) •Supercapacitor ( ) -8 Supercapacitor 5000 250 200 (Wh/Kg) Thin-Film Batteries Li Alloy 150 100 50 Li-polymer Li-Ion Ni-MH Ni-Cd 0 0.01C 0.1C 1C 10C 100C Supercapacitor • Porous carbons are frequently applied as electrode materials. ~ low -cost (NT 25 -100/kg), stable, high porosity (> 800 m 2/g) Basic principle • • • • France Germany Japan Japan Japan Russia Russia/Canada USA USA USA USA USA USA USA Alcatel Dornier"*" Matsushita Elna NEC/Tokin Elit Econd Maxwell Evans Sigma Polystor Cesiwid Redox Pinnacle"*" Memory switch UPS ………… ... ... 2C decharge Nanofiber Materials for Supercapacitor 2 Cyclic voltammetry 20 mV/s 1 Electric current (mA) 0 -1 10 mV/s -2 -3 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.4 0.2 Rate capability Charge-discharge curves 25 Potential (V vs. Ag/AgCl) 20 0.0 5C 20C 100C Potential (V vs. Ag/AgCl) Capacitance (F/g) 15 -0.4 10 -0.8 5 -1.2 0 80 160 240 320 0 0 10 20 30 40 50 Time (s) Current density (mA/cm2) Nanofiber/Carbon Composite Materials for Supercapacitor Tech. Key Points : •The mesopore volume and specific capacitance are limited for traditional active carbon materials. Active carbon/Nanofiber Active carbon Tech. Breakthrough Points : Increase the surface area and mesopore volume of the active carbon materials by the surface treatment of nanofibers . The nanofiber/carbon materials has nano composite structure and show high rate capability (>100C rate). Effect of pore size distribution on capacitance Micropore (<2nm) Original mesopore (2~50 nm) macropore 30% 45% Tech. Results: •High Mesopore Volume (30% 45%) •High specific volumetric capacitance (0.275 F/m 2 0.39 F/m2) Incremental area (m 2 /g nm ) C NFs /C composite •Cycle Life>10000 cycles accessible pore size (function of Pore size ( nm ) electrolyte/hydration molecule size ) Nanofiber/Carbon Composite Materials for Supercapacitor 160 5C 160 100C CNFs/C 120 S p e c i f i c c a p a c it a n c e ( F / g ) CNFs/C S p e c if i c c a p a c i t a n c e ( F / g ) 120 Original C Original C 80 80 40 40 0 0 0 2 4 Discharge current density (mA/cm ) 6 8 2 10 0 1000 2000 3000 Cycle number 4000 5000 6000 7000 ...
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