Combining the high power of the supercapacitors and high energy of the lithium-ion batteries,lithium ion supercapacitors(Li-SCs)have attracted much attention.The positive and negative mass matching is crucial for the performance of the lithium-ion supercapacitors.In this paper,the pouch-like Li-SCs based on lithium manganate oxide(LMO)cathodes,activated carbon(AC)anodes and acetonitrile-based electrolyte with different cathode/anode mass ratios were designed and fabricated.The effects of cathode/anode mass ratio on the electrical performance,operating voltage and low temperature performance of Li-SCs were systematically investigated.The results show that the capacity,rate capability and low temperature performances were improved with the increase of the mass ratio.The charge and discharge curves of Li-SCs with high mass ratios were linear.The energy density increased first and then decreased with the increase of the mass ratio.Both excessive and insufficient mass ratio lead to the decay of the cycle life.These results can aid in the improvement of the design for Li-SCs.When the cathode/anode mass ratio is 2/1,the comprehensive performance of Li-SC is the best.The capacity at 50C is 78.0％of that at 1C.The maximum power density and energy density at 2.3 V are 7247 W·kg-1and 9.5 Wh·kg-1,respectively.The energy densities based on the mass of device and the active materials are increased to 20.2 Wh ·kg-1 and 65.0 Wh·kg-1,respectively when the operating voltage is increased to 3.1 V.However,the wide operating voltage brings life attenuation.The capacity retention is 93.0％after 10000 cycles under 1-2.3 V,which is reduced to 84.5％after 5000 cycles under 0.5-2.5 V.The capacity at-40 ℃ is 57.8％of that at 25 ℃,and the energy density is still 5 Wh·kg-1(2.3 V).
关键词
锂离子超级电容器/锰酸锂/活性炭/质量比/电压/能量密度
Key words
lithium ion supercapacitor/lithium manganese oxide/activated carbon/mass ratio/voltage/energy density
维普
万方数据