Study on the Influence of N/P Ratio on the Performance of Li-Ion Hybrid Supercapacitor
Lithium-ion hybrid supercapacitors have attracted great attention because of their advantages of combining high specific energy of lithium-ion batteries and high specific power of supercapacitors.However,the change in the negative/positive capacity ratio(N/P)will not only cause capacity loss and consumption of active lithium during the initial cycle,but also may lead to overcharge and overdischarge.The N/P ratio has a great impact on the long-term cycle stability,fast charge performance and safety performance of lithium-ion hybrid supercapacitors.Therefore,it is important to study the influence of N/P ratio on initial Coulomb efficiency(ICE),cycle performance,fast charge performance and safety performance.In this paper,the battery-type material LiNi0.5Co0.2Mn0.3O2 and capacitor-type material activated carbon were used as the composite positive electrode material(AC/NCM),and hard carbon(HC)was used as the negative electrode material.Pouch-type lithium-ion hybrid supercapacitors with different N/P ratios(0.5,0.6,0.8,1.2,1.8,2.7)were designed and prepared.When the N/P ratio is much greater than 1,it is unfavorable to the energy density and ICE,and when the N/P ratio is less than 1,it is extremely unfavorable to the safety performance.
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