Study on Preparation and Potassium Storage Properties of Porous Graphene Nanosheet Arrays
Compared with lithium-ion batteries,potassium-ion batteries(PIBs)have received extensive attention in the field of energy storage due to their abundant potassium resources and standard electrode potential close to lithium.The fast energy storage characteristics are of great significance for the practical application of potassium ion batteries.Graphene,with its large specific surface area and good electrical conductivity,is an ideal choice for the negative electrode of fast potassium-ion batteries.The storage mechanism of graphene for potassium is divided into ion intercalation and defect/edge adsorption.Among them,the adsorption storage mechanism is usually conducive to fast energy storage and longer electrode life.Therefore,this paper aims to improve its fast potassium storage performance by modifying graphene.Specifically,few-layered graphene nanosheet(GNS)arrays were first loaded with ultrafine ZnO particles,and porous graphene nanosheet(P-GNS)array electrodes were prepared through the carbothermal reduction method,which were applied in PIBs.Experimental results show that this material can effectively improve the rate performance of PIBs.The capacity of P-GNS can reach 181.6 mAh·g-1 at a high current density of 3 A·g-1.After 1 000 cycles at 1 A·g-1,the capacity retention is as high as 80.6%,showing excellent cycle performance.In addition,the full cell also displays good high-rate performance,the capacity is still 87.4 mAh·g-1 at a current density of 1 A·g-1 after 50 cycles.The energy storage mechanism study revealed that the porous graphene electrode can significantly increase the active sites for adsorption/desorption capacitive energy storage,thereby effectively improving the high-rate charge-discharge performance;in addition,the adsorption/desorption potassium storage process will not destroy the material structure,which is beneficial to graphene.Maintaining structural stability can greatly improve the cycle life.This work provides a reference for constructing graphene-based fast energy storage materials and developing high-rate and long-life PIBs.
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