新型钾离子电池层状正极材料P3型K_(0.5)MnO_(2)的制备及储钾性能研究

Preparation and Potassium Ions Storage Properties of P3-Type K_(0.5)MnO_(2)as an Advanced Layered Cathode Material for Potassium-Ion Batteries

【目的】钾离子电池具有低成本和能量密度高等优势,成为锂离子电池潜在的替代品,受到人们广泛的关注。但是,由于缺乏高比容量、循环寿命长的正极材料,使得这类新型电池的发展受到了限制。【方法】采用水热前驱体法、溶胶凝胶法和草酸盐共沉淀法制备了新型钾离子电池正极材料P3型K_(0.5)MnO_(2).【结论】结果表明与其他两种方法相比,水热前驱体法制备的K_(0.5)MnO_(2)(H-K_(0.5)MnO_(2))具有粗糙的表面和较多的内部孔隙,有利于电子的传递和提供更多的活性位点。H-K_(0.5)MnO_(2)电极在电流密度20 mA/g下,首周放电比容量最高,达到85 mAh/g,60周循环后电极片的XRD和EIS测试结果表明在重复的脱嵌K^(+)后,H-K_(0.5)MnO_(2)仍保持最稳定的结构以及最小的电荷传递阻抗。储钾性能研究的结果表明在高倍率下H-K_(0.5)MnO_(2)赝电容占比最高,从而能够实现快速的可逆充放电。

【Purposes】K-ion batteries(KIBs)have attracted considerable attention as a potential alternative to Li-ion batteries because of their low cost and high energy density.However,the development of KIBs has been severely limited by the lack of cathodes with high specific capacity and good cycle performance.【Methods】In this research,P3-type K_(0.5)MnO_(2)as a new cathode material for KIBs was prepared through hydrothermal method,sol-gel method,and oxalate co-precipitation method,separately.【Conclustions】It is shown that K_(0.5)MnO_(2)synthesized through the hydrothermal precursor method(denoted as H-K_(0.5)MnO_(2))has a rough surface and more internal pores,which are beneficial to electron transfer and can provide more active sites.At a specific current of 20 mA/g,H-K_(0.5)MnO_(2)electrode can achieve the highest first discharge specific capacity of 85 mAh/g.XRD and EIS results of the H-K_(0.5)MnO_(2)electrodes after 60 cycles demonstrate that H-K_(0.5)MnO_(2)still maintains the most stable structure and has the smallest charge transfer resistance,leading to a desirable capacity retention.The potassium-ions storage properties indicate that the pseudo-capacitance accounts for the highest proportion in HK_(0.5)MnO_(2)at a high rate,enabling fast reversible charge-discharge.