离子掺杂Na_(0.67)Ni_(0.18)M_(0.15)Mn_(0.67)O_(2)(M=Cu、Fe、Ti)的合成及作为钠电正极材料研究

Synthesis of Cation Doped P2-Na_(0.67)Ni_(0.18)M_(0.15)Mn_(0.67)O_(2)(M=Cu,Fe,Ti)as Sodium Ion Batteries Cathode

具有P2结构的Na_(0.67)Ni_(0.33)Mn_(0.67)O_(2)是一种理想的钠离子电池正极材料,但存在放电容量低、所用Ni价格较高等问题。利用固相法在Ni位掺杂了Fe、Ti和Cu元素,经掺杂后制备的材料具有良好的结晶性和相纯度,颗粒尺寸在1~3μm,并具有单晶特性。Fe和Ti掺杂提高了材料放电容量但降低了循环稳定性和放电电压;Cu掺杂能够在不牺牲容量和电压的基础上,适度提高循环稳定性。制备的Na_(0.67)Ni_(0.18)M_(0.15)Mn_(0.67)O_(2),从第25次到第100次循环,容量仅衰减2.6%,在400 mA/g的电流密度下,放电容量达63.0 mAh/g,为50 mA/g电流下的78.5%。

P2-Na_(0.67)Ni_(0.33)Mn_(0.67)O_(2)is an ideal cathode material for sodium-ion batteries,but it also has issues such as low discharge capacity and the high cost of Ni used.Solid-state synthesis has been used to dope Fe(iron),Ti(titanium),and Cu(copper)elements at the Ni site.The material prepared after doping has good crystallinity and phase purity,with particle sizes between 1-3μm and single-crystal characteristics.Doping with Fe and Ti increases the discharge capacity of the material but reduces its cycling stability and discharge voltage;Cu doping can moderately improve cycling stability without sacrificing capacity and voltage.The prepared Na_(0.67)Ni_(0.18)M_(0.15)Mn_(0.67)O_(2),from the 25th to the 100th cycle,only has a capacity decay of 2.6%,and at a current density of 400 mA/g,the discharge capacity reaches 63.0 mAh/g,which is 78.5%of that at 50 mA/g.