锂离子电池新型正极材料xLiF-(Ni_(1/6)Co_(1/6)Mn_(4/6))_3O_4的制备及电化学性能研究

Synthesis and Electrochemical Properties of xLiF-(Ni_(1/6)Co_(1/6)Mn_(4/6))_3O_4 Composite as a Novel Cathode Material for Li-Ion Batteries

采用高能球磨法通过不同球磨时间制备xLiF-(Ni_(1/6)Co_(1/6)Mn_(4/6))_3O_4新型正极材料,并对材料进行石墨烯复合改性,提高其性能。结合X-射线衍射、扫描电镜、电化学性能测试和X-射线电子能谱对所制备的正极材料性能进行表征。结果表明,球磨24h的产物的放电比容量最高,为157. 3mAh·g^(-1)。此外,正极材料添加石墨烯能改善其电化学性能,当石墨烯复合量为20%,在室温、0. 05C(1C=250mAh·g^(-1))、1. 5～4. 8V下,材料首圈的放电比容量为235mAh·g^(-1),相较于无石墨烯的材料,在1C和5C倍率下,放电比容量分别提高到151和114 m Ah·g^(-1)。文中还分析了正极材料放电容量随截止电压的变化,确定了复合正极材料在高电压下有获得更高放电容量的潜力。

A novel cathode material xLiF-(Ni1/6Co1/6Mn4/6)3O4 composites are synthesized by the high energy mechanical milling with different time and the as-prepared composites were modified by the graphene to improve electrochemical performance.X-ray diffraction(XRD),scanning electron microscopy(SEM),electrochemical test and X-ray photoelectron spectroscopy(XPS)are employed to further characterize the properties of the composites.The resultant cathode has the highest discharge capacity of 157.3 m Ah·g-1 when ball milling 24 h.The xLiF-(Ni1/6Co1/6Mn4/6)3O4 composites with 20%graphene exhibit a discharge capacity of 235 m Ah·g-1(1 C=250 m Ah·g-1)at 0.05 C from 1.5~4.8 V.The rate capability is also promoted as the discharge specific capacity reaching 151 and 114 m Ah·g-1 at 1 C and 5 C respectively.Moreover,the variation of the discharge capacity of the composite cathode along with the cut-off voltage are analyzed,which confirms the potential of higher discharge capacity of the cathode at higher voltage.