Sufficient Utilization of Zirconium Ions to Improve the Structure and Surface properties of Nickel‐Rich Cathode Materials for Lithium‐Ion Batteries. Issue 10 (14th April 2018)

• Record Type: Journal Article
• Authors: He, Tao; Lu, Yun; Su, Yuefeng; Bao, Liying; Tan, Jing; Chen, Lai; Zhang, Qiyu; Li, Weikang; Chen, Shi; Wu, Feng
• Is Part Of: ChemSusChem. Volume 11:Issue 10(2018)
• Page Start: 1639
• Page End: 1648
• Publication Date: 2018-04-14
• Subjects: batteries -- doping -- lithium -- nickel -- zirconium; Green chemistry -- Periodicals; Sustainable engineering -- Periodicals; Chemistry -- Periodicals; Chemical engineering -- Periodicals; 660
• DOI: 10.1002/cssc.201702451
• Languages: English
• ISSNs: 1864-5631

Abstract

Abstract: We doped Zr 4+ ions in the outer layer of Ni0.8 Co0.1 Mn0.1 (OH)2 by coprecipitation. The distribution of Zr 4+ in the final cathode materials showed a gradient distribution because of ion migration during the thermal treatment. The doped layer was confirmed by using various analysis methods (energy‐dispersive X‐ray spectroscopy, XRD, X‐ray photoelectron spectroscopy, and TEM), which implies that Zr 4+ can not only occupy both the transition metal slabs and Li slabs but also form a Li2 ZrO3 layer on the surface as a highly ion‐conductive layer. The doped Zr 4+ in the transition metal slabs can stabilize the crystal structure because of the strong Zr−O bond energy, and the doped Zr 4+ in the Li slabs can act as pillar ions to improve the structural stability and reduce cation mixing. The gradient doping can take advantage of the "pillar effect" and restrain the "blocking effect" of the pillar ions, which reduces irreversible capacity loss and improves the cycling and rate performance of the Ni‐rich cathode materials. The capacity retention of the modified sample reached 83.2 % after 200 cycles at 1C (200 mA g −1 ) at 2.8–4.5 V, and the discharge capacity was up to 164.7 mAh g −1 at 10C. This effective strategy can improve the structure stability of the cathode material while reducing the amount of non‐electrochemical active dopant because of the gradient distribution of the dopant. In addition, the highly ion‐conductive layer of Li2 ZrO3 on the surface can improve the rate performance of the cathode. Abstract : Steep gradient : The gradient distribution of Zr 4+ in LiNi0.8 Co0.1 Mn0.1 O2 decreases the amount of dopant while maintaining the structure stability. Zr 4+ in Li sites act as pillars to stabilize the Li layer and the Zr 4+ in transition‐metal sites can stabilize the crystal structure through a strong Zr−O bond energy. A highly ion‐conductive Li2 ZrO3 coating layer can increase Li + migration and protect the material surface from corrosion by the electrolyte. This increases the cycling stability and rate performance for the Ni‐rich cathode materials.