High-voltage electrochemical performance of LiNi0.5Co0.2Mn0.3O2 cathode material via the synergetic modification of the Zr/Ti elements

Highlights: • Synergetic effects of Zr and Ti elements on NCM523 are studied detailedly. • Zr and trace Ti doping stabilize the NCM523 host structure. • Lithium residues are absorbed to form Li₄Ti₅O₁₂/Li₂TiO₃ mixed coating layers. • Interfacial structure of the NCM523 is enhanced after Zr/Ti modification. • High voltage properties have been significantly improved after Zr/Ti modification. The stabilities of the host and interfacial structure for layered LiNi_xCo_yMn_1-x-yO₂ cathode materials are critical for their electrochemical properties, especially at high voltage. This study reports the synergetic effect of the Zr and Ti elements on the LiNi_0.5Co_0.2Mn_0.3O₂ cathode material (NCM523). The as-obtained Zr/Ti modified LiNi_0.5Co_0.2Mn_0.3O₂ cathode material shows the excellent electrochemical performance at high voltage. It delivers 167.3 mAh·g⁻¹ at 1 C over 3.0–4.4 V corresponding 94.20% capacity retention after 200 cycles. Moreover, the rate capability of Zr/Ti co-modified NCM523 at 16 C (3.0–4.4 V) rises to 139.4 mAh·g⁻¹ and corresponding capacity retention (vs. 0.5 C) is 79.57%. In addition, its capacity retention reaches to 91.71% after 100 cycles at 1 C rate even at 3.0–4.6 V. Such superior electrochemical performances are ascribed to the Zr doping and Ti modification. The synergetic modifications of the Zr/Ti elements not only stabilize the crystal structure, but also absorb the lithium residues to form mixed Li₄Ti₅O₁₂/Li₂TiO₃ coating layers, which strengthen the stability of the interfacial structure and the kinetic characteristics of the cathode materials.