Reaching the initial coulombic efficiency and structural stability limit of P2/O3 biphasic layered cathode for sodium-ion batteries

• Published in: Journal of colloid and interface science Vol. 638; pp. 758 - 767
• Main Authors: Zhou, Jingkai, Liu, Jing, Li, Yanyan, Zhao, Zhongjun, Zhou, Pengfei, Wu, Xiaozhong, Tang, Xiaonan, Zhou, Jin
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.05.2023
• Subjects: Initial coulombic efficiency; Ni/Cu co-doping; P2/O3 biphasic structure; Sodium ion batteries; Structural stability; Sodium ion batteries; P2/O3 biphasic structure; Structural stability; Initial coulombic efficiency; Ni/Cu co-doping
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2023.02.001

The P2/O3-Na0.75Mn0.6Ni0.3Cu0.1O2 electrode exhibits stable phase evolution during the charging/discharging process. The Na full cell of hard carbon//P2/O3-Na0.75Mn0.6Ni0.3Cu0.1O2 presents fascinating cycle stability with 75.03% retention after 300 cycles. [Display omitted] The P2/O3 biphasic layered oxide (NaxMn1-yMyO2, M: doping elements) is a cathode family with great promise for sodium-ion batteries (SIBs) because of their tunable electrochemical performance and low cost. However, the ultrahigh initial coulombic efficiency (ICE) and inferior cycling performance of P2/O3-NaxMn1-yMyO2 need to be improved for practical application. Herein, Ni/Cu co-doped P2/O3-Na0.75Mn1-yNiy-zCuzO2 materials are well-designed. The ultrahigh ICE can be restrained by altering the ratio of P2/O3 via adjusting Ni content, and the structural stability can be improved by Cu doping via enlarging parameter c of O3 phase and suppressing irreversible P2-O2 phase transformation. The optimal P2/O3-Na0.75Mn0.6Ni0.3Cu0.1O2 delivers a capacity of 142.4 with ICE of 107.8%, superior capacity retention in the temperature range of −40 ∼ 30 °C, and rate performance of 95.9 mAh g−1 at 1.2 A g−1. The overall storage mechanism of P2/O3-Na0.75Mn0.6Ni0.3Cu0.1O2 is revealed by the combination of electrochemical profiles, in situ X-ray diffraction, and first-principles calculations. The Na-ion full battery based on P2/O3-Na0.75Mn0.6Ni0.3Cu0.1O2 cathode can achieve a remarkable energy density of 306.9 Wh kg−1 with a power density of 695.5 W kg−1 at 200 mA g−1. This work may shed light on the rational design of high-performance P2/O3 biphasic layered cathode for SIBs.