Single-crystalline Mg-substituted Na4Mn3(PO4)2P2O7 nanoparticles as a high capacity and superior cycling cathode for sodium-ion batteries

Hanxue Xu; Jixian Ma; Xuexia He; Jie Sun; Longhai Yang; Ruibin Jiang; Zhibin Lei; Zong-Huai Liu; Qi Li

doi:10.1039/d2nr05442f

Single-crystalline Mg-substituted Na₄Mn₃(PO₄)₂P₂O₇ nanoparticles as a high capacity and superior cycling cathode for sodium-ion batteries

Nanoscale. 2023 Mar 9;15(10):4830-4838. doi: 10.1039/d2nr05442f.

Authors

Hanxue Xu^{1

2}, Jixian Ma^{1

2}, Xuexia He^{1

2}, Jie Sun^{1

2}, Longhai Yang³, Ruibin Jiang^{1

2}, Zhibin Lei^{1

2}, Zong-Huai Liu^{1

2}, Qi Li^{1

2}

Affiliations

¹ Key Laboratory of Applied Surface and Colloid Chemistry, Shaanxi Normal University, Ministry of Education, Xi'an, 710062, P. R. China. clliqi@snnu.edu.cn.
² School of Materials Science and Engineering, Shaanxi Normal University, Xi'an, 710119, P. R. China.
³ School of Electrical and Control Engineering, Xi'an University of Science and Technology, Xi'an 710054, Shaanxi, P. R. China. ylonghai@hotmail.com.

PMID: 36800192
DOI: 10.1039/d2nr05442f

Abstract

Mn-based mixed phosphate Na₄Mn₃(PO₄)₂(P₂O₇) (NMPP) is a promising cathode for high-potential, low-cost and eco-friendly sodium-ion batteries. However, this material still faces some bottleneck issues in terms of low conductivity, disturbance of impure crystalline phase, micron-sized agglomerated particles and the Mn³⁺ Jahn-Teller effect. Herein, a Mg-substituted NMPP (NM_2.7Mg_0.3PP)@C composite was constructed via modified solution combustion and subsequent calcination treatment. The obtained NM_2.7Mg_0.3PP presents a highly pure phase and single-crystalline characteristics. It is noteworthy that the sample shows a smaller particle size of 100-300 nm due to the Mg²⁺ incorporation, and the prepared NM_2.7Mg_0.3PP@C cathode exhibits considerable discharge capacity (119 mA h g^-1), an improved rate capability and excellent long cycling stability of 1000 cycles. A series of measurements indicated that the Mg-substitution enhanced the electronic conductivity and ion diffusion rate, and effectively relieved the lattice distortion influenced by the multiphase transition from the Mn Jahn-Teller effect of the NM_2.7Mg_0.3PP@C cathode. In addition, NM_2.7Mg_0.3PP adopts an optimal 3Mg_0.1-Mn1-Mn2-Mn3 crystal structure based on density functional theory (DFT) calculations and refined X-ray diffractometry results. These findings provide new insight into the design of highly stabilized and high-conductivity polyanionic cathodes for sodium-ion batteries.