Intelligent phase-transition MnO2 single-crystal shell enabling a high-capacity Li-rich layered cathode in Li-ion batteries

Deyuan Liu; Jian Yang; Junming Hou; Jiaxuan Liao; Mengqiang Wu

doi:10.1039/d1ra01561c

Intelligent phase-transition MnO₂ single-crystal shell enabling a high-capacity Li-rich layered cathode in Li-ion batteries

RSC Adv. 2021 Apr 6;11(21):12771-12783. doi: 10.1039/d1ra01561c. eCollection 2021 Mar 29.

Authors

Deyuan Liu¹, Jian Yang¹, Junming Hou¹, Jiaxuan Liao¹, Mengqiang Wu¹

Affiliation

¹ School of Materials and Energy, University of Electronic Science and Technology of China 2006 Xiyuan Ave, West High-Tech Zone Chengdu 611731 P. R. China mwu@uestc.edu.cn.

Abstract

Layered, Li-rich Mn-based oxides (LLMOs) are the most promising next-generation, high-energy batteries due to their relatively high specific capacities and high voltages. However, the practical application of LLMO cathodes is limited by low initial coulombic efficiencies (CEs) and poor cycling performance. Herein, we used the reaction of KMnO₄ and MnSO₄ under hydrothermal conditions to grow a nano-SCMO shell on the LLMO material surface (SCMO@LLMO). The unique particle/sheet compound structure of the SCMO shell is beneficial to the electrochemical reaction. SCMO has good Li storage characteristics and excellent surface structure stability in the single-crystal phase which further improves the reversible capacity, CE, and cyclic stability of the LLMO cathode. Therefore, the optimal coated sample (feedstock: 2 M KMnO₄, SCMO@LLMO-2.0) exhibits a good initial discharge capacity (238.2 mA h g^-1 at 1C and 173.8 mA h g^-1 at 5C), initial CE (89.6% at 1C and 86.5% at 5C), and cycling performance (capacity retention of 84.67% at 1C and 62.72% at 5C after 200 cycles). This work adopts a hydrothermal method to synthesize a nano-single crystal composite material, laying a foundation for the preparation of the SCMO@LLMO cathodes for LLMO primary battery cathodes with high electrochemical performance.