Functional surface modification of P2-type layered Mn-based oxide cathode by thin layer of NASICON for sodium-ion batteries

P2-type layered manganese-based oxides, as promising high-energy-density and low-cost cathodes, have been triggered considerable attentions in sodium ion batteries (SIBs). Nevertheless, P2-type manganese-based oxides still suffer from the sluggish kinetics and unfavorable Jahn-Teller effect. Herein, motivated by the high ionic conductivity and rigid three-dimension framework of NASICON-type materials, the well-known Na3Zr2Si2PO12 thin layer was coated on P2-type Na0.612K0.056MnO2 surface to modify electrochemical sodium storage and structural stability. The optimal Na0.612K0.056MnO2@Na3Zr2Si2PO12 exhibited a high discharge capacity of 203 mA h g−1 within 1.8 − 4.3 V at a low current density of 10 mA g−1. When the current density enhances into 500 mA g−1, it delivers a high initial discharge capacity of 145.7 mA h g−1 within 1.8 − 4.3 V at 500 mA g−1 and maintains 69% capacity retention after 100 cycles. Besides, at low temperature of −20 °C, it offers 100.1 mA h g−1 after 100 cycles within 1.8 − 4.3 V at 100 mA g−1, which is much higher than that of NKMO (65.2 mA h g−1). The Na3Zr2Si2PO12 can decrease Mn3+ content and avoid the Jahn-Teller effect of Na0.612K0.056MnO2 in structural level, enabling the enhanced Na+ diffusion coefficient of Na0.612K0.056MnO2. Such strategy NASICON coating on cathode would pave a new pathway on rational design of high-performance cathode for SIBs.