Ultrahigh rate and durable sodium-ion storage at a wide potential window via lanthanide doping and perovskite surface decoration on layered manganese oxides

Abstract

P2-type layered manganese oxides are recognized as one of the most compelling cathode candidates for sodium-ion batteries, but these materials suffer from the intrinsic structural Jahn-Teller distortion and oxygen loss, which causes limited rate capability and long-cycle fading under a wide potential window. Here we demonstrate a new approach to realize a simultaneous enhancement on both rate performance and long-term duration over a wide potential window through dilute La lattice doping and perovskite surface modification. We reveal for the first time through both DFT calculations and experimental results, that the La-doping and perovskite LCM surface decoration can efficiently suppress oxygen loss by providing O 2p holes and oxygen vacancies, and meanwhile enhance the electronic and ionic conductivity. The as achieved LNCM/LCM (LaNa0.06Co0.06Mn0.88O3/ Na0.56Co0.17Mn0.8La0.03O2) demonstrates a record high rate performance of 20C (1C=180 mA g−1) and outstanding cycling performance of 300 cycles (70% capacity retention) at a wide potential range (1.5-4.4V), which outperform the state-of-the-art Mn-based layered oxides. We confirm the reversible solid solution reaction during the charge/discharge process using the operando synchrotron XRD analysis. This work demonstrates an applicable approach to realize significant improvement on both rate capability and cycle stability without sacrificing the potential window.