A New Electrode Material for High-Performance Sodium-Ion Batteries: Lithium-Substituted Tunnel/Spinel Heterostructured Cathode

Abstract

The tunnel-type Na0.44MnO2 as promising cathode materials for sodium-ion batteries (SIBs) have attracted interest owing to its abundant resources and potential low cost. Unfortunately, due to the disproportionation of manganese associated with Mn3+, the electrochemical performance of this material is hindered, resulting in rapid capacity decline and poor rate capability. Herein, a Li-substituted, tunnel/spinel heterostructured cathode is successfully synthesized for addressing these limitations. The Li dopant can acts as a pillar inhibiting unfavorable multiphase transformation, improving the structural reversibility and sodium storage performance of the cathode. Meanwhile, the tunnel/spinel heterostructure provides three-dimensional Na+ diffusion channels to effectively enhance the redox reaction kinetics. The optimized [Na0.396Li0.044][Mn0.97Li0.03]O2 composite delivers an excellent rate performance with a reversible capacity of 97.0 mA h g-1 at 15 C, corresponding to 82.5% of the capacity at 0.1 C, and a promising cycling stability over 1200 cycles with remarkable capacity retention of 81.0% at 10 C. Moreover, by combining with hard carbon anodes, the full cell demonstrates a high specific capacity and favorable cyclability. After 200 cycles, the cell provides 105.0 mA h g-1 at 1 C, demonstrating the potential of the cathode for practical applications. This strategy might apply to other sodium-deficient cathode materials and inform their strategic design. References J.-Y. Hwang, S.-T. Myung, Y.-K. Sun, Chem. Soc. Rev. 2017, 46, 3529. J.-Y. Hwang, J. Kim, T.-Y. Yu, Y.-K. Sun, Adv. Energy Mater. 2019, 9, 1803346. P. Zheng, J. Su, Y. Wang, W. Zhou, J. Song, Q. Su, N. Reeves‐Mclaren, S. Guo, ChemSusChem 2020, 13, 1793.