A monocrystalline orthorhombic Na0.44Mn0.9Li0.1O2 cathode with outstanding stability and negligible structural strain for sodium-ion batteries

The application of sodium ion batteries (SIBs) in future large-scale energy storage equipment has been facing great challenges due to their unstable cathode materials. Herein, a monocrystalline orthorhombic Na0.44Mn0.9Li0.1O2 cathode with high crystallinity has been designed and synthesized via a simple sol-gel method. The wide tunnel structure of Na0.44Mn0.9Li0.1O2 can not only adapt to structural strain in the electrochemical process, but also provide a rapid migration path for Na+. Furthermore, the introduction of Li promotes the transformation from trivalent manganese to tetravalent manganese so that the structural distortion caused by the Jahn-Teller effect is effectively alleviated. High Na+ mobility and low Na+ diffusion resistance are further evidence of its excellent rate performance. As a consequence, the Na0.44Mn0.9Li0.1O2 electrode delivers an initial discharge capacity of 111.71 mA h g(-1) at 1 C with an excellent retention of 80% after 900 cycles. So far, to the best of our knowledge, the as-synthesized Na0.44Mn0.9Li0.1O2 cathode shows the most excellent stability at 1 C. Such a material with superior stability and high rate performance is suggested to be one of the promising cathodes for SIBs.