Sodium titanate nanowires for Na+‐based hybrid energy storage with high power density

Abstract

Abstract It is crucial to enhance the rate capability of the titanium‐based materials for fulfilling their promising potential as the anode materials of sodium‐ion batteries (SIBs). Herein, Mn‐doped sodium titanate (Mn‐NTO) nanowires with homogeneously distributed ultrathin carbon nanosheets (Mn‐NTO@C) are synthesized by a one‐step salt‐template‐assisted method, showing much‐enhanced power density. The as‐prepared Mn‐NTO@C demonstrates the realization of hybrid energy storage, which reconciles the diffusion‐controlled behavior with the pseudocapacitive‐controlled behavior. It has been revealed that the Mn heteroatoms can raise the proportion of Na2Ti3O7 phase with the expanded crystal lattice, facilitating the diffusion‐controlled insertion/extraction process of sodium ions. Meanwhile, the hybrid morphology of Mn‐NTO nanowires and carbon nanosheets provides a promoted structure stability. As a result, the assembled Na||Mn‐NTO@C half‐cells work well at an extreme current density of 24 A g−1 for 10 000 cycles with a capacity retention of 95.2%. Moreover, the Mn‐NTO@C||Na3V2(PO4)3 (NVP) full cells exhibit an attenuation of only 0.0015% per cycle at 20 A g−1 for over 10 000 cycles, and the energy density and power density of the full cells reach an ultrahigh level of 262 Wh kg−1 and 16.3 kW kg−1, respectively.

Keywords

• carbon nanosheets
• hybrid energy storage
• Mn‐doping
• rate capability