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

[摘要] 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 Na 2 Ti 3 O 7 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||Na 3 V 2 (PO 4 ) 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.

[学科分类] 电力

[关键词] carbon nanosheets;hybrid energy storage;Mn-doping;rate capability