Superior Sodium Storage in Na₂Ti₃O₇ Nanotube Arrays through Surface Engineering

Abstract

Sodium‐ion batteries have attracted extraordinary attention owing to their low cost and raw materials in abundance. A major challenge of practical implementation is the lack of accessible and affordable anodes that can reversibly store a substantial amount of Na ions in a fast and stable manner. It is reported that surface engineered sodium titanate (Na2Ti3O7) nanotube arrays directly grown on Ti substrates can serve as efficient anodes to meet those stringent requirements. The fabrication of the nanotube arrays involves hydrothermal growing of Na2Ti3O7 nanotubes, surface deposition of a thin layer of TiO2, and subsequent sulfidation. The resulting nanoarrays exhibit a high electrochemical Na‐storage activity that outperforms other Na2Ti3O7 based materials. They deliver high reversible capacities of 221 mAh g−1 and exhibit a superior cycling efficiency and rate capability, retaining 78 mAh g−1 at 10 C (1770 mA g−1) over 10 000 continuous cycles. In addition, the full cell consisting of Na2Ti3O7 nanotube anode and Na2/3(Ni1/3Mn2/3)O2 cathode is capable of delivering a specific energy of ≈110 Wh kg−1 (based on the mass of both electrodes). The surface engineering can provide useful tools in the development of high performance anode materials with robust power and cyclability.

Sodium‐Ion Batteries: From Academic Research to Practical Commercialization

“…The Na 2 Ti 3 O 7 //VOPO 4 and Na 2 Ti 3 O 7 //Na 2/3 Ni 1/3 Mn 2/3 O 2 full cells delivered outstanding rate capability and excellent cycling stability. [89,90] It is worth pointing out that Na 2 Ti 3 O 7 //VOPO 4 full-cell SIBs offered a high energy density of 220 W h kg −1 compared to existing LIBs. Hard carbon (HC) has also been presodiated to ameliorate the unsatisfactory initial coulombic efficiency and cycle life for the full cell and to compensate for Na loss in the formation of the solid electrolyte interphase (SEI) layer.…”

Glycol Derived Carbon- TiO2 as Low Cost and High Performance Anode Material for Sodium-Ion Batteries

“…Titanium-based materials, a cost effective, structurally stable and sustainable material, is considered to be promising Na-storage anode1415. Among various polymorphs of Ti-based anode materials, anatase TiO 2 exhibit much better electrochemical performances owning to the three dimensional open structure, which is favorable for the Na + transport and storage16.…”

Monoclinic Sodium Iron Hexacyanoferrate Cathode and Non-Flammable Glyme-Based Electrolyte for Inexpensive Sodium-Ion Batteries

“…Despite such harsh demands, there have been a few promising NIB electrode materials reported which meet most of the above requirements for grid-storage batteries. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Among them, there is a class of cathodes belonging to the Prussian Blue Analogue (PBA) family which is very appealing due to its reliance on Fe and/or Mn as the redox active centers and possession of high sodium storage capacities (theoretical capacity limit as high as 170.8 mAh g −1 assuming two mole sodium storage per mole of material) at relatively high voltages. 23 The general formula for PBAs relevant for NIBs is Na x M 1 [M 2 (CN) 6 ] 1-y y .nH 2 O with 0 ≤ x ≤ 2 and 0 ≤ y < 1.…”