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3D scaffolds and heterogeneous seeds are two effective ways to guide Li deposition and suppress Li dendrite growth. Herein, 3D TiO2 nanotube (TNT) arrays decorated using ultrafine silver nanocrystals (7–10 nm) through cathodic reduction deposition are first demonstrated as a confined space host for lithium metal deposition. First, TiO2 possesses intrinsic lithium affinity with large Li absorption energy, which facilitates Li capture. Then, ultrafine silver nanocrystals decoration allows the uniform and selective nucleation in nanoscale without a nucleation barrier, leading to the extraordinary formation of lithium metal importing into 3D nanotube arrays. As a result, Li metal anode deposited on such a binary architecture (TNT‐Ag‐Li) delivers a high Coulomb efficiency at around 99.4% even after 300 cycles with a capacity of 2 mA h cm−2. Remarkably, TNT‐Ag‐Li exhibits ultralow overpotential of 4 mV and long‐term cycling life over 2500 h with a capacity of 2 mAh cm–2 in Li symmetric cells. Moreover, the full battery with 3D spaced Li nanotubes anode and LiFeO4 cathode exhibits a stable and high capacity of 115 mA h g–1 at 5 C and an excellent Coulombic efficiency of ≈100% over 500 cycles. [ABSTRACT FROM AUTHOR]

Heteroatom doping is an effective way to modulate the local structure of TiO2-based materials, enabling enhanced electrochemical performance. However, current studies generally adopt a single atom doping strategy, and ionic group doping has rarely been achieved and is a distinctly bigger challenge. Herein, doping of the phosphate group at high concentrations into blue TiO2(B) nanowires is proposed and realized for the first time by skillfully utilizing the defects induced during the dehydration and topology transformation process of the H-titanate precursor; based on experimental characterization and first-principles calculations, it has been demonstrated that this material possesses exceptional electrical properties, a remarkably reduced band gap, magnetic characteristic from the extra electrons outside the Ti atomic nucleus and remarkable phase stability. Benefiting from the unusual structure properties, phosphate-doped TiO2(B) exhibits the ultra-fast sodium storage capability of 124 mA h g−1 at the extremely high rate of 50 A g−1 and excellent long cycling stability even at 10 A g−1 after 5000 cycles. Moreover, this electrode material was tested at low temperatures and exhibited comparable reversible capacity and outstanding cycling stability to those at normal temperatures. We also assembled a B–TiO2(B)–P//(NVPF) full cell, which delivered the maximum energy density of 170 Wh kg−1 and the maximum power density of 5000 W kg−1. [ABSTRACT FROM AUTHOR]

The development of suitable host materials for the reversible storage of divalent ions such as Mg 2+ is still a big challenge and its progress to date has been slow compared to that of monovalent Li + or Na + . Herein, we present the study of layered sodium trititanate (Na 2 Ti 3 O 7 ) and sodium hexatitanate (Na 2 Ti 6 O 13 ) nanowires as anode materials for rechargeable Mg-ion batteries. It is found for the first time that the structural evolution from layered Na 2 Ti 3 O 7 to Na 2 Ti 6 O 13 with a more condensate three-dimensional microporous structure enables remarkably enhanced Mg-ion storage performance. The Na 2 Ti 6 O 13 electrode can achieve a large initial discharge and charge capacity of 165.8 and 147.7 mA h g -1 at 10 mA g -1 with a record high initial coulombic efficiency up to 89.1%. Ex situ XRD, Raman measurements and EDX mapping were used to investigate the electrochemical reaction mechanism. It is suggested that the irreversible structure change and the formation of insoluble NaCl with high yield and large particles when Na + is replaced by inserted Mg 2+ for the Na 2 Ti 3 O 7 electrode could be ascribed to the rapid decline in capacity. By contrast, the Na 2 Ti 6 O 13 electrode exhibits good structure stability during the Mg-ion insertion/extraction process, leading to good rate performance and cycling stability.