Synthesis and Electrochemical Performance of C-Base-Centered Lepidocrocite-like Titanates for Na-Ion Batteries

Abstract

Lepidocrocite-like titanate, Na 0.9 [Ti 1.7 Li 0.3 ]O 4 , having a C-base-centered lattice (C-type) is prepared by dehydration of Na 0.9 [Ti 1.7 Li 0.3 ]O 4 •nH 2 O having a primitive lattice (P-type) and influence of the interlayer water on its electrochemical performance is examined in nonaqueous Na cells. Upon heating up to 350 °C, P-type Na 0.9 [Ti 1.7 Li 0.3 ]O 4 •nH 2 O transforms into the anhydrous C-type phase as a result of gradual removal of the interlayer water. The C-type Na 0.9 [Ti 1.7 Li 0.3 ]O 4 delivers reversible capacity of 120 mAh g −1 between 2.0 and 0.1 V vs Na with high Coulombic efficiency at an initial cycle and good capacity retention over 50 cycles. Structural change of the C-type phase during sodiation is investigated by using operando X-ray diffraction measurement.

Experimental and Computational Investigation of Lepidocrocite Anodes for Sodium-Ion Batteries

“…al, 20 who found that in the C-type material K 0.8 Ti 1.73 Li 0.27 O 4 that has been ball milled and carbon coated, the capacity decreases from 110 mAh/g to 60 mAh/g when increasing the current from 20 mA/g to 200 mA/g, with full capacity recovery when current is decreased back to 20 mA/g. Superior performance is also reported in work by Katogi et al, 34 which shows that the C-centered lepidocrocite Na 0.9 Ti 1.7 Li 0.3 O 4 has excellent rate capability, with over 80% capacity retention when increasing the current from C/17.5 to 10C.…”

A layered nonstoichiometric lepidocrocite-type sodium titanate anode material for sodium-ion batteries

“…Different lattice symmetries are possible for lepidocrocite titanates depending on the identities and positions of the interlayer species and details of the synthesis: e.g., upon heat treatment, the P-type (primitive lattice) Na x Ti 2-x/3 Li x/3 O 4 •nH 2 O (x = 0.8 or 0.9) transforms into the anhydrous C-type (C-based centered lattice) phase. 11,13 Reasonably high reversible capacities are obtained for some of these materials although less than expected based on structural considerations; e.g., 140 mAh g -1 for P-type Na 0.8 Ti 1.73 Li 0.27 O 4 •nH 2 O, 11 and 120 mAh g -1 for C-type Na 0.9 Ti 1.7 Li 0.3 O 4 . 13 A computational study indicated that both interlayer site limitations and electrostatic considerations govern the capacity that can be obtained practically, particularly for C-type structures.…”

Recent Progress and Prospects of Layered Cathode Materials for Potassium‐ion Batteries

“…Katogi et al also reported that interlayer water was thought to hinder and disturb sodium diffusion in layered Na 0.9 [Ti 1.7 Li 0.3 ]O 4 ·nH 2 O, where enhanced reversibility and higher initial Coulombic efficiency are achieved by dehydration. [ 81 ] Although vanadium oxides show high capacities for potassium storage, the deficiency of K limits their use in full cells. Recently, a new layered compound K 0.83 V 2 O 5 with a higher K content was synthesized by Zhang et al, via the chemical potassiation of γ‐V 2 O 5 .…”

“…Komaba's group reported a layered K 2 FeP 2 O 7 , which consisted of layers that were constructed by cornersharing FeO 4 tetrahedra and PO 4 tetrahedra. [81] K 2 FeP 2 O 7 delivered a reversible capacity of 58 mAh g À1 (0.67 eq. K + ), with a relatively low [77] Copyright 2018, American Chemical Society.…”