TITLE:
Novel Cathode Materials for Sodium Ion Batteries Derived from Layer Structured Titanate Cs2Ti5O11·(1 + x)H2O
AUTHORS:
Masao Ohashi
KEYWORDS:
Cathode Material, Sodium Ion Battery, Layer Structured Titanate, Environmentally Benign
JOURNAL NAME:
Materials Sciences and Applications,
Vol.9 No.6,
May
28,
2018
ABSTRACT: A layer
structured titanate Cs2Ti5O11·(1 + x)H2O
(x = 0.70) has
been prepared in a solid state reaction using Cs2CO3 and anatase
type TiO2 at 900°C. Ion exchange reactions of Cs+ in
the interlayer space were studied in aqueous solutions. The single phases of Li+, Na+ and H+ exchange products were obtained. The
three kinds of resulting titanates were evaluated for use as the cathodes in
rechargeable sodium batteries after dehydrations by
heating at 200°C in a vacuum. The
electrochemical measurements showed that they exhibited the reversible Na+ intercalation-deintercalation in a voltage range of 0.5 - 3.5 V or 0.7 - 4.0 V. The Li+ exchange product showed the best performance of the
discharge-charge capacities in
this study. The initial Na+ intercalation-deintercalation capacities
of the Li2Ti5O11 were 120 mAh/g and
100 mAh/g; the amounts of Na+ correspond to 1.9 and 1.6 of the
formula unit, respectively. The titanates are nontoxic, inexpensive and environmentally benign.