An O3-type Oxide with Low Sodium Content as the Phase-Transition-Free Anode for Sodium-Ion Batteries.

An O3-type Oxide with Low Sodium Content as the Phase-Transition-Free Anode for Sodium-Ion Batteries.
Angew Chem Int Ed Engl. 2018 Apr 17;:
Authors: Zhao C, Avdeev M, Chen L, Hu YS
Abstract
Layered transition metal oxides NaxMeO2 (Me = transition metal) with P2 or O3 structure have attracted extensive attention in sodium-ion batteries (NIBs). Herein, we find a universal law to distinguish structural competition between P2 and O3 types based on the ratio of interlayer distances of alkali metal layer d(O-Na-O) and transition-metal layer d(O-Me-O). It is demonstrated that the ratio of ~1.62 can be used as an indicator. O3-type Na0.66Mg0.34Ti0.66O2 oxide is prepared as stable an anode for NIBs, in which the low Na-content (≈0.66) usually undergoes a P2-type structure with respect to NaxMeO2. This material delivers an available capacity ~98 mAh g-1 within a voltage range of 0.4-2.0 V and exhibits a better cycling stability (~94.2% of capacity retention after 128 cycles). Furthermore, in-situ X-ray diffraction results reveal a single-phase reaction in the discharge-charge process, which is different from the common phase transitions reported in O3-type electrodes, ensuring a long-term cycling stability.
PMID: 29664221 [PubMed - as supplied by publisher]

Source: Angewandte Chemie - April 17, 2018 Category: Chemistry Authors: Zhao C, Avdeev M, Chen L, Hu YS Tags: Angew Chem Int Ed Engl Source Type: research