Intrinsic rapid Na+ intercalation observed in NaxCoO2 thin film

Abstract

Electrochemical properties are investigated for thin film electrode of NaxCoO2, which was fabricated by pulsed laser deposition. A high rate of 400 C was realized in the film together with a fine cyclability where its capacity after 1000 cycles remains 84.4% of the initial one. The NaxCoO2 thin film exhibits a clear sign of the structural phase transition induced by Na+ intercalation even at the high rate of 200 C. This observation indicates bulk nature of the rapid and highly-reversible Na+ intercalation in NaxCoO2.

Mitigation of Layered to Spinel Conversion of a Li-Rich Layered Metal Oxide Cathode Material for Li-Ion Batteries

“…20 A very recent paper confirmed Na x CoO 2 have metallic conductivity which leads to rapid Na + intercalation in this material up to the 400 C-rates with only 15.4% capacity fade after 100 cycles. 21 Recently, Johnson et al reported that lithium rich layered-spinel cathode active material can be synthesized through ion-exchange reaction aiming to minimize disorder in LiMO 2 layers. However, their conclusion was not sufficient to elucidate the role of Na in the structure during cycling.…”

“…Similar improvement in charge transfer resistance was reported elsewhere for a different family of cathode active material, namely P2-Na x CoO 2 (σ >10 3 S/cm). 20,21 We used a simple Randles circuit for fitting the AC impedance data. The model used and the fitted data, which matches smoothly, are found in Figure 2b.…”

Electrode potential and activation energy of sodium transition-metal oxides as cathode materials for sodium batteries: A first-principles investigation

“…Nevertheless, case in NaNiO 2 is just the reverse of NaCrO 2 and NaCoO 2 . Obviously, a conductor whose states reside at E F is beneficial for accommodating electrons while sodium (de)sodiated and partly contributes to the cycle capacity [72]. Therefore, improved electrode might be achieved by doping with n-type impurity.…”

From Lithium-Ion Tо Sodium-Ion Batteries

“…Для кобальтата натрия Na x CoO 2 в зависимости от стехиометрии (индекс x) известно четыре стабильных модификации: α-фаза -O3 (0.9 < x < 1), α′-фаза -O'3 (x = 0.75), β-фаза -P3 (0.55 ≤ x ≤ 0.6) и γ-фаза -P2 (0.64 ≤ x ≤ 0.74), из которых наибольший интерес представляет более стабильная γ-модификация [16][17][18][19][20][21][22][23][24]. На первой гальваностатической анодной кривой, зарегистрированной в режиме C/10 до потенциала 3.8 В, для этой модификации Т. Л. КУЛОВА, А. М. СКУНДИН Na x CoO 2 отмечаются четыре площадки при потенциалах 2.72, 3.00, 3.30 и 3.60 В, а на ответной катодной кривой до потенциала 2.0 В отмечаются 8 площадок [21].…”