Niobium-doped layered cathode material for high-power and low-temperature sodium-ion batteries

Abstract

The application of sodium-based batteries in grid-scale energy storage requires electrode materials that facilitate fast and stable charge storage at various temperatures. However, this goal is not entirely achievable in the case of P2-type layered transition-metal oxides because of the sluggish kinetics and unfavorable electrode|electrolyte interphase formation. To circumvent these issues, we propose a P2-type Na0.78Ni0.31Mn0.67Nb0.02O2 (P2-NaMNNb) cathode active material where the niobium doping enables reduction in the electronic band gap and ionic diffusion energy barrier while favoring the Na-ion mobility. Via physicochemical characterizations and theoretical calculations, we demonstrate that the niobium induces atomic scale surface reorganization, hindering metal dissolution from the cathode into the electrolyte. We also report the testing of the cathode material in coin cell configuration using Na metal or hard carbon as anode active materials and ether-based electrolyte solutions. Interestingly, the Na||P2-NaMNNb cell can be cycled up to 9.2 A g−1 (50 C), showing a discharge capacity of approximately 65 mAh g−1 at 25 °C. Furthermore, the Na||P2-NaMNNb cell can also be charged/discharged for 1800 cycles at 368 mA g−1 and −40 °C, demonstrating a capacity retention of approximately 76% and a final discharge capacity of approximately 70 mAh g−1.

Zn/Ti/F synergetic-doped Na0.67Ni0.33Mn0.67O2 for sodium-ion batteries with high energy density

“…4e). [23][24][25][46][47][48][49][50][51][52][53][54] As indicated, the NNZMTOF cathode delivered better cycling performances in half-cells compared with that of other sodium-based layered oxide cathodes reported previously (Table S2 †).…”

Long‐Cycle‐Life Cathode Materials for Sodium‐Ion Batteries toward Large‐Scale Energy Storage Systems

“…[ 112,113 ] A P2‐Na 0.78 Ni 0.31 Mn 0.67 Nb 0.02 O 2 was designed with the introduction of niobium, reducing the electronic band gap and ionic diffusion energy barrier. [ 114 ] The calculated diffusion coefficient of Na + in Na 0.78 Ni 0.31 Mn 0.67 Nb 0.02 O 2 showed little change after variation of working temperature from 25 to −40 °C, indicating fast kinetics at low temperatures ( Figure 7 a). In addition, the introduction of Nb element can generate a robust CEI film, which can minimize the negative effect of the water attack on the structure and inhibit phase change and surface breakage (Figure 7b).…”

Regulating Na Occupation in P2‐Type Layered Oxide Cathode for All‐Climate Sodium‐Ion Batteries

“…Therefore, the ratio of Na e /Na f has been increased and Na + migration has been promoted. [12] Zhao et al [13] found that Nb 5+ plays the same role as Sb 5+ , and they proposed that Nb 5+ doping can reduce the electronic band gap and the energy barrier of Na + diffusion, which improve the rate and low-temperature cycling performances.…”