Achieving High-Capacity Cathode Presodiation Agent Via Triggering Anionic Oxidation Activity in Sodium Oxide

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium-ion batteries (SIBs) face challenges in energy density due to irreversible sodium loss, particularly with hard carbon anodes.
• Sacrificial cathode presodiation agents offer a solution by providing additional sodium sources.
• Anionic oxidation activity in presodiation agents is key for high capacity and efficient sodium compensation.

Purpose of the Study:

• To develop a novel sacrificial cathode presodiation agent for SIBs.
• To enhance the energy density of SIB full cells by compensating for sodium loss.
• To elucidate the mechanism of anionic oxidation in the presodiation agent.

Main Methods:

• Synthesis of a nickel-modified sodium oxide (Ni-Na2O) presodiation agent.
• Electrochemical characterization of Ni-Na2O for its presodiation capacity and decomposition potential.
• Fabrication and testing of SIB full cells using Ni-Na2O with Na3V2(PO4)3 and Na2/3Ni2/3Mn1/3O2 cathodes.

Main Results:

• Ni atoms in Ni-Na2O activate oxygen anion oxidation, enabling a high presodiation capacity of 710 mAh/g.
• The decomposition overpotential of Ni-Na2O was reduced to 2.8 V (vs Na/Na+).
• SIB full cells incorporating Ni-Na2O showed significant energy density improvements of 23.9% and 19.3%.

Conclusions:

• The developed Ni-Na2O acts as an effective sacrificial presodiation agent for SIBs.
• The study reveals the structure-function relationship governing anionic oxidation mechanisms in presodiation agents.
• This work provides a paradigm for designing advanced presodiation agents to boost SIB performance.