Injecting Excess Na into a P2-Type Layered Oxide Cathode to Achieve Presodiation in a Na-Ion Full Cell

The initial Na loss limits the theoretical specific capacityofcathodes in Na-ion full cell applications, especially for Na-deficientP2-type cathodes. In this study, we propose a presodiation strategyfor cathodes to compensate for the initial Na loss in Na-ion fullcells, resulting in a higher specific capacity and a higher energydensity. By employing an electrochemical presodiation approach, weinject 0.32 excess active Na into P2-type Na0.67Li0.1Fe0.37Mn0.53O2 (NLFMO),aiming to compensate for the initial Na loss in hard carbon (HC) andthe inherent Na deficiency of NLFMO. The structure of the NLFMO cathodeconverts from P2 to P & PRIME;2 upon active Na injection, without affectingsubsequent cycles. As a result, the HC||NLFMOpreNa fullcell exhibits a specific capacity of 125 mAh/g, surpassing the valueof 61 mAh/g of the HC||NLFMO full cell without presodiation due tothe injected active Na. Moreover, the presodiation effect can be achievedthrough other engineering approaches (e.g., Na-metal contact), suggestingthe scalability of this methodology.

Automated summary

A presodiation strategy is proposed to compensate for the initial Na loss in Na-ion full cells, resulting in a higher specific capacity and a higher energy density. The presodiation effect can be achieved through other engineering approaches, suggesting the scalability of this methodology.