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

Abstract

The initial Na loss limits the theoretical specific capacity of cathodes in Na-ion full cell applications, especially for Na-deficient P2-type cathodes. In this study, we propose a presodiation strategy for cathodes to compensate for the initial Na loss in Na-ion full cells, resulting in a higher specific capacity and a higher energy density. By employing an electrochemical presodiation approach, we inject 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) and the inherent Na deficiency of NLFMO. The structure of the NLFMO cathode converts from P2 to P′2 upon active Na injection, without affecting subsequent cycles. As a result, the HC||NLFMOpreNa full cell exhibits a specific capacity of 125 mAh/g, surpassing the value of 61 mAh/g of the HC||NLFMO full cell without presodiation due to the injected active Na. Moreover, the presodiation effect can be achieved through other engineering approaches (e.g., Na-metal contact), suggesting the scalability of this methodology.

Sodium Acetate as Residual-Free Presodiation Additive for Enhancing the Energy Density of Sodium-Ion Batteries

“…The presodiation strategy involves the introduction of extra sodium resources to the anode or cathode material before the first charge/discharge process, thereby significantly improving the ICE and cycle life of SIBs. , Cathode sodium replenishment involves the creation of sodium-rich electrodes by directly blending compounds with a high sodium content into cathode materials during the slurry preparation stage. A sodium-supplemented additive undergoes electrochemical oxidation to release sodium ions during the initial charge/discharge cycle. − The presodiation of cathode additives has gained prominence in recent years due to its simplicity and practical applicability in the manufacturing process. , The sodium-supplemented additives, reported thus far in the literature, are mainly categorized into inorganic and organic sodium salts.…”

Presodiation Architected Robust Surface Enables Packaging Optimal Performance of Sodium-Ion Batteries

“…Considering that prelithiation/presodiation has been proposed to compensate for cation losses in the electrode before cycling, − three categories are divided with chemical, electrochemical and direct contact methods . Unfortunately, the problem of reagent residues is unavoidable in chemically reactive presodiation, and in addition the process complexity greatly reduces the feasibility of electrochemical presodiation in large-scale production, putting a serious obstacle to its commercialization . Sodium metal is an efficient and direct presodiation reagent that has a high theoretical specific capacity (1166 mAh/g) and produces no byproducts after presodiation.…”