High-Efficiency Cathode Sodium Compensation for Sodium-Ion Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 32627877.
- Also identified by DOI 10.1002/adma.202001419.
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Abstract
Sodium-ion batteries have gained much attention for their potential application in large-scale stationary energy storage due to the low cost and abundant sodium sources in the earth. However, the electrochemical performance of sodium-ion full cells (SIFCs) suffers severely from the irreversible consumption of sodium ions of cathode during the solid electrolyte interphase (SEI) formation of hard carbon anode. Here, a high-efficiency cathode sodiation compensation reagent, sodium oxalate (Na<sub>2</sub> C<sub>2</sub> O<sub>4</sub> ), which possesses both a high theoretical capacity of 400 mA h g<sup>-1</sup> and a capacity utilization as high as 99%, is proposed. The implementation of Na<sub>2</sub> C<sub>2</sub> O<sub>4</sub> as sacrificial sodium species is successfully realized by decreasing its oxidation potential from 4.41 to 3.97 V through tuning conductive additives with different physicochemical features, and the corresponding mechanism of oxidation potential manipulation is analyzed. Electrochemical results show that in the full cell based on a hard carbon anode and a P2-Na<sub>2/3</sub> Ni<sub>1/3</sub> Mn<sub>1/3</sub> Ti<sub>1/3</sub> O<sub>2</sub> cathode with Na<sub>2</sub> C<sub>2</sub> O<sub>4</sub> as a sodium reservoir to compensate for sodium loss during SEI formation, the capacity retention is increased from 63% to 85% after 200 cycles and the energy density is improved from 129.2 to 172.6 W h kg<sup>-1</sup> . This work can provide a new avenue for accelerating the development of SIFCs.