Advanced Materials published a study on August 25 by researchers from Beihang University, Beijing Xibei Power and their collaborators (DOI: 10.1002/adma.74820). The team used electrochemical interface reconstruction: a tailored over-discharge step dissolves the passivating layer around inactive sodium, allowing some sodium to participate in cycling again while forming a new NaF-rich interphase.
The paper reports 83.5% capacity retention after 3,800 cycles at 2C in a 1.5Ah pouch cell, a 343% improvement over the best cycling result in the earlier literature. A separate 5Ah pouch cell delivered 181.1Wh/kg and retained 93.7% capacity after 2,500 cycles at 1C. The researchers also tested the method with different electrolytes and cathodes.
These are results from cell tests described in a research paper. The study did not report commercial production, customer deliveries or long-term field operation.