Improving the electrochemical performance of lithium-rich manganese-based cathode materials by Na₂S₂O₈ surface treatment

• Published in: Journal of alloys and compounds Vol. 1008; p. 176845
• Main Authors: Wang, Zeqing, Liu, Zhihua, Zhang, Ronglan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.12.2024
• Subjects: Lithium-rich manganese-based cathode material; Pre-activation; Spinel phase; Surface modification; Lithium-rich manganese-based cathode material; Surface modification; Pre-activation; Spinel phase
• ISSN: 0925-8388
• DOI: 10.1016/j.jallcom.2024.176845

Lithium-rich manganese-based cathode materials are well-regarded for their high specific capacity and notable voltage thresholds, making them attractive for advanced energy storage applications. However, their widespread commercialization is hindered by challenges in cycle performance, including suboptimal initial Coulombic efficiency, inadequate cycle stability, and constrained rate capability. To address these issues, this paper introduces a novel modification strategy using Na₂S₂O₈ to chemically delithiate the surface of the materials. This modification strategy dramatically enhances the initial Coulombic efficiency. The results demonstrate that the initial Coulombic efficiency of the two pre-activated samples improved to 84.6 % and 102.2 %, respectively. At the same time, the Na₂S₂O₈-treated samples exhibit a higher maximum discharge capacity at a 0.2 C rate, reaching 211.1 mAh g⁻¹ and 201.3 mAh g⁻¹, which notably surpasses the untreated sample's capacity of 188.7 mAh g⁻¹. Additionally, the treated samples exhibit improved cycling and rate performance, with capacity retention of 81.2 % and 63.5 %, respectively. After 60 cycles, these figures continue to be superior to those of the untreated material, which stands at 57.3 %. The results demonstrate that Na₂S₂O₈ treatment leads to the in situ formation of spinel phases on the material surface, thereby enhances the cycling stability and rate capability of the cathode material. Compared to traditional surface treatment methods, Na₂S₂O₈ solution treatment can induce more profound structural evolution without necessitating high-temperature calcination, thus reducing the demands on process conditions and equipment and offering greater process controllability. Moreover, this surface modification strategy paves the way for applying spinel coatings on other substrates with similar structures. •Enhanced electrochemical performance of lithium-rich manganese cathodes with Na2S2O8 surface treatment.•Na2S2O8 treatment inhibits oxygen precipitation and promotes spinel phase formation on the surface.•A hypothesis is proposed to explain the mechanism of spinel phase formation.