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Understanding the Critical Role of Binders in Phosphorus/Carbon Anode for Sodium‐Ion Batteries through Unexpected Mechanism
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2020-06-21 , DOI: 10.1002/adfm.202000060
Wei Xiao 1, 2, 3 , Qian Sun 1 , Mohammad Norouzi Banis 1 , Biqiong Wang 1 , Weihan Li 1 , Minsi Li 1 , Andrew Lushington 1 , Ruying Li 1 , Xifei Li 3 , Tsun‐Kong Sham 2 , Xueliang Sun 1
Affiliation  

Polymer binders that combine active materials with conductive agents have played a critical role in maintaining the structural integrity of phosphorus anodes with a huge volume change upon sodiation/desodiation. Herein, the role of binders on the structural/chemical stability of phosphorus/carbon anode is spectroscopically uncovered through unexpected mechanism. Surprisingly, the selection of different binders is found to determine the oxidation degree of active phosphorus in various electrodes, which correlate well with their electrochemical properties. At a high oxidation degree, the electrode applying a conventional poly(vinylidene difluoride) binder displays the worst electrochemical properties, while the electrode using a sodium alginate binder delivers the best electrochemical performance (a highly reversible capacity of 1064 mAh g−1 with a 90.1% capacity retention at 800 mA g−1 after 200 cycles and an outstanding rate capability of 401 mAh g−1 at 8000 mA g−1) for its negligible oxidation. Additionally, the emergence/decomposition of surface intermediates, including (PO2)3− and (PO4)3− species, are observed in the discharging/charging processes via the ex situ P K‐edge X‐ray absorption spectroscopies. This novel discovery of the unique role of binders in phosphorus anodes, not only provides an opportunity to ameliorate their electrochemical properties, but also enables their practical applications in high‐energy sodium‐ion batteries.

中文翻译:

通过意外机制了解粘合剂在钠离子电池的磷/碳阳极中的关键作用

将活性材料与导电剂结合在一起的聚合物粘合剂在维持磷阳极的结构完整性方面起着至关重要的作用,而磷化后的阳极体积会发生巨大变化。在本文中,通过意外的机理在光谱上揭示了粘合剂对磷/碳阳极的结构/化学稳定性的作用。令人惊讶地,发现选择不同的粘合剂来确定各种电极中活性磷的氧化程度,这与它们的电化学性能密切相关。在高氧化度下,使用常规聚偏二氟乙烯粘合剂的电极表现出最差的电化学性能,而使用藻酸钠粘合剂的电极表现出最佳的电化学性能(1064 mAh g的高度可逆容量)-1,在200个循环后在800 mA g -1下具有90.1%的容量保持率,在8000 mA g -1时具有401 mAh g -1的出色的速率容量,可忽略不计。此外,在放电/充电过程中,通过异位PK边缘X射线吸收光谱观察到了包括(PO 23−和(PO 43−在内的表面中间体的出现/分解。粘合剂在磷阳极中独特作用的这一新发现,不仅为改善其电化学性能提供了机会,而且使它们在高能钠离子电池中的实际应用成为可能。
更新日期:2020-08-08
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