Amorphous Transformation of FeP Enabling Enhanced Sulfur Catalysis and Anchoring in High-performance Li-S Batteries
Amorphous Transformation of FeP Enabling Enhanced Sulfur Catalysis and Anchoring in High-performance Li-S Batteries
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DOI：
10.1016/j.cej.2021.133705
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发表时间：
2021-11
影响因子：
15.1
通讯作者：
G. Xia;Lishu Zhang;Jiajia Ye;Zhanghua Fu;Xuting Li;Xiaoxia Yang;Zhiqiang Zheng;Chuanzhong Chen-Chuanzhong
中科院分区：
文献类型：
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作者：
G. Xia;Lishu Zhang;Jiajia Ye;Zhanghua Fu;Xuting Li;Xiaoxia Yang;Zhiqiang Zheng;Chuanzhong Chen-Chuanzhong
催化材料最近已被证明可有效解决锂硫电池中多硫化物穿梭和硫利用率低的关键挑战。虽然无定形材料在典型的电催化过程如水裂解中显示出优势，但为硫阴极开发的绝大多数催化材料是结晶的。在这里，我们证明了增强的电化学性能的非晶FeP相（aFeP）来自其结晶对应物的自氧化过程。电化学测量和理论计算表明，结晶FeP的结构各向异性不利于重要性能，如多硫化物结合能，催化活性和导电性。无定形aFeP有效地克服了这些问题。此外，无定形aFeP提供了额外且更强的结合位点，增强了Fe-S和P-S原子之间的电子交换，并降低了aFeP-Li 2S 4吸附体系的HOMO-LUMO能隙，从而显着改善了催化效果，特别是对于容量限制的液-固转化。实现了高达5C的高比容量，并且还展示了具有高面积容量（6.3 mAh cm−2）的袋式电池。该研究为高性能锂硫正极材料中非晶态催化材料的未来发展提供了有益的启示。
Catalytic materials have recently been demonstrated to be effective in addressing the critical challenges of polysulfide shuttling and low utilization of sulfur in Li-S batteries. Although amorphous materials show advantages in typical electrocatalysis processes such as water splitting, the vast majority of catalytic materials developed for the sulfur cathodes are crystalline. Herein, we demonstrate the enhanced electrochemical performance of the amorphous FeP phase (aFeP) derived from a self-oxidation process of its crystalline counterpart. Electrochemical measurements and theoretical calculation reveal that the structural anisotropy of crystalline FeP is not in favour of important properties such as polysulfide binding energy, catalytic activity and electrical conductivity. Amorphous aFeP effectively overcomes these issues. Moreover, amorphous aFeP provides additional and stronger binding sites, enhanced electron exchanging between Fe-S and P-S atoms, as well as reduced HOMO-LUMO gap of the aFeP-Li2S4adsorption system, leading to significantly improved catalytic effects especially for the capacity-limiting liquid–solid conversions. High specific capacities are achieved up to 5C and pouch cells with a high areal capacity (6.3 mAh cm−2) are also demonstrated. This study provides useful insights for the future development of amorphous catalytic materials in high-performance Li-S cathodes.