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材料科学
Sn_4P_3-induced crystalline/amorphous composite structures for enhanced sodium-ion battery anodes
The optimization of anode materials such as Sn,P and Sn_4P_3 in terms of capacity and cyclability is crucial to improve the overall performance of sodium-ion batteries.However,the delicate fabrication of these materials,including the balanced crystalline/amorphous domains,reasonable particle size and distribution,complementary components exhibiting synergetic reactions,among others,still greatly retards the realization of maximum performance.Herein,a series of Sn/P-based composite materials with a plum pudding configuration were fabricated to achieve controlled crystalline/amorphous structures as well as optimized size and distribution in a carbon framework.By using a facile and low-cost ball milling method,the structural transformation of Sn_4P_3 into phase-separated crystalline Sn and amorphous P in a carbonaceous framework can be finely controlled,producing a series of binary(Sn_4 P_3/C),quaternary(Sn_4P_3/Sn/P/C) and ternary(Sn/P/C) composites.Due to the complementary components,crystalline/amorphous adjustment,crystallite sizes and well-integrated interfaces,the quaternary Sn_4P_3/Sn/P/C composite showed the best electrochemical performance,with a noticeable long-cycle performance of 382 mA hg~(-1) and 86% capacity retention for nearly 300 cycles.Different from binary and ternary composites,the discharge of quaternary composite generates no noticeable signals of Na_(15)Sn_4 and Na_3 P in the ex-situ X-ray diffraction patterns,suggesting the crystallite growth of sodiation products can be depressed.Moreover,Sn4 P3 in the quaternary composite can be partially regenerated in the desodiation reaction,implying the significant short-range interaction and thus better synergetic reactions between Sn and P components.The results demonstrate that the design and organization of crystalline/amorphous structures can serve as an efficient strategy to develop novel electrode materials for sodium ion batteries.
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Journal of Materials Science & Technology
2020年20期

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