Improved cycling stability of the capping agent-free nanocrystalline FeS2 cathode via an upper cut-off voltage control
Improved cycling stability of the capping agent-free nanocrystalline FeS2 cathode via an upper cut-off voltage control
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DOI：
10.1007/s10853-016-0538-8
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发表时间：
2017-03
影响因子：
4.5
通讯作者：
Shuang Cheng;Jian Wang;Hongzhen Lin;Wanfei Li;Yongcai Qiu;Zhaozhao Zheng;Xinluo Zhao;Yuegang Zhang
中科院分区：
文献类型：
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作者：
Shuang Cheng;Jian Wang;Hongzhen Lin;Wanfei Li;Yongcai Qiu;Zhaozhao Zheng;Xinluo Zhao;Yuegang Zhang
过渡金属硫族化合物如fes2是很有前途的储能电极材料。然而，fes2阴极的倍率性能差，循环稳定性低，阻碍了其在二次电池中的实际应用。在本研究中，通过无表面活性剂的水反应，通过简单和环保的方法合成了具有八面体形状和200-300 nm尺寸的高纯黄铁矿fes2纳米晶体（NCs）。与相容的醚电解质结合，制备的FeS2NCs尽管尺寸远远超出量子限制范围，但由于晶体结构清晰，表面粗糙，具有较高的利用率和可逆性，可以作为阴极活性材料。此外，我们发现fes2的最后一个充电电压步骤只贡献了很小的容量，但由于可溶多硫化物的形成，导致了严重的容量衰减。通过设置适当的上截止电压抑制这一步骤，可以显著提高Li/ fes2电池的循环寿命。在1C电压窗1.0-2.4 V下运行的Li/ fes2电池的初始容量为486.1 mA h g−1，略低于在1.0-3.0 V （561.1 mA h g−1）上运行的电池，但在500次循环后（367 mA h g−1vs 315 mA h g−1），容量衰减率低至0.048%。我们的研究结果不仅为开发用于长寿命可充电电池的先进fes2材料，而且为开发其他具有各种潜在应用前景的过渡金属硫族化物纳米材料提供了有意义的途径。
Transition metal chalcogenides such as FeS2are promising electrode materials for energy storage. However, poor rate performance and low cycling stability hinder the practical application of FeS2cathode in secondary batteries. In this study, highly pure pyrite FeS2nanocrystals (NCs) with octahedral shape and 200–300 nm size have been synthesized via a facile and environmentally benign approach based on a surfactant-free aqueous reaction. Combined with a compatible ether electrolyte, the prepared FeS2NCs, despite their dimension far beyond the quantum confined regime, could achieve high utilization and reversibility as a cathode active material due to the well-defined crystal structure and the uncapped rough surfaces. Furthermore, we find that the last charging voltage step of FeS2only contributes a minor capacity but caused severe capacity fading due to the formation of soluble polysulfides. By suppressing this step through setting a proper upper cut-off voltage, the cycle life of the Li/FeS2cell is dramatically improved. The Li/FeS2cell running over a voltage window of 1.0–2.4 V at 1C delivers an initial capacity of 486.1 mA h g−1, slightly lower than that running over 1.0–3.0 V (561.1 mA h g−1), but outperforms the latter substantially after 500 cycles (367 mA h g−1vs 315 mA h g−1), corresponding to a capacity decay rate as low as 0.048% per cycle. Our results provide a meaningful approach for the development of not only the advanced FeS2material for long-life rechargeable batteries, but also other transition metal chalcogenide nanomaterials for a variety of potential applications.