采用水热合成法制备了一种三维花状SnO2微米材料,并以多巴胺作为碳源在其表面包覆一层氮掺杂碳层(SnO2@NC)。作为锂离子电池负极材料,SnO2@NC相比于SnO2表现出更为优异的电化学性能。实验数据显示:SnO2@NC在1 A·g−1电流密度下循环...采用水热合成法制备了一种三维花状SnO2微米材料,并以多巴胺作为碳源在其表面包覆一层氮掺杂碳层(SnO2@NC)。作为锂离子电池负极材料,SnO2@NC相比于SnO2表现出更为优异的电化学性能。实验数据显示:SnO2@NC在1 A·g−1电流密度下循环500圈仍然保持430.9 mA·h·g−1的可逆比容量,倍率性能在5 A·g−1电流密度下具有566.9 mA·h·g−1的高放电容量。其优异的电化学性能得益于外部包覆的碳层缓解了SnO2充放电过程中的体积膨胀,以及氮掺杂碳层加快了材料电子/离子传输速率。A three-dimensional flower-like SnO2 micromaterial was prepared by hydrothermal synthesis and coated with a nitrogen-doped carbon layer (SnO2@NC) using dopamine as a carbon source. As an anode material for lithium-ion batteries, SnO2@NC exhibits superior electrochemical properties compared with SnO2. The experimental data show that SnO2@NC maintains a reversible specific capacity of 430.9 mA·h·g−1 after 500 cycles at a current density of 1 A·g−1, and a high discharge capacity of 566.9 mA·h·g−1 at a current density of 5 A·g-1 for multiplication performance. The excellent electrochemical performance is attributed to the externally coated carbon layer that mitigates the volume expansion of SnO2 during charging and discharging, as well as the nitrogen-doped carbon layer that accelerates the electron-ion transport rate of the material.展开更多
采用水热法成功合成了一种新型氮掺杂碳修饰MnO2纳米带(MnO2@NC)。将该材料作为锂离子电池负极时,在2 A g-1的大电流密度下循环1000次后,其可逆比容量可达310.4 mAh g-1,并展现出卓越的倍率并能。与未改性MnO2相比,MnO2@NC表现出更好的...采用水热法成功合成了一种新型氮掺杂碳修饰MnO2纳米带(MnO2@NC)。将该材料作为锂离子电池负极时,在2 A g-1的大电流密度下循环1000次后,其可逆比容量可达310.4 mAh g-1,并展现出卓越的倍率并能。与未改性MnO2相比,MnO2@NC表现出更好的倍率性能、更高的比容量和容量保持率。电化学测试分析表明,MnO2@NC电化学性能提高的原因在于电荷转移电阻的降低、缩短的Li+扩散距离以及更为优异的电极动力学。?展开更多
硬碳由于其资源丰富和良好的储钠性能,被认为是最有希望得到商业化应用的钠离子电池负极材料,但其在储钠过程存在循环稳定性差和充放电容量较低的问题,因此限制了其商业化进程。为了解决上述问题,本文采用高温煅烧法将硒粉气化后对硬碳...硬碳由于其资源丰富和良好的储钠性能,被认为是最有希望得到商业化应用的钠离子电池负极材料,但其在储钠过程存在循环稳定性差和充放电容量较低的问题,因此限制了其商业化进程。为了解决上述问题,本文采用高温煅烧法将硒粉气化后对硬碳进行掺杂,硒掺杂不仅扩大了硬碳的层间距,而且在表面提供了丰富的缺陷。所制备的硒掺杂硬碳 (HC-Se)负极材料在2A g-1的大电流密度下循环500圈,仍然可提供283.3 mAh g-1的高可逆容量,倍率性能5 A g-1可释放出263.5 mAh g-1的高比容量。实验结果表明,硒掺杂有利于提高硬碳的离子传输动力学和可逆比容量,从而有效提高硬碳的电化学性能。展开更多
The Call of the Wild by Jack London depicts the protagonist Buck’s transition,i.e.from a dog to a wolf,as well as those victims eliminated in the selecting of nature.All of these reflect the perpetual theme in this n...The Call of the Wild by Jack London depicts the protagonist Buck’s transition,i.e.from a dog to a wolf,as well as those victims eliminated in the selecting of nature.All of these reflect the perpetual theme in this novel—social Darwinism which advo⁃cates“survival of the fittest”.展开更多
Rhetoric is magic used by writers in their writings to arouse strong sentiments and to touch the heartstrings of readers.Wendelin Van Draanen gives full play of rhetoric in her best-seller Flipped and successfully cre...Rhetoric is magic used by writers in their writings to arouse strong sentiments and to touch the heartstrings of readers.Wendelin Van Draanen gives full play of rhetoric in her best-seller Flipped and successfully created strong resonance for readers.展开更多
文摘采用水热合成法制备了一种三维花状SnO2微米材料,并以多巴胺作为碳源在其表面包覆一层氮掺杂碳层(SnO2@NC)。作为锂离子电池负极材料,SnO2@NC相比于SnO2表现出更为优异的电化学性能。实验数据显示:SnO2@NC在1 A·g−1电流密度下循环500圈仍然保持430.9 mA·h·g−1的可逆比容量,倍率性能在5 A·g−1电流密度下具有566.9 mA·h·g−1的高放电容量。其优异的电化学性能得益于外部包覆的碳层缓解了SnO2充放电过程中的体积膨胀,以及氮掺杂碳层加快了材料电子/离子传输速率。A three-dimensional flower-like SnO2 micromaterial was prepared by hydrothermal synthesis and coated with a nitrogen-doped carbon layer (SnO2@NC) using dopamine as a carbon source. As an anode material for lithium-ion batteries, SnO2@NC exhibits superior electrochemical properties compared with SnO2. The experimental data show that SnO2@NC maintains a reversible specific capacity of 430.9 mA·h·g−1 after 500 cycles at a current density of 1 A·g−1, and a high discharge capacity of 566.9 mA·h·g−1 at a current density of 5 A·g-1 for multiplication performance. The excellent electrochemical performance is attributed to the externally coated carbon layer that mitigates the volume expansion of SnO2 during charging and discharging, as well as the nitrogen-doped carbon layer that accelerates the electron-ion transport rate of the material.
文摘采用水热法成功合成了一种新型氮掺杂碳修饰MnO2纳米带(MnO2@NC)。将该材料作为锂离子电池负极时,在2 A g-1的大电流密度下循环1000次后,其可逆比容量可达310.4 mAh g-1,并展现出卓越的倍率并能。与未改性MnO2相比,MnO2@NC表现出更好的倍率性能、更高的比容量和容量保持率。电化学测试分析表明,MnO2@NC电化学性能提高的原因在于电荷转移电阻的降低、缩短的Li+扩散距离以及更为优异的电极动力学。?
文摘硬碳由于其资源丰富和良好的储钠性能,被认为是最有希望得到商业化应用的钠离子电池负极材料,但其在储钠过程存在循环稳定性差和充放电容量较低的问题,因此限制了其商业化进程。为了解决上述问题,本文采用高温煅烧法将硒粉气化后对硬碳进行掺杂,硒掺杂不仅扩大了硬碳的层间距,而且在表面提供了丰富的缺陷。所制备的硒掺杂硬碳 (HC-Se)负极材料在2A g-1的大电流密度下循环500圈,仍然可提供283.3 mAh g-1的高可逆容量,倍率性能5 A g-1可释放出263.5 mAh g-1的高比容量。实验结果表明,硒掺杂有利于提高硬碳的离子传输动力学和可逆比容量,从而有效提高硬碳的电化学性能。
文摘The Call of the Wild by Jack London depicts the protagonist Buck’s transition,i.e.from a dog to a wolf,as well as those victims eliminated in the selecting of nature.All of these reflect the perpetual theme in this novel—social Darwinism which advo⁃cates“survival of the fittest”.
文摘Rhetoric is magic used by writers in their writings to arouse strong sentiments and to touch the heartstrings of readers.Wendelin Van Draanen gives full play of rhetoric in her best-seller Flipped and successfully created strong resonance for readers.
