Oxygen/Fluorine Dual-Doped Porous Carbon Nanopolyhedra Enabled Ultrafast and Highly Stable Potassium Storage
Oxygen/Fluorine Dual-Doped Porous Carbon Nanopolyhedra Enabled Ultrafast and Highly Stable Potassium Storage
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氧/氟双掺杂多孔碳纳米多面体实现超快且高度稳定的钾存储
DOI：
10.1002/adfm.201906126
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发表时间：
2019-09-26
影响因子：
19
通讯作者：
Chen, Qianwang
中科院分区：
文献类型：
--
作者：
Lu, Jian;Wang, Changlai;Chen, Qianwang
碳基材料是一种很有前途的钾离子电池负极材料。然而，由于炭质阳极的显著体积膨胀和结构不稳定性，实现高容量、高倍率和长循环寿命仍然是一个挑战。首次报道了氧/氟双掺杂多孔碳纳米多面体(OFPCN)作为PIBs的新型负极材料，其在0.05A g(-1)下的可逆容量为481 mA h g(-1)，在1A g(-1)下循环2000次后的容量为218 mA h g(-1)，容量保持率为92%。即使经过5000次10Ag(-1)的强劲循环，充放电时间约为40 S，仍保持着史无前例的111 mAh g(-1)的容量。这种超快的钾储存和前所未有的循环稳定性在PIB中很少有报道。定量动力学分析表明，钾的储存机制中既有扩散过程，也有电容过程。密度泛函理论计算表明，O/F双掺杂多孔碳提高了对K的吸附能力，并能吸附多个K原子，结构扭曲较小，这是OFPCN负极具有较高的比容量、优异的倍率性能和良好的循环稳定性的原因。
Carbon-based materials are promising anodes for potassium-ion batteries (PIBs). However, due to the significant volume expansion and structural instability, it is still a challenge to achieve a high capacity, high rate and long cycle life for carbonaceous anodes. Herein, oxygen/fluorine dual-doped porous carbon nanopolyhedra (OFPCN) is reported for the first time as a novel anode for PIBs, which exhibits a high reversible capacity of 481 mA h g(-1) at 0.05 A g(-1) and excellent performance of 218 mA h g(-1) after 2000 cycles at 1 A g(-1) with 92% capacity retention. Even after 5000 robust cycles at 10 A g(-1) with charging/discharging time of around 40 s, an unprecedented capacity of 111 mA h g(-1) is still maintained. Such ultrafast potassium storage and unprecedented cycling stability have been seldom reported in PIBs. Quantitative kinetics analysis reveals that both diffusion and capacitance processes are involved in the potassium storage mechanism. Density functional theory calculations demonstrate that the O/F dual-doped porous carbon promotes the K-adsorption ability and can absorb multiple K atoms with slight structural distortion, which accounts for the high specific capacity, outstanding rate capability, and excellent cycling stability of the OFPCN anode.