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Sub-20 nm Carbon Nanoparticles with Expanded Interlayer Spacing for High-Performance Potassium Storage

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journal contribution
posted on 14.12.2018, 00:00 by Qingmeng Gan, Jiwei Xie, Youhuan Zhu, Fangchang Zhang, Peisen Zhang, Zhen He, Suqin Liu
Carbon materials are most promising candidates for potassium-ion battery (PIB) anodes because of their high electrical conductivities, rational potassium storage capabilities, and low costs. However, the large volume change during the K-ion insertion/extraction and the sluggish kinetics of K-ion diffusion inhibit the development of carbon-based materials for PIBs. Here, under the guidance of density functional theory, N/P-codoped ultrafine (≤20 nm) carbon nanoparticles (NP-CNPs) with an expanded interlayer distance, improved electrical conductivity, shortened diffusion distance of K ions, and promoted adsorption capability toward K ions are synthesized through a facile solvent-free method as a high-performance anode material for PIBs. The NP-CNPs show a high capacity of 270 mA h g–1 at 0.2 A g–1, a remarkable rate capability of 157 mA h g–1 at an extremely high rate of 5.0 A g–1, and an ultralong cycle life with a high capacity of 190 mA h g–1 and a retention of 86.4% at 1.0 A g–1 after 4000 cycles. The potassium storage mechanism and low volume expansion for NP-CNPs are revealed through cyclic voltammetry, in situ Raman, and ex situ XRD. This work paves a new way to design and fabricate carbon-based nanostructures with high reversible capacity, great rate capability, and stable long-term performance.