科研之友
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摘要
Lithium metal batteries with proud energy density gained wide research interest in the past decades. Unfortu-nately, the uneven lithium deposition and the uncontrollable lithium dendrites growth leading to low coulombic efficiency and poor cycling stability remain unresolved. Herein, advanced approach via constructing 3D hier-archical single-atom Co anchored nitrogen carbon nanosheets-carbon fiber cloth (CC@CN-SACo) is reported that enables uniform Li deposition and offers high performance of Li metal batteries. The design of active single-atom in CC@CN-SACo achieves enhanced lithophilicity that effectively reduces the nucleation overpotential. Owing to the enlarge specific area and numerous lithophilic single atom Co sites, the current density is significantly reduced and the Li+ ion flux is uniformly distributed. Density functional theory calculations also reveal that the electron-delocalized sp2 hybridized 2D carbon plane between Co sites on the CN-SACo nanosheet and the active s (Li)-dz2/dxz(Co) interactions takes a pivotal role in improving Li deposition thermodynamics as well as the diffusion kinetics of Li+ and effectively modulates the deposition/stripping behavior of Li at lithium metal anode, thereby preventing the formation of Li dendrites. As a consequence, CC@CN-SACo@Li electrode assembled with Li foil delivers a superior cycling stability with 2000 h, 1400 h, and 500 h at 1 mA cm- 2/1mAh cm-2, 2 mA cm- 2/1mAh cm-2, and 5 mA cm- 2/5mAh cm-2, respectively. The full cells assembled with LiFePO4 achieve a capacity retention of 96.6% with 2 mg cm-2 LiFePO4 and 81% with N/P ratio of 5 at 1C is attained. Surprisingly, CC@CN-SACo@Li also presents superior performances with 718.4 mAh g-1 reversible capacity after 300 cycles when applied in lithium-sulfur batteries, suggesting its universality for different high-energy batteries.
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单位中国科学院
