Lithium fiber growth on the anode in a nanowire lithium ion battery during charging
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Li necklace formation during charging a nanowire. (a) Pristine nanowire before charging. (b) Full image of the nanowire after charging. The segment above the ILE was bent and elongated, while the segment immersed in the ILE had a large chunk of jelled electrolyte on it. At the end of the jelled electrolyte, there was the long chain of Li necklace. (c) Image series showing the pulling-out process of the Li necklace from the ionic ILE. The Li crystals on the fiber were mostly faceted. (d) Magnified image of the Li crystal marked by the blue triangle in (c). (e) Magnified Li fiber tip protruding out of the thick jelled electrolyte, as marked by the red triangle in (c). (f) EELS from the Li crystals. The multiple plasmon peaks agreed well with those from metallic lithium. The inset shows the Li K-edge with significantly lower intensity than that of the primary plasmon peak, indicating tiny amount of Li compound formed on the Li fiber.
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Li fiber formed during charging a Si nanowire. (a) Pristine Si nanowire. (b) Morphology of the whole nanowire after charging. The segment above the ILE swelled and thick jelled electrolyte formed on the immersed segment. A wide and long Li fiber with bright contrast formed on the tip of the nanowire. [(c) and (d)] Schematic illustrations of Li fiber growth on a nanowire anode, M. The dense electric field lines at the apex illustrate the tip effect (c). Li plating takes place on the nanowire tip due to the high electric field, while SEI forms on the whole immersed surfaces at a lower threshold of electric field (d). Lithiation also takes place above the ILE surface with the conversion of M to .
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