A polymerized C60 coating enhancing interfacial stability at three-dimensional LiCoO2 in high-potential regime

• 3D high-temperature LiCoO2 (3D HT-LCO) is realized by laser structuring/annealing.
• 3D design enables higher surface area for electrolyte access and Li+ diffusions.
• C60@3D HT-LCO delivers initial discharge capacity of 175 mAhg−1 at 0.1 C (3.0–4.5 V).
• 3D architecture and polymerized C60 coating decrease the charge transfer resistance.
• Polymerized C60 coating prevents Co dissolutions and suppress side reactions.

The interfacial instabilities, including side reactions due to electrolyte decompositions and Cobalt (Co) dissolutions, are the main detrimental processes at LiCoO2 cathode when a high-voltage window (>4.2 V) is applied. Nevertheless, cycling the cathode with a voltage above 4.2 V would deliver an increased gravimetric capacity, which is desired for high power battery operation. To address these drawbacks, we demonstrate a synergistic approach by manufacturing the three-dimensional high-temperature LiCoO2 electrodes (3D HT-LCO) using laser-microstructuring, laser-annealing and subsequent coating with polymerized C60 thin films (C60@3D HT-LCO) by plasma-assisted thermal evaporation. The C60@3D HT-LCO cathode delivers higher initial discharge capacity compared to its theoretical value, i.e. 175 mA h g−1 at 0.1 C with cut-off voltage of 3.0–4.5 V. This cathode combines the advantages of the 3D electrode architecture and an advanced C60 coating/passivation concept leading to an improved electrochemical performance, due to an increased active surface area, a decreased charge transfer resistance, a prevented Co dissolution into the electrolyte and a suppressed side reaction and electrolyte decomposition. This work provides a novel solution for other cathode materials having similar concerns in high potential regimes for application in lithium-ion microbatteries.

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