Trace Fluorinated Carbon Dots Driven Li-Garnet Solid-State Batteries.

Garnet solid-state electrolyte Li _6.5 La ₃ Zr _1.5 Ta _0.5 O ₁₂ (LLZTO) holds significant promise. However, the practical utilization has been seriously impeded by the poor contact of Li|garnet and electron leakage. Herein, one new type of garnet-based solid-state battery is proposed with high performance through the disparity in interfacial energy, induced by the reaction between trace fluorinated carbon dots (FCDs) and Li. The work of adhesion of Li|garnet is increased by the acquired Li-FCD composite, which facilitates an intimate Li|garnet interface with the promoted uniform Li ⁺ deposition, revealed by density functional theory (DFT) calculations. It is further validated that a concentrated C-Li ₂ O-LiF component at the Li|garnet interface is spontaneously constructed, due to the significant disparity in interfacial energy between C-Li ₂ O-LiF|LLZTO and C-Li ₂ O-LiF|Li. Furthermore, The electron transport and Li dendrites penetration are effectively hindered by the formed Li ₂ O and LiF. The Li-FCD|LLZTO|Li-FCD symmetrical cells demonstrate stable cycling performance for over 3000 hours at 0.3 mA cm ^-2 and 800 hours at 0.5 mA cm ^-2 . Furthermore, the LFP|garnet|Li-FCD full cell exhibits remarkable cycling performance (91.6 % capacity retention after 500 cycles at 1 C). Our research has revealed a novel approach to establish a dendrite-free Li|garnet interface, laying the groundwork for future advancements in garnet-based solid-state batteries.
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