Sacrificial cathode additives for enhanced cycle performance for liquid and all–solid–state anode–free lithium secondary batteries

초록

Li metal anodes have been intensively studied due to the high capacity of 3860 mA h g–1 to increase the energy density of batteries. However, inevitable Li dendrite growth and poor cycle life prevent the practical use of Li metal anodes. The anode-free batteries (AFBs), constructed with a cathode and a current collector as an anode without Li metal, have many advantages in energy density, cost-effectiveness, and processability in cell fabrication. However, AFBs present continuous capacity fading due to the zero excess Li reservoir. Here, we report Li2Cu0.6Ni0.4O2 (LCNO) as a sacrificial cathode additive to provide an additional Li to the anode current collector to improve the cyclability of AFBs. LCNO, a solid solution of Li2NiO2 and Li2CuO2, presents a striking difference in electrochemical properties depending on the critical voltage windows. LCNO shows a high initial charging capacity of 393.3 mA h g–1 with a very low initial Coulombic efficiency of 5.6 %, and could not contribute to later electrochemical reactions at 4.3 – 3.0 V. We demonstrate significantly improved cyclability of AFBs with LCNO as a sacrificial cathode additive in liquid and all solid-state AFBs.

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