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Author list |
Orynbassar Mukhan, Yuvaraj Subramanian, Sharon Mugobera, Sung-Soo Kim, Kwang-Sun Ryu |
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Abstract
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In the current scenario, All-Solid-State Batteries (ASSBs) are one of the inevitable energy storage systems due to their high energy density and safety aspects. Nonetheless, they have some limitations in their implementation for high performance solid-state lithium batteries. Notably, the reactions at the electrode and electrolyte interface, which negatively affects the Li-ion transport. From this perspective, we prepared the renowned high ionic conductive solid electrolytes (Li6PS5Cl, Li6.2P0.8Si0.2S5Cl0.5Br0.5, Li5.3PS4.3Cl1.7 and Li5.3PS4.3ClBr0.7) using a ball milling process subsequent to calcination at appropriate temperatures. The prepared electrolytes exhibited ionic conductivity values of 4.5, 5.3, 9.0 and 15.9 mS cm−1, respectively. Importantly, the electrode and electrolyte interface processes are examined through microcavity electrode system using our prepared electrolyte and LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode. In this case, a single particle confined in a micro cavity electrode system, NCM523-Li6.2P0.8Si0.2S5Cl0.5Br0.5 exhibits the highest initial discharge capacity value of 5.27 nAh, and an even higher initial Coulombic efficiency of 87.9 % surpassing other micro electrode systems. This and the electrochemical kinetic parameters evaluated through the Tafel plot analysis confirm that Si substitution minimizes chemical side reactions at the interface. The electrochemical kinetic parameters reveal that Li6.2P0.8Si0.2S5Cl0.5Br0.5 electrolyte has high exchange current, low charge transfer resistance and high lithium diffusion coefficient values. This proves that a favorable interface was formed between the NCM523 and the SE, thereby resulting in high rate of lithium-ion exchange between the NCM523 and the SE. The comparative study confirms the electrochemical kinetics improved by the bromine and silicon incorporation in the Li-argyrodite structure and offers flexible Li-ion pathways for better electrochemical performances. |
