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    Electrochemical behavior of LiNi0.6Mn0.2Co0.2O2 cathode in different aqueous electrolytes
    (Springer, 2020) Kunduracı, Muharrem; Mutlu, Rasiha Nefise; Gizir, Ahmet Murat
    In the past decade, there has been a growing interest in aqueous lithium-ion batteries (LiBs) since they are a lower cost and safer alternative to their traditional organic versions. Such interest is fueled by the need for large-scale stationary energy storage systems. The introduction of “water-in-salt” LiTFSI electrolyte has paved the way for higher voltage aqueous batteries, thereby helping their energy densities. LiNi0.6Mn0.2Co0.2O2 (NMC 622) is a promising cathode material for aqueous LiBs owing to its high operating voltage and lithium capacity. However, there is no report of its use in aqueous electrolytes. NMC 622 was tested in Li2SO4, LiNO3, and “water-in-salt” LiTFSI aqueous electrolytes for the first time in this study. Our results showed that NMC 622 exhibits excellent electrochemical performance in LiTFSI electrolyte reaching a maximum discharge capacity of 152 mAh g?1. On the other hand, fast capacity decay and rise in overpotential are observed in cases of nitrate and sulfate electrolytes. This study highlights the significance of electrolyte composition and states that high-nickel cathodes in “water-in-salt” LiTFSI electrolyte present promise for future aqueous LiBs
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    Energy storage performance of LiV3O8/water-in-salt electrolyte/LiNi1/3Co1/3Mn1/3O2 cell for aqueous lithium-ion batteries
    (Elsevier, 2022) Kunduracı, Muharrem; Kılıç Çetin, Selda; Çağlayan, Uğur; Mutlu, Rasiha Nefise; Kaya, Doğan; Ekicibil, Ahmet
    Electrochemical performance of an aqueous lithium-ion battery containing LiV3O8 anode, ‘water-in-salt’ 20 M LiTFSI electrolyte and LiNi1/3Co1/3Mn1/3O2 cathode was studied. In the full cell, the cathode and anode reached a maximum lithiation capacity of 145.8 mAh g?1 and 80 mAh g?1, respectively. The full cell successfully underwent 100–110 cycles before hitting 20% capacity loss limit. The average discharge potential of the cell started at 0.849 V and stayed relatively stable in the next 140 cycles. The first cycle coulombic efficiency was as high as 80% and it stabilized at 99–100% in the subsequent cycles. These are the best numbers ever reported for this anode/cathode couple. This outperformance was achieved thanks to the increased stability of the anode and cathode materials in high molarity ‘water-in-salt’ electrolyte over lower molarity nitrate or sulfate electrolytes previously reported in literature.
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    Synergistic Coupling of High Capacity Li1.2Mn0.54Ni0.13Co0.13O2 and High Voltage LiMn1.6Ni0.4O4 Lithium-Ion Battery Cathodes
    (Springer, 2022) Kunduracı, Muharrem; Buluttekin, Rojbin; Mutlu, Rasiha Nefise; Gizir, Ahmet Murat
    Manganese-based cathode materials are good alternatives to nickel-based layered cathodes in lithium-ion batteries due to the much cheaper cost of manganese ores. Coprecipitation is a popular method to produce precursor materials for lithium-ion batteries since its versatility enables the synthesis of a wide range of compositions with various architectures. In this study, spherical 2-mu m to 4-mu m-diameter binary Mn0.8Ni0.2CO3 and ternary Mn4/6Ni1/6Co1/6CO3 precursor materials were synthesized by tuning synthesis conditions including temperature, feeding mode and reagent quantity. The binary and ternary precursor materials were mixed and reacted with Li2CO3 at 800 degrees C to obtain LiMn1.6Ni0.4O4 and Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials, respectively. LiMn1.6Ni0.4O4 had a discharge capacity of 132 mAh g(-1) and exhibited excellent cycle life and voltage retention. On the other hand, 221 mAh g(-1) discharge capacity was achieved with Li1.2Mn0.54Ni0.13Co0.13O2 , but it showed a fast capacity and voltage decay. A hybrid electrode made of 50:50 wt% of both cathodes yielded 166 mAh g(-1) capacity and 3.95 V average discharge voltage with much reduced voltage decay and capacity fading rate, thereby mitigating each other's weakness in the process.