This technology features an electrode material composed of restacked nanosheets, created by intercalating bulky organic ammonium ions—ranging from tetramethylammonium to tetradecylammonium—between exfoliated molybdenum disulfide nanosheets. The intercalated organic ions expand the interlayer spacing, increasing the specific surface area and creating pathways for sodium ion transport.
Sodium ions are larger and heavier than lithium ions, making them difficult to move within electrodes. Conventional bulk molybdenum disulfide has a narrow interlayer structure that cannot adequately accommodate sodium ions, resulting in limited charge-discharge capacity and poor cycle performance.
This technology involves reacting molybdenum disulfide with alkyllithium in an inert atmosphere at room temperature, followed by ultrasonic dispersion in distilled water for exfoliation. Tetraalkylammonium hydroxide is then added to the dispersion to induce restacking with organic ions intercalated between the layers. The interlayer spacing can be physically adjusted by varying the alkyl chain length, with nanosheet sizes ranging from 100 to 4,000 nm. Applicable to sodium-ion battery anodes, low-cost batteries for renewable energy-linked large-scale ESS, and power grid backup batteries to reduce reliance on lithium, this method allows for custom-designed interlayer spacing simply by selecting the organic ion type, achieving higher charge-discharge capacity than bulk or simple restacked MoS2.
This invention was developed with support from the Ministry of Science and ICT’s research on energy-functional hybrid catalysts based on post-graphene inorganic metal compound nanosheets.
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