Electrode-Coated Inorganic Separators for High Performance and Safe Lithium-Ion and Lithium-Metal Batteries

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Description
Lithium-ion and lithium-metal batteries are deemed to be the choice of energy storage media for the future. However, they are not entirely safe and their performance in terms of cycle life and charging rates is sub-optimal. A majority of these

Lithium-ion and lithium-metal batteries are deemed to be the choice of energy storage media for the future. However, they are not entirely safe and their performance in terms of cycle life and charging rates is sub-optimal. A majority of these issues arise from the currently used flammable polyolefinic separators and carbonate solvent based electrolytes. This work utilizes in-house developed and specific property tuned electrode-coated inorganic separators in combination with a fire-proof electrolyte to resolve the above stated concerns.Firstly, to improve the safety of the lithium-ion cell with a commercial polypropylene separator a thermally stable in-house developed electrode coated quartz silica separator is utilized. The silica separator due to its better electrolyte wettability, electrolyte uptake and lower resistance also offers better capacity retention (~ 15 %) at high rates of discharge. Subsequently, research on developing a completely safe lithium-ion battery was conducted by replacing the traditional carbonate solvent based electrolyte with a fire-proof lithium bis-fluoro sulphonyl-imide salt/tri-methyl phosphate solvent electrolyte. However, this electrolyte has a high viscosity and low separator wetting rate. A microporous in house synthesized silicalite electrode-coated separator due to its high surface energy functionalizes the viscous fire-proof electrolyte and together they are tested in a full-cell. The intra-particle pores of the silicalite separator result in a thinner and more robust solid electrolyte interface on graphite. This results in about 20 % higher capacity retention during long term cycling when compared to the polypropylene separator used in the same full-cell. To enable stable and fast charging lithium-metal batteries free from dendrite propagation related failure, plate shaped γ-alumina and silicalite electrode-coated separators with high tortuosity are developed and used in a lithium-metal full-cell battery, with the former separator having no intra-particle pores and the latter having them. The γ-alumina separators show improvements in dendrite propagation prevention up to 3 C-rate of charge/discharge but a loss in active lithium is seen beyond the 75th cycle. However, microporous plate-shaped silicalite separators did not show any loss in active lithium even at 3 C-rate for 100 cycles due to the homogenized lithium-ion flux at the anode, while also preventing dendrite propagation.
Date Created
2021
Agent

Safe Fire-resistant Electrolytes for Lithium-ion Batteries

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Description
Lithium-ion batteries that employ an electrolyte consisting of LiFSI and TMP are shown to have better cycle performance than conventional carbonate electrolyte batteries at elevated temperatures. Additionally, an inorganic alumina or silica separator also improves cycling performance at high temperatures.

Lithium-ion batteries that employ an electrolyte consisting of LiFSI and TMP are shown to have better cycle performance than conventional carbonate electrolyte batteries at elevated temperatures. Additionally, an inorganic alumina or silica separator also improves cycling performance at high temperatures. Half-cells of Li metal and Li2TiO3 were constructed with LiFSI/TMP electrolyte and inorganic separators and cycled at increasing temperatures. Their cycle performance was compared to batteries with the same anode and cathode material that were prepared with conventional components. Half-cells using either the novel electrolyte or inorganic separators were able to continue cycling at temperatures up to 80 ℃, long after the conventionally prepared batteries had failed. A cell with a combination of the LiFSI/TMP electrolyte and silica separator still showed 75% capacity retention after 10 cycles at 85 ℃ as well.
Date Created
2019-05
Agent