Available Technology

BSA 16-02 and BSA 16-03: Electrochemically Active Interlayers for Lithium Ion Batteries

This invention describes a method and materials to increase Li-S cell performance by using commercially available cathode materials as a discrete electrochemically active interlayer in electrode design. The presence of a discrete interlayer (e.g., TiS2, metal oxide layer, metal phosphate) on the top of the sulfur electrode, the sulfur utilization can be improved by ~10-30%. In addition, the selected additives are also electrochemically active with higher redox potentials than that of the sulfur system and contributing to the cell capacity and widening of the cell discharge voltage window (e.g., 1.8V to 4.0V).
Patent Abstract: 
Lithium–sulfur batteries may succeed lithium-ion cells because of their higher theoretical energy density and potential lower cost from the use of sulfur due to the large abundance of sulfur in nature. However, many challenges still exist for Li-S battery system. One of the major problem is the limited sulfur electrode utilization (typically ~50%) when commercialIy available micron sized sulfur is used in combination with large amounts of conductive carbon additive (30-40 wt.%) in the sulfur cathode formulation. Other methods to improve sulfur cathode utilization include nano­sized sulfur and/or carbon particles which lead to higher material cost. Often, the presence of large amount of electrochemically inert carbon additive in the cell leads to net weight gain resulting in low energy density at the electrode level. It is thus desirable to increase the sulfur utilization in the Li-S battery system to more than 50% by using inexpensive materials and without complex processing or synthesis procedures. This invention utilizes a discrete layer electrode design using commercially available electrochemically active metal sulfide interlayer to increase (ca. 10-30%) the utilization of sulfur cathode in a Li-S cell. The hybrid mixture alone does not realize this improvement indicating the sulfur cathode/electrolyte interface is a critical region for this positive S-interlayer interaction.
This new Li-S cell design will open up new avenues to fabricate high performance Li–S batteries in a cost-effective manner.
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