Separators for Li-S Battery

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Invention Summary This inexpensive separator membrane for lithium-sulfur batteries prevents lithium polysulfide shuttling and diffusion, and has high lithium ion conductivity. Technology Overview Lithium-sulfur batteries are promising candidates for low-cost rechargeable battery systems. However, such batteries suffer from lithium polysulfide shuttling, a process where lithium polysulfide conversion reaction products dissolve in the electrolyte and migrate to the lithium metal anode. The polysulfide shuttling induces rapid capacity degradation, poor cycling stability and low Coulombic efficiency. Current separators used in lithium-sulfur batteries are either ineffective at preventing shuttling, or are expensive and have too low ionic conductivity at room-temperature. Prof. Lynden Archer’s group at Cornell University created high-transference number separator membranes containing sulfonate groups which facilitate electrolyte wettability and lithium ion conduction, while the negative charge on the membrane simultaneously rejects sulfur species due to the repulsive electrostatic interactions. Further, the membrane was prepared using an efficient and low-cost UV-crosslinking method, which is highly tunable and applicable in many different battery systems. In experiments, a lithium sulfur battery utilizing the new separator demonstrated remarkable cycling efficiency of above 98% for 100 cycles. Potential Applications Separator for metal-sulfur batteries Advantages Prevents lithium polysulfide dissolution and shuttling High ionic conductivity Low-cost, facile manufacturing process Highly tunable