Next-Generation Battery Components Derived from Soft Dendritic Colloids

Abstract

Growing demands for energy storage are causing rapid development of next-generation batteries. Researchers typically use commercially available Li-ion components and processing techniques to investigate new chemistries and cell architectures. Herein, we propose an emerging materials-development platform: shear- driven precipitation of polymeric materials to develop application-specific battery components. In this process, polymer particles with high aspect ratios, called soft dendritic colloids (SDCs), are formed via turbulent solvent-nonsolvent induced phase separation. Two specific component applications are presented.The first application is nano-composite redox active polymer electrodes for Li-ion batteries. Redox polymer electrodes are currently limited by low intrinsic electronic conductivity. As a result, large amounts of conductive additives are added to the composite electrodes, lowering the gravimetric performance. The network forming capabilities of the SDC morphology provides intimate contact between active material and conductive material to enable free-standing electrodes that are produced via simple vacuum filtration. We present cyclic voltammetry and charge/discharge data using poly(2,2,6,6-tetramethyl-1-piperidinyloxy methacrylate) as the SDC material.The second application is composite separator assemblies to mitigate lithium polysulfide shuttling in Li-S batteries. Polysulfide shuttling is considered a technological hurdle plaguing Li-S battery development. Separators can be functionalized to reduce polysulfide shuttling by incorporating additives onto or within the separator matrix, which either bind or repel the soluble species to prevent crossover to the anode. We demonstrate that SDC materials are a promising platform for fabricating nanocomposite separators using a variety of nanomaterials. The nano composite separators show increased thermal stability, cycling stability, and polysulfide rejection as compared to commercial materials.