Lithium deposition in single ion conducting polymer electrolytes

Lithium Li metal is considered as promising anode material for high energy density rechargeable batteries, although its application is hampered by inhomogeneous Li deposition and dendritic Li morphologies that could eventually result in contact losses of bulk and deposited Li as well as cell short circuits. Based on theoretical investigations, recent works on polymer electrolytes particularly focus on the design of single ion conducting electrolytes and improvement of bulk Li transport properties, including enhanced Li transference numbers, ionic conductivity, and mechanical stability, thereby affording safer and potentially dendrite free cycling of Li metal batteries. In the present work, it is revealed that the spatial microstructures, localized chemistry, and corresponding distributions of properties within the electrolyte are also decisive for achieving superior cell performances. Thus, targeted modification of the electrolyte microstructures should be considered as further critical design parameters for future electrolyte development and to actually control Li deposition behavior and longevity of Li metal batterie

Fluorinated polysulfonamide based single ion conducting room temperature applicable gel-type polymer electrolytes for lithium ion batteries

Single ion conducting polymer electrolytes (SIPEs) comprised of homopolymers containing a polysulfonylamide segment in the polymer backbone are presented. The polymer structure contains –C(CF3)2 functional groups that due to better solubility allow for effective lithiation, yielding well-defined materials. An optimized polymer electrolyte membrane was fabricated as a 3 : 1 blend of single ion conducting polymer and PVdF-HFP, which exhibits a high ionic conductivity of 0.52 mS cm−1 and an impressive lithium ion transference number of 0.9, as well as a 7Li self-diffusion coefficient of 4.6 × 10−11 m2 s−1 at 20 °C. The presented polymer electrolyte has superior oxidative stability and long-term stability against lithium metal, thus facilitating operation in LiNi1/3Mn1/3CO1/3O2 (NMC111)/lithium metal cells at 20 °C and 60 °C, thereby clearly demonstrating the application potential of this class of materials