No abstract

Battery active materials are routinely evaluated via the electrochemical performance of their composite electrodes which are prepared with standard formulations and routine processing conditions. The relationship between electrochemical responses and these experimental variables are not commonly explored. Mechanical properties and their relationship to durability are almost never considered. We therefore offer some quite basic studies of the effects of formulation on these properties. Electrochemical and mechanical properties of composites across a broad formulation range are provided for the most common Li-Ion chemistry -LiCoO 2 electroactive particles with PVDF binders. Mechanical characterizations include evaluations of both the constituent materials and the porous electrode structures. We will show that composite electrode designs which optimize mechanical durability and ruggedness will degrade electrochemical performance for these LiCoO 2 /PVDF binder-based systems.

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The conductivity and mechanical stiffness of ethylene-oxide based Li+ conducting solid polymer electrolytes (SPE) were measured and compared for a variety of single- and two-phase systems. Our objective was to determine whether there are simple correlations between these two properties despite the fact that these systems are truly complex. Results show that molecular architecture dominates both transport and mechanical behavior of single phase systems, thereby eliminating broad correlations. Conductivity was additionally found to require not only facile local chain dynamics but also a sufficient concentration of vacancies, as per the site hopping model. Two phase systems also show complex behaviors, but offer a broader range of both conductivity and stiffness values, and good conductivity/stiffness correlations.