We have developed a method to operate lithium-silicon (Li-Si) thick-film electrodes in a manner consistent with traction applications. Key to the operating strategy is the voltage control of the electrode. It is expected that strong reducing environments, created by operating the electrode at low potentials (near that of Li), reduce battery life. We show that operating Li-Si at higher potentials is also damaging, and this is counterintuitive in that common negative electrodes (e.g., graphites and titanates) do not suffer from this limitation. Arguments based on measured Coulombic efficiencies, cycle life tests, in-situ stress measurements, and high-resolution microscopy resolve the otherwise anomalous findings. We show that promising half-cell ( Silicon film electrodes have been shown to be useful for characterization purposes insofar as one need not treat binders, various particle geometries, conductive diluents, and other complications inherent in the construction of porous electrodes. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] In this work, we focus on the potential utility of Si thick-film electrodes formed on roughened copper current collectors. If sufficient capacity can be obtained, such a geometry might simplify electrode fabrication, as the electrode host material would consist of nothing more than Si deposited on a current collector, and high specific energies (Wh/L) and energy densities (Wh/kg) could result.Four topics are examined in this endeavor. First, by controlling the potential limits over which we operate a Li-Si electrode, can we obtain sufficient stability for relatively thick-film electrodes (i.e., yielding more than 2 mAh/cm 2 )? Second, how does the electrochemical performance correlate with stress in the electrode over the potential window of operation? Third, because the electrode consists of only Li and Si, we can isolate equilibrium hysteresis behavior associated with this alloy, and we derive and implement a simple model to represent the voltage-composition data that may be useful in subsequent engineering analyses of electrodes with a significant Li-Si contribution. Last, we examine full cells (Li-Si vs. an NMC622 positive electrode, corresponding to Ni 0.6 Mn 0.2 Co 0.2 O 2 ) in the context of capacity, cycle life, cycle efficiency, microstructure, and elemental analysis. A cell modeling tool 45 is used to examine the efficacy of the Si film electrodes for actual battery electric vehicle applications based on specific energy and energy density calculations.