An electrode structure comprising a population of electrodes (21, 22) comprising an electrode active material layer (49, 50) and a population of counter-electrodes (21, 22) comprising a counter-electrode active material layer (49, 50) wherein the population of electrodes (21, 22) is arranged in alternating sequence with the population of counter-electrodes (21, 22) along a first direction, each member of the electrode population has a bottom (31, 32), a top (33, 34), a length L E, a width W E, a height H E, and a longitudinal axis A E extending from the bottom (31, 32) to the top (33, 34) of each such member and in a direction that is transverse to the first direction, the length L E of each member of the electrode population being measured in the direction of its longitudinal axis A E, the width W E of each member of the electrode population being measured in the first direction, and the height H E of each member of the electrode population being measured in a direction that is perpendicular to the longitudinal axis A E of each such member and the first direction, the ratio of L E to each of W E and H E of each member of the electrode population being at least 5:1, respectively, the ratio of H E to W E for each member of the electrode population being between 0.4:1 and 1000:1, respectively, the longitudinal axis A E of each member of the population of electrodes (21, 22) is surrounded by an electrically insulating separator layer (43, 86, 88), the electrically insulating separator layer comprising a microporous separator material disposed in regions between opposing lateral surfaces (61, 62, 63, 64) of adjacent members of the electrode and counter-electrode populations and an electrically insulating material (86, 88) disposed along front and back surfaces (65 and 67 or 66 and 68) of the members of the electrode population, and between members of the electrode and counter-electrode populations, the electrically insulating separator layer (42, 86, 88) comprises the microporous separator material having a void fraction of at least 20 vol.%. the population of electrodes (21, 22) is arranged in alternating sequence with the population of counter-electrodes (21, 22) along a first direction, each member of the electrode population has a bottom (31, 32), a top (33, 34), a length L E, a width W E, a height H E, and a longitudinal axis A E extending from the bottom (31, 32) to the top (33, 34) of each such member and in a direction that is transverse to the first direction, the length L E of each member of the electrode population being measured in the direction of its longitudinal axis A E, the width W E of each member of the electrode population being measured in the first direction, and the height H E of each member of the electrode population being measured in a direction that is perpendicular to the longitudinal axis A E of each such member and the first direction, the ratio of L E to each of W E and H E of each member of the electrode population being at least 5:1, respectively, the ratio of H E to W E for each member of the electrode population being between 0.4:1 and 1000:1, respectively, the longitudinal axis A E of each member of the population of electrodes (21, 22) is surrounded by an electrically insulating separator layer (43, 86, 88), the electrically insulating separator layer comprising a microporous separator material disposed in regions between opposing lateral surfaces (61, 62, 63, 64) of adjacent members of the electrode and counter-electrode populations and an electrically insulating material (86, 88) disposed along front and back surfaces (65 and 67 or 66 and 68) of the members of the electrode population, and between members of the electrode and counter-electrode populations, the electrically insulating separator layer (42, 86, 88) comprises the microporous separator material having a void fraction of at least 20 vol.%.