Microstructured electrode structures

An electrochemical stack for use in an energy storage device, the stack comprising:

• a stacked arrangement of a population of cathode structures having cathodically active material layers, separator layers, and a population of anode structures having microstructured anodically active material layers, the population of anode structures being interdigitated with the population of cathode structures;
• wherein each member of the population of anode structures has a height, HA of at least 100 micrometers measured in a direction orthogonal to the reference plane, and a lineal distance, DL, between at least two members of the population of anode structures, measured in a direction parallel to the reference plane, is greater than a maximum value of HA for the population of anode structures,
• wherein the direction of stacking of the cathode structures, separator layers, and anode structures is parallel to the reference plane, and a direction of travel of carrier ions between cathodically active material layers of the cathode structures and microstructured anodically active material layers of the anode structures during a charge or discharge process, is generally parallel to the reference plane,
• wherein the microstructured anodically active layer of each anode structure comprises a porous silicon layer having a void volume fraction of from 0.15 to 0.75, the thickness T of the porous silicon layer of each member of the population of anode structures as measured in a direction parallel to the reference plane is from 10 to 100 micrometers, and the pores of each porous silicon layer predominantly have major axes that are substantially parallel to the reference plane, and
• wherein the number of anode structures in the electrochemical stack is at least 10.