Battery systems, methods of in-situ grid-scale battery construction, and in-situ battery regeneration methods are disclosed. The battery system features controllable capacity regeneration for grid-scale energy storage. The battery system includes a battery comprising a plurality of cells. Each cell includes a cathode comprising cathode electrode materials disposed on a first current collector, an anode comprising anode electrode materials disposed on a second current collector, a separator or spacer disposed between the cathode and the anode an electrolyte to fill the battery in the spaces between electrodes. The battery system includes a battery system controller, wherein the battery system controller is configured to selectively charge and discharge the battery at a normal cutoff voltage and wherein the battery system controller is further configured to selectively charge and discharge the battery at a capacity regeneration voltage as part of a healing reaction to generate active electrode materials.