It follows from the definitions of a battery and a cell:
> battery: a container consisting of one or more cells, in which chemical energy is converted into electricity and used as a source of power.
> cell: a device containing electrodes immersed in an electrolyte, used for current-generation or electrolysis.
An antimatter reactor would not be a battery because it would not contain any cells. Additionally, because it converts nuclear energy into useful power, not chemical energy.
> battery: a container consisting of one or more cells, in which chemical energy is converted into electricity and used as a source of power.
> cell: a device containing electrodes immersed in an electrolyte, used for current-generation or electrolysis.
An antimatter reactor would not be a battery because it would not contain any cells. Additionally, because it converts nuclear energy into useful power, not chemical energy.