Secondary Cell

• are also known as storage cells or accumulators
• They are galvanic cells whose cell reactions can be reversed by applying an external source of current
• These can be discharged and recharged many times until the electrode material lasts
• Examples: Li-ion cell, Ni-Cd battery, Lead-acid battery
• Battery => a number of galvanic cells connected in series
• Energy storage of the battery is expressed in ampere-hour (Ah)
• Cells of same type connected in series, emf is added.

  Cells of same type connected in parallel, emf remains same but internal resistance gets halved; hence, more current can be drawn from the cell without much drop in potential
• Internal resistance of a cell depends on electrode plate area and cell chemistry.

  It is inversely proportional to electrode plate area

  It is directly proportional to size of the battery