A battery is a collection of common materials arranged in a particular way to produce electricity on demand. Well electrical energy really, but let’s keep it simple. Benjamin Franklin described four capacitors as ‘a battery’ when he linked them together in 1749 because he likened the combined power of his Leyden Cell to a battery of artillery firing away. So how does a battery work?
How Does a Battery Work in Principle?
The principles of batteries are easy to set out, although we are only just beginning to witness them with nano microscopy. All batteries have three things in common. These are anode electrodes (negative -), cathode electrodes (positive +), and an electrolyte that manages how the two electrodes interact.
When we connect the electrode terminals of a charged battery via a device with suitable resistance, two things happen simultaneously: Ions flow from the anode to the cathode through the electrolyte that filters them selectively. The electricity flows through the outside device for as long as there are sufficient ions to continue flowing inside the battery. When the anode runs out of ions, the battery is ‘flat’.
You may be wondering how does a battery work again after I recharge it? When we attach a charger to the electrode terminals, the electricity flows in the opposite direction. The ions inside the cell return from the cathode to the anode through the electrolyte while we are doing this.
In the image to the left of a demonstrator voltaic cell, the two half-cells are linked by a salt bridge separator that permits the transfer of ions.
However, this recharging cycle does not continue forever. Each time we recycle the battery some of the ions lose their way in the electrolyte. Eventually we reach a point where there are not enough ions left over to operate the external device. The battery’s useful life is over now. We should take it to a recycling station so a robot can separate the components, and recycle them for a new purpose for the sake of the earth.
Preview Image: Lithium Thionyl Chloride Batteries