In 1800, Alessandro Volta invented the world’s first battery. The following year, after observing his voltaic pile, Napoleon made Volta a count. Six decades later, French physicist Gaston Planté invented the first rechargeable battery. He wasn’t named a count for the feat, but he did leave an enduring legacy in battery history: Just pop the hood of your car.
Working in Paris as a lecture assistant in physics, Planté began designing a battery that could store a useful amount of electrical energy. The Daniell Cell, the best battery available at that time, was longer-lasting than the voltaic pile, but produced a relatively small voltage (about 1.1V) and was limited by an irreversible chemical reaction. Then, in 1859, Planté succeeded in inventing the first secondary, or rechargeable, battery, named for him.
Planté’s design contained two electrodes, an anode (negative electrode) of lead and a cathode (positive electrode) of lead dioxide, separated by a rubber strip. The electrons lost by the anode through oxidation were conducted to the cathode by an electrolyte of sulfuric acid. From there, the electrons and their accompanying charge could be transferred externally to an electricity-hungry device such as a light bulb. The resulting charge was almost double that of the Daniell cell at 2V, and combining cells into a battery further increased the voltage capacity. In 1860, Planté demonstrated for the French Academy of Sciences a series of nine connected cells, but today the most common lead-acid batteries, as they’re also called, contain six cells for a combined voltage of 12V. The Planté cell also simplified the Daniell model by using a single electrolyte for both electrodes. The most striking difference in the Planté battery, however, was that its chemical reaction was reversible. That is, by reversing the normal negative-to-positive flow of electrons (achieved by another outside source of electric current), the battery could be recharged.
Though the Planté battery was capable of delivering large, rechargeable currents, it couldn’t do so for very long. The lead dioxide cathode limited the life of the battery because it had little active material available for the chemical reaction. However, the battery functioned well in applications that required short, powerful bursts of electricity, as in powering the lights of train cars while they were stopped. Electric companies, plagued by mechanical failure caused by fluctuations in the demand for electricity supplied by a generator, used lead-acid batteries as a stand-by source of power. Utilities still use these batteries to deliver temporary high-voltage electricity, minimizing power outages during times of intense demand.
Perhaps the most familiar derivative of the Planté lead-acid battery today is the 12V automobile battery. This longer-lasting model of the original includes an important advancement in electrode design invented by French engineer Camille Faure in 1881. To overcome the limited reactivity of the solid cathode, Faure developed a more efficient set of electrodes consisting of a lead paste spread thinly on metal grids. These porous plates, easily penetrated by the liquid electrolyte, greatly increased the surface area of each electrode available for the chemical reaction, postponing the need for recharge. The resulting battery, with its prolonged life, brief surges of electricity and recharge capabilities (a feature familiar to anyone who has used jumper cables) proved useful for starting automobile engines.
Contemporary Planté batteries are usually grouped into two categories, based on the intensity and length of their electric current. The first, capable of short, powerful current only, is the starter battery (such as those used in cars). These have thinner electrode plates that maximize reaction surface area but can’t withstand long, deep discharges without being damaged. The other type, called a deep cycle battery, has thicker plates that, while less intense, can discharge electric current for longer periods. Examples of these can be found running trolling motors and lights in RVs. Combined, these lead-acid batteries power everything from electric sidewalks in airports, to lights at railroad crossings, to electric cars. Their reversible chemical reaction makes them ideal for storing electric current generated by another source, such as solar panels or windmills. The low cost of the materials and long life make them practical for developing areas.
Lead-acid batteries also have a high (as much as 98 percent) rate of recycling, which helps offset concerns about the toxicity of their materials. Once the battery can no longer be recharged, the lead from the electrodes and the plastic from the battery housing are recycled, and the sulfuric acid electrolyte is neutralized. Car batteries contain from 60 to 80 percent recycled materials.