BATTERY BASICS Battery energy storage systems: Past, present, and future
Batteries power our world and their relevance will continue to grow as further innovations are made in fields like electric vehicles and the Internet of Things (IoT).
The humble battery is by far one of the most crucial enabling technologies of the 21st Century. From smaller devices such as smartphones to vehicles on the road, batteries have a significant impact on our world and are changing the way we are looking to the future. Indeed, it is difficult to imagine where we would be now without them.
Batteries are relatively recent innovations, however, with less than three centuries’ worth history as electrochemical storage systems. And it is within the last three-or-so decades in particular that new innovations in batteries and electrochemistry have seen batteries evolve into what they are today: essential components for the electrification of many aspects of our daily lives.
Batteries of the past
All the way back in 1749, Benjamin Franklin was the first person to describe what is now widely accepted as the first battery. By linking glass Leyden jar capacitors together, he discovered that they would produce a stronger discharge than a single one. These held their charge electrostatically as opposed to electrochemically.
It wasn’t until 1799 when we saw the first electrochemical battery. Designed by Alessandro Volta, the voltaic pile consisted of pairs of copper and zinc discs piled on top of each other and separated by cloth or cardboard soaked in brine which acted as an electrolyte. Volta’s battery produced continuous voltage and current when in operation and lost very little charge when not in use. Numerous other researchers improved the voltaic pile, substituting materials for the electrodes and electrolyte. The voltaic pile was not rechargeable; it would operate until the copper and zinc electrodes were consumed by the electrochemical reaction.
The first rechargeable battery came in 1859 when Gaston Plant Planté invented the lead acid rechargeable battery. This was achieved by immersing a lead anode and cathode in sulfuric acid to produce lead sulfate. The reaction at the anode released electrons and the reaction at the cathode consumed them, creating a flow of electricity. This reaction can be reversed by passing a current in the opposite direction, recharging the battery. This is widely considered as the first commercialised battery, used to power lamps in railway carriages. This battery also made the world’s first electrified transport possible, built in 1884 by Thomas Parker. The world’s first electric car came four years later in 1888.
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Batteries of the present
The lithium-ion battery is perhaps the best and most widely known example of a present-day battery. Its development over the past three decades especially has made possible the modern world and technology as we know it, with applications in everything from cell phones and portable electronics to electric vehicles (EVs) and massive grid storage systems. In a lithium-ion battery during discharge, lithium ions move from the negative electrode (usually graphite) via an electrolyte to the positive electrode (a cathode). There, they are inserted between layers of a complex metal oxide. During the charging cycle, the lithium ions move in the opposite direction.
The first commercial production of the lithium-ion battery was achieved by Sony in 1991. Since then, it has been the go-to standard for most battery-dependent applications. It is not the only option though, and other batteries were widely used (and still are today in a limited capacity) before it.
Nickel cadmium (NiCad) batteries, despite being invented in 1899 and produced in 1906, started to become popular in many formats during the 1970s through to the early 1990s. Cameras, small electronics, cordless tools, boats, and cars all used these batteries, however, they have been largely phased out by lithium-ion and nickel metal hydride (MIMH) batteries.
NIMH batteries, developed in 1967, use sintered titanium and nickel alloys for the positive electrode and hydrogen-absorbing allows for the negative electrode. They provide two-to-three times the capacity of NiCad batteries and today have applications in hybrid electric vehicles, most notably the Toyota Prius.
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Batteries of the future
The world needs more power. While lithium-ion is currently shaping our energy storage strategies and is at the cutting edge of it, researchers are actively looking for next-generation batteries to take energy storage to the next level in increasingly demanding and complex applications such as wearable consumer devices and electric vehicles.
There are many potential “replacements” for lithium-ion batteries, and the technology that will eventually replace it may not yet have been discovered. And extensive research in graphene, lithium-sulfur, and solid-state are just three examples. The latter, solid-state, is thought by many to be most likely successor.
Researchers have found that replacing the current lithium-ion battery’s graphite anode with lithium would allow many more lithium ions to flow during discharge, producing a battery with at least twice as much capacity. During the charging cycle of a lithium metal battery, however, dendrites (spiky crystalline structures) form and can grow through the liquid electrolyte and corrupt the cathode which shorts out the battery. At present, research is focusing on finding a solid or semi-solid electrolyte that can prevent dendrite growth whilst also facilitating the easy passage of lithium ions.
Current predictions estimate that solid-state batteries with twice the capacity and faster recharging will be on the market by 2025.