The Evolution of Battery Shapes and Sizes: A Historical Perspective
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Chapter 1: Understanding Battery Diversity
Have you recently checked your utility drawer? You might be surprised by the variety of battery shapes, sizes, and types powering your devices. From the small round button cells used in watches to the familiar AA and AAA batteries that fuel calculators, clocks, and remotes, each serves a distinct purpose. Additionally, rechargeable lithium-ion batteries are common in laptops and smartphones, while lead-acid batteries are vital for vehicles.
As an academic specializing in batteries and electrochemistry, I aim to clarify why batteries come in such a wide array of designs by examining their historical development.
The first batteries appeared in the 1800s and were relatively straightforward. One of the earliest demonstrations involved a series of metal discs soaked in brine, discovered by Italian scientist Alessandro Volta, which produced an electric current. The first lead-acid battery consisted of lead pieces submerged in sulfuric acid.
Modern batteries share fundamental principles with their predecessors but benefit from improved manufacturing processes and various additives that enhance their performance.
Batteries operate by creating a voltage difference between two different electrodes, which generates electric current to power devices. Rechargeable batteries can reverse this current for recharging. Within the battery, the electric flow is accompanied by ion movement through a liquid known as the electrolyte. Each electron's movement corresponds with an ion's transport, and electrodes that can store more ions lead to batteries with greater charge capacity, thus extending their usage time. Additionally, electrodes designed for quick ion storage yield batteries that discharge rapidly for high-power needs. Lastly, the ability to endure numerous charge-discharge cycles without degradation results in longer battery lifespans.
The first video titled "Why batteries come in so many shapes and sizes" delves into the historical and technical aspects of battery design.
Section 1.1: The Lead-Acid Battery
The lead-acid battery, invented in 1859 by Gaston Plante, was the first rechargeable battery. Plante's experiments with lead plates in acidic solutions revealed that electric current could be both generated and stored.
Lead-acid batteries must be sufficiently large to provide the charge necessary to start a vehicle. They also need to function well in cold environments and have a long lifespan. Given that the electrolyte is a corrosive acid, the external casing must be robust enough to protect users and vehicle components. Thus, it's no surprise that contemporary lead-acid batteries tend to be bulky and heavy.
Section 1.2: Alkaline Batteries
In contrast, smaller household devices like calculators and digital scales can utilize compact batteries, which typically do not require as much charge. These are mostly non-rechargeable alkaline batteries, standardized in sizes such as AAAA, AAA, AA, C, and D, along with various button and coin cells.
The sizes correlate with their charge capacity—the larger the battery, the more energy it can store—and the dimensions of the devices they power. Occasionally, you might encounter rectangular alkaline batteries, like the common 9-volt type; however, upon inspection, you'll find they consist of several cylindrical cells connected internally. Given their long-standing usage, the battery industry tends to favor cylindrical designs due to established manufacturing processes, avoiding the costs of retooling for new shapes.
The second video, titled "Batteries Come in All Shapes & Sizes, But Each One Sucks in Its Own Way (Part 1 of 3)," provides insight into the performance and efficiency of different battery types.
Chapter 2: The Rise of Lithium-Ion Batteries
Nickel-cadmium batteries were the first widely utilized rechargeable batteries for consumer electronics, popular until the late 20th century. However, they had drawbacks, such as the toxicity of cadmium and the "memory effect," which limited their lifespan.
For years, lithium was investigated for potential use in rechargeable batteries due to its lightweight and high energy storage capabilities. Sony introduced the lithium-ion battery to the market in 1991, opting for cylindrical cells for their ease of manufacture. In the 1990s, with a focus on camcorders and tape production, Sony effectively repurposed their roll-to-roll manufacturing equipment to create battery electrodes, forming them into "jelly roll" cylinders.
Cylindrical batteries are constructed from numerous thin layers rolled into a cylindrical shape. The robust casing of these cells provides mechanical strength and includes a pressure relief valve for added safety. Consequently, these early lithium-ion cells quickly dominated the portable electronics market, especially for laptops and cell phones, as they offered superior energy storage and longevity compared to nickel-cadmium batteries.
Factors Influencing Battery Design
Batteries are produced in specific shapes and sizes for various reasons, including cost efficiency and manufacturability. Additionally, legacy manufacturing techniques also play a significant role. Market demand is another critical factor.
For instance, electric vehicles gained traction when Tesla adopted cylindrical lithium-ion batteries instead of the rectangular pouch or prismatic cells used by other manufacturers. While pouch and prismatic cells can be densely packed, Tesla benefited from the existing mass production of cylindrical cells for portable electronics, enabling them to produce more affordable EVs in the 2010s.
The future of battery shapes and sizes will hinge not only on energy storage capacity but also on market dynamics—such as manufacturing ease, production costs, and specific applications. These considerations blend together innovation and historical context.
This article is sourced from The Conversation, a nonprofit organization dedicated to providing context for current events. For more insights, consider subscribing to their newsletter.
Wesley Chang receives funding from SolidEnergy Systems and the Electric Power Research Institute.