Why batteries come in so many sizes and shapes

🌈 Abstract

The article discusses the history, development, and various types of batteries, including lead-acid, alkaline, and lithium-ion batteries, and the factors that shape their design and manufacturing.

🙋 Q&A

[01] The History and Development of Batteries

1. What were some of the early demonstrations and inventions of batteries?

• The first batteries were made in the 1800s and were quite simple, such as a series of metal discs soaked in brine, which Italian scientist Alessandro Volta found created an electric current.
• The first lead-acid battery was made of a few pieces of lead in a jar of sulfuric acid, and the modern versions are not that different, just easier to manufacture and containing various additives to improve performance.

2. How do batteries work in general?

• Batteries perform in the same manner: a voltage difference between two dissimilar electrodes produces an electric current, which can be discharged to power a device. Rechargeable batteries can then reverse this current to charge back up.
• Inside the battery, the electric current is accompanied by the flow of ions through a liquid, the electrolyte, and the passage of each electron in the current is accompanied by the transport of one ion through the electrolyte.

[02] Lead-Acid Batteries

1. What are the key characteristics of lead-acid batteries?

• Lead-acid batteries were the first rechargeable battery, invented in 1859 by Gaston Plante, and they need to be large enough to provide enough charge to start a car.
• They also need to be usable in cold climates and last many years, and since the electrolyte is a corrosive acid, the external casing has to be tough to protect people and car parts.

[03] Alkaline Batteries

1. How do alkaline batteries differ from lead-acid batteries?

• Household devices like calculators and digital scales can afford to use smaller batteries because they don't require a lot of charge, and these are primarily non-rechargeable alkaline batteries that have been used for decades.
• The standardized cell sizes are AAAA, AAA, AA, C and D, as well as button and coin cells, and the sizes are related to how much charge they store, with the bigger batteries holding more charge.

[04] Lithium-Ion Batteries

1. What were the advantages of lithium-ion batteries over previous rechargeable battery technologies?

• Nickel-cadmium batteries were the first widely used rechargeable batteries for household electronics but had issues with toxicity and "memory effect".
• Lithium-ion batteries, first commercialized by Sony in 1991, store more energy and last longer than nickel-cadmium batteries, making them popular for portable electronics like laptops and cellphones.

2. Why were cylindrical lithium-ion cells chosen for early production?

• Sony chose to make cylindrical cells because these were the easiest to manufacture, as they could repurpose their existing roll-to-roll manufacturing equipment for producing rolls of battery electrodes.

[05] Factors Shaping Battery Design

1. What factors influence the shapes and sizes of batteries?

• Batteries are made in certain sizes and shapes for reasons of cost and manufacturability, as well as due to legacy manufacturing processes.
• Market demand also plays a role, as seen with the adoption of cylindrical lithium-ion cells in electric vehicles by Tesla, which were already being mass-produced for portable electronics.
• The future of battery shapes and sizes will depend on a mix of innovation and history, considering factors like energy density, manufacturing costs, and intended use.