BU-002: Introduction

BU-002: Introducción (Español)

The word “battery” comes from the Old French word baterie, meaning “action of beating,” relating to a group of cannons in battle. In the endeavor to find an energy storage device, scientists in the 1700s adopted the term “battery” to represent multiple electrochemical cells connected together.

The battery consists of two electrodes that are isolated by a separator and soaked in electrolyte to promote the movement of ions. New active materials are being tried, each offering unique attributes but none delivering an ultimate solution.

Improvements have been slow. Whereas Moore’s Law* doubled the number of transistors in an integrated circuit every two years, capacity gain of lithium-ion (Li-ion) has been about 8 percent per year in the decades following its introduction in 1991. Figure 1 compares the energy storage capability of a battery over time compared to innovations in computing technologies.

*In 1965, Gordon Moore said that the number of transistors in an integrated circuit would double every two years. The prediction became true and is being carried into the 21st century. Applied to a battery, Moore’s Law would shrink a starter battery in a car to the size of a coin.

The battery is a feeble vessel that is slow to fill, holds limited energy, runs for a time like a wind-up toy, fades and eventually becomes a nuisance. It exhibits human qualities in that it needs recuperation from the daily travails by applying a long and restful charge. It then delivers for a time and quits on its own terms. Some batteries need as much charging time as they deliver, and there is a resemblance to growing teenagers. (I raised five.)

The lithium-ion family receives the most attention and is gradually replacing the nickel-based predecessors that dominated the battery world until the 1990s. Lead acid with its many warts and blemishes holds a solid position for starter and standby batteries. No other system can meet its price and robustness for now.

Li-ion is expensive but when calculating the price-per-cycle, it wins over lead acid when repeat cycling is required. Basing calculations on cost per kilowatt hour (kWh) no longer holds; operational costs must be considered. A battery expert said that the switch from lead acid to Li-ion will be faster than the advancement of the Internet.

We want to learn as much about batteries as possible, but this book addresses only the most commonly used battery systems. My background is in electrical, and I tackle batteries from the electrical side rather than studying chemical reactions. I avoid formulas, and I back my material with practical and hands-on field data.

Reference

[1] Source: Amprius