Difference Between Lead Acid Battery and Alkaline Battery

The key difference between lead acid battery and alkaline battery is that lead acid batteries are rechargeable while alkaline batteries are mostly non-rechargeable.

A battery is a device that has one or more electrochemical cells. It has external connections we can connect to power devices such as smartphones, flashlights, etc. Moreover, it has a positive terminal/cathode and a negative terminal anode. Lead acid battery and alkaline battery are two such batteries that can provide these devices with the required electricity.

CONTENTS

1. Overview and Key Difference
2. What is Lead Acid Battery
3. What is Alkaline Battery
4. Side by Side Comparison – Lead Acid Battery vs Alkaline Battery in Tabular Form
5. Summary

What is Lead Acid Battery?

The lead acid battery is one of the earliest rechargeable batteries and is still in use widely. It has very low energy to weight ratio. Moreover, it has low energy to volume ratio. Also, this battery is able to supply high surge current; thus, it has a large power to weight ratio. These batteries are low-cost devices.

In the fully charged state of the battery, its negative plate is lead, and the positive plate is lead oxide. Here, we use concentrated sulfuric acid as the electrolyte. The electrolyte stores most of the chemical energy. However, when charging, overcharging will cause the generation of oxygen and hydrogen gases due to the electrolysis of water. It is a loss to the cell.

During the discharging of the battery, hydrogen ions form at the negative plate, and these ions move to an electrolyte solution and are consumed at the positive plate. HSO₄^– ion consumption occurs at both plates. During the charging process, the reverse of these reactions occur.

In the discharged state of the battery, both positive and negative plates become lead(II) sulfate. The electrolyte loses most of its dissolved sulfuric acid and becomes water. A diagram showing the fully discharged state of the lead acid battery is as follows:

What is Alkaline Battery?

The alkaline battery is a type of primary battery, and its energy is generated via the reaction between zinc metal and manganese oxide. The name alkaline battery originates from its alkaline electrolyte: potassium hydroxide. Some of these batteries are rechargeable, but the attempt to recharge the battery will often rupture it.

In this battery, the negative electrode is zinc metal, and the positive electrode is manganese oxide (MnO₂). However, the alkaline electrolyte does not take part in the reaction. It remains unchanged because equal amounts of hydroxide ions are consumed and formed during the discharging. Here, the chemical energy is stored in the zinc metal.

What is the Difference Between Lead Acid Battery and Alkaline Battery?

The lead acid battery is one of the earliest rechargeable batteries still in use widely. Meanwhile, the alkaline battery is a type of primary battery, and its energy is generated via the reaction between zinc metal and manganese oxide. The key difference between lead acid battery and alkaline battery is that lead acid batteries are rechargeable while alkaline batteries are mostly non-rechargeable.

Moreover, most of the chemical energy of the battery is stored in the electrolyte in the lead acid battery, but in alkaline batteries, the energy is stored in the zinc metal. A further difference between lead acid battery and alkaline battery is that the lead acid battery consumes the electrolyte during discharging, but the alkaline battery does not.

Summary – Lead Acid Battery vs Alkaline Battery

The lead acid battery is one of the earliest rechargeable batteries still in use widely. But, the alkaline battery is a type of primary battery, and its energy generates via the reaction between zinc metal and manganese oxide. The key difference between lead acid battery and alkaline battery is that lead acid batteries are rechargeable while alkaline batteries are mostly non-rechargeable.

Reference:

1. “Lead-Acid Battery.” Lead-Acid Batteries, Available here.

Image Courtesy:

1. “Photo-CarBattery” By Shaddack assumed (based on copyright claims). – No machine-readable source provided. Own work assumed (based on copyright claims) (Public Domain) via Commons Wikimedia
2. “Discharged” (CC BY 3.0) via Commons Wikimedia
3. “LeakedBattery 2701a” By © Túrelio (via Wikimedia-Commons), 2009 (CC BY-SA 3.0 de) via Commons Wikimedia