Applications of Chemistry in Battery

A chemical cell, or a battery, is a device that converts chemical energy into electrical energy through electrochemical reactions. Some of the examples of these batteries are alkaline batteries, lithium ion batteries, lead acid batteries, etc. The functioning of these batteries are based on various chemical reactions. In this article, we will discuss the application of chemistry in batteries, i.e., how chemistry is involved in the functioning of these batteries.

What is Battery?

A battery is an electrochemical device that stores and releases energy through chemical reactions. It typically consists of electrodes, an electrolyte, and a separator, facilitating the flow of electrons. Chemical cells or batteries, are essential power sources for countless applications, providing portable and reliable electrical energy for devices ranging from cell phones and laptops to electric vehicles and grid-scale energy storage systems. Common types of batteries that we see around us are lithium-ion batteries, lead-acid batteries, nickel cadmium batteries, etc.

Properties of Battery

Batteries come in various shapes, sizes, and chemistries, each with its own set of properties tailored to specific applications. Some key properties of batteries include:

• Higher energy density means more power in less space or weight, crucial for portable electronics and EVs.
• Voltage indicates the potential difference between a battery’s terminals, crucial for device compatibility.
• The number of charge-discharge cycles a battery can endure before capacity drops significantly.
• Ensuring batteries are safe from malfunction or failure, crucial for human health and environmental protection.
• The financial factor determining battery viability, influenced by manufacturing, scale, and technology advancements.

Chemistry in Battery

All the examples of batteries that we learnt above are electrochemical in nature. This means they use chemical reactions to generate electricity. The chemistry in a battery revolves around electrochemical reactions that convert chemical energy into electrical energy. Batteries consist of one or more electrochemical cells, each containing two electrodes (anode and cathode) immersed in an electrolyte solution or separated by an electrolyte-soaked medium. When a battery is connected to an external circuit, chemical reactions occur at the electrodes, generating an electric current that can power devices.

Let’s first understand chemistry of electrochemical cell.

Electrochemical Cell

An electrochemical cell is a device that converts chemical energy into electrical energy through spontaneous redox reactions. It consists of two half-cells connected by a conductive bridge.

Example: Daniel Cell (Zinc-Copper cell)

Cathode reaction: Cu²⁺(aq) + 2e⁻ → Cu(s)

Anode reaction: Zn(s) → Zn²⁺(aq) + 2e⁻

Some of other examples of electrochemical cell are dry cell and galvanic cell.

Dry cell

A dry cell is a common type of electrochemical cell used in batteries. It contains a paste electrolyte and is typically used in household applications.

Example: Leclanché Cell

Cathode reaction: 2MnO₂(s) + 2NH₄Cl(aq) + 2Zn(s) → Mn₂O₃(s) + 2NH⁴⁺(aq) + 2Zn²⁺(aq) + H₂O(l)

Anode reaction: Zn(s) → Zn²⁺(aq) + 2e⁻

Galvanic cell

A galvanic cell is a type of electrochemical cell that generates electrical energy from spontaneous redox reactions. It consists of two different metal electrodes connected by a salt bridge or porous membrane.

Example: Voltaic Pile

Cathode reaction: Cu²⁺(aq) + 2e⁻ → Cu(s)

Anode reaction: Zn(s) → Zn²⁺(aq) + 2e⁻

Now, let’s understand chemistry behind various batteries that we see around ourselves

Lithium Ion Batteries

In lithium-ion batteries, the chemical reactions occur between the lithium ions (Li⁺) and the electrode materials during charging and discharging cycles. The battery typically consists of a lithium-containing compound as the anode material, a lithium-containing compound as the cathode material, and an electrolyte solution that allows the movement of lithium ions between the electrodes.

The chemical reaction at the anode during charging can be represented as follows:

Anode (Discharging): LiC₆→Li⁺+ C₆+ e⁻

At the same time, during charging, lithium ions move from the electrolyte to the cathode material, which typically consists of lithium metal oxides such as lithium cobalt oxide (LiCoO₂), lithium iron phosphate (LiFePO₄), or lithium manganese oxide (LiMn₂O₄).

The chemical reaction at the cathode during charging can be represented as follows:

Cathode (Charging): LiCoO₂ + Li⁺+ e⁻→LiCoO₂

The chemical reactions in lithium-ion batteries involve the reversible intercalation of lithium ions into the crystal lattice of electrode materials during charging and discharging cycles, enabling the storage and release of electrical energy.

Alkaline Batteries

In alkaline batteries, the chemical reactions occur between the anode (zinc) and the cathode (manganese dioxide) materials, as well as the electrolyte (potassium hydroxide) solution. These reactions generate electrical energy that powers the battery.

Anode Reaction (Oxidation)

At the anode (negative terminal), zinc undergoes oxidation to form zinc oxide and release electrons:

Anode (Oxidation): Zn → Zn²⁺+ 2e⁻

Cathode Reaction (Reduction)

At the cathode (positive terminal), manganese dioxide undergoes reduction by accepting electrons from the external circuit:

Cathode (Reduction): 2 MnO₂ ​+ 2e− + H₂​O → Mn₂​O₃ + 2OH⁻

Overall, the chemical reactions in alkaline batteries involve the reversible conversion of zinc and manganese dioxide between different oxidation states, facilitated by the potassium hydroxide electrolyte. These reactions generate electrical energy that can be used to power various devices.

Lead Acid Batteries

In lead-acid batteries, the chemical reactions occur between lead dioxide (PbO₂) at the positive electrode (cathode), lead (Pb) at the negative electrode (anode), and sulfuric acid (H₂SO₄) electrolyte. These reactions produce electrical energy that powers the battery.

Positive Electrode (Cathode) Reaction:

At the positive electrode (cathode), lead dioxide undergoes reduction and reacts with sulfate ions (SO₄^2-) from the electrolyte to form lead sulfate (PbSO₄) and water.

Cathode (Reduction): PbO₂ + 4H⁺ + SO₄²⁻+ 2e⁻→PbSO₄ + 2H₂O

This reaction results in the conversion of lead dioxide to lead sulfate and the production of water.

Negative Electrode (Anode) Reaction:

At the negative electrode (anode), lead metal reacts with sulfate ions (SO₄^2-) from the electrolyte to form lead sulfate (PbSO₄) and release electrons.

Anode (Oxidation): Pb+SO₄²⁻→PbSO₄ + 2e⁻

This reaction results in the conversion of lead metal to lead sulfate and the release of electrons.

Real Life Applications of Battery

Batteries are important in modern society, powering a wide range of devices that enhance our daily lives. Here are just a few examples of their real-life applications:

Portable Electronics: Perhaps the most familiar application of batteries is in portable electronics such as smartphones, laptops, tablets, and digital cameras. Lithium-ion batteries, known for their high energy density and rechargeability, are commonly used in these devices, providing long-lasting power in a compact form.

Electric Vehicles (EVs): The automotive industry has seen a significant shift towards electric vehicles powered by batteries. Lithium-ion batteries dominate the market due to their high energy density and ability to deliver the power required for electric propulsion.

Energy Storage: Batteries play a crucial role in storing renewable energy from sources such as solar and wind power. They help balance supply and demand, providing a reliable source of electricity when renewable sources are unavailable, and storing excess energy for times of high demand.

Medical Devices: Batteries power a variety of medical devices, from pacemakers to insulin pumps and hearing aids. Reliability and longevity are critical in these applications, where the continuous operation of life-saving devices is essential.

Military and Aerospace: Batteries are vital components in military and aerospace applications, powering communication systems, navigation equipment, unmanned aerial vehicles (UAVs), and satellites.

FAQs on Application of Chemistry in Battery

Are all batteries rechargeable?

No, not all batteries are rechargeable. While lithium-ion and nickel-metal hydride batteries can be recharged multiple times, alkaline and zinc-carbon batteries are designed for single use.

How long do batteries typically last?

The lifespan depends on factors like chemistry and usage. Rechargeable batteries degrade over cycles, while primary batteries have fixed lifespans.

Can batteries be recycled?

Yes, many types can be recycled to recover valuable materials like lithium, cobalt, and nickel, reducing environmental impact.

What are the environmental impacts of battery production and disposal?

Production and disposal impact the environment through resource extraction and waste. Although they pose risks, but recycling and sustainable alternatives help mitigate these concerns.

What is the future of battery technology?

Research focuses on improving energy density, cycle life, safety, and sustainability. Emerging technologies like solid-state and lithium-sulfur batteries show promise, driving towards a cleaner future.