
Batteries power much of our modern lives, from phones to laptops to electric vehicles. Secondary batteries, also known as rechargeable batteries, allow us to use and reuse the same battery multiple times by recharging it through an external power source. In this article, we will explore the working, types, applications and future scope of secondary batteries.
Types of Secondary Batteries
Secondary batteries come in different types based on their chemistry. Some of the most common types are:
Lead-Acid Batteries
The lead-acid battery is one of the earliest rechargeable batteries invented in 1859. It uses lead for the negative electrode and lead dioxide for the positive electrode with sulfuric acid as the electrolyte. Lead-acid batteries are commonly used to start engines in vehicles due to their high current delivery ability. These batteries also find applications as backup power sources. However, they have low energy densities and require regular maintenance.
Nickel-Cadmium (NiCad) Batteries
Developed in 1899, NiCad batteries use nickel oxide hydroxide and metallic cadmium for positive and negative electrodes respectively with an alkaline electrolyte. They have high energy densities, long life cycles and can deliver high currents. However, their use has reduced due to environmental concerns over toxic heavy metals like cadmium.
Nickel-Metal Hydride (NiMH) Batteries
NiMH batteries were commercialized as an alternative to NiCad batteries in 1989. They use nickel hydroxide for the positive electrode and an alloy of metallic hydrogen absorbing for the negative electrode with potassium hydroxide as electrolyte. NiMH batteries have higher energy densities than NiCad but lower than lithium-ion batteries. They are commonly used in hybrid electric vehicles, mobile phones and cameras due to their design simplicity.
Lithium-ion Batteries
Lithium-ion batteries are currently the most widely used Secondary Battery technology. First commercialized in 1991, they use a lithium-ion intercalated into carbon as the negative electrode and lithium-ion intercalated into a metal oxide or polymer as the positive electrode with a non-aqueous liquid electrolyte. Li-ion batteries have very high energy densities, no memory effect and low self-discharge. This has made them ideal for consumer electronics and electric vehicles. Continuous research is trying to improve their capacities, lifecycles and reduce costs.
Applications of Secondary Batteries
The versatility of secondary batteries has enabled their diverse applications across various industries:
Consumer Electronics
Rechargeable batteries have revolutionized consumer electronics with their ability to power devices portably. Almost all portable electronics today like smartphones, laptops, earphones use lithium-ion battery technology. Their high energy densities conveniently power our digital lifestyles.
Electric Vehicles
Several electric vehicle manufacturers are developing Li-ion battery packs with capacities over 50kWh to power EVs. Plug-in hybrids also employ smaller lithium-ion batteries for their electric-only range. Lead-acid batteries continue powering start-stop functions in hybrids. Mass adoption of EVs depends on developing affordable high-capacity batteries.
Energy Storage Systems
Lithium-ion batteries are employed in large stationary storage applications to store electricity from renewable energy sources like solar and wind. This stabilizes energy grids by addressing intermittent power supply issues. Home energy storage is another emerging application.
Medical Devices
Rechargeable batteries find use in medical implants like pacemakers requiring long-lasting portable power sources. They are also used in portable medical equipment like defibrillators.
Satellites and Spacecrafts
Lithium-ion and silver-zinc secondary batteries power satellites and spacecrafts in space applications requiring reliable power management in extreme conditions.
Future Outlook and R&D Focus
With growing demand, battery technologies will likely evolve to achieve higher energy densities, improved safety, longer lifetimes and reduced costs. Some key areas of ongoing R&D include:
- Solid-state lithium batteries for higher energy densities and safety.
- Lithium-sulfur and lithium-air batteries with theoretical capacities over 10x of Li-ion.
- Sodium-ion batteries as a lower-cost alternative to lithium-ion.
- All-solid-state polymer electrolytes for improved safety.
- Novel anode and cathode materials for higher capacities.
- Advanced characterization techniques for material and interface engineering.
- Modular designs and intelligence systems for applications like EVs.
Secondary batteries have transformed portable power through their ability to store and deliver electricity repeatedly. Continuous innovations aim to improve their performance for applications ranging from consumer electronics to electric transportation and stationary storage. As battery technologies progress, they will play an even greater role in powering our sustainable energy future.
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