Glossary

3.2 Nickel-cadmium battery technology and characteristics

3 min read•august 7, 2024

Nickel-cadmium batteries pack a punch with their rapid charging and low-temp performance. They use and cadmium electrodes with a . These tough batteries can handle over 1000 cycles, making them great for industrial and aerospace uses.

But there's a catch – the can zap capacity if not fully discharged regularly. Plus, cadmium is toxic, leading to environmental concerns. This has pushed the development of safer alternatives like nickel-metal hydride batteries.

Electrodes and Electrolyte

Nickel Hydroxide Positive Electrode

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  • Composed of nickel hydroxide (Ni(OH)2) active material
  • During charging, nickel hydroxide is oxidized to nickel oxyhydroxide (NiOOH)
  • Nickel electrode provides high and good cycling stability
  • Nickel foam or nickel-plated steel used as current collector to support active material

Cadmium Negative Electrode

  • Consists of metallic cadmium (Cd) as active material
  • During discharging, cadmium is oxidized to (Cd(OH)2)
  • Cadmium electrode has high hydrogen overpotential, preventing hydrogen evolution during charging
  • Cadmium is toxic and environmentally hazardous, leading to the development of alternative negative electrodes (nickel-metal hydride)

Potassium Hydroxide Electrolyte

  • Aqueous solution of potassium hydroxide (KOH) serves as the electrolyte
  • Typical KOH concentrations range from 20% to 30% by weight
  • Potassium hydroxide is highly conductive and allows efficient ion transport between electrodes
  • Electrolyte concentration affects cell performance, with higher concentrations improving low-temperature operation but reducing

Performance Characteristics

Memory Effect and Capacity Loss

  • Nickel-cadmium batteries can develop a "memory effect" when repeatedly charged after partial discharge
  • Memory effect occurs due to the formation of large cadmium hydroxide crystals, reducing active surface area
  • Capacity loss can be temporary or permanent, depending on the severity of the memory effect
  • Periodic full discharge cycles (deep discharge) can help mitigate the memory effect and restore capacity

Rapid Charging Capability

  • Nickel-cadmium batteries can be charged rapidly, typically in 1 to 2 hours
  • Fast charging is possible due to the high current acceptance of the nickel and cadmium electrodes
  • Rapid charging requires specialized chargers with temperature monitoring to prevent overheating
  • Proper charge termination methods (delta-V or temperature cut-off) are crucial to avoid overcharging

Low Temperature Performance

  • Nickel-cadmium batteries maintain good performance at low temperatures compared to other chemistries
  • Capable of delivering high currents at temperatures as low as -20°C to -40°C
  • Low-temperature performance is attributed to the high conductivity of the potassium hydroxide electrolyte
  • Cold temperatures reduce battery capacity and increase internal resistance, but performance remains acceptable for many applications (aviation, aerospace)

Cycle Life and Durability

  • Nickel-cadmium batteries offer long cycle life, often exceeding 1000 charge-discharge cycles
  • Robust and durable construction withstands mechanical stress and vibration
  • Cycle life depends on factors such as depth of discharge, charging protocol, and operating temperature
  • Proper maintenance, including regular full discharge cycles and storage at moderate temperatures, can extend battery life

Cell Types and Environmental Impact

Vented Nickel-Cadmium Cells

  • Vented cells have a pressure relief valve to allow the escape of gases during overcharge or high-rate discharge
  • Venting prevents cell rupture and maintains safety in case of gas buildup
  • Vented cells require periodic water addition to replenish electrolyte lost through gassing
  • Commonly used in industrial and aerospace applications where reliability and performance are critical

Sealed Nickel-Cadmium Cells

  • Sealed cells are designed to recombine gases internally, eliminating the need for venting
  • Oxygen generated at the positive electrode diffuses to the negative electrode and reacts with cadmium
  • Sealed cells are maintenance-free and can be operated in any orientation
  • Widely used in portable electronics, power tools, and emergency lighting due to their convenience and safety

Environmental Concerns and Regulations

  • Cadmium is a toxic heavy metal that poses environmental and health risks
  • Improper disposal of nickel-cadmium batteries can lead to soil and water contamination
  • Strict regulations govern the manufacture, use, and disposal of nickel-cadmium batteries
  • Battery programs aim to recover valuable materials and prevent environmental pollution
  • The use of nickel-cadmium batteries has declined due to environmental concerns and the development of alternative chemistries (nickel-metal hydride, lithium-ion)

Key Terms to Review (20)

Battery disposal guidelines: Battery disposal guidelines are regulations and best practices designed to ensure the safe and environmentally responsible disposal of batteries at the end of their life cycle. These guidelines address the potential hazards associated with battery waste, particularly for types like nickel-cadmium batteries, which can release toxic substances if not disposed of properly. By following these guidelines, individuals and organizations can minimize environmental impact and promote sustainability in energy storage technologies.
Cadmium hydroxide: Cadmium hydroxide is a chemical compound with the formula Cd(OH)₂, commonly used as an electrolyte in nickel-cadmium (NiCd) batteries. It plays a crucial role in the electrochemical reactions that occur within these batteries, allowing for the storage and release of electrical energy. The compound's properties, such as its solubility and stability, significantly influence the overall performance and longevity of NiCd batteries.
Charge efficiency: Charge efficiency is a measure of how effectively a battery can convert input electrical energy into stored energy during the charging process. In nickel-cadmium (NiCd) batteries, this efficiency is influenced by factors such as temperature, charging rate, and the state of charge. High charge efficiency means that more of the energy supplied during charging is actually stored, leading to better performance and longer battery life.
Cost efficiency: Cost efficiency refers to the ability to achieve desired results or outputs while minimizing expenses. In the context of energy storage technologies like nickel-cadmium batteries, it highlights the importance of balancing performance, lifespan, and maintenance costs against the overall economic viability of the technology. Understanding cost efficiency helps in making informed decisions about energy storage investments and their long-term sustainability.
Cycle life: Cycle life refers to the number of charge and discharge cycles a battery can undergo before its capacity falls to a specified percentage of its original capacity, often around 80%. It serves as a crucial performance indicator for assessing the longevity and efficiency of energy storage systems, influencing design choices and applications across various battery technologies.
Development Timeline: A development timeline is a chronological representation of the key milestones, advancements, and innovations in the evolution of a technology or product. It outlines how a specific technology, such as nickel-cadmium battery technology, has progressed over time, including important events like breakthroughs, market introductions, and regulatory changes that have influenced its adoption and performance.
Energy density: Energy density refers to the amount of energy stored per unit volume or mass of a substance. This key metric helps compare different energy storage systems, influencing their effectiveness in applications ranging from consumer electronics to large-scale energy management.
EPA regulations: EPA regulations refer to the rules and standards established by the Environmental Protection Agency to protect human health and the environment from harmful pollutants. These regulations set limits on emissions and waste, impacting various industries, including those related to battery technology, by ensuring they comply with environmental standards and promote sustainability.
Low temperature performance: Low temperature performance refers to the ability of a battery to function effectively at lower ambient temperatures, which can impact the overall efficiency, capacity, and longevity of the battery. In nickel-cadmium batteries, low temperature performance is crucial because these batteries can experience reduced capacity and slower discharge rates when exposed to cold environments. Understanding how nickel-cadmium batteries behave in such conditions is vital for their application in various industries, including aviation and emergency power systems.
Memory effect: Memory effect is a phenomenon observed in some rechargeable batteries, notably nickel-cadmium (NiCd) batteries, where the battery appears to 'remember' a lower capacity due to repeated partial discharges. This effect leads to a reduced effective capacity if the battery is not fully discharged before recharging, causing users to experience diminished runtime over time. This can significantly impact the performance and longevity of the battery, making it crucial to understand its implications in battery management and usage.
NiCd vs. Li-Ion: NiCd (Nickel-Cadmium) and Li-Ion (Lithium-Ion) are two distinct types of rechargeable battery technologies with varying characteristics, applications, and performance attributes. While NiCd batteries have been used for decades in various devices due to their robust performance, they face environmental concerns due to cadmium toxicity. On the other hand, Li-Ion batteries have surged in popularity due to their higher energy density, lighter weight, and longer cycle life, making them suitable for modern electronics and electric vehicles.
Nickel hydroxide: Nickel hydroxide is a chemical compound composed of nickel, oxygen, and hydrogen, represented by the formula Ni(OH)₂. It plays a critical role as the positive electrode material in nickel-cadmium (NiCd) batteries, significantly influencing their performance and energy storage capabilities. Nickel hydroxide's electrochemical properties allow it to undergo oxidation and reduction reactions during battery operation, directly impacting the battery's efficiency, charge capacity, and cycle life.
Nickel-cadmium battery: A nickel-cadmium (NiCd) battery is a type of rechargeable battery that uses nickel oxide hydroxide and cadmium as its active materials. This technology is known for its reliability, long cycle life, and ability to deliver high discharge rates, making it suitable for various applications, especially in power tools and emergency lighting. NiCd batteries have unique characteristics such as memory effect and environmental concerns due to cadmium's toxicity.
Performance Improvements: Performance improvements refer to the enhancements in the efficiency, capacity, and overall effectiveness of a battery system, specifically focusing on how well it can store and deliver energy. In the context of nickel-cadmium batteries, performance improvements can be achieved through various means, such as optimizing the electrode materials, refining manufacturing processes, and implementing advanced charging techniques, all of which contribute to better energy density and cycle life.
Potassium hydroxide electrolyte: Potassium hydroxide electrolyte is a highly alkaline solution used in various electrochemical applications, including nickel-cadmium batteries. This electrolyte enables efficient ionic conduction within the battery, facilitating the flow of charge during discharge and charging processes. Its presence enhances the overall performance and longevity of the nickel-cadmium battery by providing an optimal environment for chemical reactions.
Rapid charging capability: Rapid charging capability refers to the ability of a battery to be charged at a significantly higher rate than standard charging methods, allowing for reduced downtime and increased convenience. In the context of nickel-cadmium battery technology, this feature enables faster recharge cycles, which is particularly beneficial for applications requiring frequent use, such as power tools and emergency backup systems.
Recycling: Recycling is the process of collecting, processing, and converting waste materials into new products to reduce consumption of fresh raw materials and minimize waste. This concept is particularly crucial in energy storage technologies as it helps address environmental concerns and resource scarcity associated with battery production and disposal.
Sealed nickel-cadmium cells: Sealed nickel-cadmium cells are rechargeable batteries that use nickel oxide hydroxide and cadmium as their active materials, enclosed in a sealed casing to prevent electrolyte leakage and contamination. This design enhances safety and allows the cells to operate in a variety of orientations, making them suitable for portable devices. The sealed nature also improves performance in high-drain applications and reduces maintenance needs.
Toxic metals: Toxic metals are heavy metals that can cause harm to human health and the environment when they accumulate in living organisms or ecosystems. These metals, including lead, cadmium, and mercury, are often found in industrial applications and consumer products, and their presence in battery technology raises significant environmental and health concerns.
Vented nickel-cadmium cells: Vented nickel-cadmium cells are a type of rechargeable battery that allows gases, mainly hydrogen and oxygen, to escape during the charging process through vents. This design prevents the buildup of gas pressure inside the cell, which can lead to leakage or rupture, enhancing the safety and reliability of the battery. These cells are commonly used in applications where high discharge rates and temperature stability are critical, making them an important part of nickel-cadmium battery technology and its characteristics.
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