14.2 Battery technologies for harvested energy storage
3 min read•august 9, 2024
Energy storage is crucial for piezoelectric harvesting systems. Batteries play a key role, with different types offering unique advantages. Lithium-ion dominates due to , while NiMH and lead-acid serve specific needs.
Battery performance is measured by , efficiency, and longevity. These factors vary among battery types and are influenced by environmental conditions. Understanding these characteristics is essential for choosing the right battery for energy harvesting applications.
Battery Types
Lithium-Ion and Nickel-Metal Hydride Batteries
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- Lithium-ion batteries dominate portable electronics and electric vehicles due to high energy density and long
- Lithium-ion batteries use lithium ions moving between electrodes to store and release energy
- Lithium-ion batteries offer from 3.6V to 3.7V per cell
- Nickel-metal hydride (NiMH) batteries serve as an alternative to lithium-ion in some applications
- NiMH batteries use a hydrogen-absorbing alloy as the negative electrode and nickel oxyhydroxide as the positive electrode
- NiMH batteries provide a nominal voltage of 1.2V per cell
- NiMH batteries offer lower energy density than lithium-ion but are more cost-effective for certain uses (power tools, hybrid vehicles)
Lead-Acid and Advanced Battery Technologies
- Lead-acid batteries remain widely used for automotive starting, lighting, and ignition systems
- Lead-acid batteries consist of lead dioxide cathode, spongy lead anode, and sulfuric acid
- Lead-acid batteries provide a nominal voltage of 2V per cell
- represent an emerging technology for miniaturized energy storage
- Thin-film batteries use solid electrolytes and thin layers of electrode materials, allowing for flexible and compact designs
- employ solid electrolytes instead of liquid or gel, enhancing safety and energy density
- Solid-state batteries aim to overcome limitations of conventional lithium-ion batteries, such as flammability risks and limited energy density
Battery Performance Characteristics
Energy Density and Efficiency Metrics
- Energy density measures the amount of energy stored per unit volume or mass
- Energy density expressed in watt-hours per kilogram (Wh/kg) for gravimetric density or watt-hours per liter (Wh/L) for volumetric density
- Lithium-ion batteries typically achieve 100-265 Wh/kg, while lead-acid batteries reach 30-50 Wh/kg
- indicates the ratio of energy output to energy input during a complete cycle
- Lithium-ion batteries boast high charge-discharge efficiencies of 95-98%
- NiMH batteries exhibit lower efficiencies around 66-70% due to internal resistance and heat generation
Longevity and Environmental Factors
- Cycle life refers to the number of complete charge-discharge cycles a battery can undergo before capacity falls below a specified percentage of its original capacity
- Lithium-ion batteries can achieve 500-1000 cycles, while lead-acid batteries typically last 200-300 cycles
- measures the gradual loss of stored charge when a battery is not in use
- Lithium-ion batteries have of 2-3% per month
- Lead-acid batteries exhibit higher self-discharge rates of 5-20% per month
- Temperature effects significantly impact battery performance and longevity
- High temperatures accelerate chemical reactions, potentially increasing capacity but reducing overall lifespan
- Low temperatures decrease battery capacity and power output due to increased internal resistance
- Optimal operating temperature range for most batteries falls between 20°C and 25°C (68°F to 77°F)
Key Terms to Review (19)
Anode materials: Anode materials are the substances used to construct the anode, which is the electrode where oxidation occurs in electrochemical cells, such as batteries. These materials play a crucial role in determining the efficiency, capacity, and overall performance of energy storage systems by facilitating electron flow during discharge. The choice of anode material can significantly impact the energy density and longevity of the battery, making it a critical aspect of battery technology for harvested energy storage.
Charge-Discharge Efficiency: Charge-discharge efficiency refers to the ratio of the amount of energy that can be retrieved from a battery during discharge to the amount of energy that was initially stored during charging. This efficiency is crucial for understanding how well a battery converts and retains energy, impacting its effectiveness in harvested energy storage systems.
Cycle Life: Cycle life refers to the number of charge and discharge cycles a battery can undergo before its capacity significantly degrades. This term is crucial when evaluating energy storage solutions, as it directly impacts how long a device can effectively operate on harvested energy, influencing both performance and maintenance costs.
Electrolyte: An electrolyte is a substance that produces ions when dissolved in a solvent, typically water, allowing it to conduct electricity. In the context of energy storage, especially in batteries, electrolytes play a critical role by facilitating the movement of ions between the anode and cathode during charge and discharge cycles. This ion transfer is essential for the conversion of chemical energy into electrical energy, making electrolytes a key component in enhancing the efficiency of harvested energy storage systems.
Energy Conversion Efficiency: Energy conversion efficiency is a measure of how effectively a system converts input energy into usable output energy. In the context of energy harvesting, this efficiency is crucial as it determines how much of the ambient energy can be captured and converted into electrical energy for practical applications.
Energy Density: Energy density refers to the amount of energy stored in a given system or region of space per unit volume or mass. It plays a crucial role in evaluating the efficiency of energy harvesting systems, as it directly impacts how much energy can be captured and utilized from various sources, influencing applications from sensors to larger-scale devices.
High energy density: High energy density refers to the amount of energy stored in a given volume or mass of a material, making it crucial for efficient energy storage solutions. This concept is significant for applications like batteries and hybrid storage systems, as higher energy density translates to longer operational times and reduced weight, which is particularly beneficial in portable electronics and electric vehicles. Additionally, materials with high energy density can improve the overall efficiency of energy harvesting technologies by allowing for more compact energy storage solutions.
Lead-acid battery: A lead-acid battery is a type of rechargeable battery that uses lead dioxide and sponge lead as its electrodes, with sulfuric acid as the electrolyte. This technology is widely used for energy storage due to its relatively low cost, high reliability, and ability to deliver high surge currents. Lead-acid batteries are essential for various applications, including electric vehicles and renewable energy systems, where energy harvested from sources like solar or wind needs to be stored efficiently.
Lithium-ion battery: A lithium-ion battery is a type of rechargeable battery that uses lithium ions as a key component of its electrochemistry, enabling it to store and release energy efficiently. This technology has become prevalent due to its high energy density, lightweight design, and ability to undergo numerous charge and discharge cycles. Its importance is highlighted in energy harvesting systems, where it provides a reliable storage solution for the energy captured from various sources, and in hybrid systems, where it complements other forms of energy storage for enhanced performance.
Low self-discharge rates: Low self-discharge rates refer to the ability of a battery to retain its charge over time when not in use. This characteristic is crucial for energy storage solutions, especially in devices that rely on harvested energy, as it ensures that the stored energy remains available for longer periods, enhancing efficiency and reliability.
Nickel-metal hydride battery: A nickel-metal hydride (NiMH) battery is a type of rechargeable battery that uses nickel oxide hydroxide and a hydrogen-absorbing alloy as electrodes. It is known for its higher capacity compared to nickel-cadmium batteries and is often used in various applications, including energy storage for harvested energy systems. NiMH batteries are particularly valued for their environmental friendliness and reduced toxicity compared to older battery technologies.
Power Management Systems: Power management systems are essential components designed to efficiently control and distribute electrical power within various devices, ensuring optimal energy use and storage. These systems play a critical role in maximizing the performance of energy harvesting technologies by managing the flow of harvested energy, regulating battery charging, and maintaining system stability during operation. This is particularly important for applications that rely on harvested energy sources, such as those generated from piezoelectric materials and other renewable energy technologies.
Recyclability: Recyclability refers to the ability of a material or product to be processed and transformed into new materials or products after its initial use, thereby minimizing waste and conserving resources. This concept is particularly significant in the context of energy storage technologies, where sustainable practices can greatly influence the lifecycle management of batteries used for harvested energy, ensuring that valuable materials are recovered and reused rather than discarded.
Self-discharge rate: The self-discharge rate refers to the phenomenon where a battery loses its stored energy over time, even when not in use. This characteristic is crucial for energy harvesting applications, as it directly impacts the efficiency and longevity of the energy storage solutions employed. Understanding self-discharge helps in selecting the right battery technology to maximize energy retention for harvested sources.
Solid-State Batteries: Solid-state batteries are a type of energy storage device that use solid electrolytes instead of liquid or gel electrolytes found in traditional batteries. These batteries offer numerous advantages, such as improved safety, higher energy density, and longer cycle life, making them a promising technology for energy storage, particularly in applications like harvested energy systems.
Sustainability: Sustainability refers to the ability to meet present needs without compromising the ability of future generations to meet their own needs. It encompasses environmental, economic, and social dimensions, aiming for a balance that ensures resources are used efficiently and responsibly. In energy harvesting, sustainability is crucial as it shapes the development and implementation of technologies that minimize environmental impact while maximizing energy efficiency and reliability.
Thermal management: Thermal management refers to the process of controlling the temperature of a system to ensure optimal performance and reliability. It plays a crucial role in energy harvesting systems, as temperature fluctuations can impact voltage regulation, energy storage efficiency, and overall system stability. Proper thermal management strategies help prevent overheating and ensure that devices operate within safe limits, ultimately improving their efficiency and lifespan.
Thin-film batteries: Thin-film batteries are a type of battery technology that utilizes thin layers of active materials to store and release electrical energy. These batteries are known for their compact size, lightweight nature, and flexibility, making them suitable for integration into various applications, especially in energy harvesting systems where space and weight constraints are critical.
Voltage Ranges: Voltage ranges refer to the specific limits of voltage levels that electrical devices, including batteries and energy harvesting systems, can safely operate within. Understanding these ranges is crucial for ensuring that the harvested energy is effectively stored and utilized without damaging the components involved in the process.