You use the Ragone plot for determining power deliver by the Ragone plot in battery storage systems, especially with lithium batteries. This approach lets you visualize the tradeoff between power and energy, helping you select the right battery for optimal storage and battery performance. Recent studies highlight how battery aging impacts both energy and power.
Part 1: Ragone Plot Basics
1.1 Axes and Scale
You use the Ragone plot to compare battery systems by plotting specific energy against specific power. The vertical axis shows the available energy per kilogram, measured in watt-hours per kilogram (Wh/kg). The horizontal axis displays the power per kilogram, measured in watts per kilogram (W/kg). Both axes use a logarithmic scale, which allows you to visualize a wide range of battery chemistries and storage materials. This approach helps you quickly identify the tradeoff between power and energy for different lithium battery systems. The Ragone framework also includes iso curves, which represent constant operating times and help you evaluate how long a battery can deliver a certain power output.
Aspect | Description | Units | Scale Type |
|---|---|---|---|
Vertical Axis | Energy per unit mass | Wh/kg | Logarithmic |
Horizontal Axis | Power per unit mass | W/kg | Logarithmic |
Iso Curves | Constant operating time | Hours | Straight lines |
1.2 Plot Interpretation
When you analyze a Ragone plot, you see each point as a snapshot of battery performance under specific conditions. Devices that appear toward the upper right corner deliver both high energy and high power, which is ideal for demanding applications. The Ragone framework highlights the nonlinear power-energy tradeoff, showing how increasing power output often reduces available energy. For lithium battery packs, this visualization helps you select the right chemistry for your application, whether you need long runtime or rapid discharge. Adjusting operational limits, such as reducing maximum cell power by 9%, shifts the position of the battery on the plot, making it easy to see how design changes affect performance.
1.3 Ragone Applications
You rely on Ragone plots to guide battery selection and system design across industries. Researchers and engineers use the Ragone framework to compare lithium, NMC, LCO, LMO, and LiFePO4 battery chemistries for medical, robotics, security, infrastructure, consumer electronics, and industrial applications. The plot supports material research, design optimization, and performance benchmarking. You can also apply the Ragone framework to thermal storage materials and thermal energy storage, expanding its value beyond electrochemical batteries. Recent studies even use Ragone plots for thermal energy storage to evaluate new materials and system configurations.
Part 2: Determining Power Delivery by the Ragone Plot
2.1 Power Delivery Analysis
When you analyze lithium battery packs for demanding applications, determining power deliver by the ragone plot becomes essential. The ragone plot allows you to visualize the relationship between specific energy and specific power for different battery chemistries and configurations. This framework helps you select the optimal battery for your storage system, ensuring you meet both energy and power requirements.
Practical Example: A123 APR18650M1 Lithium Iron Phosphate Cell
Consider the A123 APR18650M1 lithium iron phosphate (LiFePO4) cell. This battery delivers a continuous discharge current of 30A and can provide up to 40W of power for short bursts. On the ragone plot, this cell appears in the high-power region, outperforming many other lithium cells in terms of discharge power. For comparison, Sanyo UR18650F and Sanyo UR18650W cells offer higher energy but lower power. The table below summarizes key performance metrics for these lithium batteries:
Model | Chemistry | Capacity (mAh) | Max Discharge (A) | Specific Energy (Wh/kg) | Specific Power (W/kg) | Typical Application |
|---|---|---|---|---|---|---|
A123 APR18650M1 | LiFePO4 | 1100 | 30 | 100-180 | Up to 4000 | Power tools, EVs |
Sanyo UR18650F | NMC | 2600 | 5 | 160-270 | 500-1000 | Consumer electronics |
Sanyo UR18650W | LMO | 1500 | 20 | 120-170 | 2000-3000 | Robotics, industrial |
You see that the A123 cell excels in maximum discharge power, making it ideal for applications that require rapid energy delivery. The ragone plot visually separates these chemistries, helping you identify which battery best matches your storage and discharge power needs.
Step-by-Step: Identifying Power Delivery Capabilities
To determine power deliver by the ragone plot for lithium battery packs, follow these steps:
Gather Experimental Data
Collect specific energy (Wh/kg) and specific power (W/kg) values for each battery under test. Use galvanostatic discharge at different C-rates and temperatures to measure performance.Plot Data on the Ragone Plot
Place each battery’s data point on the ragone plot. The vertical axis represents energy, and the horizontal axis shows power, both on a logarithmic scale.Analyze Iso Curves
Observe diagonal lines representing constant discharge times. These lines help you estimate how long a battery can sustain a given power output.Compare Chemistries and Configurations
Evaluate where each lithium battery pack falls on the plot. High-power cells like the A123 APR18650M1 appear further right, while high-energy cells like the Sanyo UR18650F appear higher.Select Based on Application Needs
Choose the battery that balances energy and power for your specific storage application. For example, select high-power cells for robotics or industrial tools, and high-energy cells for consumer electronics.
Tip: The ragone plot provides a clear visual framework for matching battery performance to your system’s requirements, reducing guesswork in the selection process.
2.2 Real-World Factors
When determining power deliver by the ragone plot, you must consider real-world factors that impact battery performance. These include temperature, aging, discharge rates, and storage conditions. Each factor can shift a battery’s position on the ragone plot, affecting both energy and power delivery.
Temperature Effects
High or low temperatures can reduce both energy and power output. For example, lithium batteries tested at different temperatures show performance degradation at extreme conditions. This impacts storage efficiency and energy efficiency, especially in outdoor or industrial environments.Aging and Cycle Life
As batteries age, their ability to deliver maximum discharge power and discharge energy decreases. For instance, LiFePO4 lithium batteries maintain 2000–5000 cycles, while NMC lithium batteries offer 1000–2000 cycles. You should account for this when designing storage systems for long-term reliability.Discharge Rates
Higher discharge rates increase power but reduce available energy. Experimental data shows that as you increase the discharge rate, specific energy drops while specific power rises. The table below illustrates this effect:
Parameter | 2.5 mg/cm² Loading | 3.75 mg/cm² Loading | 5 mg/cm² Loading |
|---|---|---|---|
342 | 275 | 218 | |
Specific Power Density (kW/kg) | 1.6 | 2.6 | 1.8 |
Coulombic Efficiency (%) | 90 | 80 | 70 |
Capacity Retention after 100 cycles (%) | ≈99.6 (all samples) | ≈99.6 (all samples) | ≈99.6 (all samples) |
Design Considerations
To maintain high discharge power and storage reliability, you may need to increase pack size or use multiple cells in parallel. This approach ensures sustained performance even under heavy load.
Note: Always balance specific energy and specific power when selecting lithium battery packs for your application. The right energy/power ratio ensures optimal battery performance and storage efficiency.
Application-Specific Selection
You must tailor your battery choice to the application. For medical devices, custom lithium battery solutions ensure safety and reliability. Robotics systems benefit from high-power lithium packs for rapid actuation. Security systems require stable, long-life storage. Infrastructure and transportation demand robust, high-capacity lithium battery packs. Consumer electronics need lightweight, high-energy batteries. Industrial applications rely on durable, high-discharge power lithium packs.
You use the Ragone plot to compare battery performance, optimize storage system design, and select the right lithium battery pack. By analyzing power and energy, you match battery capabilities to your storage needs. Apply these insights to improve battery selection, enhance storage reliability, and drive better system performance in your projects.
FAQ
1. How do you use the Ragone plot to select a lithium battery pack for your application?
You compare specific energy and specific power on the Ragone plot. This helps you match battery performance to your system’s power and runtime requirements.
2. What factors can shift a lithium battery’s position on the Ragone plot?
Temperature, cycle aging, and discharge rates can all affect energy and power output. These factors move the battery’s data point on the plot.
3. Where can you get custom lithium battery solutions from Large Power?
You can contact Large Power’s OEM/ODM experts for tailored lithium battery pack solutions that fit your application and performance needs.
