5.1 High-energy and high-power lithium-ion batteries

Lithium-ion batteries are the powerhouses of modern tech. They store energy for our gadgets and electric cars. But there's a constant push to make them better - more energy, more power, longer life.

Balancing energy and power is key. Engineers tweak materials and designs to boost performance. They also focus on safety and longevity, fighting battery degradation. It's a complex dance of chemistry and engineering to create better batteries.

Energy and Power Characteristics

Energy and Power Density

Top images from around the web for Energy and Power Density

• 

  Frontiers | Advanced TexSy-C Nanocomposites for High-Performance Lithium Ion Batteries View original

  Is this image relevant?

• 

  Frontiers | Recent Developments and Challenges in Hybrid Solid Electrolytes for Lithium-Ion ... View original

  Is this image relevant?

• 

  Frontiers | Safety Issues in Lithium Ion Batteries: Materials and Cell Design View original

  Is this image relevant?

• 

  Frontiers | Advanced TexSy-C Nanocomposites for High-Performance Lithium Ion Batteries View original

  Is this image relevant?

• 

  Frontiers | Recent Developments and Challenges in Hybrid Solid Electrolytes for Lithium-Ion ... View original

  Is this image relevant?

1 of 3

Top images from around the web for Energy and Power Density

• 

  Frontiers | Advanced TexSy-C Nanocomposites for High-Performance Lithium Ion Batteries View original

  Is this image relevant?

• 

  Frontiers | Recent Developments and Challenges in Hybrid Solid Electrolytes for Lithium-Ion ... View original

  Is this image relevant?

• 

  Frontiers | Safety Issues in Lithium Ion Batteries: Materials and Cell Design View original

  Is this image relevant?

• 

  Frontiers | Advanced TexSy-C Nanocomposites for High-Performance Lithium Ion Batteries View original

  Is this image relevant?

• 

  Frontiers | Recent Developments and Challenges in Hybrid Solid Electrolytes for Lithium-Ion ... View original

  Is this image relevant?

1 of 3

• Energy density refers to the amount of energy stored per unit volume or mass of the battery (Wh/L or Wh/kg)
  • Higher energy density enables longer runtime and smaller battery size
• Power density represents the rate at which energy can be delivered per unit volume or mass (W/L or W/kg)
  • Higher power density allows for faster charging and discharging
• Trade-offs exist between energy and power density
  • Increasing one often comes at the expense of the other
  • Battery design must balance energy and power requirements based on the specific application

Battery Capacity and C-rate

• Capacity is the total amount of charge a battery can store, typically measured in ampere-hours (Ah) or milliampere-hours (mAh)
  • Higher capacity batteries can provide longer runtime before needing to be recharged
• C-rate is a measure of the rate at which a battery is charged or discharged relative to its capacity
  • A 1C rate means the battery is fully charged or discharged in one hour
  • Higher C-rates enable faster charging and discharging but may impact battery life and performance

Battery Components and Design

Electrode Materials Selection

• Cathode materials significantly influence battery performance, energy density, and cost
  • Common cathode materials include lithium cobalt oxide (LCO), lithium iron phosphate (LFP), and lithium nickel manganese cobalt oxide (NMC)
  • Each material has unique properties, such as high energy density (LCO), high power density (LFP), or balanced performance (NMC)
• Anode materials also play a crucial role in battery performance
  • Graphite is the most widely used anode material due to its stability and low cost
  • Silicon and lithium metal anodes are being explored for their high theoretical capacity but face challenges in stability and safety

Electrolyte Optimization and Cell Design

• Electrolyte composition affects ion transport, stability, and safety
  • Liquid electrolytes are commonly used, consisting of lithium salts dissolved in organic solvents (ethylene carbonate, dimethyl carbonate)
  • Solid-state electrolytes and gel electrolytes are being developed for improved safety and performance
• Cell design encompasses the arrangement and packaging of battery components
  • Prismatic, cylindrical, and pouch cell designs are used depending on the application requirements
  • Optimization of electrode thickness, separator materials, and current collectors can enhance performance and safety

Performance and Longevity

Cycle Life and Capacity Retention

• Cycle life refers to the number of charge-discharge cycles a battery can undergo before its capacity falls below a certain threshold (typically 80% of initial capacity)
  • High cycle life is crucial for applications requiring frequent charging and discharging (electric vehicles, grid storage)
• Capacity retention is the ability of a battery to maintain its storage capacity over time and usage
  • Factors such as temperature, depth of discharge, and charging conditions affect capacity retention
  • Strategies like battery management systems (BMS) and optimized charging protocols can help maximize capacity retention

Degradation Mechanisms and Safety Considerations

• Various degradation mechanisms can lead to battery performance decline and failure
  • Lithium plating, electrode cracking, and electrolyte decomposition are common degradation processes
  • Understanding and mitigating these mechanisms is essential for extending battery life
• Safety is a critical consideration in high-energy and high-power battery design
  • Thermal runaway, a self-accelerating exothermic reaction, poses a significant safety risk
  • Proper cell design, protective devices (fuses, pressure relief vents), and battery management systems are implemented to ensure safe operation
  • Rigorous testing and standards (UL, IEC) are followed to validate battery safety under various conditions