Lithium Ion Battery 

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Over recent years the Lithium Ion battery has become popular in applications requiring high power densities with small weight and footprint.  Today Lithium Ion batteries are commonly found in mobile phones, portable electronics, power tools, electrically operated vehicles and military applications. In addition to high power densities, Lithium Ion batteries are chargeable and have no memory effect.

litiumIonBattery
Charge/discharge mechanism of a Lithium Ion battery
Image Source: http://batteryuniversity.com
Developed in the early 1970's  at Birmingham University in the UK, Lithium Ion batteries consist of a Lithium Metal Oxide positive electrode (cathode), carbon negative electrode (anode) and electrolyte of a lithium salt organic solution. During the discharge process, Lithium Ions move from the negative to the positive electrode, via the external circuit.   During the charging the process is reversed by applying an over voltage.

The Lithium Metal Oxide cathode is constructed using various metals with resulting differences in performance:

  • Lithium Cobalt Oxide - high energy density, some safety issues
  • Lithium Iron Phosphate - low energy density, long life, safe
  • Lithium Manganese Oxide - low energy density, long life, safe
  • Lithium Nickel Manganese Cobalt Oxide - low energy density, long life, safe
  • Lithium Nickel Cobalt Aluminum Oxide - special applications
  • Lithium Titanate - special applications

Advantages of Lithium Ion Batteries:

  • variety of shapes and sizes
  • lighter than other battery types
  • no memory effect
  • low self discharge rate (5-10% per month)
  • low maintenance

Disadvantages of Lithium Ion Batteries:

  • capacity diminishes with charging
  • internal resistance increases with charging
  • capacity loss increases at high temperatures
  • capacity loss on ageing

As a note of caution, there is the possibility of thermal runaway if a Lithium Ion battery is over charged.  Where this is a risk, internal fail safe circuits to shut battery down are incorporated.

Typical Battery Characteristics

Lithium Cobalt
LiCoO2
Lithium Manganese
LiMn2O4
Lithium Iron Phosphate
LiFePO4
Lithium Manganese Cobalt Oxide
LiNiMnCoO2
Lithium Nickel Cobalt Aluminum Oxide
LiNiCoAlO2
Lithium Titanate
Li4Ti5O12
  LCO LMO LFP NMC NCA LTO
Voltage 3.60V 3.80V 3.30V 3.60/3.70V   2.4V
Charge Limit 4.20V 4.20V 3.60V 4.20V    
Cycle Life 500–1,000 500–1,000 1,000–2,000 1,000–2,000    
Operating Temperature Average Average Good Good    

Specific Energy

150–190Wh/kg

100–135Wh/kg

90–120Wh/kg

140-180Wh/kg

   
Safety Average. Needs protection circuit.
Average. Needs protection circuit.
Very safe. Needs voltage protection. Safe. Needs protection circuit.    
Thermal. Runaway 150°C
(302°F)
250°C
(482°F)
270°C
(518°F)
210°C
(410°F)
   
In Use Since 1994 1996 1999 2003    
Application very high specific energy, limited power; cell phones, laptops high power, good to high specific energy; power tools, medical high power, average
specific energy, elevated self-discharge
very high specific energy, high power; tools, medical
electric powertrain and grid storage
electric powertrain and grid storage

 

Storage

Capacity loss due to storage is a problem with Lithium Ion batteries.  This loss is dependent on the charge state, storage time and storage temperature.  The normal recommendation is to store batteries approximately 40% charged.  If stored for one year at 40% charge and 0oC, the recoverable capacity at the end of this period would be around 98%.  As storage temperature increases to 60oC, the recoverable charge will decrease typically to around  75%.  If the batteries were fully charged the recoverable charge would be 94% and 60%. 

 

If anyone has any tips or other information to add, just leave a comment and I’ll incorporate it into the article.



Steven McFadyen's avatar Steven McFadyen

Steven has over twenty five years experience working on some of the largest construction projects. He has a deep technical understanding of electrical engineering and is keen to share this knowledge. About the author

myElectrical Engineering

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