Symtech Solar Tech Corner




January 2019

Lithium Ion Batteries & Energy Storage Explained

 

The first manufacturing of Li-Ion Batteries – A brief history

The Lithium Ion battery manufacturing process was first developed by Sony in 1991 which features significantly longer life-time and energy density compared to nickel-cadmium rechargeable batteries.  Sony was the first to introduce commercial lithium-ion batteries in large numbers and since Sony was already manufacturing magnetic tape for recorders and due to the new demand for CD’s realized that the process for manufacturing tape could be adapted to making lithium-ion batteries.   The technology and equipment for the magnetic tape were already available.  The magnetic tape process applies iron oxide or other metal oxide slurry to sheets of tape, dries them, and cuts them into reels of tape.  Thus, when Sony changed over to the production of Li-Ion batteries they changed to  sheets of copper and aluminum foil instead.  They coated the foil and sheets with metal oxides and graphite, layered them with a separator, packaged, and filled with electrolytes.

Common Types of Li-Ion Batteries

  • LCO – Lithium Cobalt Oxide
  • NMC – Lithium Nickel Manganese Cobalt Oxide
  • LMO – Lithium Manganese Oxide
  • NCA – Lithium Nickel Cobalt Aluminum Oxide
  • LFP – Lithium Iron Phosphate

Different Elements in Rechargeable Lithium Ion Batteries

The most common Li-Ion battery layouts include:  Cylindrical, Pouch, and Prismatic.

Different types of Lithium Ion Battery Designs

For the sake of this Blog we will look at 2 common types that Symtech Solar has or is using in its solar kits.

Lithium Iron Phosphate (LFP)

The University of Texas in the USA (and other contributors) discovered phosphate as a cathode material for rechargeable lithium batteries.  Li-phosphate offers good electro-chemical performance with a low resistance.  The key benefits are high current rating and long cycle life, besides good thermal stability, enhanced safety.

Lithium Nickel Manganese Cobalt Oxide (NMC)

One of the most successful Li-ion cathode formulas developed to date is obtained by combining nickel, manganese, and cobalt.  Lithium-Nickel-Manganese-Cobalt-Oxide (LiNiMnCoO2), abbreviated as NMC, has become the go-to cathode powder to develop batteries for power tools, e-bikes and other electric powertrains.   This formula delivers strong overall performance, excellent specific energy, and the lowest self-heating rate of all mainstream cathode powders, which makes it the preferred option for automotive and now residential energy storage batteries.

NMC powder can refer to a variety of blends, with formulas typically consisting of  blends, sometimes referred to as 1-1-1 (33% nickel, 33% manganese and 33% cobalt).  This is a popular option for mass-produced cells in applications requiring frequent cycling (automotive, energy storage) due to the reduced material cost resulting from lower cobalt content.  There are a number of different blends being used in the market today.  Examples would be:

  • NMC 333
  • NMC 532 – This means the cathode is 20 % cobalt:  Currently this formula is used in Symtech Solar Hybrid Battery Kits 
  • NMC 622
  • NMC 811

Lithium Ion Batteries NMC 811 vs NMC 532 performance

Our New Hybrid NMC 532 Battery for Aurora Hybrid PV Kits – 6000 cycles – 10 year warranty

Symtech Solar New 2019 Hybrid Solar Battery Storage System

 

How the Li-Ion battery is used:

Solar power is directed from the panels and charge controller towards the bank of batteries, in this case Li-Ion.  In most residential situations the batteries are secured onto the interior (or exterior) wall of the house. The charging process continues while the sun shines until the battery bank is charged.

If you turn on the appliances in your house, electricity is drawn in the form of direct current (DC) from the battery. The inverter is used to convert the DC current into alternating current (AC) as most household appliances use AC power.

The majority of new solar and battery bank installations in residential properties utilize the Lithium-Ion battery because they have a longer lifespan (which varies between 10 and 18 years depending on use, type, and temperature).  Lithium-Ion batteries tends to be lighter and have an increased DoD (Depth of Discharge) with better round trip efficiency.

What Are The Advantages And Benefits of Li-Ion Batteries?

  1. Extensive Life Cycle – up to 6000
  2. Easy Maintenance – unlike FLA
  3. High Energy Capacity – +- 1500Wh/kg
  4. Reduced Size and Weight – 3 times less then lead acid and twice as small for the same power

Looking towards the future

It is likely the lithium-ion battery with solar storage will become an automatic inclusion of planning most autonomous solar energy systems.  It will be the most cost effective option for electrical generation.  As solar PV has dramatically come down in price over the last 10 years we also expect as the supply chains and technology improves for Li-Ion the price will also come down significantly for this energy storage technology.

 

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