Lithium Ion Batteries

Australia’s burgeoning battery storage market is currently dominated by lithium ion technologies – Lithium Ion, Lithium Iron, Lithium NMC, Lithium Polymer.

Spelling and flash branding aside, what’s the difference?

We’ve put together a summary to clarify the distinctives behind the marketing.

Battery Basics

To bring things right back to basics, batteries contain 3 essential components:

  1. Anode (an electrode that releases electrons during discharge, creating a negative charge)
  2. Cathode (an electrode that absorbs electrons during discharge, creating a positive charge)
  3. Electrolyte

An electrode is an electrical conductor, a piece of conductive material through which electric current can flow; it is used to make contact with the non-metallic part of the battery circuit (containing the electrolyte).

The electrolyte is a chemical medium that promotes the movement of charged molecules (ions) from the positive to negative electrode (charging), or the negative to positive electrode (discharging). It may be a soluble salt, acid, or other base in liquid, gel (micro-porous), or even dry form.

When a battery is charging/discharging, the ions in the electrolyte are attracted to one electrode, while repelled by the other. This movement of ions creates an electrical current.

 

 Lithium Batteries & Lithium Ion Batteries

A lithium battery is a non-rechargeable battery that uses pure metallic lithium as the anode.

In contrast, a lithium-ion battery is a rechargeable battery that uses a lithium compound (a mixture of lithium + one or more other material) as the cathode.

The term ‘Lithium Ion’ includes all the various rechargeable lithium-compound batteries that have been developed, including lithium iron-phosphate (LFP), lithium nickel-manganese-cobalt (NMC), lithium polymer, and others.

 

 Lithium Iron Phosphate

Also known as a ‘LFP’ or lithium ferro-phosphate batteries, these batteries use only one main lithium compound, lithium iron phosphate.

Examples of this type of lithium battery include Sonnen, BYD, and Enphase AC batteries.

Offgrid Lithium Ion System

Pros:

  • Considered more environmentally friendly
  • Greater chemical stability
  • Longer cycle life

Cons:

  • Lower charge/discharge rates (i.e,  lower power output. In a home back-up context, this may limit the number of devices that can be used all at once)
  • Slightly heavier, bulkier
  • Higher self-discharge than other Li-Ion batteries (self-discharge is a tendency of batteries to slowly lose charge over time, even when not in operation)

 Lithium NMC

This form of lithium battery uses a mixture of different lithium compounds, rather than a single lithium compound. NMC stands for Nickel-Manganese-Cobalt, the three primary lithium compounds used in this style of battery.

Well-known examples of this variation include Tesla and LG Chem.

Lithium NMC is considered one of the most functional lithium-ion battery designs. The combination of the individual lithium-ion compounds work together to provide high capacity and power output, while still providing practicable stability and shelf-life.

Cobalt provides high energy density; manganese provides greater stability & safety; and nickel provides high specific energy (capacity) and greater cycle life.

 

Tesla Powerwall

Pros:

  • Highest energy density (they can store more energy for their size or weight than other lithium-ion batteries)
  • Generally higher charge/discharge rates
  • Not as heavy/bulky as LFP Batteries

Cons:

  • Cobalt especially requires careful recycling to reduce environmental impact
  • Technically lower stability and cycle life than LFP Batteries

 Lithium Polymer

Lithium polymer is not  considered a unique battery chemistry.  The designation generally relates to the physical (rather than chemical) structure of the battery, where a gel-polymer micro-porous electrolyte replaces a traditional porous separator soaked with electrolyte.

Examples of this home battery storage type include both BYD (chemical composition of Lithium Iron Phosphate) and LG Chem (Lithium NMC).

8. Battery & Inverter in Context

Pros:

  • Lighter weight
  • High specific power (charge/discharge capability; this is the reason that BYD, a Lithium Iron Phosphate battery, is able to achieve such efficient charge/discharge rates for its cell chemistry and makes it ideal for off-grid applications)
  • Can be made thinner than conventional lithium ion batteries

Cons:

  • Higher manufacturing cost
  • Packaging may be less durable
  • Slightly lower cycle life than the traditional lithium ion battery technology

  Other Lithium Ion Batteries

There are a number of other Lithium Ion battery technologies that have been developed, including:

  • Lithium Titanate (LTO)
  • Lithium Nickel Cobalt Aluminium (NCA)
  • Lithium Cobalt Oxide (LCO)
  • Lithium Manganese Oxide (LMO)

Due to either cost of manufacture, or stability/performance parameters, none of these technologies are generally available as grid-connected home storage batteries in Australia at this time.

 

Summary of Lithium Ion Home Storage Battery Types

References

 

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