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Lithium primary

About

  • Anode: lithium 
  • Cathode: manganese dioxide, lithium thionyl chloride, carbon monofluoride, iron disulphide, various 
  • Electrolyte: various 
  • Type: primary 
  • Nominal cell voltage: 1.5 - 3+ volts 
  • Energy density: 300 - 1,500 W·h/L 
  • Monthly self-discharge rate: 0.2 - 1% 

Pros:

  • Excellent performance - lithium has a high energy density and electrochemical potential (a thermodynamic measure of chemical potential that does not omit the energy contribution of electrostatics)
  • Light weight - 50 to 60% lighter than their lead-acid equivalents 
  • Long lasting - long operating life (15 to 20 years for lithium thionyl chloride) 

Cons:

  • Not rechargeable - primary lithium cells are single use only  
  • Economically inefficient - these cells produce only 2% of the power needed to create them 
Lithium primair

General information on lithium primary 

Lithium primary refers to non-rechargeable batteries that use metallic lithium as the anode material. There are many different electrolyte and cathode options (manganese dioxide, carbon monofluoride, and iron disulphide are among the most common cathode materials today). 

Gilbert Newton began experimenting with lithium batteries in 1912, but it took until the late 1960s to develop the first commercially viable lithium primary cell. This sparked research into lithium rechargeable batteries soon after. Since then, a lot of research has been carried out to refine the chemistry involved, exploring how lithium reacts and functions in different states and with various other materials. 

Most common applications

Today lithium primary batteries are used in many long-life devices. Lithium primary batteries are often used in toys and serve as a high-end replacement for alkaline / zinc-carbon batteries if the voltage is appropriate. They have also found a niche in implanted medical electronic devices such as pacemakers due to their longevity, energy density and high voltage output. 

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Why recycle lithium primary batteries? 

While most lithium primary batteries don’t contain any toxic metals (the exception being LiSOCl2 which contain thionyl chloride), they are highly combustible due to the metallic lithium content. Lithium metal can explode if exposed to moisture or air, which is why these batteries (and lithium-ion for that matter) are considered a fire hazard. They are often recycled in small batches or fully discharged before treatment for safety reasons.   

Process highlights

Discharging and comminution

The first step in recycling lithium batteries is usually discharging them completely or making the contents inert using liquid nitrogen. Comminution of the batteries is then often carried out in a rotary shredder in a carbon dioxide and argon atmosphere to convert any remaining elemental lithium into lithium carbonate (LI2CO3). 

Physical separation

Next step - sieving; separating the smaller particles of metal oxides and carbon from the large steel, paper and plastics fragments. A series of different meshes can then be used to separate out copper particles from the black mass (containing cobalt and lithium particles).

  • A paper and plastics stream will usually have been separated out and sent off to be used in recycling or as fuel for industrial processes. 
  • Steel and copper would also be on the way to a metal works facility. 
  • The remaining lithium, cobalt, and carbon rich fraction (black mass) would then be treated using metallurgy. 

Lithium could be leached and precipitated into lithium salts, however the process is prohibitively expensive and the quantities of lithium in question are too small to warrant this in many countries. Instead, in most present-day industrial-level recycling methods, the lithium content ends up in the slag as it’s cheaper to buy new lithium than it is to recycle it. However, this may soon be changing due to new laws and legislation. 

End products

Given the variety of cathode and electrolyte materials used for lithium primary batteries, end products may vary accordingly. However, in most cases the output fractions are: 

  • Polymer plastics 
  • Papers 
  • Steel 
  • Lithium salts 
  • Electrolyte and cathode materials 
Steel