About Lithium-Ion Batteries
The LIB market is relatively large and shows high growth potential. Graphite for this market has to meet many challenging performance characteristics before it can be used in a LIB. Some of the critical performance criteria include high charge/discharge capacity, low irreversible capacity loss during initial cycling, long cycle life, long shelf life, high packing density, chemical stability and easy process ability.
To meet these criteria, the natural flake graphite from China used in this application, is milled, shaped, purified and coated before it can be used as anode powder. There is approximately 40-60% yield loss in the milling and shaping process for most natural flake graphite suppliers in this industry today. Also the traditional graphite anode material is usually purified using expensive chemical or thermal processes. Zenyatta is working to develop a purification system that does not require use of these traditional processes for its unique graphite material.
Graphite’s Role in Lithium-Ion Batteries
Graphite is used as a host material in the anode to hold active lithium-ions which move in and out of the graphite layers during charging and discharging. Both natural and synthetic graphite can be used in battery applications depending on the manufacturer’s needs. Generally the choice comes down to cost, purity and various other critical specifications.
Purity levels required are high with most end-users stating that low impurity levels of certain metallic elements be kept to less than 200 parts per million (‘ppm’). Zenyatta graphite does not contain any metallic impurities. Metallic impurities are very problematic to battery manufacturers and can cause the batteries to ‘short’ and disrupt the flow of charge; they can also react with the electrolyte. Reactions with the electrolyte can lead to decomposition and premature aging of the anode.
Additionally, it is critical that the graphite has a narrow particle size distribution and consistency throughout the anode material. Battery manufacturers are very strict on specifications and require rigorous testing. Once supply contract negotiations start, they generally will not allow any change in the agreed specifications without further repeated and thorough testing.
The market for rechargeable lithium batteries can be split into four product groupings:
- Computing, communication and consumer (‘3C’) products – used in small devices that are portable or used in the home such as mobile phones, laptops, MP3 players;
- Power devices and small motive power – power tools and electric bicycles;
- Heavy duty – on and off grid energy storage; and
- Transportation – electric vehicles (‘EVs’) and hybrid electric vehicles (‘HEVs’), buses and trains.
Future growth in demand for rechargeable batteries in unit terms will continue to be led by 3C products through to 2018, but in capacity terms (MWh), power applications, heavy duty, and particularly transportation, will grow in importance. The current market for graphite in batteries is approximately 100,000 tonnes and is forecast to grow by 10-15% per year to >180,000 tonnes in 2018, based mostly on the growth in the LIB sector.