Lithium metal is extremely sensitive to even the smallest amounts of moisture in air and temperature inconsistencies in production.

The slightest exposure leads to reduced performance and impacts on reduced product life of Lithium-ion batteries.

Room temperature should be maintained at recommended levels, around 25°C (77°F), with tolerance of +/(-) 2°C (36°F) along with low dew points in the range of <1%.

The air change rate in the production room should be 20 to 50 air changes per hour while maintaining minimum fresh air introduction for positive room pressure and essential ventilation for operators.

Contamination of any type into the battery materials or wound into the cell can lead to direct or soft electrical shortages – leading to end of line rejects or low battery range performance.

ISO 8 cleanroom condition (or higher) is likely with major focus on contamination removal in the environment as well as on personnel.

Of course, contamination cannot always be removed and so there is still a risk of contamination and an impact on production yields. 

Problems and free particles can also be created within the processes of unwinding/winding, changeovers, coating, calendaring, slitting, stamping, laser cutting and more.  

All of these have potential to find their way into the anode/cathode/separator film layers.

Some contamination will be dry, free, unbound particles, while others will be moist, or bound contamination which is more difficult to remove.

Another risk area is toxic contamination from the coating materials as they are transferred over rollers, cut, wound and rolled – this can dissipate into the air and become a breathing hazard for the operator.

Static charges within the manufacturing environment can lead to a number of problems:

EV battery components are very sensitive to static charges – components must be uncharged within the process.

Uncontrolled static charges will also affect the material flow and will cause material misbehaviour or failure.

If uncontrolled, static discharges (sparks) will create surface dendritic burns affecting the dielectric properties of the separator film – leading to inconsistent charge and discharge behaviours and product failure.

Static charges generated on insulative materials such as the separator film also attract particles adding to contamination risk problems.