US developer G4 Synergetics has launched an ‘ultra-high power’ advanced nickel metal hydride (NiMH) secondary battery.
G4’s NiMH design is primarily for power-dependent applications, rather than high energy as most commercial cells are designed. The batteries have a low internal resistance, which enables the batteries to deliver extremely high power.
The reduced internal resistance translates into less heat generation during charge and discharge, and allows G4 batteries to be charged quicker – typically five minutes – than conventional battery constructions.
G4 has characterised the rate dependency of their 25Ah 10 cell module at both charge and discharge rates ranging from 25A – 1C rate (1 hour charge or discharge) to 400A – 16C rate (less than four minutes charge or discharge). Due to the modular nature of the design, stack size can vary to produce batteries with voltages ranging from 1.2V to 24V per module (nominal at C-rate).
G4 has evolved their design since it started with a bi-polar cell some years ago, which it no longer manufactures. Mark Kohler, G4’s Project Manager, told BEST: “We have made a completely new high power rechargeable NiMH cell architecture, with a very high rate charge acceptance and superior thermal management.”
“The design is truly a disruptive and transformational technology. This is the product we are going to market with.” The US company licenses nickel metal hydride technology from Ovonic, the battery materials arm of giant Germany chemicals firm BASF.
G4 puts the cost of the ‘G4-NiMH’ at $1,500/kWh in volume production.