GMG's graphene G CELLS maintain capacity after 489 fast-charge cycles

Graphene Manufacturing Group (GMG) has reported that its fast-charging G CELLS have completed 489 charge and discharge cycles without measurable capacity loss. This data, current as of September 4, 2026, was collected by the Battery Innovation Center of Indiana (BIC). The 1 Ah pouch cells were charged and discharged within six minutes per cycle at a 10 C rate.

The test cells were constructed by BIC using graphene materials developed and supplied by GMG from its Brisbane Battery Development Centre. This work is part of a joint development agreement between GMG and Rio Tinto.

According to GMG, G CELLS are graphene aluminum-ion cells that do not use lithium or rare earth materials and are designed to be interchangeable with lithium-ion battery applications.

In comparison, a lithium titanate oxide (LTO) cell subjected to the same testing conditions fell to 86% of its original capacity within 64 cycles. GMG states that this represents more than seven times the cycle life for G CELLS under identical conditions.

The internal resistance of the G CELLS was measured at approximately 5 mΩ, compared to up to 30 mΩ for the LTO cell. Lower resistance results in less resistive heating at a given current. During testing, the G CELLS operated 4° C above ambient temperature, while the LTO cells ran 19° C above it.

GMG notes that the specific energy of the G CELLS is lower than previously reported. The company describes the cells as unoptimized and aims to achieve around 50 Wh/kg at the same charge rate after further optimization.

The voltage of the G CELLS remained nearly flat across approximately 80% of the discharge, which GMG claims facilitates easier control of constant-power discharge.

Bob Galyen, GMG Director and former Chief Technology Officer of CATL, commented on the development: "Having built and scaled battery manufacturing for the world’s largest lithium-ion producer, I know how rare it is to see this combination of fast-charge durability and thermal control this early in a cell’s development. There is clear further work ahead on some of the energy density optimisation and further scaling of the cell size, but the fundamentals being demonstrated here are the right ones to be solving first."