Transport is one of the largest sources of human-induced greenhouse gas emissions and fossil-fuels consumption. This has lead to a growing demand for hybrid-electric vehicles (HEVs) to reduce air pollution and consumption of fossil fuels. CSIRO Energy Technology has developed the ultra-battery, a new technology that will reduce the cost and boost the performance of batteries in HEVs. The ultra-battery is a hybrid energy-storage device, which combines an asymmetric supercapacitor, and a lead-acid battery in one unit cell, taking the best from both technologies without the need for extra electronic controls. The capacitor will enhance the power and lifespan of the lead-acid battery as it acts as a buffer in discharging and charging. Consequently, this hybrid technology is able to provide and absorb charge rapidly during vehicle acceleration and braking. The ultra-battery has been subjected to a variety of tests. To date, results show that the discharge and charge power of the ultra-battery is ∼50% higher and its cycle-life is at least three times longer than that of the conventional lead-acid counterpart. Furthermore, the ultra-battery is able to be produced as either flooded-electrolyte or valve-regulated designs in the existing lead-acid factory and also able to reconfigure for a variety of applications, such as conventional automobile, power tool, forklift, high-power uninterruptible power supply and remote-area power supply. The prototype ultra-batteries have been constructed and are under laboratory evaluation and field trial. The success of the ultra-battery will obviously make HEVs more affordable and widespread. This, in turn, will reduce greenhouse gas emissions in the urban environment and the consumption of limited supplies of fossil fuels.