PowerGenix, the developer of nickel-zinc (NiZn) rechargeable batteries (earlier post), has signed a product evaluation contract with HELLA, a Tier 1 supplier to major automotive manufacturers worldwide. HELLA will conduct real-world vehicle tests to evaluate NiZn’s ability in meeting the high-power requirements of 48-volt mild hybrid systems, while substantially reducing overall system complexity and cost.
High-rate, high-power capabilities are critical to the performance of 48-volt systems, but cost and complexity of Li-ion battery technologies capable of meeting such requirements pose the biggest challenge to their widespread adoption. Advanced battery solutions such as NiZn offer a promising alternative, while meeting both the cost and technical performance targets of mild hybrids, PowerGenix suggests.
Nickel-Zinc could offer some unique benefits in 48-volt systems. It’s inherently very safe and also promises to provide equivalent emissions reductions, but at a lower cost. We believe our evaluation will open up a lower cost product to our OEM customers interested in reaching the fuel economy gains offered by 48-volt mild hybrid systems.—Dr. Marc Nalbach of HELLA
|NiZn offers superior energy and power density compared to lead-acid and Nickel-Metal Hydride (NiMH) and avoids the high costs and safety issues associated with Lithium-ion (Li-ion) batteries. Source: PowerGenix. Click to enlarge.|
The market for micro hybrid and mild hybrid vehicles is on track to grow nearly eightfold to 39 million vehicles in 2017, driving a $6.9-billion market for energy storage devices, according to a 2012 Lux Research report on micro and mild hybrids.
Micro hybrid vehicles are traditional gasoline- or diesel-powered cars with automatic, battery-powered stop-start systems that shut off the engine while the vehicle is at rest and restart it upon re-engaging the gas pedal. Mild hybrids take fuel economy one step further by allowing the engine to be turned off while coasting, which enhances the stop-start application as well as enabling high power regenerative braking. In addition, a starter alternator motor is used to supplement the internal combustion engine with some level of power assist during acceleration.
In 2011, PowerGenix delivered its first production prototype product for the micro-hybrid stop-start market. (Earlier post.) In July of this year, the company entered into an innovation contract with PSA Peugeot Citroën Automobiles under which PSA will conduct a comprehensive evaluation of the use of PowerGenix’s NiZn batteries as a replacement for lead-acid in stop-start vehicles. (Earlier post.) Then, in August, the NiZn batteries achieved certification for start-stop applications by China National Laboratory’s Tianjin Automotive Test Center. (Earlier post.)
HELLA is a leading provider of Intelligent Battery Sensors (IBS), DC/DC converters and automotive energy management products for micro-hybrid vehicles for the world’s leading automotive OEMs (Original Equipment Manufacturers).
NiZn. NiZn batteries were first developed in the 1920s, but suffered from short cycle life due to dendrite growth leading to short circuiting, caused by the high solubility of zinc oxide—a discharge product of the zinc anode in the alkaline electrolyte. In addition to dendrite formation, zinc oxide solubility can result in shape change and densification of the anode on repeated charge/discharge cycles.
The basis of PowerGenix’s approach to making its NiZn battery commercially viable is a patented electrolyte formulation that reduces zinc solubility and prevents the dendrite shorting and shape changing problems. Further enhancement of cell capability is due to cathode and anode materials that are free of any heavy metal elements.
Additionally, the company has intellectual property addressing engineering and construction details that enable the use of existing nickel-cadmium equipment manufacturing for production of the cells. (Nickel-zinc batteries are chemically very similar to nickel-cadmium, NiCd. Both use an alkaline electrolyte and a nickel electrode but differ significantly in their voltage. The nickel-zinc cell delivers more than 0.4V of additional voltage both at open circuit and under load.)
The PowerGenix battery has up to a third more energy density than a traditional NiCd battery when measured by either weight (Wh/kg) or by volume (Wh/l).