Energizer Zinc Air Prismatic Handbook Including performance and design data for the PP355
Page |2 Energizer Zinc Air Prismatic Handbook 1. Battery Overview ............................................................................................................................. 3 1.1 Zinc Air Chemistry ............................................................................................................................... 3 1.2 Construction ........................................................................................................................................ 3 1.
Page |3 Section 1: Battery Overview For over 35 years, Energizer has manufactured miniature Zinc Air batteries primarily designed to provide power to miniature hearing aids. Zinc Air chemistry provides the highest available energy density compared to other commercially available batteries. Energizer Zinc Air Prismatic batteries employ technology similar to what is used in hearing aid batteries, but with a thin prismatic form factor providing power for a broad range of applications. 1.
Page |4 Figure 1: Cross Section View of Zinc Air Prismatic Battery Energizer Zinc Air Prismatic batteries are designed to allow air to enter the air holes and to prevent the transport of liquid electrolyte out of the battery. A gasket is used to seal between the anode cup and the cathode can. The gasket also electrically insulates the negative cup from the positive can. An air electrode and a loose layer of Teflon are compressed onto a band of sealant on the bottom of the can.
Page |5 Figure 2: Runtime for Equivalent Volume AAAA Batteries in 50 mW Devices 50 38 40 30 14 12 20 10 0 AAAA Alkaline Lithium Ion ZAP PP355 The high energy density of Zinc Air is made possible by using a thin air electrode where the cathode reaction takes place and by using atmospheric oxygen as the cathode reactant. The result is greater internal volume for zinc, the active anode material. More zinc translates into longer runtime in similar overall volume.
Page |6 Figure 4: Comparison of Discharge Curves at 50 mW Continuous 1.6 1.4 Voltage (V) 1.2 1.0 0.8 NiMH AAA Alkaline AAAA 0.6 Zinc Air PP355 Alkaline AAA Lithium AAA 0.4 0 5 10 15 20 25 30 35 40 45 Discharge Time (hrs) The impedance of Energizer Zinc Air Prismatic batteries is higher than similar volume Alkaline batteries, and it decreases slightly through the life of the battery. The impedance should not impact battery performance at low to moderate discharge rates.
Page |7 Section 2: PP355 Performance Characteristics This section describes the performance of the PP355 battery. Standard discharge curves, performance at a variety of environmental conditions, pulse capability, and service maintenance data are presented. 2.1 ‐‐ Performance at Standard Conditions Standard conditions for Energizer Zinc Air Prismatic batteries are defined as 21°C and 50% relative humidity (RH).
Page |8 Figure 7: Comparison of Performance under Continuous Constant Power Continuous Discharge Time (hrs) AAAA PP355 25 mW 24 88 50 mW 11 38 75 mW 6 24 100 mW 4 15 2.2 ‐‐ Performance at Other Environmental Conditions When a Zinc Air battery is exposed to a non‐standard environment, a driving force for water transport in or out of the battery exists.
Page |9 Lower Temperature Conditions: Air holds less moisture as temperature decreases, and the difference between low and high relative humidity becomes less significant. At 0°C, the difference between the humidity of the PP355 and the environment is negligible. While the service obtained from a PP355 at temperatures lower than standard conditions is less, the loss is similar to Alkaline batteries. In general the “up to 3X” service advantage for Zinc Air batteries over Alkaline batteries is maintained.
P a g e | 10 Figure 8: Pulse Capability of PP355 Batteries 1 Maximum Pulse Duration (s) 1.1V Cutoff 1.0V Cutoff 0.1 0.9V Cutoff 0.8V Cutoff 0.01 0.001 0.0001 0 200 400 600 800 1000 1200 1400 1600 Current (mA) 2.4 ‐‐ Service Maintenance Zinc Air batteries are stored with adhesive backed tabs prior to use. These tabs seal the air holes against oxygen and water ingress. To obtain the full battery performance, the tab should be removed only immediately prior to use.
P a g e | 11 2.5 ‐‐ Activation Time and Air Requirements When batteries are stored with the adhesive tab intact, they have a lower open circuit voltage (OCV) since the oxygen contained in the battery is consumed during storage. When the tab is removed the OCV will rise as oxygen activates the air electrode. With multiple air holes for added rate capability, the PP355 may take a couple of seconds to air up enough to sustain a 50 mW load above 1 volt.
P a g e | 12 Section 3: Application and Design Considerations Excessive exposure to air can have an adverse affect on Zinc Air battery operation, primarily due to carbon dioxide reacting with the electrolyte in the air electrode. The battery can also absorb water or dry out depending on ambient conditions. Balancing the air requirement of the battery during discharge versus the need to minimize exposure during rest is called air management.
P a g e | 13 Figure 11: Overview of Different Air Management Techniques Discharge Rate high none or small degree of air management needed, since cell capacity is quickly used (1‐3 months) high degree of air management needed, cell has high air access but is expected to be in service with long periods of “off” time (>3 months) throttling needed to maximize service time (>3 months) low continuous intermittent Duty Cycle 3.
P a g e | 14 Figure 12: Air Management Design Concept 3.3 ‐‐ Battery Compartment The design of a Zinc Air Prismatic battery compartment depends on several factors including battery dimensions, battery orientation, and air flow needed to maintain power to the device. Other considerations are the ease of battery insertion and removal, contact materials, reversal protection, and the shape and location of device contacts.
P a g e | 15 Contact Materials: Nickel plated stainless steel is recommended because it provides good conductivity and environmental stability at a reasonable cost. Nickel plating must be adherent, continuous, and non‐porous. The nickel plating must also resist the wear that occurs during the insertion and extraction of batteries. The suggested plating thickness is 5‐6 micrometers. Battery Orientation: How the battery is situated in the compartment is an important design consideration.
P a g e | 16 3.4 ‐‐ Multi‐Battery Applications In some situations, a higher voltage or an increased performance level is desired for a certain application. Zinc Air batteries can be arranged in series or in parallel as needed. Devices that use more than one Zinc Air Prismatic battery introduce additional design considerations. An air plenum and air access is required for each battery, and these can be independent or shared.
P a g e | 17 Section 4: Handling Procedures 4.1 ‐‐ Recommended Operating and Storage Conditions For optimum performance and capacity retention, Zinc Air Prismatic batteries should be used in a temperature range of ‐10⁰C to 55⁰C and in a relative humidity range of 25% to 80%. Zinc Air batteries should be stored between 10°C and 30°C and at 40% to 70% relative humidity. Batteries should be stored with the tab in place to prevent performance degradation due to environmental exposure.
