The Ideal Battery for Backup

January 22, 2021

Story

The truth is that nickel-zinc battery technology is hardly new. It goes all the way back to Thomas Edison, who received a patent for it 120 years ago. What is new is the current generation that provides superior performance in data center backup systems, in terms of power density, reliability, safety, and sustainability.

2X power density means small size and weight

To understand why nickel-zinc is a better battery for backup, consider the fundamental differences between an “energy” battery and a “power” battery. Data center backup batteries must discharge the battery at a high rate for a short period of time to maintain operations during brief outages or while backup generators spin up. Battery power density is what delivers a high rate of discharge, ideally in a relatively small footprint.

Lead-acid, and many lithium-ion batteries, are energy batteries designed to discharge the energy out of the battery at a lower rate for as long as possible. In EVs, for example, industry is spending billions of dollars to increase the energy density of EV batteries and get more miles of range. This won’t help your data center uptime.

On the other hand, NiZn batteries are power batteries with twice the power density of lead-acid batteries, the traditional choice for data center backup. This means they have one-half the footprint and one-half the weight for the same power output. They excel at high discharge rates and fast recharging while retaining thermal stability, a key characteristic for data center uptime.

Reliable Performance for Backup

NiZn technology has proven reliability, with tens of millions of operating hours for UPS backup power in mission-critical applications. One key difference from other technologies is in battery string operation. When a lead-acid or lithium-ion battery cell fails, it creates an open circuit that halts string operation. A weak or depleted NiZn cell, on the other hand, remains conductive, allowing the string to continue operating. This turns an emergency situation with other battery chemistries into a simple battery replacement at the next planned maintenance cycle with little cost and no operational impact. In addition, NiZn battery strings tolerate string imbalances better and maintain constant power output at significantly lower states of charge and health than the other technologies.

There are other characteristics of NiZn batteries that make UPS systems highly reliable. NiZn is an alkaline chemistry that does not sulfate over time, a contributing factor to an operational life as long as three lead-acid battery replacement cycles. Moreover, NiZn batteries operate over a wider operating temperature range, so they can endure accidental high heat excursions, such as a cooling system failure, without compromising the performance or voiding the warranty.

The Safer Battery Technology

In addition to uptime, data center operators are responsible for the safety of their facilities and personnel. NiZn technology has clear advantages over lead-acid by eliminating the caustic chemicals and regular maintenance required to keep the batteries fully functional.

To compare the safety of nickel-zinc with lithium-ion technologies, engineers can consult the NFPA 855: Standard for the Installation of Stationary Energy Storage Systems (ESS). This covers energy storage installations like battery backup systems. To assess safety during operation, NFPA 855 references the UL9450A Test Method for Evaluating Thermal Runaway Fire Propagation in Battery Energy Storage Systems. ZincFive’s NiZn batteries have been rigorously tested by UL according to the UL9540A Test Method at the cell level and they did not exhibit thermal runaway across the five arduous and destructive test types.

Conversely, lithium-ion batteries are typically tested above the cell level and utilize a Battery Management System (BMS) and other safety mechanisms to help prevent the propagation of the thermal runaway events that could occur at the cell level. The cell-level safety of NiZn batteries is a clear advantage.

A More Environmentally Responsible Technology

As data centers go hyperscale and proliferate in smaller facilities to support edge computing, sustainability has become a key concern. NiZn chemistry is easier on the environment than lead-acid and lithium-ion batteries. The bill of material for NiZn batteries mainly consists of common highly available, non-hazardous materials, as opposed to lead-acid batteries containing significant amounts of lead and other hazardous materials. Even better, with their longer useful life, data center operators do not have to replace NiZn batteries nearly as often as lead-acid batteries. Similarly, the rare earth elements contained in lithium-ion batteries are difficult and highly polluting to mine and source.

In addition, NiZn is one of the most recyclable battery chemistries on the market. Lead-acid batteries contain significant amounts of lead and other hazardous materials that create a highly pollutive and hazardous recycling process. In fact, environmental organizations have identified used lead-acid battery recycling as the world’s #1 pollution problem. ^[1]

In a recent Climate Impact Report performed by Boundless Impact Research & Analysis, ZincFive’s NiZn batteries ranked higher than lead-acid and lithium-ion chemistries in several criteria including avoided greenhouse gases (GHGs), carbon return on purchase and carbon payback time. When compared with other popular battery chemistries, ZincFive’s NiZn technology received the highest overall score of 9.4 out of a possible top score of 10.

Helping data centers meet their mission

NiZn is the world’s only high-power, fail-safe, fully recyclable battery technology which makes it an ideal choice for uninterruptible power supply (UPS) battery backup. Data center operators can use NiZn battery back-up systems today to reduce their operating expenses through simpler maintenance and fewer battery replacement cycles. Being safer and operating over a wider temperature range, data centers can employ NiZn batteries closer to revenue-generating servers to pursue a distributed power architecture. The environmental advantages help the operators to continue to expand their operations and remain environmentally responsible. With NiZn, battery backup is not just for peace of mind, but also data center innovation.

References

[1] Pure Earth/Green Cross 11th annual 2016 report, “World’s Worst Pollution Problems” https://www.worstpolluted.org/2016-report.html, “World’s Worst Pollution Problems”, Fact Sheet - Lead-Acid Battery Recycling and Lead Pollution; https://www.worstpolluted.org/projects_reports/display/133

About the Author

Steve Jennings leads the ZincFive sales and marketing organization and brings 24 years of executive experience in technology companies serving the energy, clean tech, communications, computing and semiconductor industries. Steve is focused on providing superior support of customers using nickel-zinc battery-based solutions.