source: Electronic Production article
From electric vehicles to harvested-energy IoT, supercapacitors are helping solve power challenges. By Spencer Chin, contributing editor
Supercapacitors continue to gain usage as more applications require storing and releasing high amounts of energy in short periods. The devices, which have two plates soaked in an electrolyte and are separated by a very thin insulator, store considerably more energy than conventional capacitors. Compared to batteries, they have lower overall storage capacity but higher energy density.
The performance characteristics of supercapacitors are suiting them for applications requiring a high number of rapid charge and discharge cycles and for systems implementing energy recovery. These include hybrid-electric vehicles, wind turbines, rail transit, consumer electronics, and electric grid systems.
Market research studies continue to project a bright future for the technology. One recent study, by Zion Market Research of Sarasota, Florida, projects the supercapacitor market to grow from $684.7 million in 2016 to over $2 billion by 2022, at a compound annual growth rate of 20.5%.
Another recent study, by Research and Markets, projects the supercapacitor market to grow at a compound annual growth rate of 18.6% from 2017 through 2022, reaching $2.44 billion. The study adds that the limitations to more rapid growth include high supercapacitor prices and the lack of industry-wide experience.
Dr. Priva Bendale, Senior Director of Applications Engineering at supercapacitor supplier Maxwell Supercapacitor (San Diego, California), said that supercapacitor adoption will increase as users become more familiar with the technology.
“The industry’s limited understanding of supercapacitor technology, performance, and perception of high-cost solutions creates barriers for supercapacitor integration. Through continuing education about products and performance benefits in a variety of applications, we are overcoming these hurdles and growing new markets for products.”
Supercapacitor manufacturers continue to improve the power handling and performance of their parts. One recent supercapacitor introduction from AVX Corporation (Fountain Inn, South Carolina), the SCC Series (see Fig. 1), is rated 2.7 V and delivers capacitance values from 1 F to 3,000 µF and low ESR from 0.16 to 200 mΩ. The SCC is designed to deliver good pulse-power-handling characteristics. It can be used alone or in conjunction with primary or secondary batteries to provide extended backup time, longer battery life, and instantaneous pulse power as needed. The supercapacitor is available in various case sizes with diameters from 6.3 to 60 mm, case lengths from 12 to 165 mm, and a choice of radial, solder pin, or cylindrical leads.
Fig. 1: AVX’s SCC Series is rated 2.7 V and delivers capacitance values from 1 F to 3,000 µF and low ESR from 0.16 to 200 mΩ.
Nesscap Energy Inc. (Toronto) has introduced its N60 3-volt (3-V) 3,400-farad ultracapacitor cell, which, according to the company, delivers 40% more energy and 42% greater power density compared with the company’s older 2.7-volt 3,000-farad cell.
According to the company, the N60 offers a number of benefits to system integrators, including the ability to scale up system voltages to attain more power and energy within the size and weight specifications of their existing designs. Systems can also be designed with fewer cells resulting in smaller size, reduced weight, and lower cost. N60 may be used as a standalone solution or integrated with battery technology to achieve optimal power, energy, and cost parameters, depending on the needs of the application.
Maxwell Technologies Inc. now offers a 51-V ultracapacitor module (see Fig. 2) that uses the company’s 2.85-V, 3,400-F ultracapacitor to optimize the performance of hybrid buses and other high-duty-cycle applications. The module is pin-compatible with the company’s existing 48-V supercapacitor module.
Fig. 2: Maxwell’s 51-V ultracapacitor module uses the company’s 2.85-V, 3,400-F ultracapacitor to optimize the performance of hybrid buses and other high-duty cycle-applications.
The ultracapacitor module incorporates an active cooling system that improves the part’s continuous current rating by nearly 90% and ensures optimal performance over temperatures from –40°C to 65°C. It incorporates Maxwell’s proprietary DuraBlue™ Advanced Shock and Vibration Technology into the design, which provides three times the vibrational resistance and four times the shock immunity of previous ultracapacitor-based competitive offerings.
Supercharging portable devices
Supercapacitors are also targeting portable devices such as wearables and mobile phones to meet peak power needs. Earlier this year, Murata Manufacturing Co. Ltd. introduced the DMH Series supercapacitor (Fig. 3). This part stands just 0.4 mm high to fit in thin devices, yet supplies 35 mF at 4.5 V, which provides an ample boost for lithium-ion batteries. The supercapacitor achieves an equivalent series resistance of 300 mΩ at 1 kH and operates over a –40°C to 85°C range.
Fig. 3. Measuring only 0.4 mm high, Murata’s DMH Series supplies 35 mF at 4.5 V to boost the peak capacity of lithium-ion batteries.
Along the same lines, Australia-based CAP-XX earlier this year launched its first compact cylindrical supercapacitors to provide high performance at low cost to power IoT industrial and consumer devices, from energy harvesting for wireless sensors to peak power support for wireless transmissions.
CAP-XX offers single-cell (2.7 V) or dual-cell (5.4 V) cylindrical supercapacitors in lengths as short as 12 mm long and available in diameters of 6.3 mm (400 mΩ) and 8 mm (180 mΩ). The largest 400-F supercapacitor is 68 mm long and 35 mm in diameter (3 mΩ).
Future applications
Scientists continue to look at new applications and materials for supercapacitors. Recently, researchers at UCLA and the University of Connecticut developed a biofriendly energy storage system called a biological supercapacitor, which operates using charged particles, or ions, from fluids in the human body. The biosupercapacitor comprises a carbon nanomaterial called graphene layered with modified human proteins as an electrode, a conductor through which electricity from the energy harvester can enter or leave.
The research team envisions the supercapacitor leading to longer-lasting cardiac pacemakers and other implantable medical devices.
Scientists are also looking at alternative materials to the conventional carbon, which require high processing temperatures and the use of harsh chemicals to produce. Researchers at the Massachusetts Institute of Technology developed a supercapacitor that uses no conductive carbon, instead employing a series of metal organic frameworks that provide a large surface area. According to the researchers, the technology has the potential to produce high-power supercapacitors with performance comparable to existing carbon-based ones.
For more insight into supercapacitors and their uses, check out these articles and product briefs from the AspenCore network:
Supercapacitor boasts large capacity, low ESR — Murata has launched what it calls the world’s lowest-profile 0.4-mm supercapacitor. The DMH Series of supercapacitors is designed to facilitate peak power assist with lithium-ion batteries in wearable and other portable devices such as smartphones and smartcards.
Simple-to-use auto-balancing for supercaps — Advanced Linear Devices offers a universal PCB designed to automatically balance leakage currents and manage overvoltage, enabling ultra-low-power usage in supercapacitors used in a series stack.
High-energy-density supercapacitors: alternative to battery power storage — This technology could revolutionize devices that have previously relied on battery power to operate.
Plug and play your way to balancing supercapacitors — Balancing supercapacitors can be difficult, but a new solution combines all of the circuitry needed to balance them quickly.
Using a supercapacitor for power management and energy storage with a small solar cell, Part 1 — This two-part series will examine solar cell performance, how to select and size the supercapacitor, requirements of supercapacitor charging circuits, and charging IC characteristics. Part Two (linked to at end of Part One) includes two case studies illustrating how to use supercapacitors.
