The use of Nichicon SLB rechargeable batteries in IoT applications

The Internet of Things, i.e. IoT technologies, have been with us for years. Although many beneficiaries of these devices may not realise it, they owe much convenience to small, energy-efficient devices that perform complex measurements and calculations in our everyday surroundings. They allow to gather accurate data about traffic, weather, air quality in cities, our health — they improve forwarding of courier shipments, warehouse order collection, road, rail and even air transport — what’s more, they make our homes and workplaces safer. And it’s all before we even get to the convenience offered by smart devices: activity sensors, household automation, etc. At the heart of all these technologies are energy-efficient wireless communication modules, based on BLE or LoRa modules, powered by miniaturised, yet efficient, energy sources.

Today, a technological revolution is taking place in the field of mobile power supply. Until recently, the main obstacle on the way to progress was not the capacity of integrated circuits, but techniques for supplying them with sufficient energy. Among the most modern methods of energy storage, those that stand out are the miniature solutions which are used in remote sensors or personal wearable devices. There are hundreds of products available on the global market dedicated to such applications, but only a few of them match the performance standard offered by the lithium-ion batteries from Nichicon, included in the SLB series. They are based on Toshiba’s proprietary SCiB^™ technology — used primarily for high-current energy storage. In a miniaturised form supplied by Nichicon, they maintain their excellent electrical performance, but are enclosed in packages whose size does not exceed that of a tiny electrolytic capacitor.

The Japanese supplier, specialist in the construction of components for power supply and amplification systems, has introduced the SLB series to its range of products to cater for the needs of producers of portable devices, industrial sensors, as well as consumer goods. These batteries allow to maximise the efficiency of energy storage in small systems powered traditionally or with the use of energy harvesting.

Technological advantages of Nichicon SLB rechargeable batteries

Before we focus on the possibilities that SLB rechargeable batteries offer, let’s look at their characteristics. In comparison with standard solutions, for example with the average 18650 cell, Nichicon products stand out in virtually every field. They are designed to meet high demands not only in terms of dimensions, but also in terms of electrical performance and physical endurance.

Long cycle life and safety

SLB cells offer a service life of 25,000 charge/discharge cycles. Thanks to this, they can be used in circuits to which external energy is supplied irregularly, periodically or even sporadically. For example, these may be devices that use photovoltaic panels or miniature wind turbines, or consumer products that are charged only when it is convenient for the user. Recharging the battery repeatedly during the day (e.g. due to cloud cover or changing winds) will not significantly affect the energy storage capabilities of SLB cells.

Charge and discharge current

The current capabilities of Nichicon batteries are noteworthy. Their charge/discharge current reaches the 20C rating, i.e. 20 times the battery capacity divided by 1 hour. This means that for the SLB12400L1511CV (150mAh) model, the current supplied and consumed can be as much as 150 mA * 20 = 3 A. With such parameters of charging, full charging of the cell will be achieved after just 3 minutes. Conversely, the battery can deliver high current in a short period of time, e.g. to switch on a light/alarm, send a message using a long range radio module etc. In combination with the long cycle life, this opens way to the construction of devices which will be: (a) charged only periodically (during maintenance, when reading the meter value), using the accumulated energy sparingly on a daily basis; (b) or also charged gradually, e.g. with a small solar cell, but under certain conditions capable of activating not only electronic circuits, but also electromechanical components such as servos, solenoid valves etc.

Resistance to environmental conditions

As we have already suggested, many of the applications in which the SLB series cells are and will be used involve harsh environmental conditions. This includes remote sensors used in agriculture as well as wearable consumer devices, i.e. body-worn electronics such as medical wristbands, location tags or smart watches. Therefore, a particularly important characteristic of lithium-ion rechargeable batteries by Nichicon is their thermal tolerance. These products can operate without any difficulty in temperatures ranging from -30 to 60°C. Furthermore, even when these parameters are exceeded, there is a very low probability of failure, spontaneous ignition or explosion. This will be a particularly important feature for manufacturers of consumer appliances.

Energy harvesting – it’s time to fulfil Tesla’s dream

One of the most popular stories about the beginnings of electronics is Nikola Tesla’s project: a large-scale network that would aim to distribute electricity wirelessly. Although the project never made it outside the demo prototypes’ phase, which we would call proof of concept today, modern technology to some extent legitimises the Serbian inventor’s concept. Here, in the era of energy-sufficient IoT (Internet of Things) circuits, the construction of devices powered “out of thin air” no longer seems like a pipe dream.

Technologies grouped under the term energy harvesting include a range of methods for extracting small amounts of energy from the environment. These include “classic” solutions such as photovoltaic cells and wind turbines, but also less conventional techniques. In addition to movement caused by atmospheric phenomena, energy can actually come from any flow of gases and liquids, such as in water pipes, sewage pipes, as well as near roads or in air conditioning ducts. Piezoelectric materials are also used to aggregate energy, whereby voltage is generated by varying pressure (e.g. on pavements or roads). As IoT technology is developing, we are observing the growing use of thermoelectric sources based on the Peltier effect, allowing the use of temperature differences (e.g. between the atmosphere and a thermal source, a warm water supply or even the human body to generate small electrical currents. These will not provide very much, but sufficient power for e.g. BLE modules. And finally, the method that is closest to Tesla’s idea should be mentioned here: RF energy harvesting. RF harvesting uses ubiquitous radio signals (Wi-Fi, TV and even satellite signals) as its source of power.

The SLB rechargeable batteries from Nichicon provide performance parameters that are perfectly suited to the needs of devices using the energy harvesting technology. Since they can be charged with very high, but also very low currents (for SLB03070LR351BS model it is 3.5µA), they can be implemented in circuits using the above-mentioned solutions. This means the construction of a completely new type of electronic devices — self-sufficient solutions. As a further consequence, it means huge savings connected with the limited needs for construction of power supply infrastructure and maintenance, as well as possibility to construct scalable and complex networks both in industry (e.g. commerce, warehousing, shipping) and public space (traffic management systems, public transport, meteorological, seismic sensor networks etc.). Beacons or environmental sensors powered by SLB cells from Nichicon (charged used commonly available energy sources) are another step towards a computerised, safe and environmentally friendly future.

Image credit: iStock.com/alengo

Originally published here.