Category Archives: Batteries

Explosion and Damage Proof High Energy Density Batteries

We seem to spend a major part of our waking life charging batteries of our smartphones, laptops, watches, wearables, and more. Although most of our gadgets work at lightning speeds, one common frustrating weakness lingers on—the batteries. Of course, they have improved tremendously in the last fifty years, yet they have retained characteristics such as being toxic, expensive, bulky, finicky, and most maddeningly, short-lived. The quest for a super battery does not end with smartphones alone, rather it continues with electric cars and renewable energy sources such as wind and solar power, holding the keys to a greener future.

Mike Zimmerman, a Professor at the Tufts University just outside Boston, and his team have created what they claim is the next generation of the Lithium-ion battery. The main characteristic of this new type of battery is it is safe to power up cars, phones, and other gadgets.

The current breed of Lithium-ion batteries relies on a liquid electrolyte between their positive and negative electrodes. When hit or pierced, the leaking liquid electrolyte makes the battery vulnerable to fire or even explosion. The Galaxy Note 7 phones from Samsung aptly demonstrated this—it had spontaneously exploding batteries that would catch fire as the battery casing caused one of the electrodes to bend, increasing the risk of short circuits.

However, Zimmerman’s battery won’t explode or catch fire even if most of it has been chopped away. Rather, it will continue to power the device. It will endure repeated damage without risk of fire or explosion, thanks to its solid electrolyte.

Besides being the Holy Grail for safe batteries, solid electrolytes can hold more charge for a given volume compared to what the liquid electrolytes can. The solid plastic electrolyte developed by Professor Zimmerman does not allow the formation of dendrites—tendrils of Lithium that originate from the electrodes and spread throughout the electrolyte—that cause the dangerous short-circuits.

Other researchers have been looking at charging times for batteries and trying to speed up the process. Rather than improve the charging times for Lithium-ions, scientists have been experimenting with different types of batteries, and claim to have hit success with batteries made from Aluminum foil.

Although research on Aluminum batteries has continued for years, most prototypes were incapable of withstanding more than a few dozen charges, before they lost their potency. Most cellphones, on the other hand, sustain more than a thousand charge cycles before their capacity deteriorates.

The Aluminum foil batteries can sustain a staggering 7,000 charge cycles. They are also safe—researchers could drill a hole into the battery while it was operating, and unlike a Lithium-ion battery, the Aluminum battery did not explode. However, Aluminum batteries are not yet ready for the market, as they are heavier than Lithium-ion batteries of the same capacity.

The researchers used a solution of Aluminum Trichloride dissolved in an organic solvent containing Chlorine. Although the Aluminum atom has three electrons in its outer shell, the present chemistry utilizes only one of them. Lithium atoms also do the same, as they have only one electron in their outer shell. However, Lithium atoms are only one-third as heavy as the Aluminum atoms.

Monitoring Batteries Wirelessly

Lithium-ion batteries, when used to drive automobiles, can operate reliably over long periods, but require considerable care. That means not operating them to the extreme ends of their state of charge or SOC. With passage of time and usage, the capacity of a lithium ion cell changes, and therefore, each cell in the system has to be managed so that it remains within its constrained SOC.

As vehicle operation requires generating as much as 1000 V or higher, tens or hundreds of cells are necessary, configured in series and parallel strings, to provide sufficient power for the vehicle. The battery electronics has to operate at these high voltages, while rejecting common mode voltage effects, and differentially measuring and controlling each cell in the strings. At the same time, the electronics has to transmit the information from each cell in the battery stack to a central point for processing.

High-power applications such as vehicles employing a high voltage battery stack impose tough conditions, including operation with wide operating temperatures and significant electrical noise. Therefore, the battery management electronics has to maximize its operating range, safety, lifetime, and reliability. At the same time, it has to minimize the weight, size, and cost.

Linear Technology has made steady advances in battery cell monitoring, increasing the life and reliability of battery packs in automobiles, and enabling high performance. For further improving the safety and reliability of full battery systems, Linear Technology is moving towards wireless Battery Management Systems or BMS.

Monitoring Batteries

Each LTC68xx IC from Linear Technology can monitor up to 12 Li-ion cells and they can be connected in series to enable simultaneous monitoring of every cell within a long, high voltage battery string. This enables precision battery management in hybrid/electric vehicles, electric vehicles, and other high power, high voltage battery stacks.

For instance, each LTC6811 has two built-in serial interfaces operating at 1 MHz each, one SPI interface for connecting to a local microprocessor, and the proprietary 2-wire isoSPI interface. Two communication options are possible with the isoSPI interface—you can connect and address multiple devices in parallel to the BMS master, or connect multiple devices in a daisy chain to the BMS master.

Wireless BMS

When employing a wireless BMS, a wireless connection interconnects each module rather than the twisted pair of the isoSPI. For instance, Linear Technology combines its SmartMesh wireless mesh networking with the LTC811 battery stack monitors to replace the traditional wired connections between the battery packs and the battery management system. This is a significant breakthrough offering a huge potential for lowering costs, reducing wiring complexity, thereby improving the reliability for large multicell battery stacks for electric and hybrid vehicles.

Automakers are ensuring the safety and reliability of their electric and hybrid vehicles by addressing the potential mechanical failure of connectors, cables, and wiring harness, as these have to operate in high-vibration automotive environments. Until now, automakers were under the impression that wireless systems would be unreliable in the metal and high-EMI surroundings within a vehicle. With SmartMesh networking, the interconnect system has proved to be truly redundant.

Ohm Battery: A Battery That Refuses To Die

A dead battery in the car is a misfortune any driver would willingly avoid. When it is important to reach a destination, a car that does not start because its battery is dead gives a terrible feeling. Most people do not want to think about the car battery too much, preferring rather to have it just work every time they start the car. The smart battery from Ohm Laboratories, Silicon Valley, does just that and makes sure you do not have to replace your car battery almost ever.

In spite of modern advancements in car technology, the car battery is still the same huge, heavy electromechanical block that it has been from generations. Although it requires replacement sometimes, it does its job quite well, and does not give you much trouble, unless you have forgotten to switch off the car lights.

One of the major reasons for a dead battery, when it has not yet reached the end of its life cycle, is when you accidentally leave the car lights on making the battery drain itself overnight. The Ohm battery, being smart, can detect when the energy in the battery is reaching its critical level, and shuts itself off. Therefore, next morning, there is still some reserve power left over to allow you to start your car. While driving, the Ohm battery recharges just as any other battery will.

The self shut-off feature is useful while the battery is within its effective life cycle, but it cannot deal with the end of life situation. Therefore, Ohm Laboratories has also provided the battery with a replacement warning system. When the system starts beeping, you know that it is time for a replacement. According to Ohm, the beeper offers a more accurate and quicker warning as compared to the battery warning light on the car dashboard.

Instead of the typical car battery with a lead-acid construction, Ohm offers a unique combination battery consisting of LiFePO4 or lithium iron phosphate and super-capacitors. The super-capacitors deliver the quick burst of energy necessary for starting the car. The LiFePO4 part of the battery keeps the super-capacitors topped up when the engine is off. Therefore, the battery system is ready to go when you perk up the key for ignition.

According to Ohm, the combination of super-capacitors and LiFePO4 has a seven-year lifespan. This is nearly twice that compared to the average life of a lead-acid battery. Ohm claims its battery also performs better in cold weather.

There is another advantage to the Ohm battery. Compared to the lead-acid type, the Ohm battery is a lot lighter. A group size 35 lead acid battery can easily weigh as much as 16 Kg. Therefore, an Ohm battery, at 2.7 Kg, may seem light as a feather in comparison. Not only does that make your vehicle lighter, handling an Ohm battery is easier during replacements.

Ohm Laboratories have made the body of their battery the same size as that of a typical lead-acid battery, which makes it a drop-in replacement. The only downside to their design is the small 10Ah reserve capacity, because of the self shut-off feature. That does not allow running electrical equipment with the engine turned off.

How Safe Are the Batteries You Use?

There is occasional news about exploding smartphone batteries. As this is a safety related issue, the topic has generated a lot of interest. Several researchers, from the National Physical Laboratory, UK, the Imperial College, London, ESRF the European Synchrotron, and UCL, the University College, London have tried to find out the reasons and the mechanism behind batteries exploding. Their research reveals how damage to the internal structure of the batteries can spread to neighboring batteries.

Now, researchers at the Stanford University, San Francisco, have developed a safe lithium-ion battery. Based on the temperature inside, the battery can shut itself down to prevent starting a fire.

When lithium batteries are packed tightly, they can overheat and catch fire if they experience short circuits or damage in some way. In fact, fires from lithium batteries have brought down two cargo jets in the past decade. Tests conducted by the US Federal Aviation Administration have found that overheating batteries can cause major fires.

When punctured or shorted, traditional lithium-ion batteries can catch fire. Temperatures inside the battery under these conditions can rise to 300 degrees Fahrenheit, causing the battery to explode. Preventive techniques of adding flame-retardants to the electrolyte of the battery usually do not work because they make the battery nonfunctional, thus defeating the purpose.

Zhenan Bao, professor of chemical engineering, and Zheng Chen, a postdoctoral scholar, have turned to nanotechnology for solving the issue of explosion of lithium-ion batteries. For this, they used a wearable body temperature monitor that Bao has recently invented. The sensor, made of plastic material, has tiny particles of nickel embedded inside. Nano scale spikes protrude from the surface of these nickel particles. To use the sensor in batteries, researchers used a one-atom thick graphene layer to coat the spiky nickel particles. They embedded the coated particles in a thin film of elastic polyethylene.

The researchers attached the polyethylene film to one electrode of the battery such that the load current of the battery would flow through the film. Under normal temperatures, the spiky particles touch one another and allow conduction of electricity. If the temperature rises, the polyethylene stretches due to thermal expansion. This makes the particles to spread out leading to the film becoming non-conductive. That stops the flow of electricity through the battery, until it cools down.

The polyethylene film starts expanding above 160 degrees Fahrenheit. That causes the spikes on the particles to move apart, causing the battery to shut down. As temperatures drop below 160 degrees, the particles come into contact again with each other, allowing the battery to start functioning again and generate electricity. According to the researchers, they can tune the temperature based on the type of polymer used and the number of nickel particles.

With the film in place, the battery shut down as soon as it got too hot and stopped working. Moreover, it resumed operation quickly as soon as the battery cooled down. As there is no electricity flowing when the battery is hot, chances of it catching fire and exploding are practically nil.

SOUNDBOKS: Batteries to Power the Next Speakers

Your next portable speakers may be able to violate county noise ordinances without the necessity of them being plugged into a vehicle power inverter, a portable generator or even a wall socket. This is what Soundboks is claiming, and their speakers will be battery-powered.

Most portable speakers are limited in their size and their power output. Usually, if you want sizes and power capacity beyond those, it becomes necessary to power the speakers through AC adapters or wall plugs so they can output continuous power. That does not help when catering to outdoor gatherings, where truly wireless music at extreme volumes is the norm. With the battery-operated speakers from Soundboks, you can now expect 30-hours of nightclub-level decibels on a single charge.

In the market, one can find plenty of audiophile-grade boom-box sized speakers such as the Nano HiFi NH1 or the rugged JBL Xtreme suitable for supplying ample amounts of power for pool events, camping, or backyard cookouts. However, the portable speakers from Soundboks beats them hollow, as they house a pair of low-frequency drivers each of 96 dB, and a pair of high-frequency drivers, also of 96 dB SPL or sound pressure level speaker units, along with 42 W digital amplifiers.

With high-efficiency custom-designed amplifiers, Soundboks speakers enhance the life of the driving batteries while optimizing the sound for outdoor usage. They have designed the speakers for dual-phase boost function and these can belt out a maximum of 119 dB of sound. You can easily get an experience of a live concert, simply by turning up the volume dial on the speaker to position 11.

Weighing in at 14.5 Kg (32 lb.), the 66x43x32 cm (26x17x13 in) Soundboks speaker is not much different from other carry-on luggage used. The low weight is because of the wood and aluminum construction of the case and that makes it shockproof, weather proof and temperature resistant. The case has an integrated side handle that makes it easy to carry about on the beach as easily as a cooler filled with beverages and ice. Wireless and wired connectivity are offered. Bluetooth 3.0 with extended range allows you to connect wirelessly while a 3.5 mm audio input provides the wired connectivity.

The truly remarkable thing about the Soundboks speaker is its ability to play music for 30 hours at 113 dB. That easily violates the county noise ordinance and that too without any help from a vehicle power inverter, portable generator, or wall socket. Each speaker comes with two external batteries, which you can swap and that gives the capability to play for a total 60 hours continuously.
The batteries are special, as they are not the usual lithium-ion type. Rather, Soundboks uses LiFePO4 or lithium-Ferro phosphate batteries that need only three hours to charge, can meet power demands and are safe. Therefore, you only need six hours of charging time, and then enjoy a full weekend-long festival program or a complete week with the volume toned down. Shipments are scheduled to start this April, as Soundboks has already raised 174% of its Kickstarter goal in one day.

What are Flexible Batteries?

We are accustomed to thinking of batteries as heavy and chunky implements capable of storing energy and powering electronic devices. For long, use-and-throw carbon-zinc batteries along with rechargeable Lead-acid and Nickel-Cadmium batteries dominated.

With the advent of portable devices such as netbooks, ultrabooks, and other hand-held devices, the battery market exploded with various types, of which, the most popular was the Lithium-ion rechargeable battery. However, with electronic gadgets getting slimmer and flexible, it is now necessary for the battery also to shed its rigid form and embrace the curves of the gadget – hence, the market for thin-film flexible battery.

In their new report, market watcher IDTechEx predicts that by 2026, the presently tiny market for thin-film batteries is going to hit $470 million. According to Xiaoxi He, a technology analyst with IDTechEx, this is the reason companies such as TDK, STMicroelectronics, LG, Samsung, Apple, and many others are all becoming increasingly involved. Considering the rate at which the Internet of Things, wearables, and other environmental sensors are being increasingly deployed, replacing traditional battery technologies is becoming imperative. New form factors and designs are urgently required.

For instance, Samsung has a curved battery in their Gear Fit wristband. STMicroelectronics is producing, in limited quantities, thin-film solid-state lithium batteries. Two other companies are now producing printed batteries, according to the report. Therefore, the market now has a variety of flexible batteries vying to power several kinds of devices.

Other companies are trying other strategies as well. For instance, TDK is working on battery-free energy harvesters. The idea is since IoT nodes and wearable devices require extremely low power to operate, these can be operated via energy harvesters rather than batteries. Others such as in South Korea have gone ahead and now TDK is planning to invest heavily in the fiscal years of 2016 and 2017 to ramp up their production of lithium-ion batteries to match.

Other companies such as the Oakridge Global Energy Solutions Inc., plan to ramp up their production capacity in their Brevard County plant at Florida. They will make electrodes and cells for thin-film, solid-state lithium batteries. They acquired this technology in 2002 from Oak Ridge Micro-Energy Inc., and plan to start volume manufacturing in early 2017.

Large varieties of flexible batteries are soon going to be available in the market. Among these will be thin-film batteries, printed batteries, laminar lithium-polymer batteries, micro-batteries, advanced lithium-ion batteries, thin flexible supercapacitors, and stretchable batteries.

Understandably, they will have diverse uses.

For instance, wearables are expected to have the highest potential of high-energy thin-film batteries, followed by printed rechargeable zinc batteries. Printed batteries, in the form of skin patches are already in use in the healthcare industry and the market is steadily increasing. At present, the high cost of printed zinc batteries is preventing widespread use despite having the highest potential for this application. According to the IDTechEx report, there will be rapid expansion in the market for micro-power batteries powering disposable medical devices.

There are additional requirements for batteries to power diverse types of power sources, displays, and flexible sensors. The US Department of Defense has invested $75 million for creating the Flexible Hybrid Electronics Manufacturing Institute in San Jose.

Flexible Aluminum Battery for Smartphones

Would you be interested in a battery that takes only a second to charge up and is flexible enough to wrap around your smartphone? While manufacturers would be more interested in the flexibility feature, most users will welcome the quick charging time. At Stanford University, researchers claim to have developed such a battery from cheap, plentiful materials. It is flexible and charges up very fast as well.

The new aluminum battery has a foil anode made of flexible aluminum, a cathode of graphite foam and an electrolyte of liquid salt. Researchers at the Stanford University say they discovered this aluminum and graphite battery quite by accident, but have worked on their discovery to improve its performance, especially the graphite cathode part.

Compared to a lithium-ion battery, the aluminum battery with its porous graphite cathode offers only one-third the capacity at a terminal voltage of 2.5V. Therefore, two aluminum batteries must be used in series to power most devices requiring 5V. However, the aluminum battery has a property that gives it an edge over its lithium-ion rival – a very high Coulombic efficiency of above 95%. Researchers are currently engaged in optimizing the capacity and other desirable qualities to match or surpass those of lithium-ion batteries.

The aluminum battery uses a liquid electrolyte, making it cheap and nonflammable. This is an ionic liquid made by mixing two solid precursors – EMIC and AlCl3, where EMIC stands for 1-ethyl-3-methyl-imidazolium chloride and AlCl3 is aluminum chloride. While both compounds are individually solid, mixing them significantly lowers the melting point of the mixture so that it remains a liquid at room temperatures. The liquid electrolyte and the porous graphite electrode contribute to the super-fast recharging time, and the amount of current the aluminum battery can deliver.

The porous graphite foam cathode presents a large surface area, which is the governing factor for accessing the electrolyte. While charging, the large surface area presents a low energy barrier to the process of intercalation. The team expects the flexibility of the battery will be useful to manufacturers making flexible smartphones in the future.

The main attraction of the aluminum battery as compared to the lithium-ion batteries currently available is its capability of fast recharge. In fact, even the prototype reached 7.5 times the rate of charging of a commercial lithium-ion battery. Typically, lithium-ion batteries loose significant capacity after they have reached about 1000 recharge cycles. In comparison, an aluminum battery is capable of withstanding more than 7500 charges without any loss of capacity.

That makes the aluminum battery suitable for large installations such as storing solar energy during the day for release at night on the grid. These batteries are a perfect replacement for the lithium-ion batteries that occasionally burst into flames and for alkaline batteries that are bad for the environment. According to the researchers, even if someone were to drill through an aluminum battery, it will not catch fire.

At present, the only drawback is the terminal voltage. However, the researchers are optimistic that with a better cathode material, the aluminum battery can be made into a more powerful commercial battery.

Rechargeable Batteries from Packing Materials

Sweden was in the news recently for their extreme recycling capacity. Swedes recycle waste to the extent that they have to import garbage from other countries for use as landfills. Others countries struggling to recycle their garbage may be interested in generating rechargeable batteries from discarded packing materials that do not degrade when used as landfills.

At Purdue University, researchers have found a new way to recycle discarded peanut-shaped packing materials. They are turning these materials into components that can be used for making rechargeable batteries. Additionally, they claim their batteries can outperform those currently in use.

Packing materials have always presented a challenge when they have to be disposed. It is not very cost-effective to recycle them. For one, they are light and their large size makes it expensive to transport them to the recycling center. Additionally, they take up a lot of space in landfills. Vinodkumar Etacheri, Ph.D. explained this in a presentation of the research at the National Meeting & Exposition of the American Chemical Society.

The other reason why packing materials are not suitable is they can be harmful to the environment. Although they may not contain CFCs or ozone depleting gasses, packing materials are usually made from recycled or new polystyrene, which was also used for making Styrofoam. While the exact constituents may vary, packing materials usually contain different types of chemicals.

Among them may be potentially harmful substances such as heavy metals, chlorides and phthalates. These leach into the environment easily when in a landfill. They deteriorate the soil and water quality. Although marketers claim newer material they use for making packing material is more environmentally friendly, the chemicals and detergents used in the starch-based alternatives also contaminate the ecosystem.

A new process developed by the researchers converts the packing material into high-tech nano-particles and carbon micro sheets. These are useful in making anodes for rechargeable batteries.

Lithium ion batteries have lithium ions moving between electrodes as the batteries charge and discharge. When the new anodes replace the conventional graphite ones in commercial lithium ion batteries, the performance gain is dramatic. The anodes made of nano-partcles and carbon micro sheets increase the storage capacity of the lithium ion batteries several folds.

The porous microstructure of the new anodes allows the lithium ions to diffuse in quickly and create more surface area within the micro sheets. The increased surface area offers greater electrochemical interactions. In addition, the disordered crystal structure and the porous nature of the new anodes can store more lithium ions beyond their theoretical limit.

According to the researchers, they use a relatively low temperature for the new process. This is a crucial factor in producing these new materials with their advantageous architecture. While other researchers make micro sheets at temperatures as high as 4,000°F, researchers at Purdue University have kept the temperature of their process at only 1,100°F. Instead of the more layered arrangement of carbon atoms at the higher temperature, the lower temperature generates less-ordered materials. That actually increases the electrical storage capacity by about 15%. The lower temperature process also allows the materials to remain more environmentally friendly.