A look inside the world of batteries

15Feb 2019

Everyone’s excited about 5G. And with good reason. All the great things we have been able to do on our smart phones with 4G LTE will multiply into bigger and better things in the 5G Era. We’ll be able to send and receive huge text and image files in the blink of an eye. Entire movies will download in seconds. In short, 5G will make our smart phones vastly more useful as business productivity tools and as entertainment platforms. I don’t know about you, but I can’t wait.

There’s just one thing. The excellent experiences of 5G can’t happen without battery power.

Unfortunately, batteries are a major stumbling block of the smart phone era. Explosions and fires, although rare, are a serious problem. One such mishap is too many.

A little history: Introduced commercially in 1991, lithium-ion batteries are a tremendous advance over previous-generation technology, such as nickel-cadmium and nickel-metal hydride, and they have made the 4G LTE era possible. But in the 5G era, lithium-ion batteries risk being exposed as the weakest link in the chain of 5G-enabling technologies.

This looming catastrophe is no secret. Smart phone manufacturers and network operators I speak with are concerned about 5G and the demands that will be placed on handsets. They know something must be done. But what?

Researchers are working night and day to come up with breakthrough battery technology, such as solid-state batteries or batteries using nano materials. But battery breakthroughs often take a decade or more, and billions of dollars in investments. Much more work needs to be done before these next-generation batteries are ready to be deployed in large volumes. Realistically, we need to accept the fact that 5G will dawn on smart phones equipped with lithium-ion batteries. The only sensible approach is to get those batteries as ready as they can be for the new era.

Briefly, here’s the issue: Every battery has a cathode and an anode, in a substance called the electrolyte. During charging, ions move from the cathode to the anode through the electrolyte. In lithium-ion batteries, tiny tree-like growths called dendrites may form on the anode over repeated charging cycles. These dendrites can grow so large that they eventually reach through, touching the cathode and causing an electrical short, possibly leading to an explosion or fire. Dendrite formation is accelerated by factors that stress the battery, such as rapid charging or overcharging. Damage caused by these stresses accumulates over time.

5G will put stress on batteries as never before, thanks to several factors:

  • The higher-frequency bands of 5G require more power. 5G encompasses new frequency bands of 3 GHz to 6 GHz and above 24 GHz. Power consumption increases linearly with frequency, so going from 900 MHz to 6 GHz, for example, incurs a 5x increase in power demand all else being equal.
  • Data traffic will increase substantially. Even though 5G is highly efficient, throughput rates will be higher and displays will be larger. More bits will be streaming at rates exceeding 1 Gbit per second, requiring additional power.
  • 5G apps will require low latency, about one millisecond. For example, streaming video on a larger screen will sharply reduce idle time for the processor and battery. That means greater power consumption.
  • 5G will require denser placement of antennas across the landscape, and until carriers add more antennas, handsets and their batteries will have to work harder.

In all, network operators estimate 25% to 50% increase in power demand.

Preparedness

There is hope, however, if intelligent battery management software is implemented. The first step is to reduce the stress on the battery; the second is to monitor battery health so that danger is spotted before problems occur. These twin tasks are simple in principle but challenging in practice.

To measure the chemical processes at work, it is possible to utilize the electrical current that charges the battery as a kind of messenger. By applying principles similar to sonar, it is possible to retrieve information from the electrical current’s echo about the chemical reactions within the battery. Based on that information, the reactions can be tuned to make them better performing. These same signals also relay information as to any problems that are developing, such as the dendritic formations that produce electrical shorts.

By lessening battery stress and monitoring battery health, doubling battery longevity is a reasonable expectation. Most phone batteries are rated at 500 charging cycles, but that can be increased to 1000. And battery life isn’t the only thing that can be improved. As a battery charges and recharges, it enlarges in size, gaining perhaps 10 percent in volume. Intelligent battery management can cut that swelling in half.

Simply put, intelligent battery management is a must-have for all smart phones. Nothing else does a better job ensuring battery health and safety. As we await the arrival of 5G, there is no need to despair or to become impatient with the slow progress of battery chemistry technology, when intelligent battery management is here today.

17Jan 2019

Ted Miller, senior manager of energy storage at Ford Motor Co., recently stated:  We don’t see another way to get there without solid-state technology.” The statement is in regard to more powerful batteries for electric vehicles. Mr. Miller goes on clarifying: “What I can’t predict right now is who is going to commercialize it.”

So what is a solid state battery and why is it so difficult to commercialize? 

First, let’s clarify some misconceptions. 

A polymer battery, known as a LiPo, is a lithium-ion battery. 

A cylindrical battery, like an 18650 cell (used in the early Tesla models) is also a lithium-ion battery.

A prismatic battery is too a lithium-ion battery with a hard shell.

And so is a solid-state battery. It involves newer manufacturing processes, but it is a lithium-ion battery. 

All of these variances of lithium-ion batteries have one physical principle in common: the lithium ions contribute to storing the electrical energy.

Simplistically, a lithium-ion battery operates with lithium ions shuffling back and forth between two electrical layers: an anode and a cathode. When the ions are at the cathode, the battery is discharged. When they move to the anode, then the battery is charged. The cathode and anode are called electrodes.

The motion of the ions between these two electrodes is facilitated by an intermediate medium called electrolyte. It is a solution that is electrically conductive: it permits ions to travel through it with little impediment. One key property is called conductivity: it is a scientific measure of the ease at which ions can travel through the electrolyte. High conductivity means the ions can travel easily and quickly. Low means the opposite.

In a lithium-ion battery, the two electrodes are immersed in an electrolyte solution. Today’s batteries use a liquid or gel-like electrolyte. Battery manufacturers go to great lengths to formulate unique electrolytes for their batteries. The formulations do have an impact on many of the battery’s specifications, in particular cycle life (the number of times a battery can be charged and discharged). 

In a solid-state battery, the liquid or gel electrolyte disappears. It is instead replaced by a “solid-state” layer sandwiched between the two electrodes. “Solid-state” means this layer is not a liquid, but a physical solid. The material can consist of a ceramic, glass, or even a plastic-like polymer, or some type of mixture of all three.

So why use a solid electrolyte? There are two major reasons. First, a battery with solid electrolyte occupies a lot less space than one with liquid electrolyte. That means one can pack more energy in the same volume. Consequently, energy density — an important metric of batteries — goes up.

The second reason is safety. Liquid or gel electrolytes are more prone to catching fire than a solid electrolyte.

Traditionally, the primary challenge with solid electrolytes is poor conductivity especially at room temperature (25 °C or 77 °F). A liquid or gel electrolyte has a conductivity that is about 1,000 times better than that of solid electrolyte. In other words, solid electrolytes exhibit a far higher resistance to the flow of lithium ions. This results in several performance challenges, starting with poorer cycle life and inability to charge at fast rates. 

Some companies proposed operating their solid-state batteries at elevated temperatures (> 80 °C) to improve conductivity. But this is not practical under most use scenarios.

Therefore the quest for solid electrolyte materials continues to be a much active field of exploration and discovery. There is confidence in the industry better materials will be discovered, yet, we really can’t predict when a breakthrough will be widely adopted. 

Another challenging aspect is the surface stability and manufacturability of solid electrolytes.  Unlike liquid solutions, glass and ceramic electrolytes are not deformable. They must be assembled with the two electrodes using high external pressure, equivalent to about 1,000 atmospheres. It becomes questionable whether existing battery manufacturing factories can be retooled for this purpose. If not, the economics of solid-state batteries will undoubtedly suffer as is the present case.

In a nutshell, there is much promise in breakthrough material innovations to make solid-state batteries a reality. Yet, many challenges remain ahead. I personally do not expect to see solid-state batteries in commercial scale for several years to come. We will continue to see evolutionary progress with traditional lithium-ion batteries especially as prices continue to decline.

But in all cases, solid-state batteries are subject to the same physical principles that govern traditional lithium-ion batteries. Consequently, many of the battery management solutions developed for traditional lithium-ion batteries will evolve and continue to apply. And that is good news.

14Nov 2018

Geoffrey Fowler at the Washington Post recently published an article observing that phone battery life is getting worse. I enjoyed my conversations with Geoffrey as he researched the topic. But why is the phone battery life getting worse? Why are batteries not keeping up with the new crop of smartphones? 

Like so many things in life, it is all about energy balance. Our doctors tell us that we need to balance our calories: Calories we eat versus the calories we expand on exercise. And so the smartphone needs to balance its energy stored in the battery versus the energy it spends on use. So I distill this to two simple questions on energy demand and supply:

  1. Why is the energy demand growing with increased use of our smartphones?
  2. Why can’t we have a bigger battery to supply our growing energy needs in a smartphone?

So let’s tackle the first question by examining the sources that drive energy consumption in a smartphone. There are three parts in your smartphone that are energy hogs:

  • Your screen….ok, I am sure you all know that ;
  • Your processor….some of you probably know that too ;
  • Your radios. Not your FM radio! Radios means the cellular connection, WiFi connection, bluetooth, GPS….anything that communicates with the outside world using radio waves.

Energy consumption for each of these parts depends on the nature of the hardware and you, the user — that’s the length of time you spend on the device. 

The energy used by a screen is quite large, even with the new OLED screens. Screens are getting a bigger numbers of pixels. Each pixel consumes energy. More pixels means more energy.  Every time you turn the screen on, it’s more energy that the battery has to supply.  And that adds up rapidly. 

If you follow various chatrooms, you probably know that “screen time”, meaning the total amount of available battery time with your screen on, is probably about 6 hours, give or take – regardless of what the smartphone maker advertises about all day use or more.

Next is the processor. Fortunately, that piece of hardware used to be a major energy hog but with the new generation of processors from Qualcomm or Apple or Samsung, they have become quite efficient. How much efficient? About twice more efficient than the previous generations from a few years back. All good news, right? well, not quite.

You see, processors have become efficient indeed, but now they are running a lot more frequently than they ever did. Think about an SUV parked in the garage versus a Honda Civic used for Ubering. Which one uses more energy?

A few years ago, we used our smartphones for texting and emailing….now, we stream videos. So while these processors are efficient, they are being taxed by video and social media. Net net, they are consuming more energy from the battery. How can you tell? watch how hot your smartphone becomes when you stream videos or take 4k movies on your device. That’s your processor getting hot.

Let’s talk now about radios. That’s a growing problem for the battery, so much that carriers like AT&T and Verizon in the US, or DoCoMo in Japan are really worried about it.

On one hand, carriers love that you use more and more data…that’s how they make money. But data use means your cellular connection is on, a lot more than before. 

But you say wait, isn’t 5G cellular connection better than LTE? Think of 5G as adding more lanes on the internet superhighway as compared to LTE. It means more cars, a lot more cars, will use the highway. It means more energy will be consumed. And the battery needs to supply this energy.

The FCC is just auctioning a new range of frequencies between 24 GHz and 47 GHz for the future 5G spectrum. By comparison, LTE runs at frequencies between 0.5 GHz and 2 GHz. Why is this important? Energy use goes up with frequency. So by going to the new 5G frequency, energy consumption will grow with it, worsening the burden on the battery. In other words, the future will tax the battery even more!

Bottom line: our smartphones and our user behavior mean our appetite for more energy will continue to grow.

Now we can tackle the second question: Why can’t the device manufacturer put a bigger battery in the smartphone? 

It is simple: Bigger battery capacity means a physically bigger battery. Batteries are improving so slowly such that the only way to give users more battery capacity is by making the device larger or thicker. The recent iPhone XS, XR and XS Max show a clear trend to making larger devices that can hold larger batteries.

Will that be enough for the future? not really. Smartphone sizes can’t get any bigger. At 6 in or greater screen sizes, they are already too large to hold in one hand. They may get a little thicker but not by much. Our human hands determine the optimal physical form for a smartphone.

So what gives? I don’t know yet, but most likely, our behavior and expectations. It is quite likely that users may charge their smartphones more frequently in one day…perhaps charge twice instead of once. Some users might be happy with fewer pixels in their devices. Others may turn off their Facebook and social media apps. 

Regardless of how we adapt to the future of smartphones, the battery will continue to be the weakest link, and the one in most need for innovation.

31Oct 2018

The break I took from writing is over. I hope many of the readers took the time to read, re-read and digest the insight I shared in my earlier blogs. 

My return theme is around battery safety.  Since 2016, when the Samsung Note 7 became headline news, there have been countless reports of battery safety problems, several of them with catastrophic outcomes. As ominous as they are, these events are covered on the second page, not the first page. But that should not offer any of us any peace of mind….as the old saying goes “where there is smoke, there is fire.”

The Washington Post and other media outlets reported today that Lime, the company that is deploying thousands of electric scooters on US streets, has recalled some of its scooters because of the risk of fire in their batteries. The company, in a statement, admitted that a “manufacturing defect” may result in the “battery smoldering.” Indeed, on August 27, a Lime scooter caused a fire at the company’s Lake Tahoe facility.

Lime said that the problem is rare, with only 0.01 percent of its fleet of scooters recalled. The fact is that 0.01 percent is not a small number when it comes to battery safety. For the Samsung Note 7, that figure was less than half….yet, it was not pretty. 

The Lime scooter story is not the only one that highlights the rising safety risks of lithium-ion batteries. On June 22 of this year, Nazrin Hassan, CEO of Malaysian tech company Cradle Fund died at the hands of his smartphone which allegedly exploded in his bedroom as he slept nearby. Hassan’s brother-in-law said that he had two smartphones, a Blackberry and a Huawei. They did not know which one exploded. 

These are just two recent examples where battery safety caused or risked causing a tragic and catastrophic outcome. A web search for “lithium-ion battery fire” returns over 21 million entries. So if battery fire risks are so real and increasingly common, why are we not taking this issue more seriously?

The coming year will witness the deployment of 5G wireless network. It is an amazing new evolution in how we communicate via wireless devices. But 5G will also place a severe burden on the battery. We are already testing new generations of lithium-ion cells with terminal voltage of 4.45 V. To put in perspective, the battery voltage used to be 4.2 V only a few years ago. The increase in battery voltage has erased any safety margin that was built in the older generations of batteries. 

Electric vehicles are growing in numbers. The Tesla model 3 was ranked among the best selling sedans in North America this summer. More auto manufacturers are introducing more electric models on our streets. It is a great evolution towards green transportation. But how will we react to battery fires in vehicles?

Statistically speaking, battery events occur at the rate of about 10 to 100 failures for every one million devices (in technical lingo, 10 to 100 ppm). This may sound like a small numerical figure, but when multiplied with the billions of devices that use batteries, the number of safety problems becomes very troubling.  Yet, there are technologies that can reduce this figure by a factor of 100 (down to parts per billion or even lower). It’s time that the battery safety is taken far more seriously.

17May 2018

I googled the question “ should I charge my phone to 100”. Google returned 467 million results. From folks offering opinions on “how to properly charge” to others calling on “science”, there seems no obvious consensus in the media. Yet,  unlike views on more socially charged topics, this question ought to be a lot simpler and ought to have a clear cut answer. Let’s explore.

I start with an easy experiment. Take two batteries. Charge one of them continuously to 100% and discharge it back to zero. Repeat. Take the second battery and charge it only to 90%. Discharge it. Repeat. Now compare the two batteries.  Are there differences? the answer is yes, there is difference. The battery that was charged to 100% will age considerably faster. 

What do I mean by aging? The technical term is “cycle life.” In practice, it means that the battery charged to 100% will lose its ability to store electric charge faster than the other battery. The difference between the two batteries can vary between 100 and 300 charge cycles.

So is that good? Well, it depends on what your use is. The definition of “good” is relative.

For a smartphone, my answer is “I really don’t care.” 

For an electric vehicle, my answer is “yes, it is better, but may be only marginally.”

For energy storage batteries used by electric utilities, my answer is “yes, absolutely.”

Now, let’s dive into the details.

A smartphone battery usually lives about 500 to 800 cycles. By cycles, I mean the number of times you will be able to charge it (to 100%) and discharge it before it becomes old and useless. Some smartphone manufacturers do better than others. Apple’s and Samsung’s batteries tend to be closer to 500 cycles. Others like LG, Sony and Huawei tend to be closer to 800 cycles. 

Let’s convert cycles to real-life years. Most smartphones are charged once a day. So 800 cycles is about 2 years of use before your battery becomes old. That corresponds well with the average time for consumers to upgrade. But wait, you might say you plan to keep your smartphone for longer than 2 years. What should you do?

Naturally, one option is to spend $30 to $50 once your battery is depleted and get your phone serviced after 2 years. The other option is to charge your phone to only 80% or 90% instead of 100%. That exercise will probably get you an extra year of usage.

But that is not the only way to get more longevity. You probably don’t know that if you use a small AC adapter instead of a bigger one, you will probably get the same benefit. For this method, look for an AC adapter that is rated 5 Watts, or use the USB port in your PC to charge you handset. And that applies to iPhones or Android phones. What do you give up? You are giving up fast charging. If you charge your handset overnight, then you really don’t care.

A self-serving plug for Qnovo: Smartphones with intelligent charging algorithms will take care of longevity issues for you so you really don’t have to think about this question and its answer. 

Now, let’s talk about electric vehicles. Should you top off the battery in your electric vehicle (EV)? First, it is important to know that EV manufacturers (from GM and Tesla to Nissan and VW) already limit the charging of the car battery to somewhere near 80%. The 100% that you read in your dashboard is actually 80% of the what the battery is rated for. That figure usually is sufficient to meet the warranty terms of the vehicle, often 100,000 miles or 10 years.

If you are leasing your car, then you really don’t care. Your lease will expire long before any meaningful battery aging sets in. But if you purchased your EV and plan to keep for a long time, then you may have an incentive to not top off your battery.

But wait, that is also not the only way to get more longevity. Every time you use a supercharger or DC fast-charging, you are causing serious damage to the battery. So instead, try to avoid using superchargers. This is particularly acute for the Panasonic batteries used in some of the Tesla models.

Lastly, I will add a few final words about electric utilities and batteries they use. These are complex systems that are slated to operate for at least 20 years! They are also very expensive assets that cost millions of dollars. So longevity is a serious matter. Naturally, users have no say in how these batteries get charged. Utilities and battery manufacturers do watch over these batteries so that they can last for a long time.