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The Problem with Batteries


Unlike other electronics-related technologies, batteries don’t seem to advance that quickly. What gives?

First off, it helps to know what a battery is and how it works. How Stuff Works has a great article on this, but I can also give you the short version. All batteries consist of positive and negative terminals, which are attached to cathodes and anodes (collectively known as electrodes), respectively, within the battery. Some medium must exist between the two to transmit energy, and this is the electrolyte. A battery’s life is always limited because the energy contained within the anode and cathode is limited. Their chemical reactions produce the energy that allows batteries to do work. Once the chemicals required to release that energy are used up, the battery is kaput. In the case of a rechargeable battery, the chemical reaction can be reversed, at least to some extent. All rechargeable batteries eventually wear out, too–they can no longer reverse the chemical reactions that restore them to a useful state.

Having a brief overview of how batteries work, the next question is why battery technology seems to lag far behind, say, computer processing power. The smartphone in my hand today is more powerful than the biggest supercomputers of 30 years ago. That’s an enormous leap in technology! But batteries now are only modestly more powerful than they were 30 years ago. The technology has improved, to be sure, but not by several orders of magnitude–not even close.

The first problem is one of chemistry. A given quantity of anode and cathode material can only produce so much energy. To get more energy out of it, you simply have to make them bigger. For obvious reasons, this quickly becomes impractical. For computers, the problem is much the opposite. Originally, transistors were very large–a single transistor vacuum tube could easily fill the palm of your hand. These were horribly inefficient, and progress over the past several decades has made them ever smaller. Nowadays, the transistors in CPUs are so tiny you’d need an electron microscope to see them individually. It’s not that each transistor has itself become dramatically more powerful, but that we’ve managed to make them thousands of times smaller.

Unfortunately, the same is almost impossible with batteries, because we are limited by physics. In the past, battery improvements came from trying new materials for the electrodes and the electrolyte. So far, the best practical combination we’ve found for a rechargeable battery is the lithium-ion type. Lithium ions move from one electrode to the other, depending on whether the battery is charging or discharging, and these cycles can be performed hundreds of times on a single battery. They also don’t develop a capacity-limiting “memory” as other types of batteries. But thus far, we’ve yet to find any chemical reaction that is similarly stable, reversible, portable, and practical. Some reduction is size is possible, but that will only get you so far. We simply lack the materials to make better batteries at this point.

How else do you get more energy out of a battery, then? You make the applications of those batteries more efficient! Ironically, smartphones have represented a huge step backward in terms of battery efficiency. Prior to the iPhone, which came out in 2007, smartphones were a niche market made up mostly of Palm Pilots and PocketPCs. While their battery life was subpar compared to more traditional cellphones of the era, it was still over and above the kind of battery life the iPhone offered. Today, we’ve more or less become accustomed to smartphones which require charging every night. But even the smartphones of the early 2000s could boast charge cycles measured in days. Some cell phones could go for a couple weeks without needing to be recharged.

Today’s smartphones can’t deliver this kind of performance for a few reasons: their hardware is much more powerful and thus draws more energy; the software involved is much more sophisticated and likewise requires more power to do the same work; and phones today bring a lot of features to the table that simply didn’t exist in most phones 15 years ago, such as GPS, onboard cameras, wireless networking, and so on. When each new generation of smartphones brings improved battery life, this is primarily because of improvements in software and hardware efficiency, not because of strides in battery technology.

It may well be the case that efficiency gains are where we make up most battery life improvements for the foreseeable future. This means writing better software and designing hardware that uses energy more effectively rather than wasting it while idling or radiating it as heat. Short of some major breakthroughs in materials, this will be the state of the art in batteries for some time to come.

On the other hand, research into better batteries is seeing more attention than ever because batteries themselves are seeing more applications than ever. Everything from wearable technologies–smart watches, fitness trackers–to electric and hybrid cars are pushing investment into better and more efficient batteries. There may yet be breakthroughs in store, but like the path that led to the ubiquitous lithium-ion battery, it may take decades of false starts and relatively inefficient technology before we reach that epiphany.

One thing is certain: batteries are everywhere and are not going away. Whether we learn to use them better through more efficient applications, or actually make the batteries themselves more technically sophisticated and powerful, our technological futures are inextricably bound to them.