Whether it's smartphones, tablets, or the wildly popular Tesla electric vehicles, the lithium-ion battery technology used in all electronic devices is essentially no different from the first commercially available lithium-ion battery announced by Sony in 1991.
Over the past 23 years, innovation has not been absent; researchers around the world have never given up on developing new battery technologies. 2014 saw a series of breakthroughs, with traditional lithium-ion batteries showing increasingly better performance in terms of charging efficiency, battery capacity, and heat dissipation. Many new battery technologies also seem to be seeing the dawn of commercialization.
However, even now, battery life is still far from satisfactory, and battery technology remains the biggest bottleneck in the evolution of all electronic devices. Moreover, from an industrialization perspective, battery technology is still quite far from a revolutionary breakthrough.
You can't have your cake and eat it too.
Why is it so difficult for battery technology to achieve revolutionary breakthroughs? What exactly is wrong with the mainstay lithium-ion battery?
Lithium has an atomic number of 3, which means it has three protons and is the lightest alkali metal element, making it the most suitable material known for preparing the positive electrode of a portable battery.
Of course, besides lithium, lithium-ion batteries also include other metallic and non-metallic materials such as iron phosphate, manganese, graphite, and titanates. Compared to the earlier nickel batteries, lithium-ion batteries are smaller, lighter, and have a higher energy density. In less than 15 years, they replaced nickel batteries and have become the mainstream battery technology for electronic devices.
However, it also has many problems, the most important of which is heat generation. During the charging and discharging process of lithium-ion batteries, a large amount of heat is generated inside the high-density space.
For small electronic devices such as smartphones, the problem of heat generation is not too big due to capacity limitations, and the heat dissipation problem can be basically solved by the internal heat conduction design of the phone. However, for large devices such as Tesla electric cars, whose chassis are covered with thousands of lithium-ion batteries, corresponding cooling measures must be taken.
This is why almost all electric or hybrid vehicles have a large liquid cooling system attached to their lithium-ion battery packs. However, even so, accidents involving electric vehicle batteries exploding and catching fire still occur from time to time.
The number of lithium ions in a lithium-ion battery is fixed. To extend battery life, more batteries must be added, which means heavier devices, greater heat generation, and a higher risk of overheating and explosion. Conversely, greater safety or portability often comes at the cost of fewer batteries and longer battery life.
Replace the lithium-ion battery
Following this line of thought, one breakthrough the researchers envisioned was finding safer materials with higher energy density to replace lithium-ion batteries.
Air may well be one of the better options. Not long ago, an Israeli technology company developed a new type of battery that uses aluminum and air as electrodes. This battery can utilize the chemical reaction between water molecules in the air and aluminum to discharge.
In fact, this metal-air battery technology was first introduced in the 1960s. Its principle is to use 99.9% high-purity aluminum as the anode, oxygen in water molecules as the cathode, and use aqueous solution as electrolyte to allow the aluminum plate to absorb oxygen and complete the discharge process.
The final product in the entire chemical process is aluminum hydroxide, making this battery technology appear more stable and safer. Furthermore, the energy density of aluminum-air batteries is significantly higher than that of lithium-ion batteries of the same mass, with a theoretical energy density reaching 8.1 kWh/kg. Currently, the high-energy lithium-ion batteries used in Tesla electric vehicles have an energy density of only about 0.3 kWh/kg.
Another breakthrough approach popular in battery technology is to find a different charging method if lithium-ion batteries cannot be replaced.
The most promising alternative charging method to become widespread is wireless power delivery technology. Note that this refers not to the wireless charging phones with charging trays that manufacturers introduced a few years ago, but to the more efficient wireless power delivery technology.
In principle, wireless charging and wireless power supply are not significantly different; both utilize electromagnetic induction, resonance, or coupling. It originated from the idea of Nikola Tesla, the father of alternating current, in the 1890s. He proposed using magnetic resonance to transfer charge in the air between the charger and the device, with coils and capacitors creating resonance between them, thus achieving efficient power transfer.
To put it more vividly, it's similar to how a high-pitched singer might break a glass with the same vibration frequency, except that electromagnetic induction and resonance wouldn't cause an electronic device to explode.
Compared to wireless charging, wireless power delivery has the advantage of overcoming distance limitations. A US company is working on a transmitter solution that can transmit power over distances of up to 10 meters.
Although the transmission distance of wireless power supply is still relatively short compared to wireless networks that can easily reach hundreds of meters, at least from a technical perspective, achieving wireless power supply is already a first step forward.
An even bigger problem
So why haven't we seen similar wireless power hotspots in airports, hotels, or coffee shops?
In fact, the biggest obstacle to the widespread adoption of wireless power is not technical problems such as insufficient transmission distance, but rather the compatibility issues of wireless power standards among various electronic devices on the market, which is beyond the control of researchers.
Just like the example of a high-pitched singer, if each cup vibrates at a different frequency, it's impossible for all the cups to burst from the sound.
However, in 2008, several international companies and associations in the industry established the Wireless Power Transmission International Standards Alliance, dedicated to unifying the technical standards for wireless power supply. A member of the alliance from a Chinese company said that the time for the release of a unified standard similar to WiFi should not be too far off.
In comparison, new battery technologies to replace lithium-ion batteries are much more difficult to develop. The most promising metal-air battery technology still has many practical problems to solve. For example, water needs to be added to the battery pack regularly during use, and because it is a non-rechargeable battery, the aluminum plates must be replaced after they are completely oxidized into aluminum hydroxide.
This will undoubtedly increase costs and hinder the application of metal-air battery technology. However, the good news is that researchers are working hard to extend the oxidation reaction time of aluminum plates and reduce the cost of recycling aluminum plates, striving to commercialize this technology as soon as possible.
Kevin, a researcher at the Mott Engineering Science Center at Kettering University, believes that even if the technology has reached commercialization standards, large-scale application of these technologies in various electronic devices will be another long process. Without a specific catalyst, it's unlikely we'll see truly mature, revolutionary battery technology for at least the next five years.
