Long Lasting Lithium Batteries that Don’t Explode

2,000 Cycles; Charge from 0 to 100% in 10 Minutes; No Explosions

After several charge-discharge cycles, lithium batteries tend to grow “dendrites” that can short-circuit the cell and start fires:

There’s a problem with lithium batteries that stems from those internal short circuits that can develop. The batteries can explode because the lithium in them reacts to water, or to the water vapor that’s present in ordinary air. Lithium batteries are generally safe, but if a battery is damaged or has a manufacturing defect, it can explode or catch fire. __ Source

When a lithium–ion battery charges, lithium ions travel from the cathode to the anode; the ions flow the other way during discharge. At a lithium metal anode, lithium ions leave and return to the surface unevenly. This means that after several charging cycles, spiny projections called dendrites begin to grow from the electrode’s surface. As these lithium dendrites grow, they can pierce the membrane separator in the middle of the battery, touch the cathode and short circuit the cell. This can starts fires.
Image Source

What if there were a cheap and reliable way of getting thousands of cycles from lithium batteries, with a 0 to 100% charge time of 10 minutes (!), without risk of starting fires? A recent research study from UCSD suggests a clever modification of existing battery concepts, which may help bring about some startling changes in capabilities for consumer electronics, electric cars, and more.

Researchers showed that a lithium metal battery equipped with the device could be charged and discharged for 250 cycles and a lithium ion battery for more than 2000 cycles. The batteries were charged from zero to 100 percent in 10 minutes for each cycle.

“This work allows for fast-charging and high energy batteries all in one,” said Ping Liu, professor of nanoengineering at the Jacobs School and the paper’s other senior author. “It is exciting and effective.”

The team details their work in the Feb. 18 online issue of the journal Advanced Materials. __ UCSD via New Energy and Fuel

With today’s primitive lithium batteries, high numbers of rapid charge-cycles increase the chances for dendrite formation and battery fires. But if lithium batteries undergo the right modifications, everything can change.

In this work, we expect to overcome the two underlying problems hampering rechargeable battery progress for over 50 years: protracted charging times and inadequate lifetime due to unfavorable morphological changes. We especially seek to avoid Li dendrites when metal deposition processes are employed in a carbonate‐based electrolyte, EC/DEC, which is notorious20 for Li dendrite formation and caused by ion depletion in the electrolyte adjacent the anode. A SAW‐integrated LMB (SAW LMB) is therefore proposed, as shown in Figure 1, as a new route to potentially overcome these longstanding problems. By driving sufficient flow of the electrolyte through the interelectrode gap, it becomes possible to prevent the formation of Li ion depletion regions, thus preventing dendrites, adverse heating, and electrolyte breakdown. The flow is driven by acoustic (fluid) streaming generated by the SAW device, significantly reducing the Li concentration gradient in the electrolyte—even during rapid charging—and uniform Li deposition is made possible. The power consumption of the SAW device is around 10 mWh cm−2, relatively small in comparison to the charging itself, and in any case occurring when power consumption is acceptable: during charging. During LMB discharge, dendrites do not form, and so the SAW device may remain off. __ Enabling Rapid Charging Lithium Metal Batteries

There have been many attempts to make the cheaper lithium metal batteries as rechargeable as more expensive lithium ion batteries, while keeping them safe from dendrite formation. One method by XNRGI involves the use of a silicon matrix to increase capacity and prevent propagation of battery faults in a fire. Another approach from Waterloo University researchers involves adding phosphorus and sulfur to the electrolyte to protect the lithium metal in the anode from explosion-causing contact with water, in a crash. Northwestern University scientists devised yet another approach using graphene. And scientists at Rensselaer Polytechnic Institute developed yet another way to prevent the dendrites from growing and causing short-circuits, using short bursts of current.

In the UCSD approach we are looking at today, the use of a cheap mass-produced ultrasound emitter borrowed from the cell phone industry seems to do the trick:

The device that the researchers developed is an integral part of the battery and works by emitting ultrasound waves to create a circulating current in the electrolyte liquid found between the anode and cathode. This prevents the formation of lithium metal growths, called dendrites, during charging that lead to decreased performance and short circuits in LMBs.

The device is made from off-the-shelf smartphone components, which generate sound waves at extremely high frequencies—ranging from 100 million to 10 billion hertz. In phones, these devices are used mainly to filter the wireless cellular signal and identify and filter voice calls and data. Researchers used them instead to generate a flow within the battery’s electrolyte. __ UCSD via Brian Westenhaus

There are multiple ideas here:

  1. Making all lithium batteries safer and longer lasting
  2. Making cheap rechargeable high capacity lithium metal batteries safe
  3. Making rapid (10 minute) 0 to 100% Charge times safe

Currently, LMBs [lithium metal batteries] have not been considered a viable option to power everything from electric vehicles to electronics because their lifespan is too short. But these batteries also have twice the capacity of today’s best lithium ion batteries. For example, lithium metal-powered electric vehicles would have twice the range of lithium ion powered vehicles, for the same battery weight. __ Brian Westenhaus

If this technology works and is affordable, it could boost the capacity and safety of battery-run devices while helping to reduce battery costs.

More from Brian Westenhaus: Learning to substitute sodium ion batteries in place of lithium-ion batteries. Sodium is much cheaper and more abundant than lithium, after all.

Another new battery: Potassium metal batteries —

As well as being cheap and abundant, potassium tends to be easier to work with, meaning manufacturing costs are lower as well as material costs. Using full potassium metal anodes, batteries can be built with energy densities (both by volume and weight) that are comparable to what lithium offers.

The problem up until now has been one that’s been present in lithium batteries as well: dendrite formation. Over time, as the battery is charged and discharged again and again, bits of the metal – ether lithium or potassium – start to attach themselves to the anode. This doesn’t happen evenly; little spiky branches called dendrites begin to form, and eventually, they get long enough to poke through the insulating membrane separating the anode from the cathode, and they short circuit the battery. This causes heat build-up and occasionally fires, and effectively reduces the lifespan of a battery.

… Now, a team of scientists from the Rensselaer Polytechnic Institute in New York state say they’ve developed a self-healing technique that can clean these dendrites off the anode as you charge the battery overnight, preventing them from ever getting long enough to cause problems. They believe it’s now possible to bring cheap, long-lifespan potassium metal batteries into mass-market use. __ Source

The sooner the better.

Reality Check

Better batteries are a good thing — but the electricity still needs to be generated in the first place. This is best done with reliable forms of power generation, such as nuclear power, hydroelectric, or reliable hydrocarbon generators powered by fuels such as natural gas or combined cycle coal gasification (IGCC). There is no battery in the world that can make “junk electricity” workable or affordable on the scale of continental power grids.

Even so, high cycling, rapid charging, high capacity, affordable electric storage batteries can find a lot of niches to fill for consumer products, and for products suited for the commercial and industrial sectors.

More: Another approach to improving the performance of lithium ion batteries

New type of lithium metal battery from Australia

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