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The course of science seldom goes smoothly, but new research from Rice University shows that experiments with an everyday object such as adhesive tape can provide an energy technology breakthrough.
A sticky problem hinders the development of lithium metal anode (LMA) batteries. Short circuits, thermal jumps and loss of efficiency can be caused by the buildup of inactive lithium and lithium dendrites – prickly protrusions that can short circuit a battery – during the life cycle of the battery.
Now researchers from Rice University may have found a new solution to such problems. The team has found a way to turn self-adhesive tape into a silicon oxide film that can solve these problems by protecting the lithium anode, the element that creates the problems. The technology used by the team is similar to that used to produce graphene sheets.
The team used a standard industrial infrared laser cutter to convert a commercially available silicone-based tape into a porous silica coating. The researchers added a small amount of laser-induced graphene derived from the polyimide tape’s support. The silica layer is deposited directly on the battery’s current collector, which gives it protection, preserves efficiency and suppresses the formation of unwanted lithium.
Research showing Rice University crew results is published in the journal Advanced materials.
In addition to preserving the efficiency of the lithium battery, you avoid forming the silicon oxide film with a laser the use of toxic organic solvents and the need for long drying times.
The development can be a significant boost for the lithium battery market. These batteries are already known for their long life, which gives a much higher current density than alternative batteries. The fact that lithium is highly reactive means that this type of cell has been gradually replaced in many areas with lithium ion technology. However, this development could turn that changer on full cycle and get lithium metal batteries back to the front.
A disadvantage of lithium-ion batteries is that the dosing of them with graphite, the process that separates them from lithium metal batteries, makes them quite heavy. This means that a battery with pure lithium metal is much lighter, a blessing for use in technology as extensive as telephones and other compact technology, as well as cars and other vehicles.
The technology that introduces adhesive tapes to lithium metal batteries
The researchers’ inspiration for adapting sticky tape with lasers to fill a role in lithium metal batteries arose from previous attempts to produce a stand-alone film of laser-induced graphene with commercially available tape.
During the experiments, materials scientists found that they could not only produce the graphene, but also recover a foamy, transparent film from the side of the tape that had held the adhesive.
This layer was formed after the team attached the tape to the current collector and blew it up several times with a laser. This laser exposure had the effect of raising the tape temperature to about 2000 ⁰C, which resulted in a porous coating of mainly silicon and oxygen around the conductor. A small amount of carbon was also present.
The team realized that the foamy by-product they had created could be applied to lithium-metal batteries, as it soaked up and released lithium without the formation of dendrites. These dendrites can be a significant problem for lithium metal batteries and can, in extreme circumstances, cause fires that pose a major safety hazard. Therefore, any method of eliminating them is a significant breakthrough for this technology.
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Another issue that exists in lithium metal batteries and in lithium ion batteries is the dissolution of the lithium anode during the charge / charge cycle. This leads to lithium clustering at the cathode, which severely limits battery life. Researchers from Rice University found that when the current collector was coated with their laser-induced silica, the breakdown did not occur.
Lithium anodes – Battery technology of the future
The main difference between the batteries that the team proposes to improve this breakthrough – lithium-metal batteries – and commonly used lithium-ion batteries is that in the latter, lithium ions are introduced into layers of graphite with six carbon atoms that seal a single lithium-ion. When the battery is charged and recharged, they are released from this graphite structure.
Lithium-metal batteries eliminate the need for graphite, allowing lithium ions to be transported directly from the anode. This results in a capacity that is up to ten times higher than graphite-lithium-ion batteries.
The lack of graphite means that more lithium must be added to the anode to compensate for the degradation, which means that the resulting battery is light with high performance, but with a shorter life. The team’s film also removes all security issues.
The use of the silica film seems to have eliminated the use of excess lithium and increased the life of the lithium metal battery by about three times. They found that the silica system resulted in a lithium metal cell that could go through 60 charge / charge cycles and lost only 30% capacity. The team believes that the system they have paved in the pioneers can be ideal for outdoor expeditions or in the short term in the countryside.
Silica films can be manufactured with standard industrial lasers, which means that the scaling up of production is relatively simple. The laser technology does not contain any toxic solvents and can be performed at room temperature in an area with normal safety problems.
The team suggests that the system used to produce the film can also be used to create films that can produce coatings and filters for metal nanoparticles.
The research provides an example of how scientific development and breakthroughs can arise from the most unexpected sources, such as household objects.
Click here to read more about thin film characterization systems.
References and further reading
Chen. W., Salvatierra. R, Ren. M et al. (2020) Laser-induced silica for anode-free lithium metal batteries. Advanced materials. https://doi.org/10.1002/adma.202002850.