Research team develops semi-solid electrode to prevent short-circuiting in next-generation lithium batteries -Lithium - Ion Battery Equipment
In order to push the boundaries of battery design and accommodate more and more power and energy in a given space or weight, researchers are exploring a more promising technology that uses solid-state electrolyte materials between the two electrodes of lithium-ion batteries, while Not electrolyte.
However, a problem with these batteries has always been that metal dendrites can form on one of the electrodes, eventually connecting the electrolyte and shorting out the battery. According to foreign media reports, researchers at institutions such as the Massachusetts Institute of Technology (MIT) have now found a way to prevent the formation of dendrites, which is expected to improve the potential of this new type of high-power battery.(Lithium - Ion Battery Equipment)
The MIT researchers involved in this research include graduate student Richard Park, professors Yet-Ming Chiang and Craig Carter, and the rest of the researchers are from Texas A&M University, Brown University and Carnegie Mellon University. (Carnegie Mellon University).
Solid-state batteries combine safety and energy density, so this technology has attracted much attention. But researcher Yet-MingChiang said: "The only way to achieve energy density is to use metal electrodes." Coupling metal electrodes with liquid electrolytes can achieve good energy density, but not the same safety advantages compared to solid electrolytes. Solid-state batteries only make sense with metal electrodes, but development of such batteries has been hampered by the growth of dendrites, which can eventually fill the gap between the two electrode plates, causing the battery to short out. It is well known that in the case of fast charging, generally the higher the current, the faster the dendrites form. Currently, the current densities achievable with experimental solid-state batteries are far below the demands of commercial rechargeable batteries. But the researchers believe it holds promise because the experimental version of the battery can store almost twice as much energy as conventional lithium-ion batteries.
The team took a compromise between solid and liquid states to solve the dendrite problem. The researchers fabricated semi-solid electrodes that were in contact with solid electrolyte materials. Semi-solid electrodes can provide a self-healing surface at the interface, rather than a solid brittle surface that can lead to tiny cracks that set the stage for dendrite formation.
The inspiration came from experimental high-temperature batteries in which one or both electrodes are made of molten metal. According to reports, this molten metal battery can reach temperatures of hundreds of degrees Celsius and cannot be used in portable devices. But this work does show that high current densities can be achieved at liquid interfaces without dendrite formation. "The starting point was to develop electrodes based on carefully selected alloys in order to introduce a liquid phase that can act as a self-healing component of the metal electrode," says researcher Richard Park.
The material is not so much a liquid as a solid, but still able to flow and form, similar to the solid metal amalgam dentists use to fill cavities. In this case, it's made of a mixture of sodium and potassium, which, at normal battery operating temperatures, are in a state that has both a solid and a liquid phase. The team demonstrated that, without any dendrite formation, it is possible to operate the system at currents up to 20 times greater than when using solid-state lithium. The next step will be to replicate this performance with actual lithium-containing electrodes.
In a second version of the solid-state battery, the team introduced a very thin layer of liquid sodium-potassium alloy between the solid-state lithium electrode and the solid-state electrolyte. The results show that this method can also overcome the dendrite problem, providing another avenue for further research.
The new method is applicable to many different versions of solid-state lithium-ion batteries, the researchers say. The next step for the team is to demonstrate the applicability of the system to various battery architectures.
However, a problem with these batteries has always been that metal dendrites can form on one of the electrodes, eventually connecting the electrolyte and shorting out the battery. According to foreign media reports, researchers at institutions such as the Massachusetts Institute of Technology (MIT) have now found a way to prevent the formation of dendrites, which is expected to improve the potential of this new type of high-power battery.(Lithium - Ion Battery Equipment)
The MIT researchers involved in this research include graduate student Richard Park, professors Yet-Ming Chiang and Craig Carter, and the rest of the researchers are from Texas A&M University, Brown University and Carnegie Mellon University. (Carnegie Mellon University).
Solid-state batteries combine safety and energy density, so this technology has attracted much attention. But researcher Yet-MingChiang said: "The only way to achieve energy density is to use metal electrodes." Coupling metal electrodes with liquid electrolytes can achieve good energy density, but not the same safety advantages compared to solid electrolytes. Solid-state batteries only make sense with metal electrodes, but development of such batteries has been hampered by the growth of dendrites, which can eventually fill the gap between the two electrode plates, causing the battery to short out. It is well known that in the case of fast charging, generally the higher the current, the faster the dendrites form. Currently, the current densities achievable with experimental solid-state batteries are far below the demands of commercial rechargeable batteries. But the researchers believe it holds promise because the experimental version of the battery can store almost twice as much energy as conventional lithium-ion batteries.
The team took a compromise between solid and liquid states to solve the dendrite problem. The researchers fabricated semi-solid electrodes that were in contact with solid electrolyte materials. Semi-solid electrodes can provide a self-healing surface at the interface, rather than a solid brittle surface that can lead to tiny cracks that set the stage for dendrite formation.
The inspiration came from experimental high-temperature batteries in which one or both electrodes are made of molten metal. According to reports, this molten metal battery can reach temperatures of hundreds of degrees Celsius and cannot be used in portable devices. But this work does show that high current densities can be achieved at liquid interfaces without dendrite formation. "The starting point was to develop electrodes based on carefully selected alloys in order to introduce a liquid phase that can act as a self-healing component of the metal electrode," says researcher Richard Park.
The material is not so much a liquid as a solid, but still able to flow and form, similar to the solid metal amalgam dentists use to fill cavities. In this case, it's made of a mixture of sodium and potassium, which, at normal battery operating temperatures, are in a state that has both a solid and a liquid phase. The team demonstrated that, without any dendrite formation, it is possible to operate the system at currents up to 20 times greater than when using solid-state lithium. The next step will be to replicate this performance with actual lithium-containing electrodes.
In a second version of the solid-state battery, the team introduced a very thin layer of liquid sodium-potassium alloy between the solid-state lithium electrode and the solid-state electrolyte. The results show that this method can also overcome the dendrite problem, providing another avenue for further research.
The new method is applicable to many different versions of solid-state lithium-ion batteries, the researchers say. The next step for the team is to demonstrate the applicability of the system to various battery architectures.
