Lithium-ion batteries have brought revolutionary changes to mobile electronic devices and are making progress in transportation. But to further improve battery life and power, new technologies are needed. One option is: lithium metal batteries, which have a longer life and faster charging speed, but there are problems with this technology. Lithium deposits (often referred to as lithium dendrites) tend to grow on the anode, which can cause short circuits that can cause battery failure, fire, or explosion.
Now, researchers from the Institute of Chemistry of the Chinese Academy of Sciences, the University of Chinese Academy of Sciences, Nankai University, Shantou University, and the China Advanced Research Center for High-Pressure Science and Technology have designed a diaphragm based on a carbon allotrope (called graphyne), which is used Lithium ion filter and prevents dendrite growth. Researchers published the results of this research in "Materials Today Energy".
Lithium metal batteries are similar in concept to lithium-ion batteries, but rely on lithium metal anodes. During discharge, the lithium metal anode supplies electrons to the cathode through an external circuit. However, during charging, lithium metal is deposited on the anode. It is in this process that unwanted dendrites can form.
This is where the diaphragm comes into play. The thin membrane is made of ultra-thin (10nm) graphite acetylene (graphene is a two-dimensional single-layer carbon atom hexagon connected by butadiene bonds), which has some significant characteristics. Graphyne is not only flexible and sturdy at the same time, its chemical structure forms a uniform porous grid, allowing only one lithium ion to pass through each pore. This regulates the movement of ions through the film, making the diffusion of ions highly uniform. It is important for the battery that this feature of the film effectively inhibits the growth of lithium dendrites.
"Suppressing lithium dendrites can stabilize the solid electrolyte mesophase, thereby increasing the lifetime and Coulomb efficiency of the device," explained Li Yuliang of the Institute of Chemistry of the Chinese Academy of Sciences. "It can prevent short circuits caused by dendritic lithium dendrites, thereby improving battery safety."
Researchers believe that graphene alkyne films can overcome thorny problems such as lithium dendrites that lithium and other alkali metal batteries have long faced.
"Graphyne is a perfect material with a super conjugate structure, inherent band gap, natural macroporous structure, and semiconductor characteristics, which raises huge hopes for solving major scientific problems in this field," Li said.
This two-dimensional material is also simple and easy to produce under normal laboratory conditions.
"Although more efforts are needed to improve the quality of large-scale graphyne films, we believe that graphyne may bring some major breakthroughs in the safety of lithium batteries." Li said.