Lithium-ion batteries have revolutionized mobile electronics and are being used in new energy equipment, but further improvements in life and power will require new technologies. One option is lithium-metal batteries, which last longer. Charging is faster, but there is a problem with this technique. Lithium deposits, known as dendrites, tend to grow on the anode, potentially causing a short circuit, which can cause battery failure, fire or explosion.
Now, researchers at the Institute of Chemistry of the Chinese Academy of Sciences, the University of Chinese Academy of Sciences, and the China High Voltage Science and Technology Research Center have designed a membrane separator based on carbon allotropes. It is called graphdiyne and is used as Lithium ion filter and prevent dendrite growth 'Shang et al., Material.10 (2018) 191-199'.
A lithium metal battery is conceptually similar to a lithium ion battery, but relies on a lithium metal anode. 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. In the process, undesired dendrites can form.
This is where the separator membrane enters. A thin film separator made of ultrathin (10 nm) graphite diyne (a two-dimensional carbon hexagonal monolayer bridged by a diacetylene chain) has some remarkable properties. Graphitic diyne is not only elastic and sturdy at the same time, its chemical structure also forms a uniform porous network, allowing only one lithium ion to pass through each hole. This regulates the movement of ions through the membrane, making the diffusion of ions highly uniform. This characteristic of the battery effectively inhibits the growth of lithium dendrites.
Li Yuliang of the Institute of Chemistry of the Chinese Academy of Sciences, who led the research, explained: 'Suppressing lithium dendrites can stabilize the solid electrolyte interface, thereby increasing device lifetime and coulombic efficiency. 'It can avoid dendritic short circuits and improve battery safety. .
Researchers believe that graphite diyne films can overcome some of the tough problems currently facing lithium and other alkali metal batteries.
'Graphite diyne is an ideal material with superconjugated structure, inherent band gap, natural macroporous structure and semiconductor properties, which shows great prospects for solving major scientific problems in this field,' said Li.
Two-dimensional materials are also simple under normal laboratory conditions and are easy to produce.
'Although more efforts are needed to improve the quality of large-scale graphite diyne membranes, we believe that graphite diacetylene may bring some major breakthroughs in the safety of lithium batteries,' the researchers told reporters.
