Lithium-oxygen systems are likely to overtake currently used lithium-ion batteries in performance because of their capacity for high energy density.
However, several key issues, such as their poor electrochemical stability must be sorted before these systems can effectively compete with today’s rechargeable batteries. Researchers report in ACS Central Science, a new type of cathode, that could transform lithium-oxygen batteries into a practical option.
Xin-Bo Zhang and colleagues state that a majority of the issues linked with lithium-oxygen battery systems arise from two highly reduced oxygen species that respond readily with the cathode and the electrolyte. Carbon is a typical strong-performing cathode; however it is unstable in these systems. Therefore, the team theorized that the key to unraveling the lithium-oxygen batteries’ potential could be to develop cathodes that are unresponsive to the reduced oxygen species, but that still have the same extremely conductive, low-weight, porous features of carbon cathodes. The Researchers were successful in creating an ultralight all-metal cathode.
The design combined three forms of nickel including a gold-nickel alloy surface directly attached to nickel foam and a nanoporous nickel interior. In comparison to carbon cathodes, the system has a much greater capacity and is stable for 286 cycles, which is among the best for lithium-oxygen batteries, and is closely competitive with existing commercial lithium-ion systems. Additional experimentation revealed that the performance and stability arise from both the metal used and its nanoporous structure, and that both these features could be enhanced to further increase performance.
The Authors received funding from the Chinese Academy of Sciences, Ministry of Science and Technology of the People's Republic of China, Technology and Industry for National Defense of the People's Republic of China, National Natural Science Foundation of China and Jilin Province Science and Technology Development Program.