Developing Practical Lithium-Air Batteries by Avoiding Negative Effects of CO₂

Abstract

The gradual popularization of new energy technologies has led to rapid development in the field of electric transportation. At present, the demand for high-power density batteries is increasing and next-generation higherenergy battery chemistries aimed at replacing current lithiumion batteries are emerging. The lithium-air batteries (LABs) are thought to be the ultimate energy conversion and storage system, because of their highest theoretical specific energy compared with other known battery systems. Current LABs are operated with pure O2 provided by weighty O2 cylinders instead of the breathing air, and this configuration would greatly undermine LAB's energy density and practicality. However, when the breathing air is used as O2 feed for LABs, CO2, as an inevitable impurity therein, usually leads to severe parasitic reactions and can easily deteriorate the performance of LABs. Specifically, Li2O2 will react with CO2 to form Li2CO3 on the cathode surface. Compared with the desired discharge product Li2O2, the Li2CO3 is an insulating solid, which will accumulate and finally passivate the electrode surface leading to the "sudden death" phenomenon of LABs. Moreover, Li2CO3 is hard to decompose and a high overpotential is required to charge LABs containing Li2CO3 compounds, which not only degrades energy efficiency but also decomposes other battery components (e.g., cathode materials and electrolytes). In recent years, researchers have proposed many strategies to alleviate the negative effects brought about by Li2CO3, such as catalyst engineering, electrolyte design, and so on, in which O2 selective permeable membranes are worth noting. This review summarizes the recent progresses on the understanding of the CO2-related chemistry and electrochemistry in LABs and describes the various strategies to mitigate and even avoid the negative effects of CO2. The perspective of CO2 separation technology using selective permeable membranes/filters in the context of LABs is also discussed.

A comprehensive overview of the electrochemical mechanisms in emerging alkali metal–carbon dioxide batteries

“…7 However, lithium-air batteries are more like lithium-oxygen batteries because they have to work in a pure oxygen environment rather than in ambient air. 8,9 In 2011, Takechi and co-workers 10 found that adding a moderate amount of CO 2 to the Li-O 2 battery atmosphere (pure O 2 ) could greatly increase the discharge capacity of the battery (up to almost 3 times), leading to the creation of the original Li-O 2 /CO 2 battery. Following this line of thinking, the first Li-CO 2 battery that worked in a pure CO 2 atmosphere was developed in 2013, which, in the next several years, rapidly became a promising strategy for CO 2 fixation and utilization.…”

“…To solve this problem, lithium–air batteries with ultrahigh energy density have been developed 7 . However, lithium–air batteries are more like lithium–oxygen batteries because they have to work in a pure oxygen environment rather than in ambient air 8,9 . In 2011, Takechi and co‐workers 10 found that adding a moderate amount of CO 2 to the Li–O 2 battery atmosphere (pure O 2 ) could greatly increase the discharge capacity of the battery (up to almost 3 times), leading to the creation of the original Li–O 2 /CO 2 battery.…”

A dual-electrolyte system for highly efficient Al–air batteries

“…23 Therefore, to achieve a high utilization ratio of Al–air batteries, the self-corrosion of Al metal and polarization should be suppressed simultaneously. 24…”

Critical CO2 Concentration for Practical Lithium–Air Batteries

“…CO 2 could participate in the discharge reactions, reacting with the superoxide intermediate and peroxide final product to form Li 2 CO 3 . However, Li 2 CO 3 hardly shows any XRD peaks due to its poor crystallinity.…”

“…CO 2 could participate in the discharge reactions, reacting with the superoxide intermediate and peroxide final product to form Li 2 CO 3 . 25 However, Li 2 CO 3 hardly shows any XRD peaks due to its poor crystallinity. Therefore, we quantify the Li 2 CO 3 in the electrodes by using DEMS as described in the Experimental Section.…”