. 2019 May 1;7:268. doi: 10.3389/fchem.2019.00268

Table 2.

Strengths and challenges of aluminum as negative electrode in a battery (in comparison to lithium).

Strengths	Challenges
•Energy density: Volumetric capacity is four times higher than for lithium. •Environment: Not harmful, environmentally benign, less electrical energy necessary for producing metallic aluminum (as negative electrode), less soil needs to be moved during mining due to higher concentrations. •Infrastructure: Matured and already well-established production, electroplating, manufacturing, recycling and scrap collecting infrastructures. •Recycling: Already established recycling technologies and plants. •Resources/prize: Small political supply risk, distribution of production and recycling plants all over the world, small price due to very high abundance. •Safety: Does not ignite in air, which can ensure greater safety of corresponding cells and ease of processing.	•Electrochemical window: Difficult to find liquid electrolytes, which enable dissolution and plating of elemental aluminum. •Coulomb interaction: High-valence state of +3 may introduce slow intercalation/deintercalation kinetics and ion conduction. •Oxide layer: Hindering of dissolution; redox potential may become more positive. •Redox potential: With −1.67 V rather low compared to lithium. •High affinity to oxygen: Influence on environmental conditions and small changes in the local chemistry. •Research efforts: Not intense; in the beginning, 30 years delay in comparison to lithium.

Strengths

Challenges

•Energy density: Volumetric capacity is four times higher than for lithium.
•Environment: Not harmful, environmentally benign, less electrical energy necessary for producing metallic aluminum (as negative electrode), less soil needs to be moved during mining due to higher concentrations.
•Infrastructure: Matured and already well-established production, electroplating, manufacturing, recycling and scrap collecting infrastructures.
•Recycling: Already established recycling technologies and plants.
•Resources/prize: Small political supply risk, distribution of production and recycling plants all over the world, small price due to very high abundance.
•Safety: Does not ignite in air, which can ensure greater safety of corresponding cells and ease of processing.

•Electrochemical window: Difficult to find liquid electrolytes, which enable dissolution and plating of elemental aluminum.
•Coulomb interaction: High-valence state of +3 may introduce slow intercalation/deintercalation kinetics and ion conduction.
•Oxide layer: Hindering of dissolution; redox potential may become more positive.
•Redox potential: With −1.67 V rather low compared to lithium.
•High affinity to oxygen: Influence on environmental conditions and small changes in the local chemistry.
•Research efforts: Not intense; in the beginning, 30 years delay in comparison to lithium.