(433e) Modeling of Nature-Inspired Hierarchical Porous Materials for Energy Storage
AIChE Annual Meeting
2017
2017 Annual Meeting
Engineering Sciences and Fundamentals
Invited Symposium: Nature-Inspired Electrochemical Systems
Tuesday, October 31, 2017 - 4:45pm to 5:15pm
2Li++ 2e-+O2 <-> Li2O2
The exact mechanism through which O2 reacts with Li ions at the electrode/electrolyte interface during discharge is a matter of debate and is critical for the future development of the Li-air battery5-8,10-11. Electrode passivation as a result of the insulating Li2O2 layer is the leading cause for early cell death due to the diminishing electrode/electrolyte interface5-7,10-11. A simple solution to this issue would be to use high donor number electrolytes like dimethyl sulfoxide (DMSO). However, such electrolytes are generally unstable5,6. A more genuine solution is the design of hierarchically porous materials like 3DOM porous carbon and hierarchical graphene as cathodes6-8,11.
Hierarchically structured porous materials are nature inspired structures in which the porosity is engineered such that the resulting material composes various porosity scales which are namely micropores (Ë 2 nm), mesopores (2 â 50 nm) and macropores (Ë 50 nm)3,9,12. The utilization of hierarchical porous materials as cathodes for the Li-air battery offers several advantages3,6,7,10,12. The porosity offers a higher interfacial contact between the electrode and the electrolyte resulting in higher capacity6. Moreover, the presence of wider voids in the form of mesopores and macropores offers transport âhighwaysâ for faster charge and molecular transport3,7,10-12. Most importantly however, the mesopores and micropores offer the possibility of discharge product (Li2O2) storage without clogging the macropores ensuring continuous oxygen transport to the reaction centres and reducing passivation6-8,11.
In a field where a fundamental understanding of electrochemical mechanisms is of great significance, we will present first principles molecular simulations to model the phenomena occurring at the electrode/electrolyte interface of a Li-air battery. In addition, classical molecular simulations have been utilized to model and characterize the hierarchical porous materials such as 3DOM carbon and hierarchical graphene as cathodes for Li-air batteries. Molecular simulations helped provide insights into the possible reaction mechanism occurring on hierarchical cathodes. We have explored the feasibility of the hierarchical cathodes in improving the efficiency of the Li-air battery, through the proposed improved diffusion and discharge product storage and results will be discussed here. We believe that our work will be of great relevance to the fields of hierarchical materials and energy storage.
References
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