Crystalline and Amorphous Phosphorus – Carbon Nanotube Composites as Promising Anodes for Lithium-Ion Batteries
Embargo End Date
2017-05-15Type
ThesisAuthors
Smajic, JasminAdvisors
Da Costa, Pedro M. F. J.Committee Members
Di Fabrizio, Enzo M.Kosel, Jürgen
Program
Material Science and EngineeringKAUST Department
Physical Science and Engineering (PSE) DivisionDate
2016-05-04Access Restrictions
At the time of archiving, the student author of this thesis opted to temporarily restrict access to it. The full text of this thesis became available to the public after the expiration of the embargo on 2017-05-15.Abstract
Battery research has been going full steam and with that the search for alternative anodes. Among many proposed electrode materials, little attention has been given to phosphorus. Phosphorus boasts the third highest gravimetric charge capacity and the highest volumetric charge capacity of all elements. Because of that, it would be an attractive battery anode material were it not for its poor cyclability with significant capacity loss immediately after the first cycle. This is known to be the consequence of considerable volume changes of phosphorus during charge/discharge cycles.In this work, we propose circumventing this issue by mixing amorphous red phosphorus with carbon nanotubes. By employing a non-destructive sublimation-deposition method, we have synthesized composites where the synergetic effect between phosphorus and carbon nanotubes allow for an improvement in the electrochemical performance of battery anodes. In fact, it has been shown that carbon nanotubes can act as an effective buffer to phosphorus volumetric expansions and contractions during charging and discharging of the half-cells [1].
By modifying the synthesis parameters, we have also been able to change the degree of crystallinity of the phosphorus matrix in the composites. In fact, the less common phase of red phosphorus, named fibrous phosphorus, was obtained, and that explains some of the varying electrochemical performances observed in the composites. Overall, it is found that a higher surface area of amorphous phosphorus allows for a better anode material when using single-walled carbon nanotubes as fillers.