Enhancing V<sub>2</sub>O<sub>5</sub> Cathode Performance through Heterostructure Engineering with the Ti<sub>3</sub>C<sub>2</sub>O<sub>2</sub> MXene: A Computational Study
Pariwut Falun, Lappawat Ngamwongwan, Sirisak Singsen, Maneerat Chotsawat, Paratee Komen, Anchalee Junkaew, Suwit Suthirakun
Abstract
High Resolution Image Download MS PowerPoint Slide V 2 O 5 has been proposed as a potential candidate for cathode materials of Li-ion batteries due to its high theoretical capacity and cost effectiveness, but it still suffers from high capacity fading and slow charge/discharge kinetics. To improve its electrochemical performance, heterostructure engineering with the Ti 3 C 2 O 2 MXene was computationally studied in this work. Herein, we carried out density functional theory calculations to study such effects on the electronic conductivity and Li intercalation kinetics of the cathode. We find that the formation of V 2 O 5 /Ti 3 C 2 O 2 is energetically favorable where the interaction at the interface is characterized as a weak van der Waals force. When the heterostructure is formed, electrons are transferred from Ti 3 C 2 O 2 to the V 2 O 5 surface where the charge accumulation induces small lattice distortion of the inner V 2 O 5 layer. Such charge accumulation and distortions, in turn, reduce the polaron–lattice interaction, leading to less stable polaron formation energy when compared with that of bulk V 2 O 5 (−0.20 vs −0.35 eV). This weakened polaron–lattice interaction enhances the polaron hopping kinetics as it correlates with smaller polaron hopping barriers. The higher hopping rate constant of the polaron alleviates the Li intercalation kinetics where the ion-coupled polaron movement, used to have polaron hopping as rate-limiting, is now ion diffusion-limiting with somewhat smaller barriers. The calculated average diffusion rate constant is slightly higher at the heterostructure (4.03 × 10 8 s –1 ) than that in bulk V 2 O 5 (2.17 × 10 8 s –1 ). Overall, it is suggested by our computational study that the improved electronic conductivity and ion diffusion kinetics could have their origin from the enhanced rate constant of polaron hopping at the interface of the heterostructure.