Dft U Studies Of Doping Effects On Charge Transort In Lifepo4 Cathode Material For Lithium-ion Batteries

Batteries are electrochemical energy storage device that converts chemical energy into electrical energy. The state-of-the-art rechargeable lithium-ion battery is the most advanced energy storage system. It has been used almost everywhere from portable electronics to large-scale applications. Cathode materials are the major factor to determine the battery overall performance and among different cathodes LiFePO4 possesses surprisingly high charge-discharge rate capability has opened the door for use in vehicle electrification. This material has been predicted to provide good capacity performance, low cost, environmental friendliness, and high stability. However, LiFePO4 batteries suffer from basically low ionic conductivity in the range of 10−11 to 10−13𝑐𝑚2𝑠−1and electronic (10−9𝑆𝑐𝑚−1) conductivity. Therefore, the objective of this study is to investigate the effect of cationic and anionic doping on the electrochemical properties of LiFePO4 cathode material by using Density Functional Theory (DFT) study as implemented in GPAW (Grid-based Projector-Augmented Wave). In this work, B (Boron) and Mg-C (Magnesium-Carbon) have been introduced as single and co-dopants to the LiFePO4 cathode material. The 𝐷𝐹𝑇+𝑈 study at 𝑈=1.5 𝑒𝑉, LiFePO4 which crystalizes in the orthorhombic pnma space group exhibited a band gap of 3.83 𝑒𝑉. Similarly, the obtained band gaps of LiFePO3.75B0.5 and LiFe0.75Mg0.5PO4 are 1.83 and 0.95 𝑒𝑉, respectively. The nudge elastic band calculation (NEB) of B doped LiFePO4 have revealed two minimum energy lithium-ion diffusion pathways along [010] and [100] directions with the activation energy of 0.5 and 0.8 eV, respectively. In bulk LiFePO4 the hole polaronic charge transport mechanism is more plausible, it displays very low hopping barriers (

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