Charge–discharge mechanism, lithium-ion diffusion in Al, Ca, and Cu doped lithium metatitanate based anodes for Li-ion batteries: first principles study

Abstract

Understanding the charge–discharge mechanism at the atomic-scale and the evolution of electrochemical properties for lithiated/de-lithiated compounds is a key challenge in lithium ion batteries (LIBs). Here, an innovative and viable protocol was addressed for the evolution of Li-ion intercalation and de-intercalation phenomena using electronic, thermal, mechanical, and electrochemical properties within the framework of DFT. The electronic property calculations are used to predict the band-gap engineering through the Al, Ca, and Cu-doping. Charge density and distribution analysis disclose that the Li-ions are diffused along the [101] direction and show wave-like pathways. Mechanical stability and superiority, provide a strong ability to withstand the volumetric and reversible change, against shear and bulk anisotropy during the charge–discharge cycle which reduces the micro cracking and capacity fading of LIBs. The thermal parameters are helpful in understanding the evolution of the chemical energy, structural disorder, and its spontaneous nature during the charge–discharge phenomenon. The electrochemical properties of the Li/Al-LTO half-cell predict an average voltage of 4.8 V, a theoretical capacity of 183.04 mA h g⁻¹, and the volumetric energy and power densities of Li/Al-LTO are 0.366 W h cm⁻³ and 0.366 W cm⁻³, respectively. The gravimetric energy and power densities of Li/Al-LTO are 6.9 kW h kg⁻¹ and 6.9 kW kg⁻¹, respectively. The average voltage of the C₆/Al-LTO full-cell is 5.4 V, and the oxidation, reduction potentials of C₆/Al-LTO are 2.99, and 2.75 V, respectively. The calculated energy and power densities of C₆/Al-LTO are 3.60 kW h kg⁻¹ and 3.60 kW kg⁻¹, respectively. This work sheds light on an innovative way to describe the charge–discharge mechanism and opens a new era of computational electrochemistry.