Tanmay Sarkar

A double layer δ-NH4V4O10, due to its high energy storage capacity and excellent rate capability, is a very promising cathode material for Li-ion and Na-ion batteries for large-scale renewable energy storage in transportation and smart grids. While it possesses better stability, and higher ionic and electronic conductivity than the most widely explored V2O5, the mechanisms of its cyclability are yet to be understood.

Sodium-ion batteries are the commercially and environmentally viable next-generation candidates for automobiles. Structural and electrochemical aspects are greater concerns towards the development of a stable cathode material. Selecting transition metals and their composition greatly influences charge order, superstructures, and different voltage plateaus. This, in turn, influences transport properties and cyclic performance. This article aims to study the electrochemical performance, diffusivity, and structural stability of Na x [M y Mn1−y ]O2 (M = Fe, Ni) as cathode.

First–principles DFT simulations are computationally demanding but are reasonably accurate in predicting properties of battery cathode materials. Properties relevant to selection of cathode
material include electrochemical potential, structural stability, energy/power density and cycle life etc. Computational screening of materials speeds up the process of material discovery by
saving on costs of experiments and time. In addition, it helps in developing correlation between properties and structural and chemical aspects. Here we analyze some of these aspects for the

Polyanion based cathode materials are most promising candidates for lithium ion batteries due to low cost, safety, environmental friendliness, etc. We performed first principles based DFT calculations to understand the stability, charge transfer mechanism and electrochemical performance of olivine phosphates, silicates and its comparison with the transition metal layered oxides based cathode materials. We have computed the changes in oxidation states using Bader method of topological analysis and charge re-distribution by analysis of partial density of electronic states.

A high concentration of lithium, corresponding to charge capacity of ∼4200 mAh/g, can be intercalated in silicon. Unfortunately, due to high intercalation strain leading to fracture and consequent poor cyclability, silicon cannot be used as anode in lithium ion batteries. But recently interconnected hollow nano-spheres of amorphous silicon have been found to exhibit high cyclability. The absence of fracture upon lithiation and the high cyclability has been attributed to reduction in intercalation stress due to hollow spherical geometry of the silicon nano-particles.

A first principle based study of the electrochemical properties of LiCoBO3 has been carried out. The theoretical energy density of LiMBO3 (M = Mn, Fe, Co) is comparable with the corresponding olivine phosphate. Low volume change during cycling gives it structural stability during full charging and discharging, hence making it a promising battery material. A 12.5% cation substitution with Mg, Mn, Ni, Cu and Zn was chosen to evaluate the electrochemical properties of the compounds.

A sodium-ion battery (NIB) cathode performance based on ammonium vanadate is demonstrated here as high capacity, long cycle life and good rate capability. The simple preparation process and morphology study enable us to explore this electrode as suitable NIB cathode. Furthermore, density functional theory (DFT) calculation is envisioned for the NH4V4O10 cathode and three possible sodium arrangements in the structure are depicted for the first time. Relevant NIB-related properties have been derived like average voltage, lattice constants and atomic coordinates etc.

Indigenisation of Lithium-ion battery manufacturing: A Techno-Economic Feasibility Assessment

In 2017, Karnataka became the first Indian state to announce an EV Policy. In this project, CSTEP identified key barriers in large-scale EV penetration, towards preparing a long-term implementation plan for public electric bus (e-bus) transportation for Bengaluru.

High energy density Li-rich layered cathode materials suffer from structural instability at high voltage. It is known that oxygen stability influence the structural stability of Li2MO3 (M=Co/Mn/Ni). Oxygen stability with partial de-lithiation has not been clarified in presence of multiple d-orbital elements. This work presents density functional theory based study of Li1.17Ni0.17Mn0.67O2. In the series of Li-rich compounds, end point material is Li2MnO3, in which oxidation of Mn4+ compensates with oxidation of O2- to O2 while charging.