Eco-Friendly Green Batteries

 

S. Hema Nagalakshmi, N. Breethi and S. Manibalan*

Kamaraj College of Engineering and Technology, Virudhunagar.

 

ABSTRACT:

At present inorganic electrodes are present in the lithium batteries which are used in a wide range of applications. Because of the demand it is mandatory to develop environmentally friendly electrode for the batteries. In order to develop sustainable and eco-friendly batteries we can use purpurin which is an organic compound obtained from the plant madder. Purpurin contain hydroxyl groups, which act as redox centres and reacts electrochemically with Li-ions during the charge/discharge process. The mechanism of lithiation of purpurin is fully elucidated using NMR, UV and FTIR spectral studies. The six membered binding core of lithium is formed with hydroxyl groups of purpurin at C-1 and C-4 positions which facilitates lithiation process, where Hydroxyl groups at C-2 remains unaltered.

 

INTRODUCTION:

The fundamental challenge in developing clean energy is to identify sustainable energy supplies and protect the environment. Lithium ion batteries have drawn utmost attention due to their reversible electrochemistry and storage capacity. lithium-ion battery  was directed mainly towards the synthesis of high capacity materials and lead to the development of several non-renewable cathodes. Current Li-ion battery technologies operating on inorganic insertion compound (e.g., LiCoO2) as cathode, face severe safety issues and 30% of globally produced cobalt is channeled into battery.. Further, recycling of current lithium ion batteries has recycling process of current lithium ion battery technology is not viable in the long term and hence, lithium ion battery industry demands environment friendly green organic electrodes.

 

Here, we report a novel organic electrode material for lithium ion batteries, purpurin, which has been extracted from a common plant Madder, most often used as a dye for fabrics. The extracted and chemically lithiated purpurin (CLP), shows very good reversible lithium ion storage properties. Hence, it could lead to the development of a green and sustainable Li ion battery.

 

MATERIALS AND METHODS:

Methods:

Synthesis of chemically lithiated purpurin. Pristine purpurin was chemically lithiated by following the basic lithiation chemistry procedures reported in the literature. Lithium acetate dihydrate (1.02 g, 10 mmol) in 10 mL of MeOH was added drop-wise to a solution of purpurin (2.56 g, 10 mmol) dissolved in 100 mL of methanol. During the addition of LiOAc solution, reddish yellow colored purpurin solution turned to pink, and the resultant solution was stirred vigorously for 10 minutes. The 151 ratio of chemically lithiated purpurin (CLP) was obtained by removing the solvent from the reaction mixture and by drying the solid product under vacuum and thus the lithiated purpurin was obtained.

 

MATERIALS:

 

Fig.1. Image of plant madder

 

·        Plant madder

·        Purpurin

·        Lithium acetate dehydrate

·        MeOH

·        Methanol

·        LiOAc

 

DISCUSSION:

The possible sequence of lithiation/de-lithiation mechanism in the purpurin molecule is schematically represented in figure 2 (a). From figure 2, (1) Molecular structure of pristine purpurin and corresponding hydrogen were labeled as Ha–Hh respectively. Possible lithium binding core in purpurin is shown by orange color circles; (2) Possible reversible intermediate of lithiated purpurin and (3) Binding of lithium ion with carbonyl groups of purpurin and hydroxyl groups at C-1 (–OHa) and C-4 (–OHc) respectively. Further, to understand the electrochemical reaction mechanism between purpurin and lithium, NMR, FTIR, UV and XPS measurements were carried out on ELP and compared the obtained spectra with that of pristine purpurin.

 

Fig.2. The mechanism of lithiation or de-lithiation

 

The first compound in the fig 1a indicates the  molecular structure of pristine Purpurin the next compound is the Intermediate of lithiated purpurin and the resultant is the binding of lithium ion with carbonyl and hydroxyl groups.

The next fig 1b is the photograph of pristine purpurin and the next is the photograph of CLP in the ratio 1:2. To realize the reversible electrochemical performance of this novel electrode material, a working electrode was prepared by mixing 80% of purpurin/CLP and 20% of carbon by weight.

CONCLUSIONS:

To conclude, we have demonstrated reversible lithiation/de-lithiation properties in purpurin molecules that is derived from a widely available plant Madder. The lithium batteries assembled using purpurin and chemically lithiated purpurin as working electrodes showed good charge/discharge characteristics with a reversible capacity of ,90 mAh/g. The chemistry behind the lithiation of purpurin molecule was studied with NMR, UV and FTIR. We demonstrate that the binding of two lithium ions with purpurin molecule by the shared binding of carbonyl and nearby hydroxyl group, lead to the formation of most favored six membered structure. Our results pay a way towards the development of green and sustainable lithium battery electrodes from plant/crop-based materials24 and agricultural wastes.

 

REFERENCES:

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6.       Lithium storage mechanisms in purpurin based organic lithium ion batteryelectrodes  by Arava Leela Mohana Reddy1, Subbiah Nagarajan2, Porramate Chumyim1, Sanketh R. Gowda1, Padmanava Pradhan2, Swapni R. Jadhav, Madan Dubey, George John and Pulickel M. Ajayan.

 

 

Received on 29.08.2013                             Accepted on 01.09.2013        

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