Covalent Organic Framework as Highly Reversible Anodes in Lithium-ion Battery

Researchers at IISER Pune have developed a covalent organic framework, a new porous material that can boost storage capacity of a Li-ion battery to nearly twice that of commercially available ones. Lithium-ion batteries are used in devices such as cell phones and laptops. They last long and are rechargeable. “If one can pack more power (higher energy density) in these batteries, it would take us one step closer to applications in electric vehicles and large power grids. For this, new Li-ion storage materials that are light-weight and have a high storage capacity are required,” informs Dr. R. Vaidhyanathan, one of the team leads at IISER Pune on this research. Towards this goal, in collaboration with Prof. Satish Ogale’s group, the team has developed IISERP-CON1, a covalent organic framework rich in nitrogen and oxygen based functionalities. Close examination of properties of IISER-CON1 revealed several similarities with that of graphite such as a layered structure and stacked organization of the layers. This motivated the authors to test battery performance by replacing the graphite anode that is typically used in commercial Li-ion batteries with IISERP-CON1. [caption id="attachment_1402" align="aligncenter" width="2667"] (Left) IISER-CON1 with Lithium ions in the pore (Pink- Lithium; Blue- Nitrogen, Grey- Carbon, Red- Oxygen and White- Hydrogen); (Right) A small LED being lit up by a coin-cell made with the IISERP-CON1 anode (Image Credit: R. Vaidhyanathan)[/caption] The authors show that IISER-CON1 possesses several desirable features of graphite but with a higher energy capacity. It can accommodate Li-ions with a specific capacity of 720 mAh/g that is retained even after 1000 charge/discharge cycles. In comparison, graphite displays a specific capacity 372 mAh/g in commercial batteries. The team attributes this higher capacity in energy storage to the structural make-up of IISER-CON1. Composition of IISER-CON1 can be tuned atom-by-atom, thereby tailor-made properties can be introduced to the material. The current study demonstrated the potential of this covalent framework as an anode in Li-ion batteries. Authors say the key challenge is to scale up the process to use the framework in a large sized battery. This paper titled “High and reversible lithium ion storage in self-exfoliated triazole-triformyl phloroglucinol based covalent organic nanosheets” has been accepted for publication in Advanced Energy Materials and is authored by Sattwick Haldar, Kingshuk Roy, Shyamapada Nandi, Debanjan Chakraborty, Dhanya Puthusseri, Yogesh Gawli, Satishchandra Ogale, and Ramanathan Vaidhyanathan. (Adv.Energy Mater. 2017:1702170; DOI: 10.1002/aenm.201702170). - Reported by Shanti Kalipatnapu, with inputs from R. Vaidhyanathan