Friday, June 21, 2024

Sodium-Ion Batteries: A Next-Generation Energy Storage System

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Researchers at the Indian Institute of Technology (IIT) Bombay have created high-performance cathodes for Na-ion batteries to solve air/water and structural-electrochemical instability.

Depiction of the influence of raised TM­-O bond covalency on the stabilization of the P2 structure for Na-TM-oxide even at a high Na-content of ~0.84 p.f.u.; thus, leading to the development of a high capacity (viz., greater than most reported to-date) and very stable P2-structured Na([]0.06Li0.04Mg0.02Ni0.22Mn0.66)O2 cathode material, which exhibits excellent performances in Na-ion cells (as published in, Chem. Mater. 34[23] (2022) 10470–10483).
Depiction of the influence of raised T-O bond covalency on the stabilization of the P2 structure for Na-TM-oxide even at a high Na-content of ~0.84 p.f.u.; thus, leading to the development of a high capacity (viz., greater than most reported to-date) and very stable P2-structured Na([]0.06Li0.04Mg0.02Ni0.22Mn0.66)O2 cathode material, which exhibits excellent performances in Na-ion cells (as published in, Chem. Mater. 34[23] (2022) 10470–10483).

Sodium-ion batteries are important for climate and India’s resources. They use cathode and anode materials for charge/discharge. Good performance needs stable electrodes, Sodium (Na) transport, and low resistance. Yet, Na-TM-oxide-based cathodes need improvements for moisture stability and handling, which requires toxic N-Methyl-2-pyrrolidone (NMP) instead of water-based slurries.

Researchers at the Indian Institute of Technology (IIT) Bombay have developed new, high-performance cathode materials for Na-ion batteries that address air/water and structural-electrochemical instability issues at the same time. The new materials have good cyclic and air/water stability, making them ideal for cost-effective and sustainable energy storage in various applications, from consumer electronics and grid storage to renewable energy and electric vehicles.

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The team used materials science and electrochemical principles to develop a universal design criterion for high-performance, stable cathodes for Na-ion batteries, supported by the Science and Engineering Research Board (SERB) and Department of Science and Technology’s (DST’s) Materials for Energy Storage scheme. They suggest adjusting the Na-TM-oxide cathode structure by modifying TM-O bond covalency to create “interslab” spacing. This allows for the successful design and widespread development of sustainable, high-performance Na-ion batteries. In the Na-TM-oxide structure, alternate NaO2 and TMO2 ‘slabs’ share O-ions with a net negative charge, which are ionic for Na-O and iono-covalent for TM-O bonds. By adjusting the degree of covalency in the TM-O bond through the combination of cations in the TM-layer, the net negative charge on the O-ion can be tuned to affect electrostatic attraction and repulsion between Na- and O-ions across the Na-layer.

The higher effective negative charge on O-ion due to reduced TM-O covalency strengthens the Na-O bond, reducing inter-slab spacing and improving air/water stability, suppressing deleterious structural transitions in Na-TM-oxide cathode materials. New water-stable cathodes for Na-ion batteries can be prepared via a cost-effective and environment-friendly aqueous processing route. Greater TM-O bond covalency results in weaker and longer Na-O bonds and an increased “inter-slab” spacing. The study shows that a reduced inter-slab spacing resulting from a lower effective negative charge on the O-ion due to greater TM-O bond covalency can enhance the rate-capability and power density of the cathode in Na-ion batteries.

The researchers stabilized the P2 structure for Na-TM-oxide cathode materials at a higher Na-content, enhancing Na-storage capacity and air/water stability. These findings are expected to facilitate the development of cost-effective Na-ion battery systems through environment-friendly electrode processing.

Reference :

I. Biswas, B. S. Kumar, A. Pradeep, and A. Mukhopadhyay: An O3-structured ‘Layered’ Sodium Transition Metal Oxide-based Cathode Material for Na-ion batteries; Indian Patent Application No.: 202321016587, dated 13-03-2023 (Patent filed)

B. S. Kumar, A. Pradeep, Amardeep and A. Mukhopadhyay: High Sodium Containing P2-type Sodium Transition Metal Oxide-based Cathode for Na-ion Batteries; Indian Patent No.: 406595; dated: 14/09/2022 (Patent granted)

Nidhi Agarwal
Nidhi Agarwal
Nidhi Agarwal is a journalist at EFY. She is an Electronics and Communication Engineer with over five years of academic experience. Her expertise lies in working with development boards and IoT cloud. She enjoys writing as it enables her to share her knowledge and insights related to electronics, with like-minded techies.

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