NMC 9.5.5 for Li Ion Batteries

Synthesis, Scale up, and Optimisation of NMC 9.5.5 for Li-Ion Batteries.

Ethan Williams, David Burnett, Peter Slater, Emma Kendrick

School of Metallurgy and Materials, University of Birmingham, Elms Rd, Birmingham B15 2SE

Abstract

• LiNi_0.9Mn_0.05Co_0.05O₂ (NMC-955) have been synthesized by a coprecipitation reaction followed by a two step firing process.
• Increasing the firing load and tuning the firing conditions results in improved structural stability and electrochemical performance.
• The molar excess of additives during firing and the impact upon the capacity and cycle life of the assembled cathode half cells.

Motivation

• The synthesis and optimisation of Ni-rich cathode materials are of interest as they have a higher energy density and limit the cobalt content However, higher Ni content is detrimental to the bulk and surface stability of material, resulting in structural breakdown and rapid capacity fade.
• Previous studies indicate use of additives can act to stabilise the 003 lattice space, thus improving battery performance.
• Optimised manufacturing methods can reduce the economic and environmental impact of this process.

Methods

1. Synthesis and Scale Up

• Ratio of 003 and 104 Bragg peaks in XRD pattern give indication of Li⁺/Ni²⁺ cation mixing disorder A higher ratio indicates lower mixing and less structural disorder.
• Initial capacity and capacity retention improves with scaling up the lithiation step associated with less Li loss during firing and lower cation mixing.

2. Firing with Additive

• Additives A and B improve initial capacity of NMC-9.5.5 at a 4 g firing scale.
• Capacity and cycling stability increases with firing scale.

3. Firing Conditions Study

• Reducing total firing time results in lower cation mixing and improved cycle life.
• Particle size reduces with lower first stage temperature. Particle growth is further limited under an O₂ atmosphere.

Improved capacity retention in B-NMC samples due to suppression of irreversible H2-H3 phase transition as revealed by cyclic voltammetry.

Conclusions

• Lithium loss during firing and cation mixing disorder can be reduced at larger firing loads.
• Reduction in lithium loss results in improved cathode capacity and cycle life Flux additives can also be used to improve the specific capacity.
• Optimising the firing time and temperature can further improve the cycle life of the NMC 955 material.

Impact / Next Steps

• Coprecipitation is an effective method for the synthesis and scale up of cathode materials.
• Optimising the firing conditions is a simple and cost effective way to stabilise Ni-rich cathodes.
• Commercialisation of Ni-rich cathodes will reduce the use of critical materials and meet high energy requirements.

References

1. L. Lehao, L. Meicheng, C. Lihua, Progress in Materials Science, 2020, 111, 100655
2. W. Che-Ya, B. Qi, D. Jenq Gong, Journal of Alloys and Compounds , 2021, 865 , 158806
3. Ronduda, H.; Zybert, M.; Szczęsna-Chrzan, A.; Trzeciak, T.; Ostrowski, A.; Szymański, D.; Wieczorek, W.; Raróg-Pilecka, W.; Marcinek, M. On the Sensitivity of the Ni-rich Layered Cathode Materials for Li-ion Batteries to the Different Calcination Conditions. Nanomaterials 2020, 10, 2018.

Researcher Bio

Ethan Williams is a PhD researcher at the University of Birmingham investigating the bulk and surface stabilization of high voltage cathode materials for Li ion batteries, with particular interest in Ni rich materials . He is working on WP3 of the CATMAT project, focusing on materials synthesis and electrode manufacture. He obtained an MChem from Durham University in Chemistry with an industrial placement at CPI working on electrode slurry optimization for Li ion cathodes.

Note: This poster has been published here with the kind permission of the University of Birmingham. All images and content are copyright of the University of Birmingham and cannot be reproduced without permission.

LITHIUM ION CATHODE MATERIALS – CATMAT

The CATMAT project will offer benefits for car makers and their supply chain that are both large and near-term. It includes work to understand the origins of the current limitations of nickel-rich cathodes (with low or no cobalt) and to understand the fundamental electrochemistry of lithium-rich oxygen redox cathodes. The project is exploiting this new knowledge to inform the discovery of novel cathode materials with enhanced properties. The most promising materials will be identified, before scaling up their synthesis and integrating them in full battery cells to demonstrate performance. The project will support the accelerated development of new cathode materials towards practical commercial applications.

Hard Carbon Anodes in Sodium-ion

A poster from the same research team at the University of Birmingham.

• Emerging battery technology – promising cost, safety, sustainability, and performance advantages over current commercialised lithium-ion batteries^1,2.
• Advantages:
  • widely available
  • inexpensive raw materials
  • rapidly scalable technology
  • meeting global demand for carbon-neutral energy storage solutions^3,4.
• Adding metals would increase the overall energy density, but results in volumetric changes leading to failure.