Hydrothermal Lithiation Boosts The Electrochemical Performance Of The NCM Cathode Materials For Lithium Ion Batteries

With the fast increasing pressure of resources and environmental issues, clean energy is becoming an urgent demand in our life. Among various candidates of cathode materials, layered Li[NixCoyMn1-x-y]O2 (0≤x≤1, 0≤y≤1) cathode materials has been gradually employed on EVs, HEVs and PHEVs and other electronic products and shows a promising future compared with the toxic LiCoO2 and the relatively low energy density LiMn2O4.

Unfortunately, many obstacles such as Li/Ni mixing, side-reactions between the electrode and electrolyte, safety and so on, especially at a high cut-off voltage, hinder the commercialization process. Many efforts such as ion substitution, surface coating and new synthetic routine etc. on NCMs are made by the researchers to improve the high cut-off voltage performance.

Recently, layered Li[NixCoyMn1-x-y]O2 (0≤x≤1, 0≤y≤1) cathode materials prepared by a hydrothermal lithiation routine has been investigated by the researchers from Central South University, P.R. China. The obtained LiNi0.5Co0.2Mn0.3O2 cathode materials exhibit an excellent electrochemical performance.

Firstly, the lithiated transition metal oxide precursor has been prepared via a hydrothermal process. Compared with the traditional solid-state method, the lithiation process assists Li+ to diffuse into the spherical-like particle’s crystal structure, resulting in the formation of the lithiated composite oxide precursor with typical α-NaFeO2-type layered structure in aqueous solution.

Besides, the aqueous lithiation process also helps the Li homogeneously distribute in the particles at an atomic level, avoiding the uneven lithium distribution by traditional solid state method. Those effectively promote the preparation of the cathode materials with high performances in the post-heat treatment.

Secondly, the obtained LiNi0.5Co0.2Mn0.3O2 cathode materials exhibit an excellent structural and interfacial stability as well as kinetic characters. The decreased Li/Ni mixing (only 2.27%) and suppressed polarization effects (the voltage drop is only 0.41 V after 100 cycles) demonstrate that the obtained NCM cathode has an enhanced structural and interfacial stability. Compared with the traditional solid state method, the as-prepared NCM523 cathode material shows a suppressed charge transfer resistance (Rct) and a higher lithium ion coefficient (10-8-10-11 cm2·s-1) upon cycling, indicating enhanced kinetic characters.

Importantly, the electrochemical properties at high cut-off voltage have been remarkably improved. The as-prepared NCM523 cathodes deliver a superior initial capacity of 187.3 mAh g-1 and corresponding to the capacity retention of 81.90% after 100 cycles over 3.0~4.6 V at 1C rate (1C= 155 mAh g-1), far higher than that of the same cathode prepared by the traditional solid-state method (the initial capacity is 186.6 mAh g-1 and the capacity retention is only 74.11%). The rate capability has also strengthened after the hydrothermal lithiation.

Based on this discovery, it is believed that the hydrothermal lithiation would be potentially applied in improving the electrochemical properties of the layered Li[NixCoyMn1-x-y]O2 (0≤x≤1, 0≤y≤1) cathode materials, especially at the high cut-off voltage.

The work is led by Prof. Yunjiao Li. The paper, Enhancing the High-voltage Electrochemical Performance of the LiNi0.5Co0.2Mn0.3O2 Cathode Materials via Hydrothermal Lithiation, is published in Journal of Material Science, (2018) 53:2115-2126.

About The Author

YL
Yunjiao Li

Dr. Yunjiao Li is a professor at  Central SouthUniversity, China.

Speak Your Mind!

READ THIS NEXT

Closing The Gaps In Photovoltaic Forecasting Methods

A photovoltaic (PV) value is the voltage output generated by solar cells that harvest solar energy to produce electricity. The PV value is a critical performance indicator of solar panels consisting of a plurality of solar cells (Fig. 1a). Appropriate PV forecasting over time can help PV farms/plants efficiently supply the solar energy for power […]

How Public Opinion Affects Air Quality: A Chinese Case Study

China has achieved notable economic development in recent decades. However, such achievement comes with serious environmental and social costs. The issue of environmental deterioration, particularly air pollution, has drawn extensive concern from the public as well as policymakers and scholars. In early 2012, the Chinese government released documents requiring the adoption of a new standard […]

Bridging Contraindicated Stability And Topological Properties Via Functionality Genes

Topological insulator (TI) is new quantum state of matter that has attracted a lot of interests. TI possesses a twisted bulk electronic structure that can be characterized by a non-trivial topological invariant (Z2 = 1) according to the quantum theory of topological phases. This twisted band structure will lead to, on TI’s surface or edge […]

Pretreatment Processes For Lignocellulosic Wastes

Today the protection of the environment from pollution is of instant concern, which can only be attained by finding an alternative to the use of chemicals for biofuel production. In recent decades, use of lignocellulosic waste as a feedstock for biofuel production has attracted researchers. It can be easily transformed into a usable form by […]

Study Finds Those Who Have Autism More Likely To Suffer From Depression

A new study done by researchers at the University of Bristol in the United Kingdom implies that depression is up to three times more likely to strike individuals with autism than individuals in the general population. Furthermore, the study found that individuals with higher functioning autism were more likely to be at risk of depression […]

How Energy And Carbon Dioxide Move Through Alpine Forests

There have been great strides in the human understanding of our impact on the global climate in recent decades. As scientists push forward with that effort, it has become necessary to improve our knowledge of the finer details of the interactions between the terrestrial biosphere and the atmosphere above. Climate models on most scales must […]

England Faces A Water Shortage

England’s Environment Agency has recently released a report stating that England is in danger of running out of water, and that people must curb their water usage as well as fix water supply leaks if future water shortages are to be prevented. Many sources of water in England are already under pressure and overused, and […]