chemistry

Lithium cobalt oxide

Lithium cobalt oxide is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Lithium cobalt oxide rather than just read about it. In short: Lithium cobalt oxide, sometimes called lithium cobaltate or lithium cobaltite, is a chemical compound with formula LiCoO2. The cobalt atoms are formally in the +3 oxidation state, hence the IUPAC name lithium cobalt(III) oxide.

Key takeaways

Lithium cobalt oxide belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Lithium cobalt oxide to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Lithium cobalt oxide from memory before moving on to harder problems.

Reference excerpt

Lithium cobalt oxide, sometimes called lithium cobaltate or lithium cobaltite, is a chemical compound with formula LiCoO2. The cobalt atoms are formally in the +3 oxidation state, hence the IUPAC name lithium cobalt(III) oxide. Lithium cobalt oxide is a black powder, and is commonly used in the positive electrodes of lithium-ion batteries especially in handheld electronics.

Structure The structure of LiCoO2 has been studied with numerous techniques including x-ray diffraction, electron microscopy, neutron powder diffraction, and EXAFS. The solid consists of layers of monovalent lithium cations (Li+) that lie between extended anionic sheets of cobalt and oxygen atoms, arranged as edge-sharing octahedra, with two faces parallel to the sheet plane. The cobalt atoms are formally in the trivalent oxidation state (Co3+) and are sandwiched between two layers of oxygen atoms (O2−). In each layer (cobalt, oxygen, or lithium), the atoms are arranged in a regular triangular lattice. The lattices are offset so that the lithium atoms are farthest from the cobalt atoms, and the structure repeats in the direction perpendicular to the planes every three cobalt (or lithium) layers. The point group symmetry is 3m in Hermann-Mauguin notation, signifying a unit cell with threefold improper rotational symmetry and a mirror plane. The threefold rotational axis (which is normal to the layers) is termed improper because the triangles of oxygen (being on opposite sides of each octahedron) are anti-aligned.

Preparation Fully reduced lithium cobalt oxide can be prepared by heating a stoichiometric mixture of lithium carbonate (Li2CO3) and cobalt(II,III) oxide (Co3O4) or metallic cobalt at 600–800 °C (1,112–1,472 °F), then annealing the product at 900 °C (1,650 °F) for many hours, all under an oxygen atmosphere.

Nanometer-size particles more suitable for cathode use can also be obtained by calcination of hydrated cobalt oxalate (β-CoC2O4·2H2O), in the form of rod-like crystals about 8 μm long and 0.4 μm wide, with lithium hydroxide (LiOH), up to 750–900 °C (1,380–1,650 °F). A third method uses lithium acetate, cobalt acetate, and citric acid in equal molar amounts, in water solution. Heating at 80 °C (176 °F) turns the mixture into a viscous transparent gel. The dried gel is then ground and heated gradually to 550 °C (1,022 °F).

Use in rechargeable batteries The usefulness of lithium cobalt oxide as an intercalation electrode was discovered in 1980 by an Oxford University research group led by John B. Goodenough and Tokyo University's Koichi Mizushima. The compound is now used as the cathode in some rechargeable lithium-ion batteries, with particle sizes ranging from nanometers to micrometers. During charging, the cobalt is partially oxidized to the +4 state, with some lithium ions moving to the electrolyte, resulting in a range of compounds LixCoO2 with 0 < x < 1. Batteries produced with LiCoO2 cathodes have very stable capacities, but have lower capacities and power than those with cathodes based on (especially nickel-rich) nickel-cobalt-aluminum (NCA) or nickel-cobalt-manganese (NCM) oxides. Issues with thermostability are better for LiCoO2 cathodes than other nickel-rich chemistries although not significantly. This makes LiCoO2 batteries susceptible to thermal runaway in cases of abuse such as high temperature operation (>130 °C (266 °F)) or overcharging. At elevated temperatures, LiCoO2 decomposition generates oxygen, which then reacts with the organic electrolyte of the cell, this reaction is often seen in Lithium-Ion batteries where the battery becomes highly volatile and must be recycled in a safe manner. The decomposition of LiCoO2 is a safety concern due to the magnitude of this highly exothermic reaction, which can spread to adjacent cells or ignite nearby combustible material. In general, this is seen for many lithium-ion battery cathodes.

Safety Although not especially acutely toxic, with an LD50 of over 5000 mg/kg in mice, LiCoO2 is a suspected human carcinogen and teratogen, and may damage fertility. It has a high acute and chronic toxicity to aquatic life.

See also List of battery types Sodium cobalt oxide

References

External links "Imaging Lithium Atoms: One Angstrom Microscope's observations of the smallest, lightest metal atoms are a first for electron microscopy". www.lbl.gov. Lawrence Berkeley National Laboratory. 13 June 2003. Archived from the original on 2008-01-13.

Illustrations

Worked examples

Example 1 — a first encounter with Lithium cobalt oxide

Start with the simplest possible case. Write down what Lithium cobalt oxide claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Lithium cobalt oxide before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Lithium cobalt oxide ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Lithium cobalt oxide

In research: Lithium cobalt oxide appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Lithium cobalt oxide in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Lithium cobalt oxide is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cobalt(III) compounds, Lithium compounds, Oxides, so understanding it makes those chapters shorter.
In everyday life: Look for Lithium cobalt oxide outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Lithium cobalt oxide in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Lithium cobalt oxide means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Lithium cobalt oxide out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Lithium cobalt oxide in simple terms?

Why does Lithium cobalt oxide matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Lithium cobalt oxide?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Lithium cobalt oxide.