Redox Reactions
Batteries operate using paired oxidation and reduction reactions. The memory aid OIL RIG refers to the movement of electrons.
- Oxidation Is Loss of electrons
- Reduction Is Gain of electrons
Unit 04 Electrochemistry
A More SustainableLithium-Ion Battery
Article
Ko, S., Han, X., Shimada, T., et al. (2023). Electrolyte design for lithium-ion batteries with a cobalt-free cathode and silicon oxide anode. Nature Sustainability, 6, 1705\u20131714.
Read The Original ArticleThe researchers paired a cobalt-free cathode with a silicon-suboxide anode and designed an electrolyte that supported operation at a high cut-off voltage and long-term cycling.
Abstract
Lithium-ion batteries are widely used in electronic devices, electric vehicles, and energy-storage systems. However, many conventional lithium-ion batteries depend on cathode materials containing cobalt. Cobalt presents challenges because it is a limited resource and its supply chain has been associated with environmental, human-rights, and mining concerns. The purpose of this study was to investigate whether a high-performance lithium-ion battery could be created using a cobalt-free cathode and a high-capacity silicon-suboxide anode.
The researchers designed a concentrated LiFSI/FEMC electrolyte that helped stabilize the electrochemical reactions occurring at both electrodes. Their full battery reached an upper cut-off voltage of 4.9 V and demonstrated cycling over 1,000 cycles under the reported test conditions. The study concluded that carefully controlling electrolyte chemistry can help stabilize both oxidation and reduction processes and could support the development of more sustainable rechargeable battery technologies.
Connection to Our Curriculum
Anode
During battery discharge, oxidation occurs at the anode. Electrons leave the anode and travel through the external circuit.
Cathode
During discharge, reduction occurs at the cathode. Electrons arriving through the circuit participate in reduction reactions.
Electrolyte
The electrolyte allows ions to travel between the electrodes. An effective electrolyte must conduct ions while remaining chemically stable. The researchers specifically engineered electrolyte chemistry to reduce unwanted reactions at the electrodes.
Cell Potential
The difference between electrode potentials determines the voltage produced by an electrochemical cell.
E°cell = E°cathode − E°anode
Gibbs Free Energy
ΔG is the Gibbs free-energy change, n is the number of moles of electrons, F is the Faraday constant, and E is the cell potential.
ΔG = −nFE
- A spontaneous galvanic-cell reaction has Ecell > 0
- and ΔG < 0
Rechargeable Batteries
A secondary cell can be driven backwards
Lithium-ion batteries are secondary cells, meaning their reactions can be driven in the reverse direction by supplying electrical energy.
During charging, electrical energy forces the reactions opposite to the spontaneous discharge direction.
Catholic Graduate Expectation
OCSGE 7A Responsible Citizen
This research demonstrates one of the strongest moral and ethical connections in the project. The researchers identify cobalt supply, scarcity, mining practices, and human-rights concerns as reasons for investigating alternative battery materials.
Scientific progress should therefore be evaluated using more than performance and cost. Scientists and companies should also consider the people who extract raw materials, working conditions, damage to ecosystems, and the long-term availability of natural resources.
Developing batteries that rely less heavily on materials associated with environmental and social concerns reflects the Catholic principles of human dignity, justice, stewardship, and responsibility for the common good.
Key Takeaway
Electrochemistry allows stored chemical energy to be converted into electrical energy, while responsible material selection can make battery technology more sustainable.