Aluminium oxide (Al₂O₃) is one of the most common and widely used inorganic materials. It is the main raw material for aluminum production. At the same time, it plays an important role in advanced ceramics, abrasives, and catalyst supports. With properties such as high temperature resistance, corrosion resistance, hardness, and insulation, aluminium oxide is applied in new energy, aerospace, environmental protection, and medical fields. As an additive, it acts like a “nutrient,” improving the performance of other materials. It is considered a multifunctional reinforcing material. This article introduces its applications in batteries, ceramics, and polymers.
Improving Lithium-Ion Battery Performance and Safety
Lithium-ion batteries are vital for energy storage and electric vehicles. Their performance depends on the cathode, anode, separator, and electrolyte. Alumina, with excellent stability and insulation, is used in all these parts.
Cathode Materials
A thin aluminium oxide coating on cathode materials improves capacity retention, cycling life, and thermal stability.
Its effects include:
- Removing HF from electrolyte, reducing metal dissolution.
- Creating a protective barrier, limiting side reactions.
- Forming lithium aluminate to enhance ion diffusion and lower charge transfer resistance.
- Reducing heat generation, improving thermal stability.
- Reacting with LiPF₆ to form LiPO₂F₂, which enhances cycling life.
- Suppressing Jahn-Teller effects to stabilize electrodes.
Separator Materials
Alumina-coated separators resist shrinkage at high temperatures. This prevents short circuits and thermal runaway. The ceramic layer also strengthens the separator mechanically. It adjusts porosity, enhances ion transport, and greatly improves safety.
Anode Materials
Coating the anode with aluminium oxide improves interfacial stability and reduces lithium loss. In needle penetration tests, ceramic-coated cells showed lower peak temperatures and no explosion. By contrast, non-coated cells reached over 400°C with smoke and explosion.
Electrolyte and Solid Electrolyte
Adding alumina powder into liquid electrolyte increases conductivity and reduces resistance. It improves charge-discharge performance and cycle life. In solid electrolytes, alumina enhances interfacial stability and lithium-ion reversibility. For example, adding 5% alumina into LLZO raised capacity retention from 82.3% to 91.4% after 200 cycles.
Reinforcing Ceramic Materials
Alumina itself is a high-performance ceramic with hardness, wear resistance, and high modulus. More importantly, it reinforces other ceramics.
Alumina Toughened Zirconia (ATZ)
Pure zirconia undergoes martensitic transformation, improving toughness but causing cracks during cooling. Stabilizers like yttria can help, but effects are limited. Adding alumina as a second phase solves this.
- Alumina is compatible with zirconia.
- It increases strength, toughness, and anti-aging properties.
- The composite resists heat, corrosion, and wear.
As a result, ATZ ceramics are widely studied for structural applications.
Other Ceramic Systems
Alumina also enhances silicon carbide and other ceramics. Even in alumina ceramics themselves, adding small amounts of nano-Al₂O₃ reduces sintering temperature and improves toughness.
Enhancing Polymer Composites for Heat Dissipation
In electric vehicles, energy storage, and 5G electronics, heat management is critical. High power density leads to higher temperatures. Overheating reduces performance and safety.
Polymers are lightweight, low-cost, and easy to process. They are widely used in thermal interface and packaging materials. However, polymers are poor heat conductors. Their thermal conductivity is usually only 0.1–0.5 W/(m·K).
To solve this, high thermal conductivity fillers are introduced. Aluminium oxide is the most common filler. It is inexpensive, electrically insulating, and chemically stable. Adding alumina particles significantly increases polymer thermal conductivity. This makes composites suitable for battery packs, 5G base stations, and electronic devices.
Conclusion
Aluminium oxide is a multifunctional reinforcing material. In lithium-ion batteries, it improves stability, cycle life, and safety. In ceramics, it enhances toughness and durability. In polymers, it boosts thermal conductivity. With these advantages, alumina has irreplaceable value in energy, electronics, and advanced materials. Its applications will continue to expand, driving innovation and industrial upgrades.