Messi Biology states that magnesium carbonate (MgCO₃) has evolved from a “peripheral filler” to a “multifunctional performance regulator” in lithium batteries, playing a role across the entire technology chain from positive electrode preparation, electrolyte, separator to safety management. With its triple advantages of “high purity, low impurities, controllable thermal decomposition, and low cost,” magnesium carbonate is undergoing a transition from an “additive” to a “key functional layer” in the lithium battery industry chain, providing a scalable material path for next-generation batteries with high energy, high safety, and low cost.
1. The “Magnesium Source + Structure Stabilizer” for Cathode Materials
- Doping Modification: In positive electrode precursors such as lithium iron phosphate (LFP) and high-nickel ternary materials (NCM811), electronic-grade magnesium carbonate (≥99.5%) is thermally decomposed at 650–750°C to produce active MgO. Mg²⁺ enters the crystal lattice, inhibiting abnormal grain growth and improving ion diffusion rate and rate performance.
- Coating Layer Precursor: MgO generated from the decomposition of magnesium carbonate can form an ultra-thin ceramic coating on the surface of the positive electrode, blocking electrolyte side reactions and reducing interfacial impedance growth, leading to an 8-12% increase in cycle life.
- Dosage Examples: Typically, 3.3–4.5 kg of magnesium carbonate is added per ton of lithium cobalt oxide; adding 1–1.5 kg per ton of lithium iron phosphate can significantly improve structural stability.
2. The “Acid Removal + Thermal Stabilization Dual-Function Additive” for Electrolytes
- HF Scavenging: High-purity, ultrafine magnesium carbonate (D50≈0.5–1µm) can rapidly neutralize HF generated by the hydrolysis of LiPF₆, reducing free HF to <20ppm and inhibiting the dissolution of positive electrode metals.
- High-Temperature Self-Heating Suppression: Adding 0.5–2wt% magnesium carbonate increases the initial decomposition temperature of the electrolyte by 15–20°C and reduces gas production by 30% during 48h storage at 80°C, significantly reducing the risk of thermal runaway.
3. The “Heat-Resistant Skeleton + Flame-Retardant Barrier” for Separators
- Ceramic Coating: MgO ceramic layers prepared using magnesium carbonate as a precursor can reduce the thermal shrinkage rate of PE separators from 60% to <5% at 150°C and increase the needle penetration rate by 40%.
- Pore Size Regulation: Ultrafine magnesium carbonate particles form uniform micropores in the separator matrix, improving ion conduction efficiency while preventing lithium dendrite penetration and internal short circuits.
4. Cost and Supply Chain Advantages
- Price and Resources: The cost of battery-grade magnesium carbonate has decreased significantly, only 1/20 of the cost of cobalt sources, and China has abundant magnesium resources, which can completely eliminate the excessive dependence on scarce metals such as cobalt and nickel.
- Process Compatibility: Whether it is co-precipitation, spray drying, or solid-state sintering, magnesium carbonate can be directly added to existing positive electrode production lines without the need for new equipment, achieving a “plug-and-play” upgrade.
5. Future Trends
- Magnesium Ion Battery Anodes: High-surface-area magnesium carbonate (>100m²g⁻¹) can be carbonized and used as an anode for magnesium ion batteries to achieve reversible magnesium intercalation/deintercalation, with a theoretical capacity of 2200mAhcm⁻³, becoming an important candidate in the post-lithium era.
- Solid-State Battery Interfacial Layer: Nano-MgO generated from the thermal decomposition of magnesium carbonate can be combined with sulfide or polymer electrolytes to construct low-impedance, high-stability positive and negative electrode interfaces, and is expected to enter solid-state battery pilot production in 2026.