Singapore's A*STAR Leads Magnesium Battery Revolution
Researchers at the Agency for Science, Technology and Research (A*STAR)'s Institute of Materials Research and Engineering (IMRE) have achieved a groundbreaking advancement in rechargeable magnesium batteries (RMBs). By engineering a bromine-rich artificial interphase on the magnesium (Mg) anode, the team has enabled unprecedented cycling stability of up to 3,600 hours. This innovation addresses longstanding challenges in magnesium metal batteries, positioning them as a viable alternative to lithium-ion batteries for sustainable energy storage.
Magnesium metal batteries promise higher safety and lower costs due to magnesium's abundance in the Earth's crust—making up about 2.3% compared to lithium's mere 0.0017%—and its reduced risk of dendrite formation, which can cause short circuits in lithium systems. In Singapore, where energy security and green technology are national priorities under the Research, Innovation and Enterprise 2030 (RIE2030) plan, this breakthrough aligns perfectly with efforts to diversify beyond lithium amid global supply chain vulnerabilities.
Understanding Magnesium Batteries: A Primer
Rechargeable magnesium batteries operate on the principle of shuttling divalent magnesium ions (Mg²⁺) between a magnesium metal anode and a cathode, typically through a non-aqueous electrolyte. Unlike monovalent lithium-ion (Li⁺) batteries, Mg batteries offer a theoretical volumetric capacity of 3,833 mAh/cm³—nearly double that of lithium's 2,061 mAh/cm³—allowing for more compact energy storage. Gravimetric capacity is comparable at around 2,200 Wh/kg, but magnesium's lower atomic weight and dendrite-free plating make it safer for high-energy applications like electric vehicles (EVs) and grid storage.
However, practical deployment has been hindered by two primary issues: anode passivation, where a blocking layer forms on the Mg surface impeding ion transfer, and sluggish Mg²⁺ diffusion kinetics due to its high charge density. These lead to low coulombic efficiency (CE)—the ratio of discharge to charge capacity—and short cycle life. Boron-centered electrolytes, like magnesium bis(hexamethyldisilazide) or Mg(HMDS)₂, bypass passivation by enabling reversible plating/stripping, but interfacial instability persists.
The Innovation: Bromine-Rich Artificial Interphase Explained
The core of A*STAR's breakthrough is the bromine-rich artificial solid electrolyte interphase (SEI), dubbed Br-Mg, formed on the Mg anode. This interphase is generated in situ by adding 1-bromooctane (OctylBr), a multifunctional organic bromide additive, to the Mg(HMDS)₂ electrolyte. During initial cycling, OctylBr decomposes to create a Br-rich layer that passivates the anode selectively, enhancing ionic conductivity while blocking electron transfer that causes degradation.
Scanning electron microscopy (SEM) reveals uniform, planar hexagonal Mg deposits on Br-Mg anodes, contrasting with irregular growth on bare Mg. Computational simulations from A*STAR's Institute of High Performance Computing (IHPC) confirm smoothed Mg²⁺ flux and uniform electric fields, preventing hotspots that lead to uneven deposition.
Step-by-Step: How the Br-Mg Interphase Functions
- Electrolyte Activation: Mg(HMDS)₂ with OctylBr is introduced. The boron-centered salt supports reversible Mg dissolution/plating.
- Interphase Formation: During first reduction, OctylBr breaks down, depositing Br⁻ ions and organic fragments to form a thin, Br-rich SEI (5-10 nm thick).
- Ion Regulation: Br-rich layer facilitates fast Mg²⁺ desolvation and transport (high ionic mobility ~10⁻⁴ S/cm), while suppressing side reactions.
- Uniform Plating: Planar growth of Mg crystals occurs, avoiding dendrites and dead Mg formation.
- Stripping Efficiency: During charge, Mg dissolves homogeneously, maintaining SEI integrity over thousands of cycles.
This process boosts CE to 99.5% and minimizes voltage hysteresis to ±68 mV.
Record-Breaking Performance Data
In symmetric Mg||Mg cells, Br-Mg anodes sustained 1,610 hours at a current density of 1 mA/cm²—over double the 796 hours for bare Mg. The full experimental RMB with Mo₆S₈ cathode reached an astonishing 3,600 hours of stable cycling, rivaling top lithium-metal batteries (800-3,500 hours). Asymmetric Mg||Mo₆S₈ cells showed 1,630 cycles at 99.5% CE versus 380 cycles at 96.5% for controls.
Rate capability tests demonstrated retention of 85% capacity at 5C rates, with full-cell energy density projected at >300 Wh/kg—competitive for EVs. These metrics were validated under ambient conditions, highlighting practical viability.
| Configuration | Bare Mg | Br-Mg |
|---|---|---|
| Symmetric Cell Cycling | 796 h, ±145 mV | 1,610 h, ±68 mV |
| Asymmetric CE/Cycles | 96.5%, 380 | 99.5%, 1,630 |
| Full Cell | 0 h | 3,600 h |
Spotlight on A*STAR IMRE Researchers
Lead author Deviprasath Chinnadurai, a Scientist at IMRE, spearheaded the experimental design, drawing from prior work on passivation-free SEIs. Senior Principal Scientist Zhi Wei Seh, corresponding author, emphasized the dual-action of OctylBr: "It mitigates passivation and promotes planar deposition for higher capacity and stability." Gaoliang Yang and team members Sonal Kumar, Jianbiao Wang, and Zhenxiang Xing contributed electrochemistry and materials analysis. Collaborators include Zdenek Sofer from Czech Technical University.
IMRE's Energy Materials department, focusing on beyond-Li systems like Na-, Mg-, and Al-ion batteries, has prototyped coin and pouch cells, accelerating translation to industry.Research jobs in battery materials at institutions like IMRE offer opportunities for PhD holders in materials science.
Read the full paperSingapore's Strategic Energy Landscape
Singapore imports 95% of its energy, making advanced storage critical for solar integration and net-zero by 2050. A*STAR's RMB work supports the National Research Foundation's S$25 billion RIE2025 plan, fostering spin-offs in green tech. Partnerships with NUS and NTU enhance higher education's role, training talent via joint labs.
Implications include grid-scale storage for Tuas Megaport and EV charging, reducing reliance on lithium amid 2026 shortages. Economic impact: Mg mining costs ~US$2,000/tonne vs lithium's US$15,000+.Singapore higher ed jobs in energy research are booming.
Mg vs Li-Ion: A Head-to-Head Comparison
- Safety: Mg: Dendrite-free, low reactivity; Li: Prone to fires (e.g., Boeing 787 incidents).
- Cost: Mg: Abundant, recyclable; Li: Supply risks, recycling <5%.
- Performance: Br-Mg: 3,600h cycles; Li-metal: ~1,000h typical.
- Energy Density: Volumetric superior for Mg; gravimetric similar.
- Challenges: Mg cathode/electrolyte development ongoing; Li mature.
Global Mg battery market projected to grow 25% CAGR to 2030, with Singapore poised as hub.
Future Directions and Challenges
Commercialization hurdles: Scale-up of OctylBr synthesis, cathode optimization (e.g., VS₂, Mo₆S₈), and pouch cell prototyping. A*STAR aims for 500 Wh/kg full cells by 2030. Collaborations with TrinaSolar and ShanghaiTech accelerate translation.
In higher education, this spurs Mg-focused programs at NUS/NTU. Aspiring researchers can explore research assistant jobs or career advice.
Photo by Brett Jordan on Unsplash
Conclusion: Powering Singapore's Green Future
A*STAR's bromine-rich interphase marks a pivotal step for RMBs, blending safety, affordability, and performance. As Singapore advances its green agenda, innovations like this from IMRE underscore research's role in energy independence. Stay ahead with Rate My Professor, higher ed jobs, and career advice on AcademicJobs.com.
