Lithium has long dominated the battery market, powering everything from the quiet hum of electric vehicles to the glow of smartphone screens. This soft, silvery white metal is light and has a high energy density, ideal for creating long-lasting and portable batteries.
Now, magnesium (Mg) batteries are stepping into the spotlight. Not only is Mg more abundant and cost-effective than lithium, it also has a higher energy density and improved safety characteristics.
On track towards lightweight, high-energy-density Mg batteries, researchers have been developing anode-free prototypes that lack static negative electrodes. Instead, they utilise a dynamic process where Mg is plated onto a current collector from the electrolyte during charging and redissolved during discharging, leading to a marked reduction in the battery's weight, size and cost.
“The implementation of an anode-free design has faced obstacles, particularly in achieving efficient and uniform Mg deposition,” said Zhi Wei Seh, a Senior Principal Scientist at A*STAR’s Institute of Materials Research and Engineering (IMRE). “Non-uniform deposition leads to rapid battery failure, caused by the accumulation of ‘dead Mg’ and the formation of a thick passivation layer that impedes efficient cycling.”
In collaboration with researchers from Zhejiang University, Beihang University, Guizhou University and ShanghaiTech University, China; and Indiana University-Purdue University Indianapolis, US; Seh and colleagues identified a potential workaround by leveraging the properties of MXene, a material known for its exceptional electrical conductivity and favourable surface properties, making it an ideal candidate for use in next-generation battery technologies.
Concepts of a standard battery with a Mg metal anode versus an anode-free battery which uses a Ti3C2Tx MXene film as its anode current collector. The unique crystallographic structure of Ti3C2Tx grants the film a potent ability to adsorb Mg2+ ions and convert them into solid Mg.
By integrating three-dimensional MXene (Ti3C2Tx) films, the team developed an innovative anode-free Mg battery. The MXene film acts as a current collector, promoting a uniform and controlled horizontal deposition of Mg ions from the electrolyte during charging to enhance the battery’s efficiency and performance.
“This uniform deposition is achieved thanks to the unique chemical composition of MXene, which contains surface oxygen groups that have a strong affinity for Mg ions, attracting them and facilitating their conversion into solid Mg on the collector’s surface,” explained Seh.
In a series of rigorous tests, the researchers achieved exceptional Mg plating and stripping efficiencies—99.7 percent over 364 cycles at a high current density, and 99.4 percent over 164 cycles with high Mg utilisation. These data highlight the battery’s potential for sustained use without substantial performance loss.
“Another significant advantage of these anode-free batteries is the simplification of their manufacturing process, eliminating the need for an anode material and thus reducing the complexity of battery production,” commented Seh, pointing out the battery’s potential for widespread applications across diverse industries.
The team's innovative design can also transform electromobility and stationary grid storage, thanks to its high energy density, cost-efficiency and enhanced safety features. The researchers have plans to construct larger battery models, such as pouch cells, to further showcase the anode-free Mg battery's potential in real-world scenarios.
The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering (IMRE).
