Practical magnesium batteries enabled by 2D crystalline polymer-based artificial electrode skins

Introduction

The intrinsic limitation of Li-ion batteries (i.e., cost, safety, and sustainability) is imposing a strong demand for next-generation battery technologies based on resource-abundant elements. Among the top candidates for this purpose are Mg batteries. However, state-of-the-art Mg batteries still encounter numerous problems (e.g., low Coulombic efficiency, energy efficiency, energy density, and cycle life) and are far from mature to satisfy practical use.

Challenges in Mg Batteries

The disappointing performance of Mg batteries is dominantly assigned to the problematic interfacial charge transfer governed by the charge-dense Mg2+ at both the anodes and cathodes.

Proposed Solution

Here, I propose the ground-breaking concept of using molecule-customisable 2D crystalline polymers (2DCPs) as artificial electrode ‘skins’ to regulate the interfacial Mg2+ transport and enable practical Mg batteries.

Synthesis of 2DCPs

Relying on dynamic imine and sp2-carbon linkage reactions, ultrathin 2DCPs with varying porosity, dense nucleophilic groups, and stable polymer skeletons will be synthesised as the artificial electrode skins for Mg batteries.

Expected Outcomes

Multifunctional 2DCPs are expected to promote practically useful Mg anode stripping/plating chemistry and high-voltage/high-capacity cathode chemistries by:

1. Forcing Mg2+ desolvation and Mg2+-anion dissociation.
2. Allowing fast and selective interfacial Mg2+ transport.
3. Inhibiting the parasitic reactions associated with the electrolyte.

Research Approach

An integrated approach combining atom-level structure investigation, Mg2+-transport study, and electrode chemistry evaluation will establish the molecular design principle for the optimal electrode skins.

Conclusion

Ultimately, with artificial electrode skins, the prototype configurations for practical Mg batteries will be formulated, offering intellectual property for future battery products. Besides, the acquired ion-transport knowledge will hold promise in many other applications, such as ion sieving, capacitive deionisation, and salinity gradient energy harvesting.