The central challenge the researchers set out to solve is a familiar one in battery materials science. Graphite, the standard anode in commercial lithium-ion batteries, stores lithium ions between flat sheets of carbon, and its performance at very high charge rates is limited by how quickly ions can diffuse into the bulk of the material. Three-dimensional graphene — a porous, interconnected network of graphene sheets — has long been considered a promising alternative because it combines high electrical conductivity with an open framework that ions can access from many directions. But making 3D graphene is only half the battle. Its macroscopic shape, whether it forms granules, plates, or a continuous honeycomb, and its microscopic surface texture, particularly the abundance of tiny micropores, both strongly influence how fast lithium ions can reach the storage sites and how efficiently electrons can travel through the electrode. Until now, tuning these two features at different length scales has required multiple, often incompatible, processing steps.

The team’s solution is a metallothermic reduction strategy, in which a reactive metal strips the oxygen from CO2, leaving elemental carbon behind. The trick is that the choice of metal reductant — sodium, potassium, or magnesium — does more than simply liberate the carbon. It dictates the entire architecture of the resulting graphene. With magnesium as the reductant, the carbon condenses into a granulated structure. With potassium, it forms plate-like sheets. But with sodium, the reaction produces something far more interesting: a three-dimensional interconnected honeycomb framework, in which graphene walls branch and merge into a continuous conductive skeleton riddled with pores at the nanometre scale. In other words, simply swapping one alkali metal for another transforms the final material from a collection of particles into a fully connected, sponge-like network.

The sodium-derived honeycomb graphene, which the authors call Na-3DG, is the star of the study. It has a specific surface area of 765.5 square metres per gram — a vast internal area packed into a small mass — and, remarkably, 84.9 percent of its pore volume is in the micropore range, the smallest class of pores. This is unusual because most porous carbons distribute their pore sizes across a broad spectrum, mixing micropores with larger mesopores and macropores. Here, the micropores dominate, and that dominance turns out to be the key to the material’s ultrafast lithium storage. Micropores act as short-range windows through which lithium ions can penetrate the electrode surface directly, rather than having to snake their way through long, tortuous channels. The result is a dramatic reduction in the distance ions must travel and, consequently, in the time it takes to charge and discharge the cell.

But porosity alone is not enough. If the carbon network were interrupted — if the graphene sheets were broken, poorly connected, or contaminated with defects — electrons could not move quickly enough to keep up with the incoming ions, and the electrode would fail at high rates. To verify that the sodium route produces a truly continuous conductive network, the researchers turned to X-ray photoelectron spectroscopy, which probes the chemical bonding of the carbon atoms, and to four-probe conductivity measurements, which directly measure how well the material conducts electricity. The spectroscopy showed that Na-3DG retains a highly continuous network of sp2-hybridized carbon — the same bonding motif that gives pristine graphene its exceptional electron mobility. The conductivity measurements confirmed this: the intrinsic electrical conductivity of the material is 16.4 siemens per centimetre, a high value for a porous carbon. Electrochemical impedance spectroscopy, which measures the resistance a battery cell presents to alternating current, revealed a series resistance of just 1.8 ohms and a charge-transfer resistance of 70.9 ohms, both low figures that indicate electrons and ions can move through the electrode with minimal obstruction.

The researchers attribute the material’s exceptional performance to a synergistic effect between two structural features that work together rather than in isolation. The continuous three-dimensional conductive skeleton minimizes what is known as interparticle contact resistance — the electrical resistance that arises where separate particles of an electrode material touch one another. In conventional electrodes made of discrete particles, electrons must hop from particle to particle, and each junction adds resistance. In Na-3DG, because the graphene network is continuous, electrons can travel along uninterrupted pathways. Meanwhile, the abundant surface micropores provide short-range ion-penetration windows, allowing lithium ions to access the carbon surface from many directions at once. The combination — fast electron transport through a connected skeleton and fast ion transport through a microporous surface — is what enables the material to sustain such extreme charge rates without collapsing.

The electrochemical results bear this out. When tested as the anode in a lithium-ion half-cell, Na-3DG delivered more than 200 mAh per gram at a rate of 150C. To put that in perspective, a rate of 150C means the battery would be fully discharged in about 24 seconds — an extraordinary figure for any anode material, and one that approaches the limits of what ion transport physics allows. At a more moderate rate of 50C, the material retained 88.9 percent of its first-cycle capacity after 2,000 charge-discharge cycles, demonstrating not only speed but also durability. Long-term cycling stability is often the Achilles heel of high-rate anodes, because repeated insertion and removal of lithium ions can mechanically stress the material and degrade its structure. The fact that Na-3DG holds up over thousands of cycles suggests that its honeycomb framework is robust enough to accommodate the strain.

Beyond its immediate performance, the study carries a broader significance for how we think about carbon materials and the carbon cycle. The starting material is CO2 — a waste product and a greenhouse gas — and the product is a high-value carbon material with a precisely engineered structure. The authors describe this as a strategy for upcycling CO2 into hierarchical porous carbon, a term that captures the idea of transforming a low-value molecule into a material with sophisticated, multi-scale architecture. This is not the first time CO2 has been converted into graphene; previous work by some of the same researchers and by other groups has explored metallothermic and plasma-based routes. But the new study is distinguished by the degree of control it offers: by simply changing the metal reductant, the macroscopic morphology can be continuously tuned from granulated to plate-like to honeycomb, all within a single reaction. That level of morphological control, achieved in one step, is rare in materials synthesis and points toward a more general design principle for porous carbons.

The work also contributes to a growing body of research on fast-charging lithium-ion batteries, a field that has become one of the most active in energy storage science. Fast charging is widely seen as a critical enabler for electric vehicles, because the time it takes to recharge remains a major barrier to widespread adoption. The bottleneck, however, is not the battery’s total capacity but its ability to accept lithium ions quickly without triggering unwanted side reactions, such as lithium plating on the anode, which can degrade the cell and pose safety risks. Anode materials that can accommodate rapid ion insertion — like the honeycomb graphene described here — are therefore central to the fast-charging agenda. The study’s structural design principles, particularly the synergy between a continuous conductive skeleton and abundant surface micropores, offer a template that other researchers can apply to different carbon architectures and even to non-carbon materials.

For now, the material remains a laboratory demonstration, and translating it into commercial batteries will require scaling up the synthesis, integrating it into full cells with compatible cathodes and electrolytes, and validating its performance under realistic operating conditions. But the study’s message is clear and, in its own way, striking: the same molecule that drives climate change can be chemically reimagined as the backbone of a next-generation battery, provided the architecture is designed with the same care as the chemistry itself. By showing that a single reaction, guided by the choice of a metal reductant, can produce a 3D graphene with a honeycomb topology, an overwhelming micropore fraction, and a continuous sp2 carbon network, the researchers have not only advanced the state of the art in anode materials — they have also offered a glimpse of a future in which carbon capture and energy storage are not separate endeavours but two sides of the same molecular coin.

Subject of Research: Synergistic tuning of topology and microporosity in 3D graphene via direct CO2 conversion for ultrafast lithium storage

Article Title: Synergistic tuning of topology and microporosity in 3D graphene via direct CO2 conversion for ultrafast lithium storage

Article References: Wang, L., Wang, X., Wu, X., Luo, J., Liu, M., & Toan, S. (2026). Synergistic tuning of topology and microporosity in 3D graphene via direct CO2 conversion for ultrafast lithium storage. Ionics. https://doi.org/10.1007/s11581-026-07593-x

Image Credits: AI Generated

DOI: 10.1007/s11581-026-07593-x

Keywords: Synergistic, tuning, topology, microporosity, graphene, direct, conversion, ultrafast, lithium, storage, scientific research