A 3D-printed lithium carbon dioxide battery uses MXene and carbon nanotube nanomaterials to deliver high energy and power with stable performance in Martian conditions for off-planet energy storage.
(Nanowerk Spotlight) Mars presents one of the hardest tests for any power system. Sunlight fades during long nights and dust storms, and temperatures swing from deep cold to daytime heat within hours. Missions need compact energy sources that can store large amounts of energy, release it quickly, and stay reliable through wide temperature changes. Solar panels alone cannot ensure steady power, while nuclear systems add weight and complexity. Batteries sit between them, but ordinary lithium ion cells lose capacity in the cold and struggle to deliver both high energy and high power under Martian conditions.
A new approach uses what Mars already provides. Its thin atmosphere is almost pure carbon dioxide, which could serve as both a reactant and an abundant local resource. Lithium carbon dioxide (Li–CO₂) batteries exploit this by reacting lithium with carbon dioxide to produce energy. They promise about four times the energy density of today’s lithium ion cells.
Yet their potential has been limited by chemical side effects and transport bottlenecks. The main discharge product, lithium carbonate, is an electrical insulator that builds up on the electrode surface and blocks further reactions. Both ions and gas move sluggishly through dense electrode layers, causing large voltage losses and rapid capacity fading.
Progress in nanomaterials and precision manufacturing has begun to overcome these barriers. Catalytic surfaces that promote reversible reactions and porous structures that let gas and ions move freely are key advances. Three dimensional printing, in particular, enables electrodes that are thick yet finely structured, with interconnected channels for liquids and gases.
Because printing can be automated, it also aligns with the long-term goal of producing energy systems directly on Mars rather than shipping all components from Earth.
In this context, a study in Advanced Functional Materials (“Powering‐On‐Mars Enabled by Ultrahigh Energy and Power Density Li‐CO2 Battery”) reports a design that meets those demands. The researchers built a lithium carbon dioxide battery with a printed, hierarchical porous cathode that achieves high energy and power densities along with stability across extreme temperatures.
The work focuses on structural engineering rather than exotic chemical additives, showing that design alone can address several long-standing issues.
Schematic illustration of powering-on-Mars enabled by Li-CO2 batteries. (Image: Reprinted with permission by Wiley-VCH Verlag) (click on image to enlarge)
The cathode is created by direct ink writing, a form of three dimensional printing that extrudes a specially prepared ink along programmed paths. The ink combines two materials. One is MXene, a two-dimensional titanium carbide compound known for high conductivity and chemical stability. The other is carbon nanotubes that connect the MXene sheets and prevent them from collapsing together. Together they form a conductive network that stays open to the movement of gas and ions.
Within this printed structure, two interlaced channel systems serve distinct roles. One holds the liquid electrolyte that carries lithium ions between electrodes. The other remains dry to let carbon dioxide gas reach the reactive surface directly.
Earlier Li–CO₂ batteries forced the gas to dissolve and diffuse through the liquid—a slow process that drained performance. By maintaining a separate gas path, the new electrode keeps the reaction evenly supplied and reduces the voltage loss known as polarization.
The team printed electrodes up to about three and a half millimeters thick, composed of 24 stacked layers with a mass loading of forty milligrams per square centimeter. In ordinary cells, thicker electrodes increase internal resistance. Here, a network of pores on multiple scales keeps all pathways open.
The largest pores, several micrometers wide, act as vertical channels for gas flow. Middle-sized pores provide room for reactions and for solid products to form and dissolve without clogging. The smallest pores, measured in nanometers, attract carbon dioxide and help retain the electrolyte.
Tests show that this multiscale design stores more carbon dioxide and offers more reactive surface area than a conventional coated electrode. Electrical measurements confirm that combining MXene and nanotubes lowers charge-transfer resistance, meaning electrons move more easily through the structure.
Performance results are strong across key metrics. The printed cathode cycles with an overpotential—extra voltage required to drive reactions—of about 0.22 volts at moderate rates. This corresponds to an energy efficiency near 98 percent, meaning almost all the charge put in during charging is recovered as usable energy on discharge.
The areal discharge capacity reaches about 172 milliampere hours per square centimeter, giving an areal energy density around 387 milliwatt hours per square centimeter and a volumetric energy density near 308 watt hours per liter. Measured by the mass of active materials only, the cell reaches about 1,143 watt-hours per kilogram. When including its full casing, the total energy density is lower but still competitive with existing lithium batteries.
Power output under high demand is equally important. Many previous Li–CO₂ cells failed at current densities above one milliampere per square centimeter. The printed version maintains performance even at ten times that rate. When a steady flow of carbon dioxide is applied to mimic Martian winds, the areal power density reaches about 133 milliwatts per square centimeter at 100 milliamperes per square centimeter. This suggests the electrode can handle short power surges without major efficiency loss.
Cycle life also improves. At a cutoff capacity of ten milliampere hours per square centimeter, the cell runs for more than 1,200 hours at moderate current. A comparable coated electrode cracks and peels under the same conditions. Microscopy shows that the printed architecture keeps its shape and pore network intact, preventing the accumulation of insulating lithium carbonate. The main discharge products form and then decompose during charge, confirming that the reactions are reversible rather than one-way.
Temperature variation poses another challenge on Mars. To test this, the researchers used two different solvents. Dimethyl sulfoxide supports high-temperature operation because of its high boiling point, while 1,3-dioxolane remains liquid at deep-cold temperatures.
In demonstrations, a small light stays powered as the cell operates from minus eighty to one hundred eighty degrees Celsius. Even at the coldest point, the voltage remains above two volts. After rate tests, the battery continues cycling for about 4,500 hours at minus 80 °C, equal to roughly 270 Martian days, or sols. At 150 °C, charging voltage stays below 2.9 volts and efficiency remains around 95 percent.
Temperature is only one of Mars’s environmental tests. Its air, though mostly carbon dioxide, also contains small amounts of nitrogen, argon, oxygen, and carbon monoxide, all under pressures about one percent of Earth’s atmosphere.
To simulate these conditions, the team used a similar gas mixture. Early cycles show a slight rise in voltage, likely from minor reactions with oxygen and carbon monoxide, but the cell continues operating with only moderate extra polarization. This result indicates that real Martian air could support the chemistry, though engineers will need to account for slower gas movement at low pressure.
To explore scalability, the researchers built a pouch-type cell with an active area of ten square centimeters. It achieves an overpotential near 0.22 volts and an energy efficiency around 96 percent at low current, retaining more than 86 percent even at tenfold higher current.
The cell performs reliably when capacity is increased to 5,000 microampere hours, suggesting the architecture can extend beyond laboratory size. Pouch testing is a practical milestone because it exposes issues such as uneven wetting and gas handling that small coin cells often hide.
The performance figures tell a consistent story. Low overpotential means the reactions run efficiently with little wasted energy. High current density shows the cell can deliver power quickly when demand spikes. And strong areal energy density confirms the design packs more capacity into limited space—an essential trait for Mars hardware.
Together, these measures point to a battery architecture that balances energy, power, and durability more effectively than earlier lithium carbon dioxide systems.
The results highlight how structural design, rather than new chemistry, can bridge the long-standing gap between energy, power, and environmental tolerance in lithium carbon dioxide systems. The printed electrode’s MXene–nanotube framework is compatible with automated manufacturing and uses materials that could, in principle, be produced or assembled where resources are limited. Because the battery draws on carbon dioxide as a reactant, it fits directly into strategies for using local Martian materials.
The combination of wide temperature stability, high efficiency, and sustained cycling performance points to a practical path for energy storage beyond Earth—technology engineered not just for survival on Mars, but for autonomy there.
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Min Zhou (University of Science and Technology of China)
, 0000-0003-2677-5472 corresponding author
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