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recently, professor tan peng's team from the university of science and technology of china created a martian battery.the battery can use components of the martian atmosphere as fuel for battery reactions and can achieve higher energy density and longer cycle performance.

at 0 degrees celsius,the battery has an energy density of 373.9wh/kg and a cycle life of 1,375 hours (approximately two martian months).

the reviewers of the relevant papers commented that this study demonstrated in detail the concept, application potential and electrochemical properties of martian batteries, and can provide certain inspiration for the development of space energy supply systems.

the researchers said:"our goal is to develop a power system that can realize the in-situ utilization of martian resources."

although there is still some distance between this and practical application, they hope to provide a certain reference for the utilization of space resources. that is, in the future, it may be possible to directly use the planet's own environmental resources to provide energy, thereby developing a more efficient energy conversion and storage system.

building batteries for mars

for lithium-air battery lithium system, oxygen in the air is the reactant in the battery. since air does not occupy the mass and space in the battery, the battery has an extremely high energy density.

however, in order to ensure that the battery can work stably, it is necessary to remove impurity gases in the air as much as possible, such as carbon dioxide and moisture, which is why some batteries are called lithium-oxygen batteries.

previously, a paper reported that if oxygen is replaced with carbon dioxide, the battery can also be charged and discharged, and its performance can be comparable to that of lithium-oxygen batteries.

this aroused tan peng's great research interest, but due to time constraints and experimental conditions, he did not conduct research on the lithium-carbon dioxide battery system at that time.

after joining the university of science and technology of china, he established his own research group and began to study lithium gas batteries such as lithium oxygen batteries and lithium carbon dioxide batteries.

to understand lithium carbon dioxide batteries, you must first understand the lithium gas battery system. the battery structure mainly includes: metallic lithium, porous air electrode, and a diaphragm containing electrolyte.

because lithium and water will react and affect the stability and safety of the battery.

therefore, although this type of battery is called an air battery, after this type of battery is assembled, it cannot be tested in the air, but must be placed in a relatively pure gas, such as oxygen or carbon dioxide for testing.

in order to create such test conditions, people usually use a test chamber and fill it with the corresponding gas.

by using this test system, the team began corresponding research, in which the lithium-oxygen battery experiment showed good repeatability and stability.

however, in experiments with lithium-carbon dioxide batteries, the research team found that the repeatability of battery discharge voltage experiments was poor.

theoretically, the balance voltage of the battery is 2.8 v. the discharge voltage measured by the academic community in existing literature is generally around 2.6 v.

however, for the same battery material, the team found in actual testing that sometimes the voltage was 2.6 v. although this is very close to what has been reported in the literature, once discharged, the voltage quickly dropped to 2.0 v.

so they began to speculate: is the cut-off voltage set too high? so they set the cut-off voltage lower or even close to 0v. as a result, they found that although the battery has a voltage platform, the voltage is only around 1.5v, which is very different from what has been reported in the literature.

this caused the research team to doubt themselves for a long time, that is, why couldn't they stably repeat the existing literature results? was there a problem with the battery clamp? was there a problem with the battery assembly method?

after all attempts failed, they turned their attention to the test chamber. everyone began to speculate: is there something wrong with the test chamber? is there a leak due to poor sealing?

therefore, they redesigned a test system to connect the battery's air electrode directly to the test atmosphere, while ensuring that there would be no

the battery itself is tested for air tightness to ensure that there is no gas leakage.

with the help of this testing system, they first tested lithium-oxygen batteries and found that the performance was very consistent with existing literature reports, which shows that the system has high reliability.

next, they tested the carbon dioxide atmosphere and found that the voltage was only about 1.1v, and the experiment showed good repeatability.

subsequently, they conducted new tests and characterizations and found that an electrochemical reaction between lithium and carbon dioxide did occur and that there were no mechanistic problems.

so why is the voltage in the experiment different from that reported in most literature? is there a leak in the test chamber? if so, what gas caused it?

to clarify the above issues, they added trace amounts of impurity gases into the carbon dioxide atmosphere and found that only a small amount of water and oxygen could significantly increase the battery voltage.

furthermore, just by loosening the test chamber a little, the voltage can magically become about 2.6 v. in other words, under a pure carbon dioxide atmosphere, the voltage of the battery can only be at a lower level.

it is precisely because of the air leakage in the test chamber that moisture and oxygen entered and the battery voltage was increased.

through this, the team revealed the true working voltage of lithium-carbon dioxide batteries. later, they compiled the above results into a paper and published it in PNAS previous [1].

in response to this paper, relevant media also published a report article titled "the future development direction of lithium-carbon dioxide batteries may be redefined."

on this basis, the research team began to think: since a pure carbon dioxide atmosphere does not bring much advantage to the battery voltage, and an impure atmosphere can significantly increase the voltage, then in what environments can lithium carbon dioxide batteries be used?

take mars as an example. the martian atmosphere contains more than 95% carbon dioxide. in fact, shortly after the academic community proposed lithium carbon dioxide batteries, there were papers pointing out that they could be used on mars.

however, when it comes to the atmosphere of mars, we cannot just consider the carbon dioxide atmosphere, because mars not only has an impurity atmosphere, but also has drastic temperature fluctuations.

so, what effects will the impurity atmosphere and temperature changes have on battery performance? to this end, the team conducted this research on martian batteries.

since the atmosphere needs to be regulated, the gas composition and partial pressure must be the same as those of mars. at the same time, the temperature must be well controlled to ensure that the test can be carried out at low temperatures for a long time.

through carefully designed experiments, they found that during the charging and discharging process of the battery, lithium carbonate is generated, electrochemical reactions are decomposed, and the battery performance is strongly dependent on temperature.

during the submission process, the research team also experienced some twists and turns. during this period, a reviewer asked them to explore the impact of cosmic rays and meteorites on battery safety.

"this is obviously beyond the scope of our research and experiment. therefore, the current results can only be regarded as a phased result. Science Bulletin it gives us the opportunity to publish papers." said the researchers.

a related paper titled "a high-energy-density and long-cycling-lifespan mars battery" was recently published in Science Bulletin（IF 18.8）。

dr. xiao xu is the first author and dr. tan peng is the corresponding author[2].

strive to contribute to deep space exploration

overall, the current work is still very preliminary and has only conceptually verified the feasibility of in-situ utilization of martian resources. for example, it has verified that when martian gas is used as fuel to generate electricity, the battery can operate within a certain stable range.

however, as mentioned earlier, some challenges need to be overcome if this achievement is to be applied in the martian environment.

first, in addition to 95% carbon dioxide gas in the martian atmosphere, there are also nitrogen, argon, oxygen and other components. what impact will the mutual entanglement of these components have on battery performance?

further research is needed to eliminate harmful gases while utilizing effective gases.

second, the average atmospheric pressure on the surface of mars does not even reach 1% of the average atmospheric pressure on earth, that is, the atmospheric pressure on mars is very low.

first, this would cause the concentration of carbon dioxide, a reactant gas, in the cell to be so low that it would affect the reaction kinetics.

secondly, this will cause the volatilization of liquid electrolyte, which will affect the stability of the semi-open system such as the martian gas battery.

thirdly, the average temperature on mars is relatively low, only about minus 60 degrees celsius, which is not only far lower than the average temperature on earth, but the climate characteristics of mars with a huge temperature difference between day and night can cause drastic fluctuations in battery performance or even failure.

finally, the gas on mars is thin and accompanied by hurricanes, which will have an important impact on the operating stability of the battery.

therefore, they plan to conduct three research areas in the future:

on the one hand, we will conduct in-depth research on the internal mechanisms of the battery, such as the influence of different gas components, pressure and temperature, and their effects on reaction kinetics.

second, high-performance battery materials will be developed, including high-performance catalysts, highly stable metal electrodes, high-permeability air electrodes, and stable electrolyte systems (such as semi-solid electrolytes or all-solid electrolytes).

third, we will develop a battery cell auxiliary system, including developing a gas control unit to filter harmful gas components, so that the gas pressure control unit can input the appropriate pressure for the battery and allow the battery to operate within a suitable stable range.

the team is currently conducting new research on the reaction mechanism of the martian battery, especially the effects of trace atmosphere and temperature on the reaction path. in the future, they will continue to explore the battery mechanism and performance optimization under special environments.

in general, they hope to develop a power system that can operate stably and efficiently in the martian environment, thereby providing a feasible solution for the in-situ utilization of martian resources and striving to contribute to deep space exploration.

in addition, for lithium-carbon dioxide batteries, the team believes that mars batteries are one of their branch applications.

since carbon dioxide gas can be used as a fuel gas to generate electricity and produce carbon, and impurity gases may also promote battery performance, can this technology be used to capture carbon dioxide?

to achieve this goal, several challenges need to be overcome:

first, the gas composition is regulated to make it more conducive to the reaction.

secondly, the solid products should be collected, that is, the generated carbon should be collected to avoid clogging of the porous electrode.

finally, since metal electrodes are consumables, a way to replenish the metal fuel must be found.

in response to these issues, the research team has also carried out a series of research. they also participated in the national college students' energy conservation and emission reduction innovation competition with the project "carbon lock - a new lithium carbon dioxide battery for industrial waste gas carbon fixation-power generation" and won the special prize.

"new related papers are on the way, so if you are interested, please stay tuned!" the researcher finally said.

references:

1.https://doi.org/10.1073/pnas.2217454120

2.https://www.sciencedirect.com/science/article/pii/S2095927324004584?via%3Dihub

layout: chu jiashi