Lithium-carbon dioxide battery technology breakthrough: while discharging, carbo
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2023/10/31 15:37:55
The application of batteries is of great significance. Power batteries are at the heart of electrification in the transport sector and can indirectly contribute to a significant reduction in CO2 emissions. The application of batteries in the field of energy storage can ensure the stability and reliability of renewable energy power supply.
But how can batteries be cheap, energy-dense, and last longer? Scientists are continuing to explore, and various technological routes are also showing up. Lithium-ion batteries are the current mainstream.
And now there is a new technology, not only the battery energy density is more than 7 times that of traditional lithium-ion Batteries, but also can fix carbon dioxide into carbonates and carbon while output electricity, it is lithium-CO2 batteries (Li-CO2 Batteries).
Lithium-carbon dioxide batteries have the dual advantages of energy storage and carbon sequestration at the same time, which can be described as "killing two birds with one stone."
This new electrochemical energy storage system with a wide range of application prospects has attracted the research interest of scientific researchers from the beginning of its birth.
However, the development and application of any new technology needs to be implemented step by step. The researchers said that the development of lithium-carbon dioxide batteries is still in the early stages, such as the production method of the most important catalyst, which is still relatively slow and inefficient, and it is necessary to find efficient electrocatalysts and in-depth understanding of their reaction mechanism.
As a result, the University of Surrey, Imperial College London and Peking University have recently developed a new electrochemical testbed that can help accelerate the evaluation and development of lithium-CO2 battery catalysts. Compared with traditional methods, this new method is highly cost-effective, efficient and controllable, and is expected to overcome the difficulties faced by the development and application of lithium-carbon dioxide batteries.
The past and present lives of lithium-carbon dioxide batteries
The secondary (rechargeable) lithium-ion battery in the modern sense was born in 1983, which also allowed Dr. Akira Yoshino, a key figure in the development of lithium-ion batteries at that time, to win the Nobel Prize in chemistry.
Later, in order to meet the requirements of use under more equipment and constraints, researchers continued to invest in the research of lithium-oxygen (Li-O2) batteries (that is, lithium-air batteries). The current lithium-carbon dioxide battery is also developed on this basis.
Lithium-carbon dioxide batteries work by moving lithium ions from the positive end of the battery through the electrolyte to the negative end when the battery is charged. The carbon as the negative electrode has a layered structure with many micropores, and the lithium ions that reach the negative electrode are embedded in the micropores of the carbon layer. Therefore, the more lithium ions embedded, the higher the charging capacity.
Similarly, in the process of battery use (discharge), the lithium ions embedded in the negative carbon layer are removed and moved back to the positive electrode. The more lithium ions that return to the positive electrode, the higher the discharge capacity.
As a rechargeable battery with great potential for development, lithium-carbon dioxide batteries have a very high energy density, and the higher the energy density of the battery, the more electricity is stored per unit volume.
It is understood that the energy density of the current mainstream lithium iron phosphate battery is below 200Wh/kg, and the energy density of ternary lithium batteries is between 200-300Wh/kg. Sun Shigang, an academician at the Chinese Academy of Sciences, said that the energy density of lithium-ion batteries has approached the ceiling. The theoretical energy density of lithium-carbon dioxide batteries is as high as 1876Wh/kg, which is more than 7 times that of ordinary lithium-ion batteries.
Moreover, the reversible electrochemical reaction in Li-CO2 cells: 4Li + 3CO2=2Li2CO3 + C (E0= 2.80V vs Li/Li+) is also a new way to fix CO2. Traditional methods of CO2 sequestration require a continuous energy supply, and if this energy supply is based on fossil fuel capacity, more CO2 is emitted. In contrast, lithium-carbon dioxide batteries sequester carbon in a much cleaner way.
It can be said that lithium-carbon dioxide batteries are both a key battery technology and an important carbon sequestration technology, which can make a dual contribution to combating climate change.
However, it is still in the initial stage of development. There are many factors that affect the performance of lithium-CO2 batteries.
In the battery reaction process, lithium carbonate (Li2CO3), as the main discharge product, is a wide-band gap insulator, which will cause its decomposition kinetics to slow down during the charging process. During the cycle, the incomplete decomposition of Li2CO3 and the formation of irreversible transformation, as well as the accumulation of solid carbonate substances on the cathode surface, will also lead to a significant decline in electrochemical performance until the "sudden death" of Li-CO2 batteries.
To solve this problem, the development of bidirectional catalysts to accelerate the conversion kinetics during discharge and charging is the key to improve the energy efficiency and cycle life of Li-CO2 batteries.
What is the use of a multifunctional electrochemical test platform?
To address this challenge, researchers from the University of Surrey, Imperial College London and Peking University have designed an on-chip electrochemical testing platform that can perform multiple tasks simultaneously. This platform facilitates electrocatalyst screening, optimization of operating conditions, and study of CO2 conversion in high-performance lithium-CO2 batteries.
According to the researchers, traditional Li-CO2 cell catalyst exploration methods, which mainly rely on trial and error and single-mode characterization/testing techniques, are time-consuming and inefficient.
Therefore, it is necessary to build a simplified multifunctional test platform to quickly screen catalysts with short time and nanoscale spatial resolution for multimodal characterization tests, so as to more fully understand the emerging technology of Li-CO2 batteries and accelerate its development.
The lab-on-a-chip LCB platform developed by the researchers is capable of three-electrode electrochemical testing, catalyst screening, and in-situ detection of chemical composition and morphological evolution.
Using this platform, the researchers systematically evaluated the potential of a range of candidate catalysts to promote conversion reactions and investigated their reversibility and reaction pathways.
Candidate catalysts include platinum, gold, silver, copper, iron and nickel in high-density nanoparticle states. Finally, it was found that when platinum nanoparticles were used as catalysts, the battery had an obvious minimum polarization performance (0.55 V), the highest reversibility and a new reaction path, showing superior performance. The results of this experiment also reveal the development potential of lithium-carbon dioxide batteries.
The researchers say the lithium-CO2 battery (LCB) platform could also play an important role in further exploration, including:
(1) By integrating a microfluidic system or pattering different quasi-solid electrolytes on the platform, screening electrolytes with stable solvents for lithium-carbon dioxide battery reactions;
(2) Explore different lithium anode protection strategies or screen other pre-lithium anodes for lithium-CO2 batteries.
"Developing new technologies for negative emissions is critical. Our lab on chip platform will play a key role in achieving this goal. It can also be applied to other systems, such as metal-air batteries, fuel cells and photoelectrochemical cells." Yulong Zhao, a senior lecturer at Imperial College London.
Overall, the design of the LCB platform is expected to overcome the challenges facing the development of lithium-CO2 batteries, including the rapid selection of catalysts, the study of reaction mechanisms, and practical applications from nanoscience to cutting-edge carbon removal technologies. Source: Global Zero Carbon
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