Pohang University of Science and Technology (POSTECH) researchers have developed a next-generation high-energy-density Lithium-ion battery system using micro silicon particles and gel polymer electrolytes. Researchers are fervently exploring the use of silicon, known for its high storage capacity, as the anode material in lithium-ion batteries for EVs. However, despite its potential, bringing silicon into practical use remains a puzzle that researchers are still working hard to piece together.
Enter Professor Soojin Park, PhD candidate Minjun Je, and Dr. Hye Bin Son from the Department of Chemistry at POSTECH whose research paper was published online in Advanced Science. They have discovered a solution, developing a pocket-friendly and rock-solid next-generation high-energy-density Li-ion battery system using micro silicon particles in the anode and gel polymer electrolytes.
Employing silicon as a battery material presents serious challenges: It expands by more than three times during charging and then contracts back to its original size while discharging, significantly impacting battery efficiency.
Utilizing nano-sized silicon (10-9m) partially addresses the issue, but the sophisticated production process is complex and astronomically expensive, making it a challenging budget proposition. By contrast, micro-sized silicon (10-6m) is superbly practical in terms of cost and energy density.
Yet, the expansion issue of the larger silicon particles becomes more pronounced during battery operation, posing limitations for its use as an anode material.
The research team applied gel polymer electrolytes to develop an economical yet stable silicon-based battery system.
The electrolyte within a lithium-ion battery is a crucial component, facilitating the movement of ions between the cathode and anode.
Unlike conventional liquid electrolytes, gel electrolytes exist in a solid or gel state, characterized by an elastic polymer structure that has better stability than their liquid counterparts do.
The research team employed an electron beam to form covalent linkages between micro-silicon particles and gel electrolytes. These covalent linkages serve to disperse internal stress caused by volume expansion during lithium-ion battery operation, alleviating the changes in micro silicon volume and enhancing structural stability.
The outcome was remarkable: The battery exhibited stable performance even with micro silicon particles (5μm), which were a hundred times larger than those used in traditional nano-silicon anodes.
Additionally, the silicon-gel electrolyte system developed by the research team exhibited ion conductivity similar to conventional batteries using liquid electrolytes, with an approximate 40% improvement in energy density.
Moreover, the team's system holds significant value due to its straightforward manufacturing process that is ready for immediate application.
Professor Soojin Park stressed: "We used a micro-silicon anode, yet, we have a stable battery. This research brings us closer to a real high-energy-density lithium-ion battery system."
This study was conducted with the support from the Independent Researcher Program of the National Research Foundation of Korea.
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This looks like the revolution that lithium-ion technology needs to stay out in front of the battery chemistry field.
There remains a lot of proving up to commit a factory production line to this technology. Foremost to consumers is going to be the discharge / recharge cycle life. If the cycle count is measured in the dozens this tech is finished at the start but if cycle length is thousands the picture changes completely.
Right now the best lithium ion batteries are good into about a thousand cycles at affordable prices. Most of those are in personal devise like cell phones laptops and tablets.
But double the cycle count or more would have a very strong effect and drive a large demand.
The other big question is the fire hazard. The current lithium-ion tech is fairly well understood. In this new tech its totally unknown. More same less? The fire issue matters.
Then there is the temperature concern. Consumers finally got the info on lithium-ion this winter. Is gel better, worse?
It will be a while if or before this tech makes it into the market. Lets hope is makes it solving the problems of current tech. A dead laptop in a dead EV on a cold January day truly is a dreadful experience.
By Brian Westenhaus via New Energy and Fuel
Brian is the editor of the popular energy technology site New Energy and Fuel. The site’s mission is to inform, stimulate, amuse and abuse the… More