Batteries modified by new method can store charge better and last longer, scientists say
Repeated charging and discharging of a lithium-ion battery results in a significant change in the volume of the anode, reducing the capacity and life of the battery. Now, researchers at GIST in Korea have developed a method to strengthen the anode, making it more resistant to changes in volume. The anode can be modified regardless of its material or the way it is manufactured, making the approach versatile and opening the door to long-lasting batteries for smartphones and electric cars.
The advent of electric vehicles has led to the demand for lithium-ion batteries with high energy density. This led to the development of anodes with high charge storage capacity. Unfortunately, this storage capacity tends to degrade over multiple charge/discharge cycles, reducing battery life.
Short battery life results from irreversible anode volume change during cycling, which causes deterioration of electrical contacts and structural collapse. During charging, lithium ions move from the cathode and combine with the nanoparticles in the anode. During discharge, the lithium ions flow back to the cathode. Over time, the nanoparticles in the anode crack and cluster together at the electrode-electrolyte interface. This causes a break in the electrical connection, reducing the amount of charge the anode can store or transport.
The method developed by the researchers strengthens the anode and makes it more resistant to changes in volume by encapsulating the nanoparticles in an elastic network-like structure.
To demonstrate their approach, the researchers used a conventional anode containing silicon nanoparticles held together by a polymer (polyvinylidene fluoride) binder. To tailor the mesh-like structure, they removed the binder by heating the anode using an annealing process. The gap between the nanoparticles was then filled with a reduced graphene oxide (rGO) solution, which dried to form a network that held the silicon nanoparticles together and prevented them from cracking. In addition, the network provides a conductive path for electrons, allowing the nanoparticles to bond with lithium.
The researchers used a technique called “spin coating” to coat the surface of the anode with rGO. The rGO coating serves as a seed layer for the deposition of a protective layer consisting of zinc oxide doped with magnesium gallium metal oxides (MGZO). This MGZO layer provides structural stability to the anode.
In testing, the modified anode can retain most of its charge even after several charge/discharge cycles. “The structure retains a high storage capacity of 1566 mA hg-1 after 500 cycles and showed 91% coulombic efficiency, which is related to battery life. This could pave the way for electric vehicles that allow us to drive long distances on a single charge,”, emphasizes Prof. Kim.
While the researchers used a silicon anode, the method developed is applicable to other anode materials, such as Sn, Sb, Al and Mg. Furthermore, anodes can be modified regardless of how they are manufactured, making it a universally applicable method of improving battery life.
Authors: Jihun Kim (1,2), Jiyoung Ma (2), Hocheol Yoon (1), Junsung Jang (3), Seokho Suh (1), Hyeonghun Park (1), Jeonghwan Song (2), Jin Hyeok Kim ( 3), Junsu Park (4), Jung-Je Woo (2) and Hyeong-Jin Kim (1)
Original Article Title: Viable Post-Electrode Engineering for Full Integrity of High Volume Li-Ion Battery Anodes
Journal: Journal of Materials Chemistry A
1) Gwangju Institute of Science and Technology (GIST)
2) Korea Institute of Energy Research (KIER)
3) Chonnam National University
4) Ground Technology Research Institute, Defense Development Agency
Corresponding Author Emails:
About Gwangju Institute of Science and Technology (GIST)
Gwangju Institute of Science and Technology (GIST) is a research-oriented university located in Gwangju, South Korea. Founded in 1993, GIST has become one of the most prestigious schools in South Korea. The University aims to create a strong research environment that will stimulate advances in science and technology and encourage collaboration between international and local research programs. With its motto of “Proud Creator of Future Science and Technology”, GIST has consistently received one of the highest university rankings in Korea.
About the author
Hyung-Jin Kim joined Gwangju Institute of Science and Technology (GIST) in 2016 as a professor in the Graduate School of Energy Convergence after serving as president of LG Chem Michigan, Inc. His group develops approaches to control electrode stability and performance by facilitating complex materials, coatings and additives. Kim’s group is also developing laser technology to build a structured surface to treat electrode inactivity. Before coming to GIST, he worked at LG Chem for 20 years. In 1993, Prof. Kim received his PhD from the University of Texas at Austin.
Gwangju Institute of Science and Technology Scientists Develop a Universal Method for Improving the Lifespan of Lithium-Ion Batteries