In the relentless pursuit of more powerful and efficient energy storage solutions, researchers have long been pushing the boundaries of lithium-ion battery technology. A recent study published in the journal Science and Technology of Advanced Materials (which translates to Advanced Materials Science and Engineering) sheds new light on a critical challenge facing the industry: the degradation of batteries during high-voltage operation. The findings, led by Seungjae Suk of the Department of Materials Science and Engineering at Pohang University of Science and Technology (POSTECH) in South Korea, could significantly impact the future of energy storage, particularly in electric vehicles and grid applications.
The quest for higher energy density in lithium-ion batteries has led manufacturers to explore high-voltage operation of mid-Ni (nickel) layered oxide cathodes. While this approach promises increased energy density, it also accelerates electrode degradation, ultimately leading to capacity loss. The underlying mechanisms of this degradation, however, have remained elusive until now.
Suk and his team focused on single-crystal mid-Ni layered oxide (SC-NCM)/graphite pouch full-cells, subjecting them to high-voltage cycling at 4.35 or 4.40 volts. Through a combination of electrochemical and post-mortem analyses, they uncovered a surprising culprit behind the capacity fade: anode slippage, driven by cross-talk between the cathode and anode.
“While it’s true that high-voltage operation induces cathode surface degradation, including lattice oxygen loss and phase transitions, these factors have a relatively minor direct impact on capacity loss,” Suk explained. “The real damage is happening at the anode, due to cross-talk effects from the cathode.”
The cross-talk effects, primarily caused by nickel dissolution from the cathode, promote the accumulation of irreversible organic byproducts within the solid electrolyte interphase (SEI) layer of the graphite anode. This buildup increases resistance and reduces the anode’s electrochemical activity, disrupting the balance between the electrodes and accelerating the full-cell’s capacity fade.
The implications of this research are significant for the energy sector. As the demand for electric vehicles and grid-scale energy storage continues to grow, so does the need for batteries that can operate at higher voltages without compromising longevity. Understanding and mitigating cross-talk-induced anode slippage could be the key to unlocking the full potential of high-voltage lithium-ion batteries.
“Our findings highlight the critical role of anode degradation in high-voltage operation,” Suk said. “By addressing these cross-talk effects, we can pave the way for the rational design of high-voltage mid-Ni full-cell systems with long-term durability.”
The study’s insights could inform the development of new battery materials and designs, as well as advanced electrolyte formulations that minimize cross-talk effects. Moreover, the research underscores the importance of a holistic approach to battery development, considering the interplay between cathode and anode rather than optimizing each component in isolation.
As the energy sector continues to evolve, driven by the urgent need for sustainable and efficient power solutions, studies like this one will be instrumental in shaping the future of energy storage. By delving into the complex interplay of factors that influence battery degradation, researchers like Suk are laying the groundwork for the next generation of high-performance, long-lasting batteries. The work published in Science and Technology of Advanced Materials represents a significant step forward in this ongoing journey, offering valuable insights that could reshape the landscape of energy storage technology.
