Enhanced Fast Charging and Reduced Lithium-Plating by Laser-Structured Anodes for Lithium-Ion Batteries

Abstract

Within this paper we report on a lithium-ion battery with laser-structured graphite anodes, alleviating current drawbacks of lithiumion batteries such as the reduced discharge capacity at high Crates and the onset of lithium-plating during fast charging. These issues are intensified at low temperatures, as reaction and diffusion kinetics decelerate, which is why a focus of the presented work lies on low temperature performance. Electrochemical impedance spectroscopy was used to show a reduction in the impedances of cells with laser-structured anodes in comparison to their conventional counterparts. The discharge capacity retention at high Crates was enhanced by up to 27% compared to conventional cells, proving potential for high power applications. For the cells with laserstructured anodes, the onset of lithium-plating at 0°C was observed at higher charging Crates by analyzing the voltage relaxation after charging. At −15°C, a smaller amount of plated lithium was detected, even though lithium-plating could not be entirely avoided. Laser structuring also enabled shorter charging times, as the upper cutoff voltage was reached at a higher SOC. The results point out that laser structuring of the anode improves the fast charging capability of lithium-ion cells, especially under demanding operating conditions.

Enabling 4C Fast Charging of Lithium‐Ion Batteries by Coating Graphite with a Solid‐State Electrolyte

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out on the graphite anode surface under fast-charging conditions in high-energydensity cells. The irreversibility associated with Li plating leads to permanent loss of Li from the accessible reservoir and capacity fade, which is the key challenge that limits fast-charging of LIBs.Strategies to prevent and/or mitigate the impacts of Li plating on graphite have drawn great interest in recent years, including: 1) alternative anode materials such as lithium titanate, [6] titanium niobate, [7] and hybrid mixtures of hard carbon with graphite; [5] 2) modifying the electrode architecture to facilitate enhanced mass transport; [8][9][10][11][12] 3) asymmetric temperature modulation; [13] 4) surface coatings to modify interface behavior; [14][15][16][17] and 5) electrolyte modifications to increase

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Challenges and Strategies for Fast Charge of Li‐Ion Batteries

“…All Li observed in the post‐mortem analyses are either isolated (dead) Li or those in the regions where the electrolyte is completely depleted. The results obtained from non‐destructive methods, such as those by analyzing the change in voltage or differential voltage during post‐charging relaxation, and those by observing the change in capacity or differential capacity in the subsequent discharge, are changed with rest time due to the issue that the plated Li chemically re‐intercalates into graphite.…”

“…In this regard, reducing the thickness (accordingly the loading) and tortuosity of graphite anode is shown to be effective in facilitating ion transport in the electrode, and hence mitigate Li plating . The graphite anode with low tortuosity, such as those made by laser cutting and freeze‐casting, is shown to offer much improved rate capability and reduced Li plating. Another strategy is to enhance the kinetics of the electrode reactions by raising the temperature of the charging process.…”

“…Although the sluggish mobility of Li + ions is an intrinsic property of the layered cathode materials, the kinetics of the electrode reactions can be improved by reducing the path of Li + ion transport with electrode engineering. Therefore, strategies such as reducing the particle size of the layered cathode materials and reducing the thickness and tortuosity of the electrodes are commonly used to enhance the fast‐charging capability. However, these strategies unavoidably result in a trade‐off in capacity and cost.…”

Effect of Low Temperature on Electric Vehicle Range

“…Apart from cabin heating, the decreased performance of the vehicle's battery at low temperatures also affects a BEV's driving range. Cold conditions cause declined reactivity and diminished ionic conductivity in Li-ion cells [15,21], which affects their usable capacity [22] and impedance [23]. In this context, Nagasubramanian et al [24] showed that under extreme cold conditions (−40 • C) a Li-ion cell can lose up to 95% of its energy and more than 98% of its power capability compared to performance levels at 25 • C. Similar research shows that a cell's capacity can drop by up to 23% at −20 • C compared to the capacity at 25 • C [25].…”