Unlocking the decomposition limitations of the Li₂C₂O₄ for highly efficient cathode preliathiations

For realizing lithium-ion batteries (LIBs) with higher energy density (350 Wh kg⁻¹), silicon-based anode materials such as nano-Si, SiO_x, and Si-C with high specific capacity (3579 mAh g⁻¹ for nano-Si) and low working potential (~0.4 V vs Li/Li⁺), together with being cost effectiven, are becoming the main force in the iteration of LIBs. However, the huge volume expansion (300% for Si) results in the formation of solid electrolyte interface (SEI) fractures and subsequent regrowth, which consumes a significant amount of active Li⁺ leading to low initial coulombic efficiency (ICE, the initial capacity loss exceeds 20% for Si). Considering the root cause of low ICE and poor electrochemical cycle performance is the insufficient lithium source, pre-lithiation technology is emerging as a better choice.

Lithium oxalate (Li₂C₂O₄) with high theoretical capacity, low cost and air stability has shown promise as a lithium compensation material. However, its inherently low electronic conductivity and sluggish decomposition kinetics pose a challenge on its further development. Therefore, a highly efficient, highly conductive, lightweight, and reliable catalyst should be excavated for pushing forward the practical application of Li₂C₂O₄.

In a study published in the KeAi journal Advanced Powder Materials, a team of researchers from Harbin Institute of Technology (Shenzhen) in China proposed a catalytic strategy based on a recrystallization treatment.

“A recrystallization strategy combined with our prepared atomic Ni catalysts (Ni/N-rGO) can be used to modulate the mass transport and decomposition reaction kinetics of Li₂C₂O₄.,” shares corresponding author Deping Li. “For instance, the decomposition potential of Li₂C₂O₄ is significantly decreased from 4.90V to 4.30V with a high compatibility with the current battery systems.”

The researchers found that single-atom Ni sites with high catalytic activity realize a significantly promoted decomposition kinetics of the Li₂C₂O₄. The adsorption model and the underlying decomposition mechanisms of Ni/N-rGO with Li₂C₂O₄ were further revealed by spin-polarized density functional theory (DFT) calculations.

“These findings highlight the potential of our proposed catalytic strategy for promoting the practical applications of pre-lithiation technologies,” says Li.

Notably, the decomposition efficiency of Li₂C₂O₄ was significantly increased from 14.6% to 100%, and the corresponding decomposition potential was modulated from 4.90 V to 4.30 V.

“Meanwhile, the assembled NCM811//SiO_x full cell with Ni-LCO delivered a 30.4% increase in the reversible capacity and a 21.5% higher capacity retention ratio,” adds Li.
“This work opens up a new direction for designing highly efficient pre-lithiation technology and offers a promising pathway towards a more sustainable and reliable energy future.”

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Contact the author: Jingyu Lu (lujingyu@hit.edu.cn)², Lijie Ci (cilijie@hit.edu.cn)¹, Deping Li (lideping@hit.edu.cn)¹.

¹ State Key Laboratory of Advanced Welding and Joining, School of Materials Science and Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China;

² School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China;

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