In a study published in Advanced Energy Materials, a research team led by Prof. ZHANG Yunxia from Hefei Institutes of Physical Science (HFIPS), Chinese Academy of Sciences (CAS) developed a solid-phase sintering strategy to enable direct conversion of the degraded LiCoO2 (D-LCO) into the cathode materials with high energy density.
With the impending influx of retired lithium-ion batteries, it is critical to investigate effective regeneration and upcycling strategies in order to alleviate resource scarcity, mitigate environmental contamination, and meet the demand for high-energy-density cathode materials.
In this research, a facile, non-constructive, one-stone-for-three-birds solid-phase sintering strategy is proposed to regenerate the degraded LiCoO2 (D-LCO) cathode and even upgrade its stability at high voltages.
"It's like hitting three birds with one stone," said Prof. ZHANG, referring to the simultaneous integration of lithium supplement, Li2SO4 coating, and Mn doping into Co sites, along with N and S doping into Li-O slabs using a one-pot solid-phase sintering approach.
The upcycled cathode not only yielded high discharge specific capacity of 188.2 mAh/g at 0.2 C, but also delivered superior cycling performance with 92.5% of capacity retention after 100 cycles at 0.5 C and excellent rate capability at a high cutoff voltage of 4.5 V, superior to the freshly commercial counterpart. Evidently, various spent LCO cathode materials from various manufacturers or with varying Li/Co molar ratios could be effectively upgraded into high-performance lithium-ion batteries, highlighting the universality and feasibility of the developed one-stone-for-three-birds solid-phase sintering method.
"Our study provided meaningful guidance for the upcycling of D-LCO into high-energy-density batteries with long-term cycling stability," said Dr. ZHANG, corresponding author of the study, "it may also be extended to upgrade other degraded cathode materials into high-performance lithium-ion batteries."
Figure 1. Schematic illustration for the upcycling procedure of D-LCO cathodes. (Image by LIU Zhenzhen)
Figure 2. In situ XRD for D-LCO (a-b) and upcycled MNS-LCO (c-d); (e) EIS spectra. (Image by LIU Zhenzhen)
