Ternary Cathodes Research Articles

Green separation and recovery of cobalt and nickel from sulphuric acid achieved by complexation-assisted solvent extraction

Ternary cathodes account for more than half of the Lithium-Ion Batteries (LIBs) cathode market share and their recycling draws the most attention. Solvent extraction is the most efficient and common method to separate and recover Co and Ni from spent ternary cathode leachates. However, the traditional extraction process produces a large amount of saline wastewater, thus will seriously pollute the environment. In this work, an environmental approach is proposed by adding a water-soluble complexing agent into the aqueous phase, the separation factor is 2 times higher and the consumption of NaOH is 90% reduced compared to the Na-saponified counterpart, which was attributed to the differences of the complexation between metal ions and complexing agent in aqueous phase. The differences in the complexing ability are enhanced with an increased local nucleophilicity index of the active sites along with a reduced molecular volume in complexing agent, thus leading to superior cobalt extraction efficiency (∼98.9%) and separation factor (∼345). In addition, because of the fact that the whole-process pollution control is needed for cleaner chemical production, a green process is developed by recovering additives through Tri-n-butyphosphate. This excellent separation performance suggests that adding complexing agent in solvometallurgical recovery process may aid in the future development of high-purity raw metals for advanced fields.

Effect of solution wash on the electrochemical performance of LiNi0.8Co0.1Mn0.1O2 cathode materials

Solution wash is a key procedure in the recycling of cathode materials for lithium-ion batteries. It is well-known that Ni-rich ternary cathode material LiNi0.8Co0.1Mn0.1O2 (NCM-811) is sensitive to water, triggering the Li+/H+ exchange and increasing the cation disorder, which ultimately leads to a large capacity loss during the battery cycling. In this study, we investigated the structural/surface chemical stability as well as the capacity loss for NCM-811 ternary cathodes after washing in five different environmentally friendly and commercially available solutions (i.e., ethanol, methanol, sodium chloride aqueous solution, sodium hydroxide aqueous solution, and deionized water). It is discovered that the capacity decay rate during cycling is closely related to the Li+ ion loss after solution wash, the more the Li+ ion loss, the quicker the capacity decay during cycling. Among all the solution-washed samples, ethanol-washed samples show minimal Li+ ion loss and the best capacity retention. Where the Li+ ion loss is only 2%, and the specific capacity after 200 cycles is 2.6 times higher as compared to the water-washed counterparts. This study paves the way towards the practical applications of ethanol in the commercial recycling of NCM-based cathodes.

A low cost single-crystalline LiNi0.60Co0.10Mn0.30O2 layered cathode enables remarkable cycling performance of lithium-ion batteries at elevated temperature

Nickel-rich and low-cobalt content in layered ternary cathodes (NCM) is considered as a promising candidate for commercial lithium-ion batteries (LIBs). Nevertheless, the traditional poly-crystalline NCM (PC-NCM) will inevitably go through intergranular cracks and structural collapse of the secondary spheres upon charge/discharge and thus result in serious performance degradation, limiting its practical application. Herein, we report a novel single-crystalline LiNi0.6Co0.1Mn0.3O2 (SC-NCM) with by far the lowest fabricating cost, and a remarkable long cycling performance under harsh conditions. Such a unique design can withstand 900 cycles at high compaction density (~3.0 g cm−3) without any cracks observed. Therefore, it exhibits a superior capacity retention of 87.4% after 150 cycles at an extremely elevated temperature (55 °C) and a high charging-voltage (4.4 V). A 10 Ah LiNi0.6Co0.1Mn0.3O2||graphite full cell delivers superior capacity retention of 73.9% after 900 cycles at 45 °C, where the highest cathode loading level (40.5 mg cm−2) and area capacity (6.48 mAh cm−2), outperforming the state-of-the-art SC-NCMs reported in literatures. This work provides a promising strategy for the development of high-energy and long-term cycle stability LIBs through controlling micron-sized single crystal particles as well as the Ni/or Co content in SC-NCM.

Recent advances in understanding and relieving capacity decay of lithium ion batteries with layered ternary cathodes

This review focuses on the capacity decay mechanism and enhancement strategies for layered ternary lithium ion batteries.

Study on the effect of Ni and Mn doping on the structural evolution of LiCoO2 under 4.6 V high-voltage cycling

The superior tap density (4.1 g cm−3) and high theoretical specific capacity (274 mA h·g−1) of LiCoO2 make it still the first choice of cathode for batteries in next-generation portable electronic devices. However, the structural instability in the deeply delithiated state severely restricts the reversible capacity of LiCoO2 for practical applications. Owing to the recently popular Ni and Mn elements in ternary cathodes, we explored the effects of Ni–Mn co-doping and each individual dopant on the electrochemical behavior and structural evolution of LiCoO2 at a high upper cut-off voltage of 4.6 V by the means of in-situ XRD and GITT measurements. LiMn0.05Co0.95O2 shows the best cycle stability at 4.6 V with a capacity retention of 55% after 100 cycles. The doping suppresses various two-phase transitions, especially, the O3/H1-3 phase transition at ∼4.55 V, leading to better cycling stability of LiCoO2 at 4.6 V. Due to the significant stabilizing effect on the structure, Mn seems to be an ideal choice for the modification of high-voltage LiCoO2 in the future.

An efficient extractant (2-ethylhexyl)(2,4,4′-trimethylpentyl)phosphinic acid (USTB-1) for cobalt and nickel separation from sulfate solutions

With the rapid growth of new energy vehicles, more and more spent LIBs have been generating. Ternary cathodes account for more than half of the LIB cathode market share and their recycling draws the most attention. Solvent extraction is the most efficient and common method to separate and recover Co and Ni from spent ternary cathode leachates. Efficient extractant is the key. In this paper, we first studied (2-ethylhexyl)(2,4,4′-trimethylpentyl)phosphinic acid (USTB-1) on separating Co from high Ni/Co ratio solutions. It extracts Co over Mg and Ca and there would be no CaSO4 precipitation problem during Co scrubbing and stripping. Its Co/Ni separation performance is superior to MEXTRAL 507P and Cyanex 272. Its ΔpH0.5 of Co and Ni was 1.9. At saponification ratio of 40%, the βCo/Ni of USTB-1 reached to 1.05 × 104, while that of MEXTRAL 507P and Cyanex 272 were only 187 and 2697, respectively. USTB-1 has larger Co saturation capacity than Cyanex 272. It loaded 99.3 mg/L of Co, while Cyanex 272 only loaded 75.1 mg/L at the same conditions. Loaded Co can be easily stripped by mineral acids HNO3, HCl and H2SO4, among which H2SO4 is the most effective. The extraction mechanism was investigated through equilibrium pH-Log D relationship in the aid of FT-IR and ESI-MS spectra of the extraction complex. USTB-1 extracts Co through cation exchange and coordinated with Co via its two oxygen atoms. In conclusion, USTB-1 was more efficient than MEXTRAL 507P and Cyanex 272 for separating Co from high Ni/Co ratio solutions. It is highly suited to separating and recovering Co and Ni from spent ternary cathode leachates. It can reduce reagent and power consumptions and lead to cleaner production.

Ce0.7Bi0.3O1.85-(La0.8Sr0.2)0.9MnO3-Y0.16Zr0.84O1.92 ternary cathodes for low temperature solid oxide fuel cells

The ternary cathodes of Ce0.7Bi0.3O1.85-(La0.8Sr0.2)0.9MnO3-Y0.16Zr0.84O1.92 (BDC-LSM-YSZ) are fabricated through infiltration for low temperature solid oxide fuel cells. The infiltrated BDC particles are 10–20 nm in size and cover on LSM and YSZ particles. The 10 wt% and 20 wt% BDC-LSM-YSZ samples show a large peak for the desorption of surface oxygen species and a large peak for the evolution of lattice oxygen, reflecting their good redox property. 0.1BDC-LSM-YSZ cell and 0.2BDC-LSM-YSZ cell give the power density at 0.6 V of 387.8 and 521.7 mWcm−2 at 600 °C, which is 3.7 and 4.9 times higher than that of LSM-YSZ cell, respectively. 0.1BDC-LSM-YSZ cell and 0.2BDC-LSM-YSZ cell exhibit low ohmic resistance and low total polarization resistance. The DRT analysis reveals that charge transfer reaction and surface diffusion are greatly accelerated on the BDC-LSM-YSZ cathodes.

Development of Ternary Cathodes Using MyCe1–x–yMnxO2–δ (M = La, Gd) as Catalysts for Oxygen Reduction Reactions

AbstractMyCe1–x–yMnxO2–δ (M = La, Gd) oxides have been investigated as oxygen reduction catalysts for LSM–YSZ based ternary cathodes. MyCe1–x–yMnxO2–δ samples are characterized by X‐ray diffraction (XRD), temperature programmed reduction of H2 (H2‐TPR), and temperature programmed desorption of O2 (O2‐TPD). The results show that the incorporation of M (M = La, Gd) ions increases the solution limit of Mn in the solid solutions, which increases the amount of oxygen vacancies and promotes oxygen adsorption and dissociation processes. The ternary cathodes show much higher electrochemical performance than LSM–YSZ binary cathode, and greatly accelerate oxygen dissociative adsorption and diffusion of oxygen species. The MyCe1–x–yMnxO2–δ catalysts exhibit greatly high activity for oxygen reduction at intermediate temperature. The ternary cathodes have high stability and high resistance to CO2 at 600 °C.

Arc deposition of Ti–Si–C–N thin films from binary and ternary cathodes — Comparing sources of C

Ti–Si–C–N thin films with composition of 1–11at.% Si and 1–20at.% C have been deposited onto cemented carbide substrates by arcing Ti–Si cathodes in a CH4+N2 gas mixture and, alternatively, through arcing Ti–Si–C cathodes in N2. Films of comparable compositions from the two types of cathodes have similar structure and properties. Hence, C can be supplied as either plasma ions generated from the cathode or atoms from the gas phase with small influence on the structural evolution. Over the compositional range obtained, the films were dense and cubic-phase nanocrystalline, as characterized by X-ray diffraction, ion beam analysis, and scanning and transmission electron microscopy. The films have high hardness (30–40GPa by nanoindentation) due to hardening from low-angle grain boundaries on the nanometer scale and lattice defects such as growth-induced vacancies and alloying element interstitials.

NOVEL COMPOSITE-BASED CATHODES FOR MOLTEN CARBONATE FUEL CELLS BY ELECTROCHEMICAL MULTICOMPONENT MODIFICATION

A multicomponent modification on the surface of porous nickel with nanoparticles is conducted by an electrophoretic deposition (EPD) technique to prepare new composite-based cathodes for molten carbonate fuel cells (MCFCs). Two new ternary composite-based cathodes, (nano- LiCoO2-LiFeO2 )- Ni and (nano- LiCoO2-CeO2 )- Ni , are inclined to possess good morphology and homogeneous element distribution when prepared under moderate current density resulting from a medium deposition voltage and suspension pH value in this work. Both composite-based cathodes manifest excellent anti-deformation and anti-dissolution performances under conditions of a simulated MCFC startup stage and are thus expected to be useful for application in the MCFC industry.