Ternary Cathodes Research Articles

Water-aerosol-assisted roasting for selective lithium extraction from spent lithium-ion batteries

Selective extraction of lithium from spent lithium-ion batteries (LIBs) represents a promising solution for efficient lithium recovery. Herein, a water-aerosol-assisted roasting technology is proposed to selectively extract lithium from spent lithium transition metal oxides (LTMOs) cathodes. In an exemplary recycling of spent LiCoO2, the cathode material undergoes a low-temperature (350°C) chlorinating roast process to convert it into metal chlorides, followed by a higher-temperature (500°C) roasting to facilitate the selective pyrolysis of CoCl2. The presence of water-aerosol significantly enhances the selective pyrolysis process of CoCl2, reducing roasting time eightfold compared to conventional air roasting. Subsequent water-leaching effectively extracts 99.1 % of lithium as LiCl, while only 0.2 % of cobalt is extracted, ensuring selective lithium recovery. The resulting high-purity LiCl solution and Co3O4 residue are directly utilizable for producing battery-grade Li2CO3 and LiCoO2, respectively. Regenerated LiCoO2 demonstrates excellent cycling stability, retaining 90.5 % of its capacity after 300 cycles at 1C rate. Moreover, this method is applicable to ternary cathodes (NCM) black mass, offering a sustainable, robust, and cost-effective approach for lithium extraction from spent LIBs.

In Situ Forming Asymmetric Gel Polymer Electrolyte Enhances the Performance of High-Voltage Lithium Metal Batteries.

With the rapid evolution of electric vehicle technology, concerns regarding range anxiety and safety have become increasingly pronounced. Battery systems with high specific energy and enhanced security, featuring ternary cathodes paired with lithium (Li) metal anodes, are poised to emerge as next-generation electrochemical devices. However, the asymmetric configuration of the battery structure, characterized by the robust oxidative behavior of the ternary cathodes juxtaposed with the vigorous reductive activity of the Li metal anodes, imposes elevated requisites for the electrolytes. Herein, a well-designed gel polymer electrolyte with asymmetric structure was successfully prepared based on the Ritter reaction of cyanoethyl poly(vinyl alcohol) (PVA-CN) and cationic ring-opening polymerization of s-Trioxane. With the aid of the sieving effect of separator, the in situ asymmetric gel polymer electrolyte has good compatibility with both the high-voltage cathodes and Li anodes. The amide groups generated by PVA-CN after the Ritter reaction and additional cyano groups can tolerate high voltages up to 5.1 V, matching with ternary cathodes without any challenges. The functional amide and cyano groups participate in the formation of the cathode electrolyte interface and stabilize the cathode structure. Meanwhile, the in situ formed ether-based polyformaldehyde electrolyte is beneficial for promoting uniform Li deposition on anode surfaces. Li-Li symmetric cells demonstrate sustained stability over 2000 h of cycling at a current density of 1 mA cm-2 for 1 mAh cm-2. Furthermore, the capacity retention rate of Li(Ni0.6Mn0.2Co0.2)O2-Li cells with 0.5 C cycling after 300 cycles is 92.2%, demonstrating excellent cycle stability. The electrolyte preparation strategy provides a strategy for the progress of high-performance electrolytes and promotes the rapid development of high-energy-density Li metal batteries.

Surface engineering of TiSiO4 nano-coating for high-voltage nickel-rich ternary cathodes: An approach to improve cyclic performance

In recent years, layered ternary transition metal oxides with a high nickel content have gained substantial attention as a potential positive electrode material for lithium-ion batteries. However, its poor rate capability, cyclability, and capacity retention at high working voltages limit its use in commercial lithium-ion batteries. To overcome these challenges, we synthesize a cost-effective wet-chemical deposition of novel TiSiO4 nano-coatings over the surface of LiNi0.83Mn0.06Co0.11O2 (NMC-83). X-ray diffraction and electron microscopy confirm the presence of a coating and verify that the deposition process did not alter the crystallinity and morphology of the NMC-83 particles. In addition, during cycling, it completely protects NMC-83 with enhancements in hexagonal phase transitions between H2 and H3, resulting in excellent cycling stability at upper cut-off voltages. Likewise, when the amount of coated material is equal to 1 wt%, it provides faster ion kinetics and a stable electrode-electrolyte interface. The 1 wt% TiSiO4 coating provides 35 % retention after 250 cycles at a 0.5C rate, while the pristine NMC-83 shows only 13.7 %. From postmortem analysis, the 1 wt% TiSiO4-coated NMC-83 cathode maintains its stable polycrystalline nature compared with pristine NMC-83. Thus, this novel TiSiO4 nanocoating has significant implications for developing high-performance rechargeable batteries for energy applications.

Recycling Spent Ternary Cathodes to Oxygen Evolution Catalysts for Pure Water Anion-Exchange Membrane Electrolysis.

Recycling spent lithium-ion batteries (LIBs) to efficient water-splitting electrocatalysts is a promising and sustainable technology route for green hydrogen production by renewables. In this work, a fluorinated ternary metal oxide (F-TMO) derived from spent LIBs was successfully converted to a robust water oxidation catalyst for pure water electrolysis by utilizing an anion-exchange membrane. The optimized catalyst delivered a high current density of 3.0 A cm-2 at only 2.56 V and a durability of >300 h at 0.5 A cm-2, surpassing the noble-metal IrO2 catalyst. Such excellent performance benefits from an artificially endowed interface layer on the F-TMO, which renders the exposure of active metal (oxy)hydroxide sites with a stabilized configuration during pure water operation. Compared to other metal oxides (i.e., NiO, Co3O4, MnO2), F-TMO possesses a higher stability number of 2.4 × 106, indicating its strong potential for industrial applications. This work provides a feasible way of recycling waste LIBs to valuable electrocatalysts.

All-Dry Solid-Phase Synthesis of Single-Crystalline Ni-Rich Co-Poor Ternary Cathodes for Li-Ion Batteries

All-Dry Solid-Phase Synthesis of Single-Crystalline Ni-Rich Co-Poor Ternary Cathodes for Li-Ion Batteries

Stabilizing High-Voltage Performance of Nickel-Rich Cathodes via Facile Solvothermally Synthesized Niobium-Doped Strontium Titanate.

Ni-rich layered ternary cathodes are promising candidates thanks to their low toxic Co-content and high energy density (∼800 Wh/kg). However, a critical challenge in developing Ni-rich cathodes is to improve cyclic stability, especially under high voltage (>4.3 V), which directly affects the performance and lifespan of the battery. In this study, niobium-doped strontium titanate (Nb-STO) is successfully synthesized via a facile solvothermal method and used as a surface modification layer onto the LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode. The results exhibited that the Nb-STO modification significantly improved the cycling stability of the cathode material even under high-voltage (4.5 V) operational conditions. In particular, the best sample in our work could provide a high discharge capacity of ∼190 mAh/g after 100 cycles under 1 C with capacity retention over 84% in the voltage range of 3.0-4.5 V, superior to the pristine NCM811 (∼61%) and pure STO modified STO-811-600 (∼76%) samples under the same conditions. The improved electrochemical performance and stability of NCM811 under high voltage should be attributed to not only preventing the dissolution of the transition metals, further reducing the electrolyte's degradation by the end of charge, but also alleviating the internal resistance growth from uncontrollable cathode-electrolyte interface (CEI) evolution. These findings suggest that the as-synthesized STO with an optimized Nb-doping ratio could be a promising candidate for stabilizing Ni-rich cathode materials to facilitate the widespread commercialization of Ni-rich cathodes in modern LIBs.

Noncombustible gel polymer electrolyte inspired by bio-radical chemistry for high voltage and high safety Ni-rich lithium batteries

For high energy density lithium-ion batteries (LIBs) with nickel-rich ternary cathodes, the chemical degradation of electrolytes caused by free radical reactions and the hazards of thermal runaway have always been significant challenges. Inspired by the free radical scavenging of living organisms and multiphase synergistic flame retardant mechanism, we innovatively designed and prepared a multifunctional flame retardant HCCP-TMP that combines flame retardancy and free radical scavenging by combining hindered amine and cyclophosphazene. Only 1 wt% HCCP-TMP can make the polyacrylate-based gel polymer electrolyte (GPE) incombustible. Moreover, the equipped NCM811//Graphite pouch cells don't exhibit combustion behavior after thermal runaway and can resist mechanical abuse. Based on the above noncombustible GPE, the NCM811//Li battery exhibits capacity retention rate of 82.2 % after 100 cycles at a current density of 2 C and in the voltage range of 3.0–4.7 V, exhibiting excellent cyclability under high voltage. This simple molecular design simultaneously improves the fire safety and high voltage stability, demonstrating enormous application potential in the field of advanced LIBs with high safety and high energy density.

Co-doped NiFe carbonate hydroxide hydrate nanosheets with edge effect constructed from spent lithium-ion battery ternary cathodes for oxygen evolution reaction

The recycling of spent lithium-ion batteries (LIBs) has received increasing attention for environment and resource reclamation. Converting LIBs wastes into high-efficiency catalysts is a win-win strategy for realizing resource reclamation and addressing sustainable energy challenges. Herein, we developed a simple method to upcycle spent-LIBs cathode powder into Co-doped NiFe carbonate hydroxide hydrate (Co/NFCH-FF) as a low-cost and efficient oxygen evolution reaction (OER) electrocatalyst. The optimized Co/NFCH-FF electrode appears very competitive OER performances with low overpotentials of 201 and 249 mV at 10 and 100 mA cm−2, respectively, a small Tafel slope of 48.4 mV dec−1, and a high long-term stability. Moreover, we reveal that the existence of Co atoms leads to the formation of a crystalline/amorphous (c/a) interface at the Co/NFCH nanosheet edge, inducing the nanosheets possess a unique edge effect to enhance electric fields and accumulate hydroxide ions (OH–) at the edge during the OER process. Benefiting from edge effect, Co/NFCH-FF shows outstanding intrinsic activity. Furthermore, Co atoms as dopants stabilize the electronic structure of Co/NFCH-FF, enabling Co/NFCH-FF to exhibit excellent catalytic stability. This work provides an effective strategy for converting the end-life LIBs to high-performance multicomponent OER electrocatalysts and proposes new insights into the mechanism of enhanced catalytic activity of Co/NFCH.

All-dry solid-phase synthesis of single-crystalline Ni-rich ternary cathodes for lithium-ion batteries

All-dry solid-phase synthesis of single-crystalline Ni-rich ternary cathodes for lithium-ion batteries

In-situ catalytic pyrolysis of cellulose with lithium-ion battery ternary cathodes and ex-situ upgrading over Ru/HZSM-5 for bio-aromatics

Bio-aromatics preparation via in-situ catalytic pyrolysis of cellulose with lithium-ion battery ternary cathodes and ex-situ upgrading over Ru/HZSM-5 was studied. Three ternary cathodes with different ratios of Ni, Co, and Mn (NCM111, NCM532 and NCM811) were selected, and the effects of ternary cathodes and bifunctional Ru/HZSM-5 on the cellulose conversion were investigated from the perspectives of thermogravimetric kinetics and fixed-bed upgrading. The results indicated that cellulose pyrolyzed with cathodes reduced the solid residue content from 13.07% to 7.78%, 7.11%, and 6.63%, and decreased the weightlessness peak temperature from 358 ℃ to 348 ℃, 347 ℃, and 341 ℃; herein, the reaction order gradually elevated from 1.34 to 1.67 with the increased cathode Ni ratio, but the activation energy and pre-exponential factor obviously reduced. In-situ catalytic pyrolysis of ternary cathodes combined with ex-situ upgrading of Ru/HZSM-5 resulted in more cellulose-derived products being converted, increasing bio-oil yield from 22.47% to 25.08%, 24.75%, and 25.42%. Furfural was largely deoxygenated and dehydrated to become the precursor of aromatics, so NCM111, NCM532 and NCM811 usage increased the MAHs selectivity from 28.42% to 78.69%, 85.98%, and 87.27%, and high Ni ratio had higher deoxygenation capability and aromatic selectivity, simultaneously, it prone to creating material basis and spatiotemporal conditions for alkylation side reaction to increase C9 and above hydrocarbons. However, 1H NMR analysis confirmed that the main reaction of aromatization was still stronger than the side reaction even under high Ni ratio condition. Aromatics and coke production from acidic zeolite catalyzed reforming of oxygenates were competing reactions. In-situ catalysis of ternary cathodes produced more small molecule products to enter the inner pores of Ru/HZSM-5, forming more difficult to remove microporous coke, and the effect of increased Ni ratio was more obvious, but coke content reduced from 4.51% to 4.11%, 4.13%, and 3.05%, respectively.

Recycling the Spent LiNi1- x - yMnxCoyO2 Cathodes for High-Performance Electrocatalysts toward Both the Oxygen Catalytic and Methanol Oxidation Reactions.

The traditional recycling methods of the spent lithium ion batteries (LIBs) involve the intricate and cumbersome steps. This work proposes a facile method of acid leaching followed by the sulfurization treatment to achieve the high Li leaching efficiency, and obtain high-performance multi-function electrocatalysts for oxygen reduction (ORR), oxygen evolution (OER), and methanol oxidation reactions (MOR) from the spent LIB ternary cathodes. By this method, the Li leaching efficiency from the spent LIB ternary cathode can reach 98.3%, and the transition metal sulfide heterostructures (LNMCO-H-450S) consisting MnS, NiS2, and NiCo2S4 phases can be obtained. LNMCO-H-450S shows the superior bifunctional oxygen catalytic activities with ORR half-wave potential of 0.763V and OER potential at 10mA cm-2 of 1.561V, surpassing most of the state-of-the-art electrocatalysts. LNMCO-H-450S also demonstrates the superior MOR catalytic activity with the potential at 100mA cm-2 being 1.37V. Using LNMCO-H-450S as the oxygen catalyst, this work can construct the aqueous and solid-state zinc-air batteries with high power density of 309 and 257mW cm-2, respectively. This work provides a promising strategy for the efficient recovery of Li, and reutilization of Ni, Co, and Mn from the spent LIB ternary cathodes.

Olivine-based nano-filling layer empowering Ni-rich layered cathodes with enhanced surface stability and thermal shock resistance

Irreversible phase transition and nerve-racking thermal runaway of NCM811 especially cycled at high charge cut-off potential hinder its full-scale commercialization. In this study, we use a facile and powerful surface modification strategy to construct modified NCM811 whose ravines are completely filled/embedded by sand-milled LiMn0.6Fe0.4PO4 (LMFP), forming the nano-filled NCM811 (LMFP@NCM811). By virtue of this compact & uniform LMFP layer, a thin and stable cathode-electrolyte interface (CEI) layer can be established on the surface of LMFP@NCM811, which leads to prominent electrochemical properties with a high capacity retention of ∼ 80% after 450 cycles at 100 mAh/g. Moreover, due to the intrinsic stability of olivine structure (LMFP), the LMFP-embedded NCM811 showcases admirable thermal stability and thermal shock resistance at high de-lithiation state. We believe that such success at the performance improvement of Ni-rich ternary cathodes can provide a good guidance for future work to achieve more efficient energy storage and utilization.

Effect of Fluoroethylene Carbonate Electrolyte Additives on the Electrochemical Performance of Nickel-Rich NCM Ternary Cathodes

It has been well established recently that fluorinated electrolyte additives such as fluoroethylene carbonate (FEC) could promote the formation of LiF-based solid electrolyte interphases that can stabilize lithium metal anodes. Meanwhile, the impact of FEC additives on the cathode side, particularly for the high energy density nickel-rich LiNi1–x–yCoxMnyO2 (NCM) ternary cathodes, remains unclear. In this study, we investigated the structural and chemical composition of a cathode electrolyte interphase (CEI) and its electrochemical performance to elucidate the effect of FEC additives on the LiNi0.9Co0.05Mn0.05O2 (NCM90) cathode for high energy lithium-ion batteries. It is discovered that the FEC additive in carbonate electrolyte (BE-FEC) can produce a LiF-based CEI, which could stabilize the NCM90 surface and improve the cycle performance at low cut-off voltage. The formation of a thick LiF layer under high cut-off voltage and high rate has been observed to result in increased polarization and slower Li+ transport kinetics, ultimately leading to a deterioration in battery performance. On the other hand, in a carbonate electrolyte (BE) and under low voltage, the unstable Li2CO3-based CEI components on the NCM90 surface with an intermediate rock salt phase in between contribute to poor long-term performance and reduced reliability. While under high voltage, the BE sample shows superior electrochemical performance due to the formation of a thin LiF layer from the decomposition of LiPF6. Our work provides a comprehensive understanding of the role of FEC in the CEI of nickel-rich cathodes, offering practical guidance for the design of electrolytes for high-energy high-voltage nickel-rich cathodes.

Enhancing the Electrochemical Properties of Nickel-Rich Cathode by Surface Coating with Defect-Rich Strontium Titanate.

Ni-rich layered ternary cathodes (i.e., LiNixCoyMzO2, M = Mn or Al, x + y + z = 1 and x ≥ 0.8) are promising candidates for the power supply of portable electronic devices and electric vehicles. However, the relatively high content of Ni4+ in the charged state shortens their lifespan due to inevitable capacity and voltage deteriorations during cycling. Therefore, the dilemma between high output energy and long cycle life needs to be addressed to facilitate more widespread commercialization of Ni-rich cathodes in modern lithium-ion batteries (LIBs). This work presents a facile surface modification approach with defect-rich strontium titanate (SrTiO3-x) coating on a typical Ni-rich cathode: LiNi0.8Co0.15Al0.05O2 (NCA). The defect-rich SrTiO3-x-modified NCA exhibits enhanced electrochemical performance compared to its pristine counterpart. In particular, the optimized sample delivers a high discharge capacity of ∼170 mA h/g after 200 cycles under 1C with capacity retention over 81.1%. The postmortem analysis provides new insight into the improved electrochemical properties which are ascribed to the SrTiO3-x coating layer. This layer appears to not only alleviate the internal resistance growth, from uncontrollable cathode-electrolyte interface evolution, but also acts as a lithium diffusion channel during prolonged cycling. Therefore, this work offers a feasible strategy to improve the electrochemical performance of layered cathodes with high nickel content for next-generation LIBs.

Roles of Trimethyl Borate in Constructing an Interphase on Li Anode: Angel or Demon?

Although coupling a lithium metal anode with a Ni-rich layer cathode is a promising approach for high-energy lithium metal batteries, both electrodes are plagued by their intrinsic unstable interfaces which trigger electrolyte decomposition, lithium dendritic growth, and transition metal dissolution during cycling. Making use of electrolyte additives is one of the most effective solutions to address this issue. In this paper, we explore the roles of trimethyl borate (TMB)─a common film-forming additive to protect high-nickel-ratio ternary cathodes─in suppressing lithium dendrite growth. It is found that, on the one hand, the borate-containing solid electrolyte interphase (SEI) derived from the decomposition of TMB facilitates Li+ transport, homogenizing the deposition of Li ions. On the other hand, TMB as an anion receptor provokes LiPF6 decomposition, prompting the formation of SEI with superfluous LiF. As a result, it is imperative to raise awareness of this double-edge additive when using it to be immune to lithium dendrite and cathodic degradation.

Research Progress of High-energy-density Solid-state Lithium Ion Batteries Employing Ni-rich Ternary Cathodes

Research Progress of High-energy-density Solid-state Lithium Ion Batteries Employing Ni-rich Ternary Cathodes

Realizing high energy-density lithium-ion batteries: High Ni-content or high cut-off voltage of single-crystal layered cathodes?

• The electrochemical properties of SC-NCM613 and SC-NCM811 are systematically studied under the similar Li + deintercalation/intercalation. • The SC-NCM613 has an improved structural and air stability along with reduced cost compared with that of SC-NCM811. • Increasing the upper cut-off voltage of layered cathodes with relatively low Ni-content is a better choice for high-energy and low-cost LIBs. Improving Ni-content or upper cut-off voltage is usually utilized to boost the specific capacity of cathodes and the energy-density of lithium-ion batteries (LIBs). However, the performance comparison and structural evolutions between the aforementioned strategies have not been reported yet, especially under the same state of charge (SOC) of single-crystal layered ternary cathodes. Herein, the properties of single-crystal LiNi 0.6 Co 0.1 Mn 0.3 O 2 (SC-NCM613) and LiNi 0.8 Co 0.1 Mn 0.1 O 2 (SC-NCM811) are systematically studied under the similar Li + deintercalation/intercalation. Both single-crystal cathodes deliver a specific capacity of about 200 mAh g −1 with a median-voltage of 3.8 V. The SC-NCM613 under the cut-off of 4.5 V shows improved cycling life than that of SC-NCM811 under 4.3 V. Both single-crystal cathodes exhibit a similar rate property at 25 °C while SC-NCM613 has enhanced high-rate capacities as testing temperature drops to 0 °C. XRD results demonstrate that the enhanced stability of SC-NCM613 is ascribed to the reduced structural distortion at high SOC. Besides, SC-NCM613 has a decreased content of Ni 3+ ions, suggesting the improved air and storage stability. And Ni substituted by Mn in SC-NCM613 will reduce the cost of cathode. These results suggest that increasing the upper cut-off voltage of layered cathodes with relatively low Ni-content is a better choice for designing high-energy and low-cost LIBs.

Improved interfacial properties of LiNi0.8Co0.15Al0.05O2 cathode by tris(trimethylsilyl) borate as an electrolyte additive to inhibit HF formation

Tris(trimethylsilyl)borate (TMSB) is selected as an electrolyte additive in Li/LiNi0.8Co0.15Al0.05O2 cell due to its low oxidation potential. Its positive effect on improving the performances of the cells is analyzed by nuclear magnetic resonance, X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma. The results show that the oxidative decomposition products of TMSB are involved in the formation of cathode electrolyte interface film. The trimethylsilyl group can react with HF to form trimethylsilyl fluoride and dimethyldifluorosilane, which reduces transition metal leaching through HF on LiNi0.8Co0.15Al0.05O2 (NCA) cathode. Meanwhile, a thinner interfacial film with a lower LiF content is formed, which contributes to the structural stability of NCA and inhibits the decomposition of the electrolyte. As a result, the NCA cathode in the electrolyte containing 1% TMSB shows higher cycling stability and rate performance, and has a lower impedance. Even at 1 C after 200 cycles, it still provides capacity retention with 86.0% compared to 67.2% for the cathode in baseline electrolyte. This work could provide an idea for the use of silicon-boron compounds as electrolyte additive to improve the electrochemical performances of ternary cathodes.

Nucleation–Oxidation coupled technology for High-Nickel ternary cathode recycling of spent Lithium-ion batteries

Demand of ternary Li-ion batteries (LIBs) has risen dramatically in recent times, making it necessary to efficiently recycle spent cathode materials to reduce environmental pollution and alleviate the tight supply of various elements including Li, Co, and Ni. Co-precipitative regeneration of spent LIBs is typically employed to recycle Li, Co, Ni, and Mn. However, it is difficult to evenly distribute metals in the regenerated materials. Moreover, the emission of heavy-metal ions makes it difficult to meet the environmental guidelines. Here, we develop a nucleation–oxidation coupled technology to efficiently recover Ni, Co, and Mn from spent ternary cathodes by forming layered double hydroxides (LDHs) in a micro-liquid-film reactor. After recycling, 98% Li remains in the liquid phase, while the Ni, Co, and Mn in the filtrate decrease to the ppb level. Atomic distribution of Ni, Co, and Mn can be achieved in LDH, which helps realize the full-life-cycle of ternary cathode materials. It is difficult for the high-nickel ternary e.g., LiNi0.8Co0.1Mn0.1O2 to regenerate into LDH through spontaneous air oxidation. The micro-liquid-film reactor has a strong shear rate (maximum 1.04 × 106 s−1 is three orders of magnitude larger than that of the stirred reactor) and large vorticity (∼1.18 × 105 s−1, three orders of magnitude greater than that of the stirred reactor). It can enhance the transfer and diffusion of oxygen in the liquid phase. Hence, the micro-liquid-film reactor can greatly strengthen air-oxidation reaction of Ni2+, Co2+, and Mn2+ to sufficiently form trivalent cations, while the nucleation–oxidation-coupled regeneration is realized during the nucleation stage.

Inhibition Role of Solvation on the Selective Extraction of Co(II): Toward Eco-Friendly Separation of Ni and Co

Ternary cathodes account for more than half of the market share for lithium-ion battery cathodes, and recycling draws considerable attention. The traditional extraction process used to separate and recover Co and Ni from spent ternary cathode leachates produces a large amount of saline wastewater; thus, a green method is urgently needed. In this work, we underscore the crucial role played by metal solvation during extraction, and this provides a new perspective for achieving green separation. The extraction mechanism can be described as follows: metal cations M2+ (M–Ni and Co) generate stable hydrated ions M(H2O)62+ upon solvation. However, Ni(H2O)62+ and Co(H2O)62+ exhibit different activities in reactions with acidic extractants (HA) and form different complexes, NiA2·2H2O and CoA2, respectively. Correspondingly, the coordinated water increases the electron density and steric hindrance of the center metal ions and thus inhibits the subsequent extraction. Therefore, a means of reducing solvation (adding lactic acid) was developed, and this approach exhibited good performance. The separation factor was improved by a factor of 192. These results open a new avenue for high-performance selective extraction of Co, which features a green recovery process and is suitable for future use in industrial production.