Upcycling of Spent Lithium Cobalt Oxide Cathodes from Discarded Lithium-Ion Batteries as Solid Lubricant Additive

Direct Regenerating Cathode Materials from Spent Lithium-Ion Batteries

Recycling cathode materials from spent lithium-ion batteries (LIBs) is critical to a sustainable society as it will relief valuable but scarce recourse crises and reduce environment burdens simultaneously. Different from conventional hydrometallurgical and pyrometallurgical recycling methods, direct regeneration relies on non-destructive cathode-to-cathode mode, and therefore, more time and energy-saving along with an increased economic return and reduced CO2 footprint. This review retrospects the history of direct regeneration and discusses state-of-the-art development. The reported methods, including high-temperature solid-state, hydrothermal/ionothermal, molten salt thermochemistry, and electrochemical method, are comparatively introduced, targeting at illustrating their underlying regeneration mechanism and applicability. Further, representative repairing and upcycling studies on wide-applied cathodes, including LiCoO2 (LCO), ternary oxides, LiFePO4 (LFP), and LiMn2 O4 (LMO), are presented, with an emphasis on milestone cases. Despite these achievements, there remain several critical issues that shall be addressed before the commercialization of the mentioned direct regeneration methods.

A critical review of the circular economy for lithium-ion batteries and photovoltaic modules - status, challenges, and opportunities

To meet net-zero emissions and cost targets for power production, recent analysis indicates that photovoltaic (PV) capacity in the United States could exceed 1 TW by 2050 alongside comparable levels of energy storage capacity, mostly from batteries. For comparison, the total U.S. utility-scale power capacity from all energy sources in 2020 was 1.2 TW, of which solar satisfied approximately 3%. With such massive scales of deployment, questions have arisen regarding issues of material supply for manufacturing, end-of-life management of technologies, environmental impacts across the life cycle, and economic costs to both individual consumers and society at large. A set of solutions to address these issues center on the development of a circular economy - shifting from a take-make-waste linear economic model to one that retains the value of materials and products as long as possible, recovering materials at end of life to recirculate back into the economy. With limited global experience, scholars and practitioners have begun to investigate circular economy pathways, focusing on applying novel technologies and analytical methods to fast-growing sectors like renewable energy. This critical review aims to synthesize the growing literature to identify key insights, gaps, and opportunities for research and implementation of a circular economy for two of the leading technologies that enable the transition to a renewable energy economy: solar PV and lithium-ion batteries (LIBs). We apply state-of-the-science systematic literature review procedures to critically analyze over 3,000 publications on the circular economy of solar PV and LIBs, categorizing those that pass a series of objective screens in ways that can illuminate the current state of the art, highlight existing impediments to a circular economy, and recommend future technological and analytical research. We conclude that while neither PV nor LIB industries have reached a circular economy, they are both on a path towards increased circularity. Based on our assessment of the state of current literature and scientific understanding, we recommend research move beyond its prior emphasis on recycling technology development to more comprehensively investigate other CE strategies, more holistically consider economic, environmental and policy aspects of CE strategies, increase leveraging of digital information systems that can support acceleration towards a CE, and to continue to study CE-related aspects of LIB and PV markets.

4-Phosphoryl Pyrazolones for Highly Selective Lithium Separation from Alkali Metal Ions

Effective receptors for the separation of Li⁺ from a mixture with other alkali metal ions under mild conditions remains an important challenge that could benefit from new approaches. In this study, it is demonstrated that the 4-phosphoryl pyrazolones, HL² -HL⁴ , in the presence of the typical industrial organophosphorus co-ligands tributylphosphine oxide (TBPO), tributylphosphate (TBP) and trioctylphosphine oxide (TOPO), are able to selectively recognise and extract lithium ions from aqueous solution. Structural investigations in solution as well as in the solid state reveal the existence of a series of multinuclear Li⁺ complexes that include dimers (TBPO, TBP) as well as rarely observed trimers (TOPO) and represent the first clear evidence for the synergistic role of the co-ligands in the extraction process. Our findings are supported by detailed NMR, MS and extraction studies. Liquid-liquid extraction in the presence of TOPO revealed an unprecedented high Li⁺ extraction efficiency (78 %) for HL⁴ compared to the use of the industrially employed acylpyrazolone HL¹ (15 %) and benzoyl-1,1,1-trifluoroacetone (52 %) extractants. In addition, a high selectivity for Li⁺ over Na⁺ , K⁺ and Cs⁺ under mild conditions (pH ∼8.2) confirms that HL² -HL⁴ represent a new class of ligands that are very effective extractants for use in lithium separation.

Understanding the Behaviors of λ-MnO2 in Electrochemical Lithium Recovery: Key Limiting Factors and a Route to the Enhanced Performance

Recently developed electrochemical lithium recovery systems, whose operation principle mimics that of lithium-ion battery, enable selective recovery of lithium from source waters with a wide range of lithium ions (Li⁺) concentrations; however, physicochemical behaviors of the key component-Li⁺-selective electrode-in realistic operation conditions have been poorly understood. Herein, we report an investigation on a λ-MnO₂ electrode during the electrochemical lithium recovery process with regards to the Li⁺ concentration in source water and operation rate of the system. Three distinctive stages of λ-MnO₂ originating from different limiting factors for lithium recovery are defined with regard to the rate of Li⁺ supply from the electrolyte: depleted, transition, and saturated regions. By characterization of λ-MnO₂ at different stages using diverse X-ray techniques, the importance of Li⁺ concentration in the vicinity of the electrode surface is revealed. On the basis of this understanding, increasing the density of the electrode/electrolyte interface is suggested as a realistic and general route to enhance the overall lithium recovery performance and is experimentally corroborated at a wide range of operation environments.

Challenges to Future Development of Spent Lithium Ion Batteries Recovery from Environmental and Technological Perspectives

Spent lithium ion battery (LIB) recovery is becoming quite urgent for environmental protection and social needs due to the rapid progress in LIB industries. However, recycling technologies cannot keep up with the exaltation of the LIB market. Technological improvement of processing spent batteries is necessary for industrial application. In this paper, spent LIB recovery processes are classified into three steps for discussion: gathering electrode materials, separating metal elements, and recycling separated metals. Detailed discussion and analysis are conducted in every step to provide beneficial advice for environmental protection and technology improvement of spent LIB recovery. Besides, the practical industrial recycling processes are introduced according to their advantages and disadvantages. And some recommendations are provided for existing problems. Based on current recycling technologies, the challenges for spent LIB recovery are summarized and discussed from technological and environmental perspectives. Furthermore, great effort should be made to promote the development of spent LIB recovery in future research as follows: (1) gathering high-purity electrode materials by mechanical pretreatment; (2) green metals leaching from electrode materials; (3) targeted extraction of metals from electrode materials.