Alkaline Roasting Approach to Reclaiming Lithium and Graphite from Spent Lithium-Ion Batteries

Recycling anode materials from spent lithium-ion batteries (LIBs) plays a significant role in relieving the environmental pollution and shortage of graphite and lithium resources. Most of the current routes employed mineral acids to leach out Li from the graphite anode, inevitably producing hazardous hydrofluoric acid (HF) because some Li exists in the form of lithium fluoride (LiF). In this study, we employ a NaOH roasting approach, by which LiF is converted to NaF and LiOH at 350 °C and thereby avoids the generation of HF. After roasting, the Li and graphite can be separated by a water leaching process without using mineral acids. The leaching efficiency of Li is close to 100%. The regeneration process of NaOH was also discussed considering the large-scale application. Additionally, the recovered graphite delivered an initial charge capacity of 370.8 mA h g–1 and a Coulombic efficiency of 90.05%, showing the comparable performances to the commercial graphite. Overall, the alkaline roasting approach does not use mineral acids and thus avoids generating toxic HF and waste acids, promising a green way to recycle anode materials from various spent LIBs

Harnessing PUF-Based Reporters for Noninvasive Imaging of the MicroRNA Dynamics in Differentiation

Precise characterization of miRNA expression patterns is critical to exploit the complexity of miRNA regulation in biology. Herein, we developed a Pumilio/FBF (PUF) protein-based engineering luciferase reporter system, PUF/miR, to quantitatively and non-invasively sense miRNA activity in living cells and animal models. We verified the feasibility of this reporter by monitoring the expression of several types of miRNAs (miRNA-9, 124a, 1, and 133a) in neural and muscle differentiated cells as well as subcutaneous or tibial anterior muscles in mice. The quantitative RT-PCR also validated the reliability and quantitative consistency of bioluminescence imaging in detecting miRNA expression. We further effectively employed this reporter system to visualize the expression of miRNA-1 and miRNA-133a in mouse models of skeletal muscle injury. As a non-invasive and convenient innovative approach, our results have realized the positive bioluminescence imaging of endogenous miRNAs in vitro and in vivo using the PUF/miR system. We believe that this approach would provide a potential means for noninvasive monitoring of disease-related miRNAs and could facilitate a deeper understanding of miRNA biology

Imaging Dendrimer-Grafted Graphene Oxide Mediated Anti-miR-21 Delivery With an Activatable Luciferase Reporter

MicroRNAs (miRNAs) are a class of post-transcriptional gene regulators involved in various physiological processes including carcinogenesis, and they have emerged as potential targets for tumor theranostics. However, the employment of antisense oligonucleotides, termed anti-miRs, for antagonizing miRNA functions in vivo has largely been impeded by a lack of effective delivery carriers. Here, we describe the development of polyamidoamine (PAMAM) dendrimer and polyethylene glycol (PEG)-functionalized nanographene oxide (NGO) conjugate (NGO-PEG-dendrimer) for the efficient delivery of anti-miR-21 into non-small-cell lung cancer cells. To monitor the delivery of anti-miR-21 into cells and tumors, we also constructed an activatable luciferase reporter (Fluc-3xPS) containing three perfectly complementary sequences against miR-21 in the 3′ untranslated region (UTR) of the reporter. Compared with bare dendrimer and Lipofectamine 2000 (Lipo2000), NGO-PEG-dendrimer showed considerably lower cytotoxicity and higher transfection efficiency. As demonstrated by in vitro bioluminescence imaging and Western blotting assays, NGO-PEG-dendrimer effectively delivered anti-miR-21 into the cytoplasm and resulted in the upregulation of luciferase intensity and PTEN target protein expression in a dose-dependent manner. Moreover, transfection with anti-miR-21 by NGO-PEG-dendrimer led to stronger inhibition of cell migration and invasion than did bare dendrimer or Lipo2000 transfection. The intravenous delivery of anti-miR-21 via NGO-PEG-dendrimer induced a significant increase in the bioluminescence signal within the Fluc-3xPS reporter-transplanted tumor areas. These results suggest that NGO-PEG-dendrimer could be an efficient and a potential nanocarrier for delivering RNA oligonucleotides. In addition, the strategy of combining NGO-PEG-dendrimer with an activatable luciferase reporter allows the image-guided monitoring of the delivery process, which can provide insights into the RNA-based cancer treatments

Recovery of LiCoO₂ from Spent Lithium-Ion Batteries through a Low-Temperature Ammonium Chloride Roasting Approach: Thermodynamics and Reaction Mechanisms

An ammonium chloride roasting approach can convert lithium metal oxides to water-soluble lithium and transition metal chlorides at 300 °C, promising an energy-efficient and environmentally benign way to recover end-of-life lithium-ion batteries. Unlike conventional chlorination processes, the roasting of LiCoO2 using NH4Cl as both reducing and chlorination agents is complex, and thus more efforts such as thermodynamics and the underlying mechanism are required to be understood. This paper aims to study the chlorination process by comprehensive thermodynamic analysis and a variety of control experiments such as operating temperature, gas atmosphere, NH4Cl/LiCoO2 mass ratios, and the way of mixing feedstocks. It is found that the chlorination of LiCoO2 is governed by a solid-to-solid reaction mechanism based on thermodynamics, thermal analysis, and roasting products. Finally, the regenerated LiCoO2 delivers a specific capacity of over 139.8 mAh g–1 at 0.5C with a capacity retention rate of 99% after 100 cycles. Overall, the chlorination process can be engineered by adjusting the temperatures, pressure, and contact area between NH4Cl and LiCoO2 to further reduce the energy consumption and thereby increase the utilization of NH4Cl and chlorination efficiencies

Recycling Spent Lithium-Ion Batteries Using Waste Benzene-Containing Plastics: Synergetic Thermal Reduction and Benzene Decomposition

Spent lithium-ion batteries (LIBs) and benzene-containing polymers (BCPs) are two major pollutants that cause serious environmental burdens. Herein, spent LIBs and BCPs are copyrolyzed in a sealed reactor to generate Li2CO3, metals, and/or metal oxides without emitting toxic benzene-based gases. The use of a closed reactor allows the sufficient reduction reaction between the BCP-derived polycyclic aromatic hydrocarbon (PAH) gases and lithium transition metal oxides, achieving the Li recovery efficiencies of 98.3, 99.9, and 97.5% for LiCoO2, LiMn2O4, and LiNi0.6Co0.2Mn0.2O2, respectively. More importantly, the thermal decomposition of PAHs (e.g., phenol and benzene) is further catalyzed by the in situ generated Co, Ni, and MnO2 particles, which forms metal/carbon composites and thus prevent the emissions of toxic gases. Overall, the copyrolysis in a closed system paves a green way to synergistically recycle spent LIBs and handle waste BCPs

A SiCl₄‑Assisted Roasting Approach for Recovering Spent LiCoO₂ Cathode

Efficiently recycling end-of-life lithium-ion batteries (LIBs) has been pursued in recent years to reduce energy consumption and secondary waste. In this paper, silicon tetrachloride (SiCl4)-assisted roasting was developed to recover LiCl, CoCl2, and Co3O4 from spent lithium cobalt oxide (LiCoO2) batteries. At 500 °C and a SiCl4/LiCoO2 mass ratio of 3:1, 95.6% of Co was recovered as CoCl2 and 98.4% of Li was recovered as LiCl. When the mass ratio was 0.7:1, 24.6% of Co was in the form of CoCl2, and the remaining was Co3O4, accompanied by the Li leaching rate of 95.6%. LiCoO2 resynthesized from recycled Li2CO3 and Co3O4 exhibits good electrochemical performance, with a capacity of over 142.5 mAh g–1 at 1C and a capacity retention rate of 93% after 100 cycles. According to the EverBatt model analysis, the SiCl4-assisted roasting method exhibits lower energy consumption and greenhouse gas emission, as well as more considerable revenue. Since SiCl4 is a byproduct of the polysilicon production process, the SiCl4-assisted chlorination at medium temperatures not only reduces the cost, but also achieves the disposal of SiCl4 and spent LIBs in a green manner