Ionothermal synthesis of activated carbon from waste PET bottles as anode materials for lithium-ion batteries.

Waste polyethylene terephthalate (PET) bottles have become a significant post-consumer plastic waste with attendant environmental problems. Hence, ionothermal synthesis has been used to prepare activated carbon (AC) anode materials from waste PET for both high performance and sustainable lithium-ion batteries (LIB). Particularly, using choline chloride deep eutectic salts (CU-DES) does not require post-synthesis washing and thereby reduces the complexity of the process and produces materials with unique low-surface area, higher levels of graphitization/ordering, and high nitrogen doping in the obtained ACs. The results show that the AC produced using CU-DES (PET-CU-A-ITP2) gave good electrochemical performance. Even though the material possesses a low surface area (∼23 m2 g-1), it displays a gravimetric capacity (GC) of ∼460 mA h g-1 and a coulombic efficiency (CE) of ∼53% in the 1st cycle and very good cycling performance with a capacity retention of 98% from the 2nd to the 100th cycle. The superior electrochemical performance of the PET-CU-A-ITP2 anode was found to be due to its better graphitization/ordering and dense structure which results in higher capacity, formation of less solid electrolyte interphase, and higher CE. These results show that dense carbons can be exploited as high-performance anodes in LIBs. Also, this research presents both a pathway for waste PET management and a waste-energy approach that could offer cheaper and greener LIBs to meet the sustainable development goals.

Meeting sustainable development goals via robotics and autonomous systems.

Robotics and autonomous systems are reshaping the world, changing healthcare, food production and biodiversity management. While they will play a fundamental role in delivering the UN Sustainable Development Goals, associated opportunities and threats are yet to be considered systematically. We report on a horizon scan evaluating robotics and autonomous systems impact on all Sustainable Development Goals, involving 102 experts from around the world. Robotics and autonomous systems are likely to transform how the Sustainable Development Goals are achieved, through replacing and supporting human activities, fostering innovation, enhancing remote access and improving monitoring. Emerging threats relate to reinforcing inequalities, exacerbating environmental change, diverting resources from tried-and-tested solutions and reducing freedom and privacy through inadequate governance. Although predicting future impacts of robotics and autonomous systems on the Sustainable Development Goals is difficult, thoroughly examining technological developments early is essential to prevent unintended detrimental consequences. Additionally, robotics and autonomous systems should be considered explicitly when developing future iterations of the Sustainable Development Goals to avoid reversing progress or exacerbating inequalities.

In Situ X-ray Diffraction and X-ray Absorption Spectroscopic Studies of a Lithium-Rich Layered Positive Electrode Material: Comparison of Composite and Core-Shell Structures.

Lithium- and manganese-rich transition-metal oxide (LMR-NMC) electrodes have been designed either as heterostructures of the primary components ("composite") or as core-shell structures with improved electrochemistry reported for both configurations when compared with their primary components. A detailed electrochemical and structural investigation of the 0.5Li2MnO3-0.5LiNi0.5Mn0.3Co0.2O2 composite and core-shell structured positive electrode materials is reported. The core-shell material shows better overall electrochemical performance compared to its corresponding composite material. While both configurations gave the same initial charge capacity of ∼300 mAh/g when cycled at a rate of 10 mA/g at 25 °C, the core-shell sample gives a discharge capacity of 232 mAh/g compared to 208 mAh/g delivered by the composite sample. Also, the core-shell sample gave better rate capability and a smaller first-cycle irreversible capacity loss than the composite sample. The improved performance of the core-shell material is attributed to its lower surface reactivity and limited structural change since the more stable Li2MnO3 shell screens the more reactive Ni-rich core material from interacting with either air or electrolyte at high potentials, thereby preventing electrode surface modification. In situ X-ray diffraction correlated with electrochemical data revealed that the composite sample shows stronger volumetric changes in the lattice parameters during charging to 4.8 V. In addition, X-ray absorption spectroscopy showed an incomplete Ni reduction process after the first discharge for the composite sample. From these results, it was shown that this leads to a more severe degradation in the composite material that affects Li+ intercalation in the subsequent discharge, thereby resulting in its poorer performance. Furthermore, to confirm these results, another LMR-NMC material with a different composition (having a Ni-poor core)-0.5Li2MnO3-0.5LiNi0.33Mn0.33Co0.33O2-was investigated. The core-shell structured positive electrode material also gave an improved electrochemical performance compared to the corresponding composite positive electrode material. These results show that the core-shell configuration could effectively be used to improve the performance of the LMR-NMC materials to enable future high-energy applications.