Lithium-ion batteries (LIBs) play a significant role in our highly electrified world and will continue to lead technology innovations. Millions of vehicles are equipped with or directly powered by LIBs, mitigating environmental pollution and reducing energy use. This rapidly increasing use of LIBs in vehicles will introduce a large quantity of spent LIBs within an 8-10-year span. Proper handling of endof-life (EOL) vehicle LIBs is required, and multiple options should be considered. This paper demonstrates that the necessity for EOL recycling is underpinned by leveraging fluctuating material costs, uneven distribution and production, and the transport situation. From a life-cycle perspective, remanufacturing and repurposing extend the life of LIBs, and industrial demonstrations indicate that this is feasible. Recycling is the ultimate option for handling EOL LIBs, and recent advancements both in research and industry regarding pyrometallurgical, hydrometallurgical, and direct recycling are summarized. Currently, none of the current battery recycling technologies is ideal, and challenges must be overcome. This article is anticipated as a starting point for a more sophisticated study of recycling, and it suggests potential improvements in the process through mutual efforts from academia, industry, and governments.

Pure organic room temperature phosphorescence (RTP) has unique advantages and various potential applications. However, it is challengeable to achieve organic RTP under visible and near-infrared (NIR)-light excitation, especially in aqueous solution. Herein we assemble difluoroboron β-diketonate compounds to form organic nanoparticles (NPs) in water. The resulting NPs are able to show efficient RTP, effective uptake, and bright imaging of HeLa cells under both visible-and NIR-light excitation. More strikingly, spectroscopic study, single-crystal Xray diffraction, and DFT calculation reveal that the efficient RTP in organic NPs is originated from dimers in their excited states. The multiple interactions and intermolecular charge transfer in the dimer structures are of significance in promoting the production of dimer triplet excited states and suppressing the nonradiative decays to boost the RTP under visible-and NIR-light irradiation in water.

displays. [1,2] In particular, perovskite-based light-emitting diodes (PeLEDs) with superior external quantum efficiency (EQE) and luminance have been demonstrated in the green, red, and near-infrared emission regions. [3][4][5][6] As display technologies continue to improve, the requirements for the emitters in the display become more stringent. As of August 2012, the Rec. 2020 standard defines the display color gamut for ultrahigh definition television (UHDTV): it requires each of the primary red, green, blue (RGB) emitters to have a precisely defined wavelength (red: 630 nm, green: 532 nm, and blue: 467 nm) and a narrow emission linewidth (<20 nm). [7] In state-of-art liquid crystal display backlights, crosstalk between color filters reduces the color purity of the RGB primaries. [8] LED displays do not require color filters and as such are promising candidate for UHDTV. Organic molecules have had success in commercial LED displays, but the wide linewidths (>50 nm) of organic emitters limit the attainable color gamut. [9] Developing emitters with precisely defined emission profiles for displays is an active Perovskite-based light-emitting diodes (PeLEDs) are now approaching the upper limits of external quantum efficiency (EQE); however, their application is currently limited by reliance on lead and by inadequate color purity. The Rec. 2020 requires Commission Internationale de l'Eclairage coordinates of (0.708, 0.292) for red emitters, but present-day perovskite devices only achieve (0.71, 0.28). Here, lead-free PeLEDs are reported with color coordinates of (0.706, 0.294)-the highest purity reported among red PeLEDs. The variation of the emission spectrum is also evaluated as a function of temperature and applied potential, finding that emission redshifts by <3 nm under low temperature and by <0.3 nm V −1 with operating voltage. The prominent oxidation pathway of Sn is identified and this is suppressed with the aid of H 3 PO 2 . This strategy prevents the oxidation of the constituent precursors, through both its moderate reducing properties and through its forming complexes with the perovskite that increase the energetic barrier toward Sn oxidation. The H 3 PO 2 additionally seeds crystal growth during film formation, improving film quality. PeLEDs are reported with an EQE of 0.3% and a brightness of 70 cd m −2 ; this is the record among reported red-emitting, lead-free PeLEDs.

electrochemical reactions in SCs, which can take advantage of the anions in electrolyte to achieve the energy storage. [3] However, SCs store ions only at the interfaces between electrodes and electrolyte, making their energy densities too low to power the high-energy devices ( Figure S1, Supporting Information). Although the recently proposed aluminium ion battery exhibits excellent cycling performance, [4] the relatively low energy density still needs to be addressed due to the low working voltage. Hence, it is highly urgent to develop the de-/intercalation reaction based dual-ion battery (DIB) with theoretically high energy density. [5] The first DIB with dual-graphite configuration was presented in 1989, in which graphite was used as both cathode and anode, realizing anion de-/intercalation in the cathodic graphite electrode. [6] In addition, the term of "dual-ion battery" was proposed for the first time by Winter and co-workers in 2012. [7] Different from the traditional Li/Na-ion batteries in which cationic charge carriers are initially originated from cathode materials, the electrolyte provides all charge carriers including anions and cations in the DIB. This means that the capacity delivered by DIB would not be limited by the usually low Coulombic efficiency (CE) of electrodes due to the sufficient supply of ions from electrolyte. [5b] However, the redox reactions of anion de-/intercalation on graphite cathode are usually taken place at a high potential, nearly or higher than 5.0 V versus Li + / Li, which exceeds the anodic stabile window of conventional carbonate electrolytes. As a result, such anion de-/intercalation processes usually suffer from severe side reactions, such as decomposition of electrolyte, [8] exfoliation of graphene layers, [9] and some unknown irreversible electrochemical reactions, leading to the very low CE (usually lower than 90%) during early cycling and hence poor cyclic stability. [10] In order to conquer these issues to improve the energystorage performance of DIB, there are four strategies proposed recently: 1) the utilization of ionic liquids with wider electrochemical stable window as the high-voltage electrolyte, which is hard to realize practicality due to the much expensive price; [11] 2) applying alloying metals (such as Al and Sn) with the higher redox potential to replace the metallic Li anode, greatly improving the cycle life of DIB to over 1500 cycles as Conventional ion batteries utilizing metallic ions as the single charge carriers are limited by the insufficient abundance of metal resources. Although supercapacitors apply both cations and anions to store energy through absorption and/or Faradic reactions occurring at the interfaces of the electrode/electrolyte, the inherent low energy density hinders its application. The graphite-cathodebased dual-ion battery possesses a higher energy density due to its high working potential of nearly 5 V. However, such a battery configuration suffers from severe electrolyte decomposition and exfoliation of the graphite cath...

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