Recycling of spent lithium-ion batteries (LIBs) has attracted ever-growing attention owing to the scarcity of critical metals and potential environmental risk. Sulfation roasting, as traditional technology, is considered uneconomical and not environmentally friendly due to tremendous consumption of energy and emission of waste gases such as SO2 or SO3. Hereby, a novel and cleaner sulfation roastinga water leaching process is proposed to recover valuable metals from spent LiCoO2 (LCO) batteries. It is found that sulfur can be recirculated thoroughly in the form of SO4 2– without the emission of SO x during the sulfation roasting process. Besides, the addition of graphite can promote the conversion of LiCoO2 under relatively milder conditions than those of traditional sulfation roasting. To further understand the conversion mechanism of LCO, the effects of various parameters including roasting temperature, roasting time, the mass ratio of carbon, and the molar ratio of H2SO4 during the recovery of Li and Co were investigated. Approximately, 92% of the global Li can be recovered as Li2CO3 with a purity as high as 99.76%, and almost 100% of Co can be recovered in the form of CoSO4 by sulfuric acid leaching. This work proposes a practicable and promising strategy for recycling valuable metals from spent LCO batteries. Meanwhile, the synergic mechanisms on carbon and sulfur for enhancing the selectivity of metal extraction are revealed.

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Metal wires are of great significance in applications such as three-dimensional (3D) printing, soft electronics, optics, and metamaterials. Ga-based liquid metals (e.g., EGaIn), though uniquely combining metallic conductivity, fluidity, and biocompatibility, remain challenging to be spun due to their low viscosity, high surface tension, and Rayleigh−Plateau instability. In this work, we showed that EGaIn as a working electrode could induce the oxidization of EGaIn and interfacial electrochemical polymerization of electroactive monomers (e.g., acrylic acid, dopamine, and pyrrole), thus spinning itself from an opening of a blunt needle. During the spinning process, the high surface tension of EGaIn was reduced by electrowetting and electrocapillarity and stabilized by polymer shells (tunable thickness of ∼0.6−30 μm on wires with a diameter of 90−300 μm), which were chelated with metal ions. The polymeric shells offered EGaIn wires with an enhanced endurance to mechanical force and acidity. By further encapsulating into elastomers through a facile impregnation process, the resultant elastic EGaIn wires showed a combination of high stretchability (up to 800%) and metallic conductivity (1.5 × 10 6 S m −1 ). When serving as wearable sensors, they were capable of sensing facial expressions, body movements, voice recognition, and spatial pressure distributions with high sensitivity, good repeatability, and satisfactory durability. Machine-learning algorithms further assisted to detect gestures with high accuracy.

Recycling of spent lithium-ion batteries (LIBs) has attracted ever-growing attention globally owing to the scarcity of critical metals and potential environmental risk. To solve the bottlenecks including poor selectivity and prominent environmental risks during the recovery of valuable metals from spent LIBs, the work proposed a novel process for selectively recovery of lithium synergized by carbon and sulfur elements. Firstly, H2SO4 was determined as the optimal roasting reagent by systematically investigating the effects of various roasting reagents including NaHSO4, (NH4)2SO4, NH4HSO4 and H2SO4 on the leaching selectivity of lithium from the LiNi1/3Co1/3Mn1/3O2 active material in spent LIBs, environmental impact and cost of reagents. Then, the effect of graphite dosage on the selectivity of lithium from LiNi1/3Co1/3Mn1/3O2 is investigated. Finally, the conversion path and mechanism under the synergistic effect of C and S elements for enhancing the selectivity of lithium is revealed. It is found that the leaching efficiency can achieve 93% under the following optimal conditions: the molar ratio of LiNi1/3Co1/3Mn1/3O2 to H2SO4 of 2∶1, graphite dosage of 20% (w), roasting temperature of 600 ℃, and roasting time of 120 min. The purity of the precipitated Li2CO3 from the obtained leachate is higher than that of battery grade Li2CO3. Ni, Co and Mn from LiNi1/3Co1/3Mn1/3O2 almost remains in the leaching residue which can be employed as the precursor materials for synthesizing cathode materials after separation and purification treatment. In addition, the separated graphite can be reused as roasting additive during the sulfation roasting of LiNi1/3Co1/3Mn1/3O2. By analyzing

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