High-entropy oxides based on transition metals, such as Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O (TM-HEO), have recently drawn special attention as potential anodes in lithium-ion batteries due to high specific capacity and cycling reversibility. However, the lithiation/delithiation mechanism of such systems is still controversial and not clearly addressed. Here, we report on an operando XAS investigation into TM-HEO-based anodes for lithium-ion cells during the first lithiation/delithiation cycle. This material showed a high specific capacity exceeding 600 mAh g–1 at 0.1 C and Coulombic efficiency very close to unity. The combination of functional and advanced spectroscopic studies revealed complex charging mechanisms, developing through the reduction of transition-metal (TM) cations, which triggers the conversion reaction below 1.0 V. The conversion is irreversible and incomplete, leading to the final collapse of the HEO rock-salt structure. Other redox processes are therefore discussed and called to account for the observed cycling behavior of the TM-HEO-based anode. Despite the irreversible phenomena, the HEO cubic structure remains intact for ∼60% of lithiation capacity, so proving the beneficial role of the configuration entropy in enhancing the stability of the HEO rock-salt structure during the redox phenomena.

The transition to a circular economy vision must handle the increasing request of metals required to satisfy the battery industry; this can be obtained by recycling and feeding back secondary raw materials recovered through proper waste management. Here, a novel and green proof‐of‐concept was developed, based on deep eutectic solvents (DESs) to fully and easily recover valuable metals from various cathode active materials, including LiMn2O4, LiNi0.5Mn1.5O4, and LiNi0.8Co0.2O2. DES composed of choline chloride and lactic acid could leach Li, Mn, Co, and Ni, achieving efficiency of 100 % under much milder conditions with respect to the previous literature. For the first time, to our best knowledge, a two‐step approach was reported in the case of LiNi0.8Co0.2O2 for selective recovery of Li, Co, and Ni with high yield and purity. Furthermore, other cathode components, namely aluminum current collector and binder, were found to be not dissolved by the proposed DES, thus making a simple separation from the active material possible. Finally, this strategy was designed to easily regenerate and reuse the leaching solvents for more than one extraction, thus further boosting process sustainability.

An improved lifetime can be achieved by exploiting higher intrinsic durability of the materials, or by repairing the deteriorated component and restoring its original properties. Indeed, in the last years, several attempts to improve the lifetime of widespread devices (prosthetics, batteries, solar cells, lighting devices, etc.) were reported. [4-8] However, traditional techniques (welding, gluing, patching) need in situ application of fresh healing materials, and are not applicable to many modern complex devices that require disassembly and targeted operations well beyond the expertise of the final user. Moreover, repair by specialized personnel may be impossible or unsustainable from an economic point of view. To overcome these problems, a radically new strategy that can pave the way for more durable materials is emerging: the concept of selfhealing (SH). [9] This term refers to those smart materials that can automatically restore some, or all, of their functions after having suffered of an external damage that degraded their original properties. This usually has to do with autonomous recovery of physical cracks, but may include a wider range of features prolonging the lifetime of a material/ device, which space from anticorrosion to bactericidal properties. [10,11] By tailoring an appropriate response of the system, it becomes possible to design a material that can respond to various external perturbations and accommodate their eventual disturbance. The idea at the base of this approach is usually defined as biomimetic, since it takes inspiration from nature and mimic it in solving complex technological problems. [12] During the years, many different materials or technologies, naively depicted in Figure 1a, have taken inspiration from nature (as Velcro tape which mimics tiny hooks on bur fruits, naturally ventilated facades that mime termites' mounds, hydrophobic lotus-leaf coatings, and iridescent or adhesive surfaces respectively inspired by butterflies and geckos) and self-healing is not an exception. [13-15] In fact, in nature many organisms are capable of healing damages and of restoring their functionalities: skin, bones, plants, and other living systems can sense any failure and reconstruct the injured biological part which recovers its original functionalities. [16-18] Since these features lengthen the life of natural living beings, analog mechanisms can be exploited in artificial self-healing materials to benefit the Major improvements in stability and performance of batteries are still required for a more effective diffusion in industrial key sectors such as automotive and foldable electronics. An encouraging route resides in the implementation into energy storage devices of self-healing features, which can effectively oppose the deterioration upon cycling that is typical of these devices. In order to provide a comprehensive view of the topic, this Review first summarizes the main self-healing processes that have emerged in the multifaceted field of smart materials, classifying them on the basis of t...

Autonomic self-healing (SH), namely, the ability to repair damages from mechanical stress spontaneously, is polarizing attention in the field of new-generation electrochemical devices. This property is highly attractive to enhance the durability of rechargeable Li-ion batteries (LIBs) or Na-ion batteries (SIBs), where high-performing anode active materials (silicon, phosphorus, etc. ) are strongly affected by volume expansion and phase changes upon ion insertion. Here, we applied a SH strategy, based on the dynamic quadruple hydrogen bonding, to nanosized black phosphorus (BP) anodes for Na-ion cells. The goal is to overcome drastic capacity decay and short lifetime, resulting from mechanical damages induced by the volumetric expansion/contraction upon sodiation/desodiation. Specifically, we developed novel ureidopyrimidinone (UPy)-telechelic systems and related blends with poly(ethylene oxide) as novel and green binders alternative to the more conventional ones, such as polyacrylic acid and carboxymethylcellulose, which are typically used in SIBs. BP anodes show impressively improved (more than 6 times) capacity retention when employing the new SH polymeric blend. In particular, the SH electrode still works at a current density higher than 3.5 A g –1 , whereas the standard BP electrode exhibits very poor performances already at current densities lower than 0.5 A g –1 . This is the result of better adhesion, buffering properties, and spontaneous damage reparation.

Is It Possible to Obtain Solvent‐Free, Li+‐Conducting Solid Electrolytes Based on Pure PVdF? Comment on “Self‐Suppression of Lithium Dendrite in All‐Solid‐State Lithium Metal Batteries with Poly(vinylidene difluoride)‐Based Solid Electrolytes”

Next-generation Li-ion batteries must guarantee improved durability, quality, reliability, and safety to satisfy the stringent technical requirements of crucial sectors such as e-mobility. One breakthrough strategy to overcome the degradation phenomena affecting the battery performance is the development of advanced materials integrating smart functionalities, such as self-healing units. Herein, we propose a gel electrolyte based on a uniform and highly cross-linked network, hosting a high amount of liquid electrolyte, with multiple advantages: (i) autonomous, fast self-healing, and a promising PF5-scavenging role; (ii) solid-like mechanical stability despite the large fraction of entrapped liquid; and (iii) good Li+ transport. It is shown that such a gel electrolyte has very good conductivity (>1.0 mS cm–1 at 40 °C) with low activation energy (0.25 eV) for the ion transport. The transport properties are easily restored in the case of physical damages, thanks to the outstanding capability of the polymer to intrinsically repair severe cracks or fractures. The good elastic modulus of the cross-linked network, combined with the high fraction of anions immobilized within the polymer backbone, guarantees stable Li electrodeposition, disfavoring the formation of mossy dendrites with the Li metal anode. We demonstrate the electrolyte performance in a full-cell configuration with a LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode, obtaining good cycling performance and stability.

The cellular uptake of nanoparticles (NPs) represents a critical step in nanomedicine and a crucial point for understanding the interaction of nanomaterials with biological systems. No specific mechanism of uptake has been identified so far, as the NPs are generally incorporated by the cells through one of the few well-known endocytotic mechanisms. Here, an alternative internalization route mediated by microvilli adhesion is demonstrated. This microvillus-mediated adhesion (MMA) has been observed using ceria and magnetite NPs with a dimension of <40 nm functionalized with polyacrylic acid but not using NPs with a neutral or positive functionalization. Such an adhesion was not cell specific, as it was demonstrated in three different cell lines. MMA was also reduced by modifications of the microvillus lipid rafts, obtained by depleting cholesterol and altering synthesis of sphingolipids. We found a direct relationship between MAA, cell cycle, and density of microvilli. The evidence suggests that MMA differs from the commonly described uptake mechanisms and might represent an interesting alternative approach for selective NP delivery.

Sodium-ion batteries (SIBs) are promising alternative to Lithium-ion batteries for massive stationary energy storage. To improve energy density, however, more performing active materials are needed. In order to allow sustainable scale-up, it is also mandatory to develop green products and processes. Herein, we report on anodes of phosphorus/carbon (P/C) nanocomposites prepared via High Energy Ball Milling (HEBM), a simple, powerful and easily scalable synthesis technique. The electrodes were prepared under oxygen-free atmosphere, using water as solvent, which enabled the use of aluminum (instead of copper) as current collector, implying significant cost reduction. The P/C nanocomposite obtained after 54 hours HEBM resulted in excellent cycling stability, delivering very high specific capacity (2200 mAh g -1 , C/20) and showing good capacity retention after 120 cycles. A careful structural analysis (XRD, FESEM-EDS, XPS), revealed that long milling times strongly increased cycling stability due to: i) significant decrease of P particle size inside the matrix and deep composite amorphization, which alleviates the buffering dimensional issues typical of black phosphorus; ii) presence of defects in the carbonaceous component, which allows easier Na + insertion into the anode. Our results show that P/C nanocomposites are very promising anode materials for SIBs, paving the way for further exploitation of nano-architectures in SIBs technology.