High-entropy oxides based on transition metals, such as Mg_0.2Co_0.2Ni_0.2Cu_0.2Zn_0.2O (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, LiNi_0.5Mn_1.5O₄, and LiNi_0.8Co_0.2O₂. 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 LiNi_0.8Co_0.2O₂ 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.

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.

The rapid growth in demand for lithium‐ion batteries (LIBs) is posing challenges in the management of end‐of‐life (EoL) systems and the supply of critical raw materials (CRMs), especially lithium, cobalt, and nickel. Such challenges can be addressed by collecting and recycling spent LIBs through economically and environmentally sustainable processes and by enabling the transition to a circular economy vision based on the use of secondary raw materials. These processes involve not only the metallurgic approaches to recover the critical metals, but also the pretreatment approaches that are crucial to enhance the recovery efficiency of other valuable materials (e.g., graphite, fluorinated compounds, binders, electrolyte). Herein, pretreatment processes ranging from the disassembling, opening, and sorting to the component separation, collection, and recovery, are described for the EoL 18650‐type commercial LIB. A closed loop of eco‐friendly recycling to fully recover the composite cathode, i.e., the cathode active material (CAM), the fluorinated binder, and the conductive carbon, as well as the separator, is presented. The recovery approach is based on green solvents and is designed to limit water consumption. The recovered materials are used to assemble a new cell, and the electrochemical characterization is used to evaluate the effective feasibility of the whole recycling process.