In lithium ion batteries (LIBs), the layered cathode materials of composition LiNi1−x−yCoxMnyO2 are critical for achieving high energy densities. A high nickel content (>80%) provides an attractive ...balance between high energy density, long lifetime, and low cost. Consequently, Ni‐rich layered oxides cathode active materials (CAMs) are in high demand, and the importance of LiNiO2 (LNO) as limiting case, is hence paramount. However, achieving perfect stoichiometry is a challenge resulting in various structural issues, which successively impact physicochemical properties and result in the capacity fade of LIBs. To better understand defect formation in LNO, the role of the Ni(OH)2 precursor morphology in the synthesis of LNO requires in‐depth investigation. By employing aberration‐corrected scanning transmission electron microscopy, electron energy loss spectroscopy, and precession electron diffraction, a direct observation of defects in the Ni(OH)2 precursor preparedis reported and the ex situ structural evolution from the precursor to the end product is monitored. During synthesis, the layered Ni(OH)2 structure transforms to partially lithiated (non‐layered) NiO and finally to layered LNO. The results suggest that the defects observed in commercially relevant CAMs originate to a large extent from the precursors, hence care must be taken in tuning the co‐precipitation parameters to synthesize defect‐free Ni‐rich layered oxides CAMs.
This paper delivers insights at high spatial resolution into various defect origins, and structural‐compositional evolution from the initial Ni(OH)2 precursor to the final LiNiO2. The Ni‐rich cathode active material synthesis from hydroxide precursors is an intricate phenomenon, consisting of material undergoing multiple 2D layered to 3D phase transformations followed by various defect formations.
The commercial breakthrough of Li‐ion batteries (LIBs) in the 1990s irrevocably shaped today's energy storage landscape, but the disposed batteries represent a growing hazard to the environment. One ...may initially assume that recycling processes are commendable technologies to ensure a counterbalance to LIBs manufacturing. However, the question remains whether current state‐of‐the‐art in LIBs recycling technologies can be considered as green. This problem is due to the application of toxic chemicals or the in situ generation of harmful substances during the recycling process. Besides the potential toxicity, current solutions are accompanied with intense energy consumption, causing carbon dioxide emissions, in disagreement with the circular economy principles. This review provides a critical assessment of both published research articles and patents to derive a broad picture on the sustainability of LIBs recycling technologies. Although the efficiency of industrially applied recycling technologies can exhibit a high overall efficiency, their general process design is generally based on waste reduction and downcycling. Contrariwise, sustainable recycling of LIBs should rely on circular processes ensuring upcycling of all materials toward zero waste and minimized energy utilization. Current solutions and expected development in LIBs recycling are presented, ranging from dismantling over components separation to application of bioderived materials.
Current recycling technologies of used Li‐ion batteries (LIBs) cannot be considered as green technologies due to their sole focus on waste minimalization. This review provides a critical assessment of recent progress in LIBs recycling with an emphasis on sustainable processes, which are designed toward zero waste, minimized energy consumption, and circular materials management.
The growing demand for sustainable energy storage devices requires rechargeable lithium‐ion batteries (LIBs) with higher specific capacity and stricter safety standards. Ni‐rich layered transition ...metal oxides outperform other cathode materials and have attracted much attention in both academia and industry. Lithium‐ion batteries composed of Ni‐rich layered cathodes and graphite anodes (or Li‐metal anodes) are suitable to meet the energy requirements of the next generation of rechargeable batteries. However, the instability of Ni‐rich cathodes poses serious challenges to large‐scale commercialization. This paper reviews various degradation processes occurring at the cathode, anode, and electrolyte in Ni‐rich cathode‐based LIBs. It highlights the recent achievements in developing new stabilization strategies for the various battery components in future Ni‐rich cathode‐based LIBs.
Degradation mechanisms of Ni‐rich cathode‐based Li‐ion batteries from a full‐cell perspective are reviewed. A comprehensive discussion on various detrimental processes occurring at the cathode, anode, and electrolyte is comprehensively addressed. The state‐of‐art remedy strategies and insights on future directions are also proposed for designing Ni‐rich‐based Li‐ion batteries with superior performance.
The ever‐growing demands for electrical energy storage have stimulated the pursuit of alternative advanced batteries. Zn‐ion batteries (ZIBs) are receiving increased attentions due to the low cost, ...high safety, and high eco‐efficiency. However, it is still a big challenge to develop suitable cathode materials for intercalation of Zn ions. This review provides a timely access for researchers to the recent activities regarding ZIBs. First, cathode materials including various manganese oxides, vanadium compounds, and Prussian blue analogs are summarized with details in crystal structures and Zn ion storage mechanisms. Then, the electrolytes and their influences on the electrochemical processes are discussed. Finally, opinions on the current challenge of ZIBs and perspective to future research directions are provided.
Recent advances in zinc‐ion batteries, especially the cathode materials including Mn‐based, V‐based, and Prussian blue analogs based materials, are comprehensively summarized here. The relationships between crystal structure, reaction mechanism, and electrochemical performance are elaborated.
Despite the significant advancement in preparing metal oxide hollow structures, most approaches rely on template‐based multistep procedures for tailoring the interior structure. In this work, we ...develop a new generally applicable strategy toward the synthesis of mixed‐metal‐oxide complex hollow spheres. Starting with metal glycerate solid spheres, we show that subsequent thermal annealing in air leads to the formation of complex hollow spheres of the resulting metal oxide. We demonstrate the concept by synthesizing highly uniform NiCo2O4 hollow spheres with a complex interior structure. With the small primary building nanoparticles, high structural integrity, complex interior architectures, and enlarged surface area, these unique NiCo2O4 hollow spheres exhibit superior electrochemical performances as advanced electrode materials for both lithium‐ion batteries and supercapacitors. This approach can be an efficient self‐templated strategy for the preparation of mixed‐metal‐oxide hollow spheres with complex interior structures and functionalities.
Complex hollow spheres: Metal oxide hollow spheres with complex interior structures were obtained by a strategy involving the solution synthesis of metal glycerate solid spheres and subsequent thermal annealing in air. The image shows NiCo2O4 core‐in‐double‐shell hollow spheres. Their structural features give rise to an outstanding electrochemical performance as advanced electrode materials for both lithium‐ion batteries and supercapacitors.
In Li‐ion batteries, the mechanical degradation initiated by micro cracks is one of the bottlenecks for enhancing the performance. Quantifying the crack formation and evolution in complex composite ...electrodes can provide important insights into electrochemical behaviors under prolonged and/or aggressive cycling. However, observation and interpretation of the complicated crack patterns in battery electrodes through imaging experiments are often time‐consuming, labor intensive, and subjective. Herein, a deep learning‐based approach is developed to extract the crack patterns from nanoscale hard X‐ray holo‐tomography data of a commercial 18650‐type battery cathode. Efficient and effective quantification of the damage heterogeneity with automation and statistical significance is demonstrated. The crack characteristics are further associated with the active particles’ packing densities and a potentially viable architectural design is discussed for suppressing the structural degradation in an industry‐relevant battery configuration.
A deep learning‐based approach is developed to extract the crack patterns from nanoscale hard X‐ray holo‐tomography data of a commercial 18650‐type battery cathode. The crack characteristics are quantified and further associated with the active particles’ packing densities. A potentially viable architectural design is discussed for suppressing the structural degradation in an industry‐relevant battery configuration.
With the ever‐increasing requirement for high‐energy density lithium‐ion batteries (LIBs) to drive pure/hybrid electric vehicles (EVs), considerable attention has been paid to the development of ...cathode materials with high energy densities because they ultimately determine the energy density of LIBs. Notably, the cost of cathode materials is still the main obstacle hindering the extensive application of EVs, with the cost accounting for 40% of the total cost of fabricating LIBs. Therefore, enhancing the energy density and simultaneously decreasing the cost of LIBs are essential for the success of EV/hybrid EV industries. Among the existing commercial cathodes, Ni‐rich layered cathodes are widely employed because of their high energy density, relatively good rate capability, and reasonable cycling performance. Ni‐rich layered cathodes containing Co are now being reconsidered due to the increasing price of Co, which is much higher than that of Ni and Mn. In this report, the recent developments and strategies in the improvement of the stabilities of the bulk and surface for Co‐less Ni‐rich layered cathode materials are reviewed.
A perspective on Co‐less Ni‐rich cathodes for lithium‐ion batteries (LIBs) is provided. LiNiO2, binary‐, ternary‐, and quaternary cathodes are classified as the past, present, and future of LIBs. Surface modification is a strategy for present ternary cathodes. Gradient strategies categorized into five types, from core–shell to hybrid structures, are the foundation for future cathodes to develop.
Binary metal oxides has been regarded as a promising class of electrode materials for high‐performance energy storage devices since it offers higher electrochemical activity and higher capacity than ...mono‐metal oxide. Besides, rational design of electrode architectures is an effective solution to further enhance electrochemical performance of energy storage devices. Here, the advanced electrode architectures consisting of carbon textiles uniformally covered by mesoporous NiCo2O4 nanowire arrays (NWAs) are successfully fabricated by a simple surfactant‐assisted hydrothermal method combined with a short post annealing treatment, which can be directly applied as self‐supported electrodes for energy storage devices, such as Li‐ion batteries, supercapacitors. The as‐prepared mesoporous NiCo2O4 nanowires consist of numerous highly crystalline nanoparticles, leaving a large number of mesopores to alleviate the volume change during the charge/discharge process. Electrode architectures presented here promise fast electron transport by direct connection to the growth substrate and facile ion diffusion path provided by both the abundant mesoporous structure in nanowires and large open spaces between neighboring nanowires, which ensures every nanowire participates in the ultrafast electrochemical reaction. Benefiting from the intrinsic materials and architectures features, the unique binder‐free NiCo2O4/carbon textiles exhibit high specific capacity/capacitance, excellent rate capability, and cycling stability.
Advanced electrode architectures consisting of carbon textiles conformally covered by mesoporous NiCo2O4 nanowire arrays are efficiently fabricated and directly applied as self‐supported electrodes for energy storage devices, such as Li‐ion batteries, supercapacitors. Because of its many advantageous structural features, such an electrode ensures that NiCo2O4 participates in the ultrafast electrochemical reaction, enabling remarkable rate performance and excellent cycling stability.
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