Konstantin Pushnitsa

Silicon is considered one of the most promising next-generation anode materials for lithium-ion batteries (LIBs) because of its very high theoretical specific capacity (≈3579 mAh·g⁻¹). However, its practical application is limited by severe volume expansion (>300%), an unstable solid electrolyte interphase (SEI), and low electronic conductivity. Recent progress in nanostructuring has significantly improved the electrochemical performance and durability of silicon anodes. In particular, nanosilicon particles, porous structures, and Si–carbon composites enhance structural stability, cycling life, and coulombic efficiency. These improvements arise from better mechanical integrity and more stable electrode–electrolyte interfaces. This review summarizes recent advances in nanostructured silicon anodes, focusing on particle size control, pore design, composite architectures, and interfacial engineering. We discuss how these nanoscale strategies reduce mechanical degradation and improve lithiation kinetics while also addressing the remaining challenges. Finally, future research directions and industrial prospects for the practical use of nanostructured silicon anodes in next-generation LIBs are outlined.

The exponential growth of lithium-ion batteries (LIBs) in electric vehicles and energy storage systems has amplified the urgent need for sustainable recycling strategies. Conventional pyrometallurgical and hydrometallurgical methods for LIB recycling are energy-intensive, chemically demanding, and fail to preserve the structural integrity of cath-ode materials. Closed-loop recycling, in contrast, enables the recovery of layered oxides with minimal processing steps, reducing environmental footprint and supporting a circular economy. This study provides a systematic comparison of two regeneration approaches—sol–gel synthesis and hydroxide co-precipitation—for closed-loop recycling of layered NCM (LiNi_xCo_yMn_zO₂) cathode materials recovered from spent LIBs. Spent cells were mechani-cally processed and leached using malic acid to recover Ni, Co, Mn, which were subsequently used to synthesize NCM622 cathode powders. The regenerated materials were characterized using SEM/EDX, XRD, and electrochemical testing in CR2032 coin cells. Both methods successfully produced phase-pure layered oxides with the R-3m structure, with distinct differences in structural ordering and electrochemical behavior. The sol–gel-derived NCM622 displayed higher crystallinity and reduced cation mixing, evidenced by an I(003)/I(104) ratio of 1.896 compared to 1.720 for the co-precipitated sample, and delivered a high initial discharge capacity of 170 mAh/g at 0.1 C. However, it exhibited significant capacity fade, retaining only 60 mAh/g after 40 cycles. In contrast, the co-precipitation route produced hierarchical porous spherical agglomerates that offered superior cycling stability, maintaining ~150 mAh/g after 40 cycles with lower polarization (ΔE_p = 0.16 V). Both materials demonstrated electrochemical performance comparable to commercial NCM. Overall, hydroxide co-precipitation emerged as the most industrially viable method due to scalable processing, compositional robustness, and improved long-term stability of regenerated cathodes. This work highlights the critical influence of synthesis route selection in LIB closed-loop recycling and provides a technological framework for industrial recovery of high-value NCM cathode materials.

This study investigates advanced strategies for r regenerating and recycling lithium iron phosphate (LiFePO₄, LFP) materials from spent lithium-ion batteries. Recovery techniques are categorized into direct regeneration, which restores positive electrode materials with high electrochemical performance, and recycling, which produces intermediate compounds such as lithium carbonate and iron phosphate. Additionally, resynthesis methods are explored to convert recovered precursors into high-quality LFP materials, ensuring their reuse in battery production. Innovative approaches, including carbothermic reduction, doping, and hydrothermal resynthesis, are highlighted for their ability to enhance material properties, improve energy efficiency, and maintain the olivine structure of LFP. Key advancements include the use of eco-friendly reagents, automation, and optimization strategies to reduce environmental impacts and costs. Regenerated and resynthesized positive electrodes demonstrated performance metrics comparable to or exceeding commercial LFP, showcasing their potential for widespread application. This work underscores the importance of closed-loop recycling systems and identifies pathways for scaling, improving economic feasibility, and minimizing the ecological footprint of the lithium-ion battery lifecycle.

In recent years, 3D printing has emerged as a promising technology in energy storage, particularly for the fabrication of Li-ion battery electrodes. This innovative manufacturing method offers significant material composition and electrode structure flexibility, enabling more complex and efficient designs. While traditional Li-ion battery fabrication methods are well-established, 3D printing opens up new possibilities for enhancing battery performance by allowing for tailored geometries, efficient material usage, and integrating multifunctional components. This article examines three key 3D printing methods for fabricating Li-ion battery electrodes: (1) material extrusion (ME), which encompasses two subcategories—fused deposition modeling (FDM), also referred to as fused filament fabrication (FFF), and direct ink writing (DIW); (2) material jetting (MJ), including inkjet printing (IJP) and aerosol jet printing (AJP) methods; and (3) vat photopolymerization (VAT-P), which includes the stereolithographic apparatus (SLA) subcategory. These methods have been applied in fabricating substrates, thin-film electrodes, and electrolytes for half-cell and full-cell Li-ion batteries. This discussion focuses on their strengths, limitations, and potential advancements for energy storage applications.

The use of additive manufacturing to fabricate current collectors with increased surface area opens new opportunities for controlling electrode morphology, improving conductivity, and thereby boosting the overall performance of batteries. This can be achieved by increasing the contact area between the active mass and the current collector. This paper focuses on the investigation of 3D current collectors with an enhanced surface area for cathodes obtained by laser powder bed fusion. The quality and dimensional accuracy of the 3D current collector structures as well as the electrical characteristics and longevity of batteries were analyzed in this study. It has been demonstrated that the utilization of printing parameters comprising a laser power of 200 W, a scanning speed of 500 mm/s, and a hatch distance of 0.25 mm, with a layer thickness of 0.03 mm, results in a decrease in the number of defects in the 3D current collector. In the first cycle, the capacitance characteristics exhibited discharge capacities of 189.79 mAh/g for Al-f and 192.06 mAh/g for AlSi10Mg. The Coulomb efficiencies for the samples were 86 and 92.5%, respectively. Anisotropy of conductive properties arises during the printing process, which must be considered when designing the 3D current collectors, as it may have an impact on the capacitive and cyclic characteristics of the samples.

A closed-loop regeneration process for spent LiCoO₂ has been successfully designed with prior synthesis of LiNi_xCo_yMn_zO₂, by the authors. This research applies the methodology to lithium-ion battery anodes, using spent graphite from a decommissioned battery in a leaching process with 1.5 mol∙L⁻¹ malic acid and 3% H₂O₂ alongside LiCoO₂. The filtered graphite was separated, annealed in an argon atmosphere, and the filtrate was used to synthesize NCM cathode material. Characterization involved X-ray diffraction, EDX, and SEM techniques. The regenerated graphite (RG) showed a specific discharge capacity of 340.4 mAh/g at a 0.1C rate in the first cycle, dropping to 338.4 mAh/g after 55 cycles, with a Coulombic efficiency of 99.9%. CV and EIS methods provided further material assessment. In a related study, the SNCM111 synthesized from the leaching solution showed a specific discharge capacity of 131.68 mAh/g initially, decreasing to 115.71 mAh/g after 22 cycles.

While past recycling efforts have primarily concentrated on extracting valuable metals from discarded cathode materials, the focus is now shifting towards anode materials, particularly graphite, which makes up 10–20% of LIB mass. Escalating prices of battery-grade graphite and environmental considerations surrounding its production highlight the significance of graphite recycling. This review categorizes methods for graphite recovery into three approaches: recovery, recycle, and reuse. Moreover, it explores their potential applications and comparative electrochemical performance analysis, shedding light on the promising prospects of utilizing spent graphite-based functional materials. The review underscores the importance of sustainable recycling practices to address the environmental and economic challenges posed by the proliferation of LIBs and the growing demand for graphite.

The environmentally friendly closed cycle of the regeneration process of spent LiCoO₂ was successfully developed and the following synthesis of triple-lithiated transition metal oxides was carried out. A hydrometallurgy recycling route with the usage of 1.5 mol/L of malic acid and 3 vol.% of H₂O₂ as a leaching solution for cobalt extraction was chosen. The efficiency of the cobalt extraction reached 95%. The obtained material was investigated using an X-ray diffraction analysis and the EDX and SEM methods. The electrochemical behavior of the synthesized NCM111 was analyzed and compared to the commercially available material of the same type. The material demonstrated a specific discharge capacity on the first cycle of 163.7 mAh/g. The cyclic resource of the material turned out to be unsatisfactory. In addition, perspective cathode materials, such as NCM622 and NCM811, were obtained. The synthesized materials were analyzed using XRD, SEM, EDX, charge–discharge and cycle life tests, and the CVA and EIS methods. The initial specific discharge capacities of the NCM622 and NCM811 were 168 and 187 mAh/g, respectively. On the fifth cycle, the NCM622 demonstrated an increasing capacity—to 179 mAh/g, unlike NCM811, as the capacity of this material decreased to 141 mAh/g.

In the search for novel anode materials for lithium-ion batteries (LIBs), organic electrode materials have recently attracted substantial attention and seem to be the next preferred candidates for use as high-performance anode materials in rechargeable LIBs due to their low cost, high theoretical capacity, structural diversity, environmental friendliness, and facile synthesis. Up to now, the electrochemical properties of numerous organic compounds with different functional groups (carbonyl, azo, sulfur, imine, etc.) have been thoroughly explored as anode materials for LIBs, dividing organic anode materials into four main classes: organic carbonyl compounds, covalent organic frameworks (COFs), metal-organic frameworks (MOFs), and organic compounds with nitrogen-containing groups. In this review, an overview of the recent progress in organic anodes is provided. The electrochemical performances of different organic anode materials are compared, revealing the advantages and disadvantages of each class of organic materials in both research and commercial applications. Afterward, the practical applications of some organic anode materials in full cells of LIBs are provided. Finally, some techniques to address significant issues, such as poor electronic conductivity, low discharge voltage, and undesired dissolution of active organic anode material into typical organic electrolytes, are discussed. This paper will guide the study of more efficient organic compounds that can be employed as high-performance anode materials in LIBs.

Research on the regeneration of cathode materials of spent lithium-ion batteries for resource reclamation and environmental protection is attracting more and more attention today. However, the majority of studies on recycling lithium-ion batteries (LIBs) placed the emphasis only on recovering target metals, such as Co, Ni, and Li, from the cathode materials, or how to recycle spent LIBs by conventional means. Effective reclamation strategies (e.g., pyrometallurgical technologies, hydrometallurgy techniques, and biological strategies) have been used in research on recycling used LIBs. Nevertheless, none of the existing reviews of regenerating cathode materials from waste LIBs elucidated the strategies to regenerate lithium nickel manganese cobalt oxide (NCM or LiNi_xCo_yMn_zO₂) cathode materials directly from spent LIBs containing other than NCM cathodes but, at the same time, frequently used commercial cathode materials such as LiCoO₂ (LCO), LiFePO₄ (LFP), LiMn₂O₄ (LMO), etc. or from spent mixed cathode materials. This review showcases the strategies and techniques for regenerating LiNi_xCo_yMn_zO₂ cathode active materials directly from some commonly used and different types of mixed-cathode materials. The article summarizes the various technologies and processes of regenerating LiNi_xCo_yMn_zO₂ cathode active materials directly from some individual cathode materials and the mixed-cathode scraps of spent LIBs without their preliminary separation. In the meantime, the economic benefits and diverse synthetic routes of regenerating LiNi_xCo_yMn_zO₂ cathode materials reported in the literature are analyzed systematically. This minireview can lay guidance and a theoretical basis for restoring LiNi_xCo_yMn_zO₂ cathode materials.