Degradation Of Surface Structures Research Articles

Efficient and Scalable Direct Regeneration of Spent Layered Cathode Materials via Advanced Oxidation.

Among direct recycling methods for spent lithium-ion batteries, solid-state regeneration is the route with minimal bottlenecks for industrial application and is highly compatible with the current industrial cathode materials production processes. However, surface structure degradation and interfacial impurities of spent cathodes significantly hinder Li+ replenishment during restoration. Herein, we propose a unique advanced oxidation strategy that leverages the inherent catalytic activity of spent layered cathode materials to address these challenges. This strategy decomposes H2O2 to generate •OH and •O2 - free radicals, facilitating oxidation reactions with the surface of the spent cathode. As a result, this approach effectively elevates the Ni valence state, modifies the surface microstructure, and eliminates fluorine-containing interface impurities, thereby promoting the solid-state regeneration process. The regenerated LiNi0.83Co0.12Mn0.05O2 cathodes demonstrate a specific capacity of 206mAhg-1 at 0.1 C, comparable to commercially available cathodes. Meanwhile, this advanced oxidation strategy proves adaptable and scalable for treating industrial dismantled LiNi0.5Co0.2Mn0.3O2 black mass. A 3.1Ah pouch cell assembled with the regenerated LiNi0.5Co0.2Mn0.3O2 exhibits impressive capacity retention of 74% after 500 cycles. Additionally, a techno-economic analysis reveals that this strategy possesses low energy consumption, minimal environmental footprint, and high economic viability, suggesting its suitability for the battery recycling industry.

Oxides Induced Preferential Growth of {110} Planes for Superior Performance Single-Crystal LiMn2O4 through Solid-State Process.

Polycrystalline lithium manganese oxide (LMO) is known to suffer from severe surface structure degradation and electrochemical polarization due to its mixed crystal plane orientations. A hexagonal prism single-crystal LMO (LMOS-HP), engineered through the SrO-induced preferential growth effect, features the most stable {111} top surfaces and the fastest Li+ diffusion {110} side surfaces, effectively addressing these challenges. Consequently, LMOS-HP exhibits superior electrochemical capability, with only 0.021% capacity fading per cycle after 500 cycles and achieves a discharge capacity of 81.9 mAh g-1 at 20C. This innovative design offers a promising approach for tuning surface crystal orientation to improve performance.

Analysis of magnesia-carbon bricks erosion in vanadium extraction converters: Insights from dynamic experiments and interface characterization

This paper uses a rotary furnace to simulate the dynamic erosion behavior of various magnesia-carbon bricks within a vanadium extraction converter, focusing on the effects of carbon content and antioxidants on erosion. The results indicate that vanadium-rich slag primarily consists of oxide solid solutions, iron vanadium spinel, and metallic Fe. Adding aluminum and silicon powders to the bricks reduces apparent porosity, increases body density, and improves slag erosion resistance. However, an increase in carbon content (12.54 wt% to 18.59 wt%) within magnesia-carbon bricks correlates with decreased high-temperature strength, exacerbating the reaction propensity with slag and consequent structural damage. Analysis of the interface phase between magnesia-carbon bricks and vanadium slag reveals a predominance of metal phase, spinel phase, and liquid slag phase. Thermodynamic calculations suggest an initial reaction between MgO and C on the brick surface, yielding Mg vapor and CO gas, while C reacts with slag to produce Cr and V elements, leading to surface structure degradation. Subsequent slag encasement and dissolution of remaining MgO via decarburization channels further erode magnesia-carbon bricks. Cumulative erosion iterations ultimately culmi nate in performance failure of magnesia-carbon bricks.

Correlating Rate-Dependent Transition Metal Dissolution between Structure Degradation in Li-Rich Layered Oxides.

Understanding the mechanism of the rate-dependent electrochemical performance degradation in cathodes is crucial to developing fast charging/discharging cathodes for Li-ion batteries. Here, taking Li-rich layered oxide Li1.2 Ni0.13 Co0.13 Mn0.54 O2 as the model cathode, the mechanisms of performance degradation at low and high rates are comparatively investigated from two aspects, the transition metal (TM) dissolution and the structure change. Quantitative analyses combining spatial-resolved synchrotron X-ray fluorescence (XRF) imaging, synchrotron X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques reveal that low-rate cycling leads to gradient TM dissolution and severe bulk structure degradation within the individual secondary particles, and especially the latter causes lots of microcracks within secondary particles, and becomes the main reason for the fast capacity and voltage decay. In contrast, high-rate cycling leads to more TM dissolution than low-rate cycling, which concentrates at the particle surface and directly induces the more severe surface structure degradation to the electrochemically inactive rock-salt phase, eventually causing a faster capacity and voltage decay than low-rate cycling. These findings highlight the protection of the surface structure for developing fast charging/discharging cathodes for Li-ion batteries.

Rational design of surface reconstruction with pinning effect to relieving bulk fatigue for high energy single-crystal Ni-rich cathodes

Single-crystal Ni-rich layered cathodes have become the mainstream commercial lithium ion batteries because of their structural and cyclic stability. In order to obtain a higher energy density, the cut-off voltage (>4.4 V) must be increased. However, the mechanism of capacity fading at high voltages remains unclear. This study proved that the capacity fading of single-crystal Ni-rich layered materials at high voltage is caused by the appearance of fatigued phases due to surface structure degradation. In particular, a structural evolution mechanism based on the premigration of rare earth elements to lithium sites to form reconstruction layers at the atomic scale was proposed in this paper. The introduction of rare earth element Sc leads to a nanoscale reconstruction layer with a pinning effect on the surface of the Ni-rich material, which alleviates the barriers of kinetic to lithium ions in the highly charged state, improves the reversibility phase transition of the H2 to H3 phase, and maintains structural stability. In particular, the Sc-doped cathodes have a superb capacity retention rate of 95.1% after 300 cycles at 5C under the voltage of 4.6 V with a loss of only 0.016% capacity per cycle. This study reveals the intrinsic link between the capacity fading and structural evolution, providing new insights for the research of Ni-rich layered cathode materials with high energy density.

Carbonized Polymer Dots Enhancing Interface Stability of LiNi0.8Co0.1Mn0.1O2 Cathodes

AbstractThe high energy density, low cost, and low toxicity of LiNi0.8Co0.1Mn0.1O2 (NCM811) cathodes has led to their large‐scale mass production. However, the poor interfacial stability between NCM811 and organic electrolytes impairs the long‐cycle performance of lithium ions batteries. In this study, carbonized polymer dots (CPDs) are successfully introduced onto the surface of NCM811 (NCM811@CPDs) via a simple physical mixing process. CPDs with rich surface oxygen functional groups form strong covalent bonds with transition metal (TM) ions at the NCM811 surface, distinctly restraining surface structure degradation, and transition metal ion dissolution. Furthermore, CPDs facilitate the formation of a compact and steady cathode electrolyte interface (CEI) layer during electrochemical cycling. As a result, the NCM811@1 wt% CPDs exhibit enhanced cycling performance with a capacity retention of 89.77% after 100 cycles at 0.5 C compared to 55.39% of the bare NCM811. This facile and effective surface decoration strategy provides valuable guidance for improving the stability and cycling performance of Ni‐rich cathodes.

Synergistic regulation of kinetic reaction pathway and surface structure degradation in single-crystal high-nickel cathodes

As a promising high energy density cathode, single-crystal Ni-rich cathode face poor diffusion dynamics, which leads to poor structural evolution, poor cyclic stability and unfavorable rate performance, thus impeding its wider application. Herein, the strategy of synergistic surface modification by ionic conductor coating and trace element doping is delicately designed. The surface protective Li3BO3 layer is wrapped on the single-crystal LiNi0.83Co0.11Mn0.06O2 (NCM83), which can improve the compatibility of cathode/electrolyte with reduced interface resistance. While Zr is incorporated into bulk to stabilize the crystal structure and migration channel. This synergistic strategy achieves the improvement of ionic transport and structural stability of single-crystal NCM83 (Zr-NCM83@B) from the outer surface to the inner body. As expected, the modified cathode Zr-NCM83@B demonstrates a satisfying electrochemical performance. It delivers a high reversible capacity of 169 mAh g−1 in coin-type half-cell at 4C within 3.0–4.3 V. Remarkably, it displays excellent capacity retention of 83.5 % in Zr-NCM83@B || graphite pouch-type full-cell over 1400 cycles at 1C with high voltage range of 2.8–4.4 V. This synergistic surface modification provides a reference for commercial development of advanced single-crystal Ni-rich cathode under harsh testing conditions.

Ultrathin Li-Si-O Coating Layer to Stabilize the Surface Structure and Prolong the Cycling Life of Single-Crystal LiNi0.6Co0.2Mn0.2O2 Cathode Materials at 4.5 V.

Single-crystal LiNi1-x-yCoxMnyO2 cathode materials can effectively suppress intergranular cracks that usually is seen in commercial polycrystal LiNi1-x-yCoxMnyO2 cathode materials. However, the surface structure degradation for single-crystal LiNi1-x-yCoxMnyO2 cathode materials is still aggravated at a higher cutoff voltage (over 4.5 V). In this work, we prepare single-crystal LiNi0.6Co0.2Mn0.2O2 cathode materials via a solid-state method and then coat an ultrathin Li-Si-O layer on their surface by a wet coating method. The results show that the single-crystal LiNi0.6Co0.2Mn0.2O2 cathode materials with a Li-Si-O coating layer deliver excellent cycling performance even at a higher cutoff voltage of 4.5 V. The optimized Li-Si-O-modified sample displays a capacity retention of 90.6% after 100 cycles, whereas only 68.0% for unmodified single-crystal LiNi0.6Co0.2Mn0.2O2. Further analysis of the cycled electrodes reveals that the surface structure degradation is the main reason for the decrease of electrochemical performance of single-crystal LiNi0.6Co0.2Mn0.2O2 at a high voltage (4.5 V). In contrast, with Li-Si-O coating, this phenomenon can be suppressed effectively to maintain interfacial stability and prolong the cycling life.

The mechanism of side reaction induced capacity fading of Ni-rich cathode materials for lithium ion batteries

Optimized domain size endows Ni-rich cathode with both sufficient electrolyte infiltration and modest side reaction. Surface structure degradation caused by HF erosion is the main reason of the capacity fading, rather than LiF deposition. • The domain size of Ni-rich cathode influences the side reaction with electrolyte. • LiF deposition from side reaction shows little impact on cycling stability. • HF erosion caused surface phase transition is the main reason for capacity fading. Ni-rich cathode materials show great potential of applying in high-energy lithium ion batteries, but their inferior cycling stability hinders this process. Study on the electrode/electrolyte interfacial reaction is indispensable to understand the capacity failure mechanism of Ni-rich cathode materials and further address this issue. This work demonstrates the domain size effects on interfacial side reactions firstly, and further analyzes the inherent mechanism of side reaction induced capacity decay through comparing the interfacial behaviors before and after MgO coating. It has been determined that LiF deposition caused thicker SEI films may not increase the surface film resistance, while HF erosion induced surface phase transition will increase the charge transfer resistance, and the later plays the dominant factor to declined capacity of Ni-rich cathode materials. This work suggests strategies to suppress the capacity decay of layered cathode materials and provides a guidance for the domain size control to match the various applications under different current rates.

UiO-66 type metal-organic framework as a multifunctional additive to enhance the interfacial stability of Ni-rich layered cathode material

To effectively alleviate the surface structure degradation caused by electrolyte corrosion and transition metal (TM) dissolution for Ni-rich (Ni content > 0.6) cathode materials, porous Zirconium based metal-organic frameworks (Zr-MOFs, UiO-66) material is utilized herein as a positive electrode additive. UiO-66 owns tunable attachment sites and strong binding affinity, making itself an efficient defluorination agent to suppress the undesirable reactions caused by fluorine species. Besides, it can also relieve TMs dissolution and block the migration of TMs toward anode side since it's a multifarious metal ions adsorbent, realizing both cathode and anode interface protection. Benefiting from these advantages, the UiO-66 assistant Ni-rich cathode achieves superior cycling stability. Particularly in full cell, the positive effects of this multifunctional additive are more pronounced than in the half-cell, that is after 400 cycles at 2 C, the capacity retention has doubled with the addition of UiO-66. More broadly, this unique application of functional additive provides new insight into the degradation mechanism of layered cathode materials and offers a new avenue to develop high-energy density batteries.

Soil Surface Structure Stabilization by Municipal Waste Compost Application

Loess‐derived soils of the northern Paris basin are prone to surface structure degradation leading to erosion, flooding, and pollution. Concomitantly, recycling of municipal solid waste (MSW) has been recognized as an important environmental issue. The aim of this study was to test the impact of compost application on soil surface structure degradation and on the resulting runoff and erosion processes. Aggregates (0–30 mm) from a silty loam Typic Hapludalf were mixed with a MSW compost at a rate of 15 g kg−1 (dry matter). Repacked seedbeds were exposed to a 19 mm h−1 simulated rainfall for 60 min. Morphological evolution of the soil surface was monitored using sequential photographs. Crust and seedbed microstructures were studied after 4, 15, and 60 min of rainfall, using thin sections from resin‐impregnated replicates. Runoff was measured every five minutes, and aliquots were sampled for sediment concentration. In control seedbeds, surface crusts quickly developed and the whole seedbed slumped because of aggregate coalescence through deformation in a viscous state. Compost application delayed crust formation and prevented seedbed slumping. This, in turn, delayed runoff from 2.5 to 9.2 mm of cumulative rainfall. Sediment concentration in the incipient runoff was decreased from 36.4 to 11 g L−1 This could be ascribed to the stabilization of the aggregate framework, which allowed the particles detached from the top of surface aggregates to illuviate a few millimeters deeper. In a highly unstable soil, MSW compost application was efficient in combating soil surface structure degradation and its consequences on runoff and erosion.

Synthesis and degradation of surface structures by growing and non-growingBacillus megaterium

Synthesis and degradation of surface structures by growing and non-growingBacillus megaterium