Cathode Active Material Research Articles

Correlative Survey of Blended LiCoO2 and LiMn2O4 Cathode Materials for Lithium-ion Batteries

We employed the lithium-ion battery model in Multiphysics to simulate the electrochemical characteristics of lithium-ion batteries. These batteries consist of a cathode mixture comprising LiCoO2 and LiMn2O4, as well as quasi-graphite anode. Our simulations successfully replicated the discharge profiles of both unblended and blended cathodes across different current rates, aligning with results obtained from experiments. The energy and power densities of the blended cathode framework were regulated by adjusting the mix ratio in the simulation model. Additionally, the blended electrodes of LiCoO2 and LiMn2O4 demonstrated an above-average electrochemical performance, combining the characteristics of the two active materials.Keywords: Lithium-ion Battery; Blended Cathode Active Materials; Simulation; Experiment

Comparative Analysis of Lithium-Ion Batteries for Urban Electric/Hybrid Electric Vehicles

This paper presents an experimental comparison of two types of Li-ion battery stacks for low-voltage energy storage in small urban Electric or Hybrid Electric Vehicles (EVs/HEVs). These systems are a combination of lithium battery cells, a battery management system (BMS), and a central control circuit—a lithium energy storage and management system (LESMS). Li-Ion cells are assembled with two different active cathode materials, nickel–cobalt–aluminum (NCA) and lithium iron phosphate (LFP), both with an integrated decentralized BMS. Based on experiments conducted on the two assembled LESMSs, this paper suggests that although LFP batteries have inferior characteristics in terms of energy and power density, they have great capacity for improvement.

Toward High Specific Energy and Long Cycle Life Li/Mn‐Rich Layered Oxide || Graphite Lithium‐Ion Batteries via Optimization of Voltage Window

Li/Mn‐rich layered oxide (LMR) cathode active materials promise exceptionally high practical specific discharge capacity (>250 mAh g−1) as a result of both conventional cationic and anionic oxygen redox. The latter requires electrochemical activation at high cathode potential (>4.5 V vs Li|Li+), though it is accompanied by capacity and voltage fade in the course of continuous release of lattice oxygen, layered‐to‐spinel phase transformation, redox couple shift, as well as transition metal dissolution, whereas the latter is particularly detrimental for graphite‐based anodes due to electrode crosstalk. Herein, the degradation is investigated in LMR || graphite full cells by systematically varying the voltage windows, analyzing electrochemical data and changes at the anode surface. Based on this, the optimal operational voltage window, i.e., upper and lower cutoff voltage (UCV and LCV), is elaborated to finally solve the dilemma of decent cycle life (at high UCVs) and insufficient LMR activation/capacity (at low UCV) and is shown to be superior via distinguishing between formation and postformation cycles of 4.5 and 4.3 V, respectively.

Proton-driven bilateral interfacial chemistry and electrolyte structure reconstruction enable highly reversible zinc metal anodes

Uncontrolled dendrite growth, severe parasitic reactions on the Zn metal anode (ZMA), and the dissolution of cathode active materials have significantly limited the development of aqueous zinc ion batteries. Herein, 3-(Cyclohexylamino)-1-propanesulfonic acid (CAPS) featured with zwitterion as a multifunctional additive is introduced into the 2 M ZnSO4 aqueous electrolyte to simultaneously regulate the interfacial chemistry of the Zn anode and the cathode, as well as the solvated structure of Zn2+, thereby improving the interfacial and structural stability of both electrodes. Thereinto, the preferentially adsorbed CAPS zwitterion onto the ZMA surface favors for constructing a cationic protective layer originated from the electrostatic shielding effect of the cationic group (>NH2+), inhibiting the growth of dendrites. Meanwhile, the CAPS zwitterion can self-regulate the bilateral interfacial pH by forming the conjugate acid-base pair, suppressing hydrogen evolution reaction and Zn anode surface corrosion. Additionally, the CAPS zwitterion alters the solvated structure of Zn2+, weakening H2O molecule activity and reducing the dissolution of vanadium element from cathode. Consequently, the Zn||Zn symmetric cells harvest excellent cycling stability (1 mA cm−2, 1 mAh cm−2, 2300 h), and the Zn||Cu asymmetric cells display a high average Coulombic Efficiency of 99.7 % after 1600 cycles in the ZnSO4+CAPS electrolyte.

Aluminum-distribution-dependent microstructural evolution of NCA cathodes: Is aluminum homogeneity really favorable?

Despite extensive research, the optimal synthesis method and Al concentration for fabricating high-performance Li[NixCoyAl1−x−y]O2 (NCA) cathodes remain to be established. This study provides an in-depth analysis of NCA cathodes prepared using different synthesis methods and Al fractions. Al overdoping (3 mol%) during coprecipitation generates a homogeneous Al distribution in the cathode active material, whereas supplying excess Al during calcination induces a hierarchical spatial arrangement. Interestingly, different Al distributions and concentrations produce strikingly different cathode microstructures, which greatly affect the electrochemical performance of the cathode. Contrary to the common belief that homogeneous Al doping is critical for optimal cycling performance, the electrochemical performance of the cathode is maximized by grain-boundary-segregated Al ions. The proposed Li[Ni0.925Co0.042Al0.033]O2 cathode demonstrates superior cycling performance, retaining 74.1 % of its initial capacity after 1000 cycles in a full cell despite cycling under severe operating conditions (3 C and 45 °C). These findings redefine the fundamental contribution of the elemental distribution to the engineering of cathode microstructures, thereby providing a viable approach for developing high-performance Ni-rich NCA cathodes for advanced Li-ion batteries.

Enhancement Mechanism of the Difference of Hydrophobicity between Anode and Cathode Active Materials from Spent Lithium-Ion Battery Using Plasma Modification

Enhancement Mechanism of the Difference of Hydrophobicity between Anode and Cathode Active Materials from Spent Lithium-Ion Battery Using Plasma Modification

Oxophilic vanadium and deprotonated ruthenium atoms on tungsten carbide with accelerated intermediate migration for high-performance seawater hydrogen evolution

Compared with traditional freshwater electrolysis, the seawater electrolysis process is confronted with low activity and poor stability problems due to the deposition of insoluble hydroxides and corrosion of chloride species; thus, engineering efficient catalysts for seawater electrolysis are extremely desirable but remain challenging. Herein, we have developed an efficient and robust electrocatalyst by engineering oxophilic vanadium and deprotonated ruthenium atoms on tungsten carbide (WC-RuV) as a highly active and anti-poisoning cathode material for superior seawater electrolysis. Benefiting from the high oxophilicity and electron transfer ability of V, the interaction between the OH* generated via water dissociation and Ru sites is weakened, which facilitates the OH* transfer process and consequently attenuates the formation of insoluble hydroxides. Notably, when working in simulated seawater electrolytes, the WC-RuV requires an ultralow overpotential, and the WC-RuV@carbon cloth can maintain high activity and stability even at 200 mA cm−2. The assembled WC-RuV||RuO2 anion exchange membrane (AEM) electrolyzer realizes long-term stability at the current of 100 mA cm−2 and achieves continuous operation powered by commercially available solar panels. This work provides an efficient strategy for modulating the water dissociation process and offers a new perspective for designing high-performance catalysts for the forthcoming application of seawater electrolysis.

Crystalline MnCO3@Amorphous MnOx Composite as Cathode Material for High-Performance Aqueous Zinc-Ion Batteries.

Rechargeable aqueous zinc-ion batteries (RAZIBs) have received extensive attention because of their advantages of low cost, high safety, and nontoxicity. However, problems such as dissolution of the active cathode material, dendrites/passivation of the zinc anode, and slow reaction kinetics hindered their further applications. In this work, a crystalline/amorphous composite-type material composed of crystalline MnCO3 and amorphous MnOx was prepared and used as the cathode material for RAZIBs. The MnCO3@amorphous MnOx (MnCO3@A-MnOx) composite possesses the merits of both the pure crystalline phase of MnCO3 and the amorphous phase of MnOx, which can deliver better electrochemical performance than the corresponding single component in repeated cycles. In addition, crystalline MnCO3 undergoes a complex phase transition to the active MnO2 during the first charge process, providing the composite with a stable structure and additional electrochemical capacity. The electrochemical measurement results indicate that the MnCO3@A-MnOx electrode can display high reversible discharge capacity at 0.1 A g-1, excellent rate performance at 5.0 A g-1, and long cycling stability over 2000 cycles, showing great potential as a cathode material for high-performance RAZIBs.

Liquid‐Phase Preparation of Low‐Tortuosity Composite Cathode for High Active Material Content All‐Solid‐State Lithium Batteries

AbstractThe all‐solid‐state lithium batteries (ASSLBs) stand as a promising candidate for the next generation of high‐energy‐density batteries with superior safety. Nevertheless, achieving high energy density in ASSLBs necessitates the simultaneous realization of high active material content and loading, posing a significant challenge in ensuring effective Li‐ion conduction within the cathode. Notably, the inhomogeneous distribution of cathode particles causes high porosity and tortuosity within the composite cathodes, thereby adversely impacting the electrochemical performance of the battery. Herein, an in situ liquid‐phase method for the fabrication of LiNi0.8Co0.1Mn0.1O2(NCM811) composite cathode is proposed. This strategy ensures the generation of uniformly distributed and densely packed composite cathode, establishing a well‐networked conduction path that ensures exceptional electronic and ionic conductivity. ASSLBs utilizing LP‐cathode exhibit outstanding electrochemical performance. It delivers a high capacity of 233.3 mAh g−1 at 0.05 C with superior rate capability and remarkable long‐term cycling stability. Moreover, ASSLBs manifest exceptional electrochemical performance, even at a high cathode active material content of 80%. This underscores the efficacy of the liquid‐phase method in constructing low‐tortuosity electrodes and accelerating charge transport kinetics, thereby enhancing the overall performance of ASSLBs. This approach holds promise for addressing the challenges associated with achieving high energy density and facilitating the development of ASSLBs.

Formulating Interfacial Impedances for Designing High-Energy and High-Power All-Solid-State Battery Cathodes.

All-solid-state batteries (ASSBs) are safe, high-energy-storage systems. However, despite the progress achieved in the development of high-ionic-conductivity solid electrolytes (SEs), the power performance of ASSBs remains low because of the high interfacial impedances in composite cathodes. Therefore, understanding the interfacial factors is crucial for obtaining high power ASSBs. This study provides a quantitative analysis of the influence of these factors using impedance spectroscopy measurements, which enables the elucidation of the interfacial impedance values of two key parameters, the grain-boundary resistance (ri,gb) and charge-transfer resistance (ri/e). Systematic investigation revealed an unexpected increase in the cathodic resistance with the decrease in the size of the cathode active material (CAM) particles, indicating that even high-reaction-surface-area CAMs yield low ri/e but high ri,gb values owing to their high porosity, resulting in a trade-off relationship. In contrast, this phenomenon is unlikely to occur in liquid-electrolyte-based batteries. Notably, we discuss how composite cathode design impacts performances of stable, high-power, and high-energy ASSBs.

La-doped Sr4Fe4Co2O13-δ as a promising in-situ self-assembled composite cathode for protonic ceramic fuel cells

Protonic ceramic fuel cells (PCFCs) exhibit a lower activation energy compared to conventional oxygen-ion conducting solid oxide fuel cells, which makes them better suited for operating at low temperatures. Regrettably, the use of PCFCs at lower temperatures is restricted due to the absence of durable and highly active cathode materials. Herein, we rationally design in-situ self-assembled composite cathodes with the nominal compositions of Sr4-xLaxFe4Co2O13-δ (SLxFC, x = 0.4, 0.8, 1, and 2) for PCFCs. The SL0.4FC, displays a composite of cubic perovskite phase and spinel phase, the other compositions yield a mixture of both orthorhombic perovskite and spinel phases. The self-assembled SL1FC composite cathode has the highest electrocatalytic activity among all samples, particularly at temperatures (<650 °C). For instance, it demonstrates a very low area-specific resistance (ASR) of 0.465 Ω cm2 at 550 °C. The PCFC with the SL1FC composite cathode provides a high peak power density (PPD) of 518 mW cm−2 at the same temperature. More importantly, the SL1FC electrode demonstrates robust long-term stability (400 h for the symmetrical cell mode and 200 h for the single cell mode). This study shows how La doping enhances the electrochemical activity of Sr4Fe4Co2O13-δ and how the synergistic effect of the two phases boosts the electrochemical performance of the composite cathode.

Characterization of co-fired sodium-ion conductive Na2Ni2TeO6 and Na2Zn2TeO6 with honeycomb layer structure

We investigated the reactivity of P2-type honeycomb layered oxides Na2Ni2TeO6 (NNTO) and Na2Zn2TeO6 (NZTO) co-fired at the temperature from 500 °C to 800 °C. From X-ray diffraction measurements, it was found that the reaction between NNTO and NZTO is unremarkable at the temperature below 700 °C. However, when annealed at 800 °C, they formed the solid-solution phase without any secondary phases. The NNTO and NZTO composite pellets co-fired at 800 °C showed sodium-ion conductivity well above 10−4 S cm−1 at room temperature, indicating that the solid-solution phase of NNTO and NZTO has good ionic conductivity. A maximum room temperature conductivity of 7.4 × 10−4 S cm−1 was confirmed at the mixing ratio NNTO: NZTO = 0.5 : 1.5. These results can be applied to the fabrication of all-solid-state batteries using NNTO as the cathode active material and NZTO as the solid electrolyte via a simple co-sintering process.

Single-Particle Elemental Analysis of μm-Sized Battery Materials by Laser Ablation Inductively Coupled Plasma Mass Spectrometry

Lithium-nickel-manganese-cobalt-oxides (NCMs) represent a preeminent class of cathode active materials for employment in commercially available lithium-ion battery applications. To realize large-scale production of the respective NCM precursors, coprecipitation is often conducted in continuous stirred-tank reactors (CSTR). However, precursors coming from CSTR processes show broad particle size distributions and undesired compositional differences within and between particles. To quantify this phenomenon, it is necessary to develop analytical tools to access quantitative data on particle composition depending on their size. Here, we demonstrate a novel application of single particle laser ablation-inductively coupled plasma-mass spectrometry to determine particle size-dependent elemental compositions by exemplary investigation of CSTR-based NCM precursors. An enrichment of Ni in larger particles with a concomitant enrichment of Co and Mn in smaller particles was identified. This compositional differences between particles persisted after calcination of the precursors with lithium hydroxide. The observed particle size-dependent concentration differences by spLA-ICP-MS were validated by scanning electron microscopy with energy-dispersive X-ray analysis.

Electrochemical Synthesis and Performance of AgCl/Ag/Sliver Mesh Collector Composite Electrode for Seawater Batteries

High-energy-density and easy-to-implement battery storage technologies are essential for the exploitation of marine resources. AgCl is a promising cathode material for seawater batteries due to its environmental friendliness and high capacities density, but its inherent low conductivity limits its application in specific scenarios. In this paper, AgCl was electrochemically grown on a sparsely conductive Ag/Sliver mesh collector (SMC) substrate, and an excellent performance AgCl/Ag/SMC composite electrode is obtained. The cathodic polarization curves indicate that the current density of the AgCl/Ag/SMC electrode was 208.2 mA cm−2 at 0.4 V (vs RHE) potential, which is significantly higher than that of the conventional AgCl cathode material. The AgCl/Ag/SMC electrode demonstrated a very high discharge capacity of 181.7 mAh g−1 at 30 mA cm−2, and the assembled cell was found to be in good condition at 100 mA cm−2 with a power density of up to 154.7 mW cm−2, showing very excellent performance. Furthermore, investigation of the mechanism and depth of discharge experiment reveal the kinetic and microscopic reasons for the high performance of AgCl/Ag/SMC composite electrodes. Therefore, this study provides an efficient and feasible solution for the electrochemical preparation of highly active cathode materials for Mg-AgCl seawater batteries.

A thermostable ionic liquid-methacrylate-based polymer electrolyte for energy storage application

In recent years, gel polymer electrolytes (GPEs) incorporating ionic liquids (ILs) have been explored extensively for lithium-ion batteries due to their favourable thermal stability and high ionic conductivity. Gel polymer electrolytes can also improve the safety of lithium-ion batteries by eliminating the flammable organic solvents which are often used in traditional electrolyte systems. Herein, we report an efficient synthesis of a thermostable ionic liquid-methacrylate-based polymer gel electrolyte via a photo-initiated phase separation (PIPS) process in an inert environment. Anionic liquid phase of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIMTFSI), coupled with a low molecular weight polyethylene glycol dimethyl ether (PEGDME), was combined with a solid phase of bisphenol A ethoxylate dimethacrylate (BEMA) at varying solid to liquid ratios to produce a thermally stable gel electrolyte. The highest ionic conductivity of 1.9 × 10−3 S cm−1 (at 30 °C) was achieved for the electrolyte with a solid-to-liquid ratio of 1:3 by weight. The Lithium metal cells utilizing these electrolytes and LiFePO4 as cathode active material exhibited the initial discharge capacity of 144 mAh g−1 with capacity retention of 85 % over 100 cycles in ambient temperature. The thermal stability of the cells was significantly improved upon increasing the EMIMTFSI content. This study illustrates the potential application of the IL-methacrylate gel polymer electrolyte system in enhancing the safety of Li-ion batteries through careful tuning of the composition. Their versatile properties also make them suitable for quasi-solid-state batteries with high energy density and safety.

Influence of Solid Fraction on Particle Size during Wet-Chemical Synthesis of β-Li3PS4 in Tetrahydrofuran

For all-solid-state batteries, the particle size distribution of the solid electrolyte is a critical factor. Small particles are preferred to obtain a high active mass loading of cathode active material and a small porosity in composite cathodes. In this work, the influence of the solid fraction in the wet-chemical synthesis of β-Li3PS4 in tetrahydrofuran (THF) is investigated. The solid fraction is varied between 50 and 200 mg/mL, and the obtained samples are evaluated using X-ray diffraction, SEM and electrochemical impedance measurements. The sizes of the resulting particles show a significant dependency on the solid fraction, while a good ionic conductivity is maintained. For the highest concentration, the particle sizes do not exceed 10 µm, but for the lowest concentration, particles up to ~73 µm can be found. The ionic conductivities at room temperature are determined to be 0.63 ± 0.01 × 10−4 S/cm and 0.78 ± 0.01 × 10−4 S/cm for the highest and lowest concentrations, respectively. These findings lead to an improvement towards the production of tailored sulfide solid electrolytes.

Redox-Active Boron Clusters.

ConspectusIn this Account, we discuss our group's research over the past decade on a class of functionalized boron clusters with tunable chemical and physical properties, with an emphasis on accessing and controlling their redox behavior. These clusters can be thought of as three-dimensional aromatic systems that have distinct redox behavior and photophysical properties compared to their two-dimensional organic counterparts. Specifically, our lab has studied the highly tunable, multielectron redox behavior of B12(OR)12 clusters and applied these molecules in various settings. We first discuss the spectroscopic and electrochemical characterization of B12(OR)12 clusters in various oxidation states, followed by their use as catholytes and/or anolytes in redox flow batteries and chemical dopants in conjugated polymers. Additionally, the high oxidizing potential and visible light-absorbing nature of fluoroaryl-functionalized B12(OR)12 clusters have been leveraged by our group to generate weakly coordinating, photoexcitable species that can promote photooxidation chemistry.We have further translated these solution-phase studies of B12(OR)12 clusters to the solid state by using the precursor [B12(OH)12]2- cluster as a robust building block for hybrid metal oxide materials. Specifically, we have shown that the boron cluster can act as a thermally stable cross-linking material, which enhances electron transport between metal oxide nanoparticles. We applied this structural motif to create TiO2- and WO3-containing materials that showed promising properties as photocatalysts and electroactive materials for supercapacitors. Building on this concept, we later discovered that B12(OCH3)12, the smallest of the B12(OR)12 family, could retain its redox behavior in the solid state, a previously unseen phenomenon. We successfully harnessed this unique behavior for solid-state energy storage by implementing this boron cluster as a cathode-active material in a Li-ion prototype cell device. Recently, our group has also explored how to tune the redox properties of clusters other than B12(OR)12 species by synthesizing a library of vertex-differentiated clusters containing both B-OR and B-halogen groups. Due to the additive qualities of different functional groups on the cluster, these species allow access to a region of electrochemical potentials previously inaccessible by fully substituted closo-dodecaborate alkoxy-based derivatives.Lastly, we discuss our research into smaller-sized redox-active polyhedral boranes (B6- and B10-based cluster cores). Interestingly, these clusters show significantly less redox stability and reversibility than their dodecaborate-based counterparts. While exploring the functionalization of closo-hexaborate to create fully substituted derivates (i.e., [B6R6Hfac]-), we observed unique oxidative decomposition pathways for this cluster system. Consequently, we leveraged this oxidative instability to generate useful alkyl boronate esters via selective chemical oxidation. We further explored a closo-decaborate cluster as a platform to access electrophilic [B10H13]+ species capable of directly borylating arene compounds with unique regioselectivity. Upon chemical oxidation of the arylated decaborate clusters, we successfully synthesized various aryl boronate esters, establishing the generality of the oxidative cluster deconstruction concept.Overall, our work shows that boron clusters are an appealing class of redox-active molecules, and this fundamental and understudied property can be leveraged for constructing novel materials with tunable physical and electrochemical properties, as well as producing unique chemical reagents for small molecule synthesis.

VOx anchored Ti3C2Tx MXene heterostructures for high-performance 2.2 V supercapacitors

Pseudocapacitive materials with superior electrochemical properties have attracted significant interest in developing high-performance supercapacitors. Herein, VOx anchored Ti3C2Tx MXene pseudocapacitive materials are synthesized via a solvothermal method to synergize metallic electrical conductivity and redox activity. Pure vanadium oxide synthesis results in VO2 formation, while in the presence of Ti3C2Tx, quasi-metallic V2O3 and VO2 (VOx) are observed due to the decomposition of surface functionalities of Ti3C2Tx. The growth of the V2O3 phase increases with an increase in the weight concentration of Ti3C2Tx. The optimal composition of heterostructure delivers a specific capacitance of 364 F g−1 in a stable potential window of −0.9 V–1 V, surpassing the specific capacitance of pure VO2 (245 F g−1) and Ti3C2Tx (140 F g−1) in 0.5 M K2SO4 electrolyte. Furthermore, the developed symmetric supercapacitor (SSC) delivers an energy density of 45.7 Wh kg−1 at a power density of 1.1 kW kg−1 with cyclic stability of 78 % for 10000 cycles with a self-discharge open circuit potential of 1.34 V. This work highlights a strategy to develop anodic and cathodic active pseudocapacitive material based SSC to improve energy density and mitigate self-discharge.

Inhibition of Vanadium Cathode Dissolution in Zinc‐Ion Batteries on Thermodynamics and Kinetics by Guest Pre‐Intercalation

AbstractAqueous zinc‐ion batteries (AZIBs), recognized for their safety and environmental friendliness, hold significant promise for large‐scale energy storage. However, the rapid capacity degradation resulting from the dissolution of active cathode materials hampers the advancement of AZIBs. Here, Ru0.2V2O5∙0.41H2O (RuVO) is synthesized with remarkable capacity retention (98.2% over 5000 cycles at 10 A g−1). The pre‐intercalation of Ru3+ enhances the stability of both intrinsic and cycling structures, elevating the Gibbs free energy and suppressing V‐dissolution thermodynamically. Additionally, Ru3+ intercalation modulates the potential energy surface of Zn2+ migration, leading to the dominance of Zn2+ in the insertion/extraction mechanism, thereby kinetically impeding the dissolution reaction. This study elucidates the dissolution thermodynamics and kinetics of V‐based cathodes through a combination of experiments, mechanism analyses, and density functional theory (DFT) calculations.

Suppressing the Shuttle Effect of Aqueous Zinc-Iodine Batteries: Progress and Prospects.

Aqueous zinc-iodine batteries are considered to be one of the most promising devices for future electrical energy storage due to their low cost, high safety, high theoretical specific capacity, and multivalent properties. However, the shuttle effect currently faced by zinc-iodine batteries causes the loss of cathode active material and corrosion of the zinc anodes, limiting the large-scale application of zinc-iodine batteries. In this paper, the electrochemical processes of iodine conversion and the zinc anode, as well as the induced mechanism of the shuttle effect, are introduced from the basic configuration of the aqueous zinc-iodine battery. Then, the inhibition strategy of the shuttle effect is summarized from four aspects: the design of cathode materials, electrolyte regulation, the modification of the separator, and anode protection. Finally, the current status of aqueous zinc-iodine batteries is analyzed and recommendations and perspectives are presented. This review is expected to deepen the understanding of aqueous zinc-iodide batteries and is expected to guide the design of high-performance aqueous zinc-iodide batteries.