Compatibility between lithium difluoro (oxalate) borate-based electrolytes and Li1.2Mn0.54Ni0.13Co0.13O2 cathode for lithium-ion batteries

Surface and Interfacial Modulation of Lithium-Rich Manganese Layered Oxide Cathode Materials: Progress and Challenges

Exhibiting exceptional energy density and capacity, lithium-rich manganese-based layered oxide (LLOs) cathode materials have garnered considerable attention and are emerging as strong contenders for future lithium-ion battery systems. However, the manner in which they are employed in practice is hindered by several challenges, such as voltage fading, exhibiting a low initial coulombic efficiency, and suboptimal cycling stability, mainly attributed to oxygen depletion and phase transformation phenomena. The current review primarily centers on recent progress in addressing these issues through surface and interfacial modification techniques, including surface doping, coating, and oxygen vacancy engineering. Other strategies, such as spinel phase engineering and hybrid coating layers, are also discussed as potential solutions to enhance electrochemical performance, stability, and capacity retention. Additionally, exploration advancements in electrolyte design aimed at stabilizing the LLOs/electrolyte interface, reducing side reactions, and enabling the development of a stable solid electrolyte interphase (CEI). The review concludes by highlighting ongoing challenges, particularly in improving long-term cycling stability, and proposes prospective research directions aimed at further unlocking the potential of LLOs cathode materials for practical battery applications.

Adsorptive Shield Derived Cathode Electrolyte Interphase Formation with Impregnation on LiNi0.8Mn0.1Co0.1O2 Cathode: A Mechanism-Guiding-Experiment Study

Lithium difluoro(oxalate) borate (LiDFOB) contributes actively to cathode-electrolyte interface (CEI) formation, particularly safeguarding high-voltage cathode materials. However, LiNixCozMnyO2-based batteries benefit from the LiDFOB and its derived CEI only with appropriate electrolyte design while a comprehensive understanding of the underlying interfacial mechanisms remains limited, which makes the rational design challenging. By performing ab initio calculations, the CEI evolution on the LiNi0.8Co0.1Mn0.1O2 has been investigated. The findings demonstrate that LiDFOB readily adheres to the cathode via semidissociative configuration, which elevates the Li deintercalation voltage and remains stable in solvent. Electrochemical processes are responsible for the subsequent cleavage of B-F and B-O bonds, while the B-F bond cleavage leading to LiF formation is dominant in the presence of adequate Li+ with a substantial Li intercalation energy. Thus, impregnation is established as an effective method to regulate the conversion channel for efficient CEI formation, which not only safeguards the cathode's structure but also counters electrolyte decomposition. Consequently, in comparison to utilizing LiDFOB as an electrolyte additive, employing LiDFOB impregnation in the NCM811/Li cell yields significantly improved cycling stability for over 2000 h.

Impact of LiBOB additive on cycle-performance degradation of lithium mono-chelated borate electrolytes: minimize the crosstalk-derived deterioration

Novel electrolyte systems are required to further improve the performance and ensure the safety of lithium-ion batteries. Lithium-monochelated borates with trifluoromethylated ligands are used as electrolytes for lithium-ion batteries (LIBs) with a lithium bis(oxalato)borate (LiBOB) additive. The capacity decay and extremely high resistance after the cycle test at 60 °C are dramatically suppressed by the addition of LiBOB. Half-cell measurements, X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS) suggested that the reductive decomposition products of the electrolytes at the negative electrode significantly increased the resistance at the positive electrode, which originated from the crosstalk of the decomposition species formed at the negative electrode. Further analysis confirmed the importance of the LiBOB-derived solid electrolyte interphase (SEI) at the negative electrode, which suppressed the formation of crosstalk species at the negative electrode and effectively suppressed the increase in resistance of the positive electrode. This study provides a reliable and promising approach for designing high-performance electrolytes with lithium borate and emphasizes the importance of considering the reactions occurring at both electrodes to improve battery performance.

High-performance Li/LiNi0.8Co0.1Mn0.1O2 batteries enabled by optimizing carbonate-based electrolyte and electrode interphases via triallylamine additive

Lithium (Li) metal batteries (LMBs), paired with high-energy-density cathode materials, are promising to meet the ever-increasing demand for electric energy storage. Unfortunately, the inferior electrode-electrolyte interfaces and hydrogen fluoride (HF) corrosion in the state-of-art carbonate-based electrolytes lead to dendritic Li growth and unsatisfactory cyclability of LMBs. Herein, a multifunctional electrolyte additive triallylamine (TAA) is proposed to circumvent those issues. The TAA molecule exhibits strong nucleophilicity and contains three unsaturated carbon-carbon double bonds, the former for HF elimination, the later for in-situ passivation of aggressive electrodes. As evidenced theoretically and experimentally, the preferential oxidation and reduction of carbon-carbon double bonds enable the successful regulation of components and morphologies of electrode interfaces, as well as the binding affinity to HF effectively blocks HF corrosion. In particular, the TAA-derived electrode interfaces are packed with abundant lithium-containing inorganics and oligomers, which diminishes undesired parasitic reactions of electrolyte and detrimental degradation of electrode materials. When using the TAA-containing electrolyte, the cell configuration with Li anode and nickel-rich layered oxide cathode and symmetrical Li cell deliver remarkably enhanced electrochemical performance with regard to the additive-free cell. The TAA additive shows great potential in advancing the development of carbonate-based electrolytes in LMBs.

Interface chemistry of an amide electrolyte for highly reversible lithium metal batteries

Metallic lithium is a promising anode to increase the energy density of rechargeable lithium batteries. Despite extensive efforts, detrimental reactivity of lithium metal with electrolytes and uncontrolled dendrite growth remain challenging interconnected issues hindering highly reversible Li-metal batteries. Herein, we report a rationally designed amide-based electrolyte based on the desired interface products. This amide electrolyte achieves a high average Coulombic efficiency during cycling, resulting in an outstanding capacity retention with a 3.5 mAh cm⁻² high-mass-loaded LiNi_0.8Co_0.1Mn_0.1O₂ cathode. The interface reactions with the amide electrolyte lead to the predicted solid electrolyte interface species, having favorable properties such as high ionic conductivity and high stability. Operando monitoring the lithium spatial distribution reveals that the highly reversible behavior is related to denser deposition as well as top-down stripping, which decreases the formation of porous deposits and inactive lithium, providing new insights for the development of interface chemistries for metal batteries.

Interface chemistry is essential for highly reversible lithium-metal batteries. Here the authors investigate amide-based electrolyte that lead to desirable interface species, resulting in dense Li-metal plating and top-down Li-metal stripping, responsible for the highly reversible cycling.

Enhancing the Electrochemical Performance of a High-Voltage LiNi0.5 Mn1.5 O4 Cathode in a Carbonate-Based Electrolyte with a Novel and Low-Cost Functional Additive

Butyric anhydride (BA) is used as an effective functional additive to improve the electrochemical performance of a high-voltage LiNi_0.5 Mn_1.5 O₄ (LNMO) cathode. In the presence of 0.5 wt % BA, the capacity retention of a LNMO/Li cell is significantly improved from 15.3 to 88.4 % after 200 cycles at 1 C. Furthermore, the rate performance of the LNMO/Li cell is also effectively enhanced, and the capacity goes up to 112 mAh g^-1 even at 5 C, which is considerably higher than that of a LNMO/Li cell in electrolyte without BA additive (95.4 mAh g^-1 at 5 C). Linear sweep voltammetry and cyclic voltammetry results reveal that the BA additive can be preferentially oxidized to construct a stable cathode electrolyte interphase (CEI) film on the LNMO cathode. Subsequently, the BA-derived CEI film can alleviate the decomposition of the electrolyte and the dissolution of Mn and Ni ions from the LNMO cathode as well as maintain the structural stability of LNMO during the cycling process; this leads to outstanding electrochemical performance. Thus, this work provides an effective and low-cost functional electrolyte for high-voltage LNMO-based LIBs.

Synthesis and electrochemical characterization of Mg–Al co-doped Li-rich Mn-based cathode materials

A novel synergistic strategy to improve electrochemical performance of Li-rich cathode by co-doping of magnesium and aluminium.

Truncated octahedral LiNi0.5Mn1.5O4 with excellent electrochemical properties for lithium-ion batteries prepared by a graphite assisted calcination method

A high-performance truncated octahedron structured LiNi_0.5Mn_1.5O₄ is synthesized by a graphite assisted calcination method, in which the {111} and {100} crystal plane group are meet the requirements of high ratio and long cycling performance.