Optimization, Surface Coating and Pilot Research of Li-rich Mn-based Cathode Material for Li-ion Batteries

由于层状富锂锰基正极材料xLi2MnO3•(1-x)LiMO2（M=Ni,Co,Mn等）的实际放电比容量高达250mAh/g，且同时具有热稳定性好、成本低以及对环境相对友好等优点，使得该材料成为高比能量锂离子电池正极材料研究的热点之一。然而,尽管富锂锰基材料的放电容量较高，由于其首次充电脱出的Li无法完全回嵌到材料晶格中，导致该材料首次不可逆容量损失较大。另外，富锂锰基材料由于充放电循环时材料结构的不可逆变化及电极/电解液界面膜改变等原因，材料容量和放电电压随循环进行衰退严重，这些问题都严重影响与制约了富锂锰基材料商品化的应用与发展。 本论文对组成为(1-x)LiNi0.4Co0...Due to specific capacity of layered Li-rich Mn-based cathodes xLi2MnO3•(1-x)LiMO2（M = Ni, Co, Mn, and so on）is higher than 250 mAh/g, besides their good thermal stability, low cost and being relative environment-friendly, this kind of cathodes gets many concerns as high specific energy cathodes of Li-ion batteries. Although Li-rich Mn-based cathodes have large discharge capacity, their first...学位：工程硕士院系专业：化学化工学院_工程硕士(化学工程)学号：X201019200

The Investigation of LiNixCoyMn1-x-yO2 as Cathode Materials and their corresponding Electrolyte Additive for Lithium-ion Batteries

三元正极材料LiNixCoyMn1-x-yO2因具有价格低、热稳定性好、对环境友好以及高电位下比容量高等突出优势成为锂离子电池研究的热点之一，引起了研究者的广泛关注。本论文选择该系列材料为研究内容，主要工作集中在优化合成条件，并成功制备出具有良好电化学性能的LiNi1/3Co1/3Mn1/3O2和LiNi0.4Co0.2Mn0.4O2正极材料，通过多种电化学与谱学手段表征它们的电化学、表面性质、热稳定以及储存等多方面的性能，并重点研究了LiNi1/3Co1/3Mn1/3O2材料首次不可逆损失严重的原因，以及LiNi0.4Co0.2Mn0.4O2粉末在空气中的储存稳定性等. 在实验技术方面，本...Recently, LiNixCoyMn1-x-yO2 material has become one of the promising cathode material systems for their high capacity, low cost, environmental-friendly, good thermal stability and stable cyclic performance in the lithium ion batteries. In this thesis, two kinds of material in this family, such as LiNi1/3Co1/3Mn1/3O2 and LiNi0.4Co0.2Mn0.4O2 with excellent electrolyte performance have been synthesiz...学位：理学博士院系专业：化学化工学院化学系_物理化学(含化学物理)学号：B20042504

Failure mechanisms of layered LiNixCoyMn1-x-yO2 cathodes for Li-ion batteries

Department of Energy Engineering (Battery Science and Technology)As the promising cathode material, Ni-containing layered Li NCM oxide has several advantages; low-cost, high capacity, etc. but hard to commercialize because of its poor cycle performance. About this, many researchers studied the failure mechanisms and regard the surface part problems as the failure mechanism of layered LI NCM oxide. However, apart from surface part problem, there are other failure mechanisms affect to the poor cycle performance of Li NCM. Among them, we focus and suggest new kinds of failure mechanism; Ni disordering as bulk part problem. To identify, at first, the half cell test shows that the poor cycle performance of Li NCM in several factors, and the degree of Ni disordering during cycling is analyzed using Rietveld refinement method. As results, when the Ni disordering is increased during cycling, the capacity of Li NCM is decreased more and more, and this indicates that Ni disordering can affect the cycle performance of Li NCM during cycling, so it is demonstrated that the Ni disordering is one of the failure mechanism of poor cycle performance of layered LI NCM. Moreover, we suggest new type solution to improve; Mg doping at Li layer of Li NCM. Several analyses, such as TEM, refinement data show the Mg is successfully doped into Li layer, and the half cell test shows its better cycle performance than bare Li NCM (1C, 30℃). Also, through refinement analysis of cycled Mg-doped Li NCM electrode, we observe that the Ni disordering is also inhibited somewhat, comparing the bare Li NCM results.ope

A critical assessment of the resource depletion potential of current and future lithium-ion batteries

Resource depletion aspects are repeatedly used as an argument for a shift towards new battery technologies. However, whether serious shortages due to the increased demand for traction and stationary batteries can actually be expected is subject to an ongoing discussion. In order to identify the principal drivers of resource depletion for battery production, we assess different lithium-ion battery types and a new lithium-free battery technology (sodium-ion) under this aspect, applying different assessment methodologies. The findings show that very different results are obtained with existing impact assessment methodologies, which hinders clear interpretation. While cobalt, nickel and copper can generally be considered as critical metals, the magnitude of their depletion impacts in comparison with that of other battery materials like lithium, aluminum or manganese differs substantially. A high importance is also found for indirect resource depletion effects caused by the co-extraction of metals from mixed ores. Remarkably, the resource depletion potential per kg of produced battery is driven only partially by the electrode materials and thus depends comparably little on the battery chemistry itself. One of the key drivers for resource depletion seems to be the metals (and co-products) in electronic parts required for the battery management system, a component rather independent from the actual battery chemistry. However, when assessing the batteries on a capacity basis (per kWh storage capacity), a high-energy density also turns out to be relevant, since it reduces the mass of battery required for providing one kWh, and thus the associated resource depletion impacts

Ultrafast laser ablation of aqueous processed thick-film Li(Ni0.6_{0.6}Mn0.2_{0.2}Co0.2_{0.2})O2_{O2} cathodes with 3D architectures for lithium-ion batteries

Lithium-ion batteries have dominated the field of electrochemical energy storage for years due to their high energy density. Recently, with the rapid development of E-mobility, the quest for high power and high energy batteries with reduced production costs has aroused great interest and is still a huge challenge. The energy density at battery level can be increased by using electrodes with thicknesses > 150 μm. However, capacity fade of thick-film electrodes at C-rates > C/2 is observed. To compensate the capacity loss, 3D architectures with a high aspect ratio are produced using ultrafast laser ablation. In addition, aqueous processing of cathodes using water-based binders can achieve environmentally friendly production and cost reduction by replacing the conventional organic PVDF binder and the toxic and volatile NMP solvent. However, the pH value of aqueous processed cathode slurries increases to 12 due to the reaction between active material and water, which decreases the specific capacity of the cells and on the other side results in chemical corrosion of the current collector during casting. In order to determine the optimal pH range and avoid the damage of the current collector, slurries with pH values ranging from 8 to 12 are manufactured. In this work, thick-film Li(Ni0.6Mn0.2Co0.2)O2 electrodes are manufactured with aqueous binders and acid adjustment, and are subsequently structured using ultrafast laser ablation. This combination is beneficial to achieve green production, low cost, high power, and high energy application of lithium-ion batteries

Ultrafast laser ablation of aqueous processed thick-film Li(Ni0.6_{0.6}Mn0.2_{0.2}Co0.2_{0.2})O2_{O2} cathodes with 3D architectures for lithium-ion batteries

Lithium-ion batteries have dominated the field of electrochemical energy storage for years due to their high energy density. Recently, with the rapid development of E-mobility, the quest for high power and high energy batteries with reduced production costs has aroused great interest and is still a huge challenge. The energy density at battery level can be increased by using electrodes with thicknesses > 150 μm. However, capacity fade of thick-film electrodes at C-rates > C/2 is observed. To compensate the capacity loss, 3D architectures with a high aspect ratio are produced using ultrafast laser ablation. In addition, aqueous processing of cathodes using water-based binders can achieve environmentally friendly production and cost reduction by replacing the conventional organic PVDF binder and the toxic and volatile NMP solvent. However, the pH value of aqueous processed cathode slurries increases to 12 due to the reaction between active material and water, which decreases the specific capacity of the cells and on the other side results in chemical corrosion of the current collector during casting. In order to determine the optimal pH range and avoid the damage of the current collector, slurries with pH values ranging from 8 to 12 are manufactured. In this work, thick-film Li(Ni0.6Mn0.2Co0.2)O2 electrodes are manufactured with aqueous binders and acid adjustment, and are subsequently structured using ultrafast laser ablation. This combination is beneficial to achieve green production, low cost, high power, and high energy application of lithium-ion batteries

Carrageenans as Sustainable Water-Processable Binders for High-Voltage NMC811 Cathodes

Poly(vinylidene fluoride) (PVDF) is the most common binder for cathode electrodes in lithium-ion batteries. However, PVDF is a fluorinated compound and requires toxic N-methyl-2-pyrrolidone (NMP) as a solvent during the slurry preparation, making the electrode fabrication process environmentally unfriendly. In this study, we propose the use of carrageenan biopolymers as a sustainable source of water-processable binders for high-voltage NMC811 cathodes. Three types of carrageenan (Carr) biopolymers were investigated, with one, two, or three sulfonate groups (SO3–), namely, kappa, iota, and lambda carrageenans, respectively. In addition to the nature of carrageenans, this article also reports the optimization of the cathode formulations, which were prepared by using between 5 wt % of the binder to a lower amount of 2 wt %. Processing of the aqueous slurries and the nature of the binder, in terms of the morphology and electrochemical performance of the electrodes, were also investigated. The Carr binder with 3SO3– groups (3SO3– Carr) exhibited the highest discharge capacities, delivering 133.1 mAh g–1 at 3C and 105.0 mAh g–1 at 5C, which was similar to the organic-based PVDF electrode (136.1 and 108.7 mAh g–1, respectively). Furthermore, 3SO3– Carr reached an outstanding capacity retention of 91% after 90 cycles at 0.5C, which was attributed to a homogeneous NMC811 and a conductive carbon particle dispersion, superior adhesion strength to the current collector (17.3 ± 0.7 N m–1 vs 0.3 ± 0.1 N m–1 for PVDF), and reduced charge-transfer resistance. Postmortem analysis unveiled good preservation of the NMC811 particles, while the 1SO3– Carr and 2SO3– Carr electrodes showed damaged morphologies.The authors acknowledge the Australian Research Council (ARC) Centre for Training Centre for Future Energy Storage Technologies (storEnergy) (IC180100049) for funding. The authors would like to thank the European Commission for financial support through funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 823989 and Spanish AEI-MINECO for funding through project PID2020-119026 GB-I00

Enabling High‐Stability of Aqueous‐Processed Nickel‐Rich Positive Electrodes in Lithium Metal Batteries

Lithium batteries occupy the large-scale electric mobility market raising concerns about the environmental impact of cell production, especially regarding the use of poly(vinylidene difluoride) (teratogenic) and N-methyl-2-pyrrolidone (NMP, harmful). To avoid their use, an aqueous electrode processing route is utilized in which a water-soluble hybrid acrylic-fluoropolymer together with sodium carboxymethyl cellulose is used as binder, and a thin phosphate coating layer is in situ formed on the surface of the nickel-rich cathode during electrode processing. The resulting electrodes achieve a comparable performance to that of NMP-based electrodes in conventional organic carbonate-based electrolyte (LP30). Subsequently, an ionic liquid electrolyte (ILE) is employed to replace the organic electrolyte, building stable electrode/electrolyte interphases on the surface of the nickel-rich positive electrode (cathode) and metallic lithium negative electrode (anode). In such ILE, the aqueously processed electrodes achieve high cycling stability with a capacity retention of 91% after 1000 cycles (20 °C). In addition, a high capacity of more than 2.5 mAh cm$^{-2}$ is achieved for high loading electrodes (≈15 mg cm$^{-2}$) by using a modified ILE with 5% vinylene carbonate additive. A path to achieve environmentally friendly electrode manufacturing while maintaining their outstanding performance and structural integrity is demonstrated

INVESTIGATION OF TRANSITION-METAL IONS IN THE NICKEL-RICH LAYERED POSITIVE ELECTRODE MATERIALS FOR LITHIUM-ION BATTERIES

Layered lithium transition-metal oxides (LMOs) are used as the positive electrode material in rechargeable lithium-ion batteries. Because transition metals undergo redox reactions when lithium ions intercalate in and disintercalate from the lattice, the selection and composition of transition metals largely influence the electrochemical performance of LMOs. Recently, a Ni-rich compound, LiNi0.8Co0.1Mn0.1O2 (NCM811), has drawn much attention. It is expected to replace its state-of-the-art cousins, LiCoO2 (LCO) and LiNi1/3Co1/3Mn1/3O2 (NCM111), because of its higher capacity, lower cost, and reduced toxicity. However, the excess Ni, as a transition-metal element in NCM811, can cause structural and cycling instability. Starting from NCM811, I modified the composition of transition metals by two approaches: 1) introducing cobalt deficiency and 2) substituting Ni, Co, and Mn with Zr. Their influences on the phase, structure, cycling performance, rate capability, and ionic transport were investigated by a variety of characterization techniques. I found that cobalt non-stoichiometry can suppress Ni2+/Li+ cation mixing, but simultaneously promotes the formation of oxygen vacancies, leading to rapid capacity fade and inferior rate capability compared to pristine NCM811. On the other hand, Zr can reside on and expand the lattice of NCM811, and form Li-rich lithium zirconates on their surfaces. In particular, 1% Zr substitution can increase the stability of NCM811 and facilitate Li-ion transport, resulting in enhanced cycling durability and high-rate performance. My studies help improve the understanding of the effects of transition metals on the degradation of the Ni-rich layered positive electrode material and provide modification strategies to enhance its performance and durability for Li-ion battery applications