Pub Date : 2024-08-08DOI: 10.1149/1945-7111/ad68e4
Macgregor F. Macintosh, Mohsen Shakouri and M. N. Obrovac
Substitutional Li[Ni0.6Mn0.2Co0.2]O2 oxides (known as NMC622) were made by all-dry synthesis with Fe and Ti substituting Co and Mn, respectively. The substitutions were performed in three series, Fe substitution for Co, Ti substitution for Mn, and Fe and Ti co-substitution for Co and Mn, according to the formula Li(Ni0.6Mn0.2−yCo0.2−xFexTiy)O2. The resulting oxides were evaluated as cathode materials for Li-ion batteries. Fe-substitution for Co resulted in increased intersite mixing, resulting in increased polarization and capacity fade. Ti-substitution for Mn also resulted in increased intersite mixing, but the mixing was due to Ti3+ in the Li-layer. As a result, Ti-substituted NMCs had improved capacity retention and reduced polarization. These effects were independent of each other, so that Ti could partially offset the negative aspects of Fe-substitution. Additionally, layered Mn-free Li(Ni0.6Ti0.2Co0.2)O2 (NTC622) was produced as an endmember of this series for the first time with low intersite mixing and superior electrochemical performance in comparison to previous reports. These results demonstrate benefits of all-dry Ti-substitution in NMC and the all-dry synthesis method as an avenue towards new cathode composition discovery.
用全干法合成法制备了取代型 Li[Ni0.6Mn0.2Co0.2]O2 氧化物（又称 NMC622），其中 Fe 和 Ti 分别取代了 Co 和 Mn。按照 Li（Ni0.6Mn0.2-yCo0.2-xFexTiy）O2 的公式，分别用 Fe 替代 Co、Ti 替代 Mn 以及 Fe 和 Ti 共同替代 Co 和 Mn 三个系列进行了替代。所得氧化物被评估为锂离子电池的阴极材料。用 Fe 替代 Co 增加了位点间的混合，从而增加了极化和容量衰减。用钛代替锰也会导致晶间混合增加，但这种混合是由于锂层中的 Ti3+ 造成的。因此，以钛替代锰的 NMC 提高了容量保持率并降低了极化。这些影响是相互独立的，因此钛可以部分抵消铁取代的负面影响。此外，作为该系列的末端成员，首次制备出了层状无锰 Li（Ni0.6Ti0.2Co0.2）O2（NTC622），与之前的报告相比，它具有较低的位间混合和优异的电化学性能。这些结果表明了全干法钛替代在 NMC 中的优势，以及全干法合成方法是发现新阴极成分的一种途径。
{"title":"Isovalent Co-Substitution of Iron and Titanium into Single-Crystal NMC622","authors":"Macgregor F. Macintosh, Mohsen Shakouri and M. N. Obrovac","doi":"10.1149/1945-7111/ad68e4","DOIUrl":"https://doi.org/10.1149/1945-7111/ad68e4","url":null,"abstract":"Substitutional Li[Ni0.6Mn0.2Co0.2]O2 oxides (known as NMC622) were made by all-dry synthesis with Fe and Ti substituting Co and Mn, respectively. The substitutions were performed in three series, Fe substitution for Co, Ti substitution for Mn, and Fe and Ti co-substitution for Co and Mn, according to the formula Li(Ni0.6Mn0.2−yCo0.2−xFexTiy)O2. The resulting oxides were evaluated as cathode materials for Li-ion batteries. Fe-substitution for Co resulted in increased intersite mixing, resulting in increased polarization and capacity fade. Ti-substitution for Mn also resulted in increased intersite mixing, but the mixing was due to Ti3+ in the Li-layer. As a result, Ti-substituted NMCs had improved capacity retention and reduced polarization. These effects were independent of each other, so that Ti could partially offset the negative aspects of Fe-substitution. Additionally, layered Mn-free Li(Ni0.6Ti0.2Co0.2)O2 (NTC622) was produced as an endmember of this series for the first time with low intersite mixing and superior electrochemical performance in comparison to previous reports. These results demonstrate benefits of all-dry Ti-substitution in NMC and the all-dry synthesis method as an avenue towards new cathode composition discovery.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"373 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141942901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-07DOI: 10.1149/1945-7111/ad6939
Rodney LaFollette and Michael D. Eskra
It is often observed that some runaway Li-ion cells with layered cathode materials become much hotter internally than existing thermal runaway models predict. Further, metals originally in the positive active material (such as Co, Ni, and Mn) are often found in cells whose temperatures became very high. It has been postulated that the formation of metals can be attributed to reduction of rock salt species (MO, where M is the metal), or the reaction of lithiated active material (LiMO2) with CO2. We propose an alternate process for formation of metals that also results in very high cell temperatures, namely thermite reactions between the Al positive electrode current collector and the positive active material. These reactions are highly exothermic, in contrast with the reactions of MO and LiMO2 mentioned. In this paper the thermodynamics of thermite reactions are presented. Incorporating thermite reactions in runaway models will likely improve temperature prediction of Li-ion cells in thermal runaway.
人们经常发现，一些采用层状阴极材料的失控锂离子电池的内部温度比现有热失控模型预测的温度要高得多。此外，在温度变得非常高的电池中，经常会发现原本存在于正极活性材料中的金属（如钴、镍和锰）。据推测，金属的形成可归因于岩盐物种（MO，其中 M 为金属）的还原，或锂化活性材料（LiMO2）与二氧化碳的反应。我们提出了另一种金属形成过程，它也会导致极高的电池温度，即铝正极集流器与正极活性材料之间的热反应。这些反应的放热程度很高，与上述 MO 和 LiMO2 反应形成鲜明对比。本文介绍了热释电反应的热力学。将热亚硝酸盐反应纳入失控模型可能会改善热失控锂离子电池的温度预测。
{"title":"The Possible Role of Thermite Reactions in Thermal Runaway of Li-ion Cells with Layered Cathodes","authors":"Rodney LaFollette and Michael D. Eskra","doi":"10.1149/1945-7111/ad6939","DOIUrl":"https://doi.org/10.1149/1945-7111/ad6939","url":null,"abstract":"It is often observed that some runaway Li-ion cells with layered cathode materials become much hotter internally than existing thermal runaway models predict. Further, metals originally in the positive active material (such as Co, Ni, and Mn) are often found in cells whose temperatures became very high. It has been postulated that the formation of metals can be attributed to reduction of rock salt species (MO, where M is the metal), or the reaction of lithiated active material (LiMO2) with CO2. We propose an alternate process for formation of metals that also results in very high cell temperatures, namely thermite reactions between the Al positive electrode current collector and the positive active material. These reactions are highly exothermic, in contrast with the reactions of MO and LiMO2 mentioned. In this paper the thermodynamics of thermite reactions are presented. Incorporating thermite reactions in runaway models will likely improve temperature prediction of Li-ion cells in thermal runaway.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"26 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141942904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-07DOI: 10.1149/1945-7111/ad6938
Wolfgang G. Bessler
Capacity and internal resistance are key properties of batteries determining energy content and power capability. We present a novel algorithm for estimating the absolute values of capacity and internal resistance from voltage and current data. The algorithm is based on voltage-controlled models. Experimentally-measured voltage is used as an input variable to an equivalent circuit model. The simulation gives current as output, which is compared to the experimentally-measured current. We show that capacity loss and resistance increase lead to characteristic fingerprints in the current output of the simulation. In order to exploit these fingerprints, a theory is developed for calculating capacity and resistance from the difference between simulated and measured current. The findings are cast into an algorithm for operando diagnosis of batteries operated with arbitrary load profiles. The algorithm is demonstrated using cycling data from lithium-ion pouch cells operated on full cycles, shallow cycles, and dynamic cycles typical for electric vehicles. Capacity and internal resistance of a “fresh” cell was estimated with high accuracy (mean absolute errors of 0.9% and 1.8%, respectively). For an “aged” cell, the algorithm required adaptation of the model’s open-circuit voltage curve to obtain high accuracies. Highlights Operando diagnosis of capacity and internal resistance of rechargeable batteries. Novel algorithm developed, validated and demonstrated. Use of voltage-controlled models: Voltage as input, current as output. High accuracy achieved for dynamic operation of an NMC-LMO/graphite pouch cell.
{"title":"Capacity and Resistance Diagnosis of Batteries with Voltage-Controlled Models","authors":"Wolfgang G. Bessler","doi":"10.1149/1945-7111/ad6938","DOIUrl":"https://doi.org/10.1149/1945-7111/ad6938","url":null,"abstract":"Capacity and internal resistance are key properties of batteries determining energy content and power capability. We present a novel algorithm for estimating the absolute values of capacity and internal resistance from voltage and current data. The algorithm is based on voltage-controlled models. Experimentally-measured voltage is used as an input variable to an equivalent circuit model. The simulation gives current as output, which is compared to the experimentally-measured current. We show that capacity loss and resistance increase lead to characteristic fingerprints in the current output of the simulation. In order to exploit these fingerprints, a theory is developed for calculating capacity and resistance from the difference between simulated and measured current. The findings are cast into an algorithm for operando diagnosis of batteries operated with arbitrary load profiles. The algorithm is demonstrated using cycling data from lithium-ion pouch cells operated on full cycles, shallow cycles, and dynamic cycles typical for electric vehicles. Capacity and internal resistance of a “fresh” cell was estimated with high accuracy (mean absolute errors of 0.9% and 1.8%, respectively). For an “aged” cell, the algorithm required adaptation of the model’s open-circuit voltage curve to obtain high accuracies. Highlights Operando diagnosis of capacity and internal resistance of rechargeable batteries. Novel algorithm developed, validated and demonstrated. Use of voltage-controlled models: Voltage as input, current as output. High accuracy achieved for dynamic operation of an NMC-LMO/graphite pouch cell.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"16 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141942902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-07DOI: 10.1149/1945-7111/ad68a9
Julian Knorr, Jiahao Li, Maximilian Schamel, Thomas Kufner, Alexander Adam and Michael A. Danzer
The energy density of lithium-ion batteries can be improved by adding silicon as a secondary active anode material alongside graphite. However, accurate state estimation of batteries with blend electrodes requires detailed knowledge of the interplay between the active materials during lithiation. Challenges arise from the current split between the active materials and the overlap of their working potentials. This study examines the lithiation behavior of blend anodes using a setup consisting of a pure graphite and a pure SiOx half-cell connected in parallel. The setup allows for current measurements of both active materials, the determination of the state of lithiation throughout the entire charging process and measurements of balancing effects between the active materials during relaxation periods. Analysis of the behavior at increased charge rates results in greater SiOx lithiation after similar charge throughput indicating better kinetics for SiOx compared to graphite. A Doyle-Fuller-Newman model of a blend anode is used to further investigate the experimental findings on the lithiation behavior and transfer them to blend electrodes. Simulation-based variations of the silicon content show that an increased SiOx content in blend anodes leads to improved rate capability.
{"title":"Active Material Lithiation in Gr/SiOx Blend Anodes at Increased C-Rates","authors":"Julian Knorr, Jiahao Li, Maximilian Schamel, Thomas Kufner, Alexander Adam and Michael A. Danzer","doi":"10.1149/1945-7111/ad68a9","DOIUrl":"https://doi.org/10.1149/1945-7111/ad68a9","url":null,"abstract":"The energy density of lithium-ion batteries can be improved by adding silicon as a secondary active anode material alongside graphite. However, accurate state estimation of batteries with blend electrodes requires detailed knowledge of the interplay between the active materials during lithiation. Challenges arise from the current split between the active materials and the overlap of their working potentials. This study examines the lithiation behavior of blend anodes using a setup consisting of a pure graphite and a pure SiOx half-cell connected in parallel. The setup allows for current measurements of both active materials, the determination of the state of lithiation throughout the entire charging process and measurements of balancing effects between the active materials during relaxation periods. Analysis of the behavior at increased charge rates results in greater SiOx lithiation after similar charge throughput indicating better kinetics for SiOx compared to graphite. A Doyle-Fuller-Newman model of a blend anode is used to further investigate the experimental findings on the lithiation behavior and transfer them to blend electrodes. Simulation-based variations of the silicon content show that an increased SiOx content in blend anodes leads to improved rate capability.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"70 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141942900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-07DOI: 10.1149/1945-7111/ad68a8
Timon Scharmann, Canel Özcelikman, Do Minh Nguyen, Carina Amata Heck, Christian Wacker, Peter Michalowski, Arno Kwade and Klaus Dröder
All-solid-state batteries (ASSBs), defined through a solid electrolyte, are emerging as a promising solution to address current challenges in energy and power density demands for electromobility. Within the various possible types of solid electrolytes, sulfide-based materials exhibit advantageous high ionic conductivities. However, due to the strong reactivity of sulfides, atmospheric exposure can lead to the formation of toxic hydrogen sulfide and additionally negatively impact the resulting battery performance. Both factors present key challenges for ASSB production, as they necessitate the development of a material-adapted, economically viable and safe process atmosphere. In the present study, the influence of different production atmospheres on sulfide-based solid electrolytes is experimentally investigated. For this purpose, sulfide sheets are exposed to defined atmospheres with dynamic air fluctuations at dew points ranging from −60 °C to 0 °C. The resulting ionic conductivities indicate a dependency on the prevailing dew point and exposure time with a discernible impact on performance even at dew points of −60 °C within atmospheres with constant air circulation. With the acquired results, a detailed and knowledge-based selection and design of dry room production atmospheres for ASSB cell assembly is possible, which is a necessary step for further industrialization.
通过固体电解质定义的全固态电池（ASSB）正在成为一种有前途的解决方案，以应对当前电动汽车在能量和功率密度需求方面的挑战。在各种可能的固态电解质类型中，硫化物基材料具有高离子电导率的优势。然而，由于硫化物具有很强的反应性，暴露在大气中会形成有毒的硫化氢，从而对电池性能产生负面影响。这两个因素都对 ASSB 的生产提出了关键挑战，因为它们要求开发一种与材料相适应、经济上可行且安全的工艺气氛。本研究通过实验研究了不同生产气氛对硫化物固体电解质的影响。为此，硫化片暴露在露点为 -60 °C 至 0 °C 的具有动态空气波动的特定气氛中。结果表明，离子电导率与当时的露点和暴露时间有关，即使在露点为-60 °C、空气循环恒定的环境中，离子电导率也会对性能产生明显影响。有了这些结果，就可以根据知识详细选择和设计用于 ASSB 电池组装的干燥室生产环境，这是进一步工业化的必要步骤。
{"title":"Atmospheric Influences on Li6PS5Cl Separators and the Resulting Ionic Conductivity for All-Solid-State Batteries","authors":"Timon Scharmann, Canel Özcelikman, Do Minh Nguyen, Carina Amata Heck, Christian Wacker, Peter Michalowski, Arno Kwade and Klaus Dröder","doi":"10.1149/1945-7111/ad68a8","DOIUrl":"https://doi.org/10.1149/1945-7111/ad68a8","url":null,"abstract":"All-solid-state batteries (ASSBs), defined through a solid electrolyte, are emerging as a promising solution to address current challenges in energy and power density demands for electromobility. Within the various possible types of solid electrolytes, sulfide-based materials exhibit advantageous high ionic conductivities. However, due to the strong reactivity of sulfides, atmospheric exposure can lead to the formation of toxic hydrogen sulfide and additionally negatively impact the resulting battery performance. Both factors present key challenges for ASSB production, as they necessitate the development of a material-adapted, economically viable and safe process atmosphere. In the present study, the influence of different production atmospheres on sulfide-based solid electrolytes is experimentally investigated. For this purpose, sulfide sheets are exposed to defined atmospheres with dynamic air fluctuations at dew points ranging from −60 °C to 0 °C. The resulting ionic conductivities indicate a dependency on the prevailing dew point and exposure time with a discernible impact on performance even at dew points of −60 °C within atmospheres with constant air circulation. With the acquired results, a detailed and knowledge-based selection and design of dry room production atmospheres for ASSB cell assembly is possible, which is a necessary step for further industrialization.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"70 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141942908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-07DOI: 10.1149/1945-7111/ad69c8
Shamik Chakrabarti and A. K. Thakur
Electrochemical properties of Li2NiPO4F were studied using density functional theory. The obtained voltage, electronic band gap, capacity (∼ for 2 Li+ extraction) and energy density are achieved as 5.33 V, 4.0 eV, 287.3 mAh g−1 and 1531.31 Wh kg−1, respectively. Although, the electrochemical properties of Li2NiPO4F are promising, large electronic band gap would certainly pose a limitation for its commercial application. Nb is a transition metal and its electronegativity is 1.6 which is less than the electronegativity of 2.19 for P. This implies, less operating voltage would be obtained if we replace P in Li2NiPO4F by Nb to form Li2NiNbO4F. However, electronic configuration of Nb is [Kr] 4d45 s1 and the valance state of Nb in Li2NiNbO4F is +5, which in turn specify that, localized Nb d states will reside in conduction band of Li2NiNbO4F and hence the electronic band-gap would be less owing to this localized Nb-d states. Our speculation gets verified by the calculated properties of Li2NiNbO4F obtained through DFT as follows; Voltage, electronic band gap, capacity (∼ for 2 Li+ extraction) and energy density achieved, respectively, are 5.01 V, 3.64 eV (less than LiFePO4), 215.71 mAh g−1, 1080.71 Wh kg−1. Lower electronic band gap of Li2NiNbO4F makes it an alternative to Li2NiPO4F.
{"title":"Tuning of Band Gap of Cathode Li2NiPO4F by Replacing P to Nb and Forming Li2NiNbO4F for Application as 5 V Cathode in Lithium Ion Battery: A Density Functional Theory Study","authors":"Shamik Chakrabarti and A. K. Thakur","doi":"10.1149/1945-7111/ad69c8","DOIUrl":"https://doi.org/10.1149/1945-7111/ad69c8","url":null,"abstract":"Electrochemical properties of Li2NiPO4F were studied using density functional theory. The obtained voltage, electronic band gap, capacity (∼ for 2 Li+ extraction) and energy density are achieved as 5.33 V, 4.0 eV, 287.3 mAh g−1 and 1531.31 Wh kg−1, respectively. Although, the electrochemical properties of Li2NiPO4F are promising, large electronic band gap would certainly pose a limitation for its commercial application. Nb is a transition metal and its electronegativity is 1.6 which is less than the electronegativity of 2.19 for P. This implies, less operating voltage would be obtained if we replace P in Li2NiPO4F by Nb to form Li2NiNbO4F. However, electronic configuration of Nb is [Kr] 4d45 s1 and the valance state of Nb in Li2NiNbO4F is +5, which in turn specify that, localized Nb d states will reside in conduction band of Li2NiNbO4F and hence the electronic band-gap would be less owing to this localized Nb-d states. Our speculation gets verified by the calculated properties of Li2NiNbO4F obtained through DFT as follows; Voltage, electronic band gap, capacity (∼ for 2 Li+ extraction) and energy density achieved, respectively, are 5.01 V, 3.64 eV (less than LiFePO4), 215.71 mAh g−1, 1080.71 Wh kg−1. Lower electronic band gap of Li2NiNbO4F makes it an alternative to Li2NiPO4F.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"23 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141942909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-06DOI: 10.1149/1945-7111/ad6937
Divya Rathore, Harold Smith Perez, Ian Monchesky, Fanny Vain, Penghao Xiao, Chongyin Yang and J. R. Dahn
NMC640, a series of Li1+x(Ni0.6Mn0.4)1−xO2 materials, are important Co-free mid-Ni cathode materials for Li-ion batteries, offering high energy density and better cost-efficiency than Ni-rich counterparts. These materials require excess Li compared to stoichiometric composition to improve the electrochemical performance in terms of rate capability and cycling stability. Although lithium-to-transition metal ratios up to 1.15 can be used to optimize the performance, less than 80% of this lithium is electrochemically active during cycling up to a 4.4 V upper cut off. This study explores whether some percentage of the inactive Li can be replaced by sodium to make these materials more cost-effective and bring potential improvements in electrochemical performance. Various amounts of excess Li were substituted by sodium in the structure. The results show that sodium can be integrated into the layered oxide structure without forming any impurity phases and effectively decreases the cation mixing observed in these layered structures. However, this does compromise cycling stability and rate capability. Na tends to occupy Li sites rather than transition metal sites, resulting in electrochemical instability and capacity loss. Even though excess Li is not electrochemically active, it cannot be effectively replaced by sodium without compromising battery performance of Li1+x(Ni0.6Mn0.4)1−xO2 materials.
{"title":"Substituting Na for Excess Li in Li1+x(Ni0.6Mn0.4)1−xO2 Materials","authors":"Divya Rathore, Harold Smith Perez, Ian Monchesky, Fanny Vain, Penghao Xiao, Chongyin Yang and J. R. Dahn","doi":"10.1149/1945-7111/ad6937","DOIUrl":"https://doi.org/10.1149/1945-7111/ad6937","url":null,"abstract":"NMC640, a series of Li1+x(Ni0.6Mn0.4)1−xO2 materials, are important Co-free mid-Ni cathode materials for Li-ion batteries, offering high energy density and better cost-efficiency than Ni-rich counterparts. These materials require excess Li compared to stoichiometric composition to improve the electrochemical performance in terms of rate capability and cycling stability. Although lithium-to-transition metal ratios up to 1.15 can be used to optimize the performance, less than 80% of this lithium is electrochemically active during cycling up to a 4.4 V upper cut off. This study explores whether some percentage of the inactive Li can be replaced by sodium to make these materials more cost-effective and bring potential improvements in electrochemical performance. Various amounts of excess Li were substituted by sodium in the structure. The results show that sodium can be integrated into the layered oxide structure without forming any impurity phases and effectively decreases the cation mixing observed in these layered structures. However, this does compromise cycling stability and rate capability. Na tends to occupy Li sites rather than transition metal sites, resulting in electrochemical instability and capacity loss. Even though excess Li is not electrochemically active, it cannot be effectively replaced by sodium without compromising battery performance of Li1+x(Ni0.6Mn0.4)1−xO2 materials.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"57 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141942968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-06DOI: 10.1149/1945-7111/ad6934
Wei He, Munaiah Yeddala, Leah Rynearson and Brett Lucht
The use of high-nickel NMC811 cathode and SiOx-Gr anode can greatly improve the overall energy densities of lithium-ion batteries. However, the unfavorable solid electrolyte interphase (SEI) layer generated from the decomposition of EC-based electrolytes lead to the poor cycling stability of NMC811||SiOx-Gr cells. Here we report an electrolyte design of 1.5 M LiPF6 dissolved in FEC/MA/BN 2:2:6 by volume, which can form thin, robust, and homogeneous SEI layer to greatly improve the charge transfer at the electrode-electrolyte interface. Importantly, the designed electrolyte shows an outstanding low temperature performance that it can deliver a capacity of 123.3 mAh g–1 after 50 cycles at −20 °C with a current density of 0.5 C, overwhelming the standard EC-based electrolyte (1.2 M LiPF6 EC/EMC 3:7 by volume) with a capacity of 35.7 mAh g–1. The electrolyte also has a superior rate performance that it achieves a capacity of 122.5 mAh g−1 at a high current density of 10 C. Moreover, the LTE electrolyte holds the great potential of extreme fast-charging ability because of the large part of CC contribution in the CCCV charging model at high charging current densities.
使用高镍 NMC811 正极和 SiOx-Gr 负极可以大大提高锂离子电池的整体能量密度。然而，基于 EC 的电解质在分解过程中会产生不利的固体电解质间相（SEI）层，导致 NMC811||SiOx-Gr 电池的循环稳定性较差。在此，我们报告了一种将 1.5 M LiPF6 按体积比 2:2:6 溶于 FEC/MA/BN 中的电解质设计，它可以形成薄、坚固、均匀的 SEI 层，从而大大改善电极-电解质界面的电荷转移。重要的是，所设计的电解液具有出色的低温性能，在零下 20 °C、电流密度为 0.5 C 的条件下循环 50 次后，其容量可达 123.3 mAh g-1，超过了容量为 35.7 mAh g-1 的标准 EC 型电解液（体积比为 1.2 M LiPF6 EC/EMC 3:7）。该电解液还具有卓越的速率性能，在 10 C 的高电流密度下可达到 122.5 mAh g-1 的容量。此外，由于在高充电电流密度下的 CCCV 充电模型中 CC 的贡献较大，因此 LTE 电解液具有极强的快速充电能力。
{"title":"Electrolyte Design for NMC811||SiOx-Gr Lithium-Ion Batteries with Excellent Low-Temperature and High-Rate Performance","authors":"Wei He, Munaiah Yeddala, Leah Rynearson and Brett Lucht","doi":"10.1149/1945-7111/ad6934","DOIUrl":"https://doi.org/10.1149/1945-7111/ad6934","url":null,"abstract":"The use of high-nickel NMC811 cathode and SiOx-Gr anode can greatly improve the overall energy densities of lithium-ion batteries. However, the unfavorable solid electrolyte interphase (SEI) layer generated from the decomposition of EC-based electrolytes lead to the poor cycling stability of NMC811||SiOx-Gr cells. Here we report an electrolyte design of 1.5 M LiPF6 dissolved in FEC/MA/BN 2:2:6 by volume, which can form thin, robust, and homogeneous SEI layer to greatly improve the charge transfer at the electrode-electrolyte interface. Importantly, the designed electrolyte shows an outstanding low temperature performance that it can deliver a capacity of 123.3 mAh g–1 after 50 cycles at −20 °C with a current density of 0.5 C, overwhelming the standard EC-based electrolyte (1.2 M LiPF6 EC/EMC 3:7 by volume) with a capacity of 35.7 mAh g–1. The electrolyte also has a superior rate performance that it achieves a capacity of 122.5 mAh g−1 at a high current density of 10 C. Moreover, the LTE electrolyte holds the great potential of extreme fast-charging ability because of the large part of CC contribution in the CCCV charging model at high charging current densities.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"373 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141942971","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
State-of-health (SOH) of lithium-ion batteries is an important indicator for measuring performance and remaining life. We propose an innovative prediction model that integrates variational mode decomposition (VMD), Dung Beetle optimizer (DBO), and support vector regression (SVR) algorithms. We extracted relevant features from the discharge characteristic curve and incremental capacity curve. We used Pearson and Spearman correlation coefficient methods for correlation analysis on the extracted health factors (HFs), selecting those that significantly impact SOH as input features. A DBO-SVR model was constructed to establish a nonlinear correlation between HFs and SOH, and the DBO algorithm was used to globally search and optimize the hyperparameters of the SVR model to improve its prediction accuracy. To reduce the impact of noise in battery signals on model performance, VMD technology was introduced to decompose battery signals into multiple intrinsic mode components, to extract useful features and remove noise to further improve prediction accuracy. The proposed method was validated using the NASA battery dataset and compared with other algorithm models. Results showed that the prediction model was significantly better than other models, with a maximum RMSE value of 0.84%, a maximum MAE value of 0.71%, and a stable prediction error value within 1%.
{"title":"State of Health Estimation of Lithium-Ion Battery for Electric Vehicle Based on VMD-DBO-SVR Model","authors":"Liang Tong, Minghui Gong, Yong Chen, Rao Kuang, Yonghong Xu, Hongguang Zhang, Baoying Peng, Fubin Yang, Jian Zhang and Yiyang Li","doi":"10.1149/1945-7111/ad6935","DOIUrl":"https://doi.org/10.1149/1945-7111/ad6935","url":null,"abstract":"State-of-health (SOH) of lithium-ion batteries is an important indicator for measuring performance and remaining life. We propose an innovative prediction model that integrates variational mode decomposition (VMD), Dung Beetle optimizer (DBO), and support vector regression (SVR) algorithms. We extracted relevant features from the discharge characteristic curve and incremental capacity curve. We used Pearson and Spearman correlation coefficient methods for correlation analysis on the extracted health factors (HFs), selecting those that significantly impact SOH as input features. A DBO-SVR model was constructed to establish a nonlinear correlation between HFs and SOH, and the DBO algorithm was used to globally search and optimize the hyperparameters of the SVR model to improve its prediction accuracy. To reduce the impact of noise in battery signals on model performance, VMD technology was introduced to decompose battery signals into multiple intrinsic mode components, to extract useful features and remove noise to further improve prediction accuracy. The proposed method was validated using the NASA battery dataset and compared with other algorithm models. Results showed that the prediction model was significantly better than other models, with a maximum RMSE value of 0.84%, a maximum MAE value of 0.71%, and a stable prediction error value within 1%.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"10 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141942907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nanocomposite electrodes comprising LaSi2 and Si exhibit satisfactory charge–discharge cycling performances but their capacity is degraded after repeated cycles. A metallographic structure, in which the Si phase was finely dispersed in the LaSi2 matrix phase, was formed before cycling. The elastic LaSi2 relieved Si-generated stress and suppressed electrode disintegration. Contrarily, the LaSi2 phase in the metallographic structure was surrounded by the Si matrix phase after cycling. The positional relationship between the two phases was reversed, and LaSi2 could not relieve the stress. For a nanocomposite electrode containing CrSi2, which exhibits stiffness to withstand the Si-generated stress, the structural changes were suppressed after cycling, resulting in good cycling stability. Here, we considered that the addition of stiff silicides as a third phase to the LaSi2/Si composite could improve the cycle life. Thus, this study prepared nanocomposite electrodes containing elastic LaSi2, stiff MSi2 (where M = Cr, Mo, Nb, Ta, Ti, or W), and elemental Si and investigated their electrochemical performances. Reaction behaviors, such as the metallographic structure, electrode thickness, and phase transition, were also clarified. The LaSi2/NbSi2/Si electrode exhibited the best cycle life without changes in its metallographic structure owing to the synergistic effect of stiff and elastic silicides.
{"title":"Silicon-Based Nanocomposite Anodes with Excellent Cycle Life for Lithium-Ion Batteries Achieved by the Synergistic Effect of Two Silicides","authors":"Yasuhiro Domi, Hiroyuki Usui, Takumi Okasaka, Kei Nishikawa and Hiroki Sakaguchi","doi":"10.1149/1945-7111/ad69c6","DOIUrl":"https://doi.org/10.1149/1945-7111/ad69c6","url":null,"abstract":"Nanocomposite electrodes comprising LaSi2 and Si exhibit satisfactory charge–discharge cycling performances but their capacity is degraded after repeated cycles. A metallographic structure, in which the Si phase was finely dispersed in the LaSi2 matrix phase, was formed before cycling. The elastic LaSi2 relieved Si-generated stress and suppressed electrode disintegration. Contrarily, the LaSi2 phase in the metallographic structure was surrounded by the Si matrix phase after cycling. The positional relationship between the two phases was reversed, and LaSi2 could not relieve the stress. For a nanocomposite electrode containing CrSi2, which exhibits stiffness to withstand the Si-generated stress, the structural changes were suppressed after cycling, resulting in good cycling stability. Here, we considered that the addition of stiff silicides as a third phase to the LaSi2/Si composite could improve the cycle life. Thus, this study prepared nanocomposite electrodes containing elastic LaSi2, stiff MSi2 (where M = Cr, Mo, Nb, Ta, Ti, or W), and elemental Si and investigated their electrochemical performances. Reaction behaviors, such as the metallographic structure, electrode thickness, and phase transition, were also clarified. The LaSi2/NbSi2/Si electrode exhibited the best cycle life without changes in its metallographic structure owing to the synergistic effect of stiff and elastic silicides.","PeriodicalId":17364,"journal":{"name":"Journal of The Electrochemical Society","volume":"41 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141942969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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