A layered nonstoichiometric lepidocrocite-type sodium titanate anode material for sodium-ion batteries

Yin, Wei; Alvarado, Judith; Barım, Gözde; Scott, Mary; Peng, Xiaoyuan; Doeff, Marca M.

doi:10.1557/s43581-021-00008-6

Cited by 5 publications

(27 citation statements)

References 29 publications

(41 reference statements)

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“…The t 2g and e g levels are associated with the twofold splitting of 3d electron energies in the octahedral ligand field. 12,13,48,49 and peak L 3 -t 2g positions shift toward lower energies as the electrode is discharged confirming that Ti is reduced. 50…”

Section: ■ Results and Discussionmentioning

confidence: 72%

“…An average operating potential of 0.6 V versus Na + /Na was measured, similar to that of other lepidocrocite type sodium titanates, and lower than that of anatase TiO 2 (0.8 V vs Na + / Na). 9,13,17,45 Figure 5b displays capacity retention and Coulombic efficiency of the LTO-30% C heterostructure. The first cycle was removed for clarity.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Appropriate electrode engineering and judicious choice of electrolytic solution has been shown to improve the first cycle Coulombic efficiency in sodium half-cells. 13 To improve first cycle inefficiency and alleviate capacity fade in the first 30 cycles, we employed an ether-based electrolyte instead of a conventional carbonate-based electrolyte. A sodium cell containing the LTO-23.4% C heterostructure was prepared with 0.5 M NaBPh 4 in DEGDME and cycling performance compared with a cell containing 1.0 M NaPF 6 in ethylene carbonate−diethylene carbonate.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Conversely, the poorest performance was observed for the cell with LTO nanosheets, which faded to 57% of the second discharge capacity after 10 cycles. Appropriate electrode engineering and judicious choice of electrolytic solution has been shown to improve the first cycle Coulombic efficiency in sodium half-cells . To improve first cycle inefficiency and alleviate capacity fade in the first 30 cycles, we employed an ether-based electrolyte instead of a conventional carbonate-based electrolyte.…”

Section: Resultsmentioning

confidence: 99%

“…Previously, our group reported on several Na + insertion anodes based on layered titanates showing high capacities (≥200 mA h g –1 ) and low sodium intercalation potentials (∼0.3–0.6 V vs. Na + /Na). − Some of them are isostructural to the lepidocrocite mineral γ-FeOOH, which has a corrugated layered structure. Lepidocrocite-type titanates have the general formula of A x Ti 2– y M y O 4 , where A = K, Rb, or Cs, and M represents Li, Mg, Mn, Fe, Co, Ni, Cu, Zn, or a vacancy. ,− Zigzag-type layered structures of lepidocrocite titanates consist of edge and corner-shared TiO 6 octahedra where A cations are located between the transition metal layers and M cations reside within layers.…”

Section: Introductionmentioning

confidence: 99%

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Heterostructured Lepidocrocite Titanate-Carbon Nanosheets for Electrochemical Applications

Barım

Dhall

Arca

et al. 2021

ACS Appl. Nano Mater.

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Lepidocrocite-type titanates that reversibly intercalate sodium ions at low potentials (~0.6 V vs. Na/Na + ) are promising anode candidates for sodium ion batteries. However, large amounts of carbon additives are often used to improve their electrical conductivity and overcome poor cycling performance in the electrode composites. To ameliorate electronic transport issues of lepidocrocite titanate (K0.8Ti1.73Li0.27O4, KTL) in sodium ion batteries, we have designed and synthesized heterostructures of exfoliated lepidocrocite-type titanium oxide nanosheets (LTO) with alternating carbon layers via a solutionbased self-assembly approach. Positively charged dopamine (Dopa) was used as the carbon precursor and intercalated between negatively charged exfoliated titania nanosheets through electrostatic interaction. Dopamine-intercalated LTO was then annealed under argon to form conductive carbon layers between titania sheets. The carbon content in the heterostructures was controlled by modifying self-assembly conditions (i.e. pH, stirring duration, and Dopa to LTO ratio). Electrodes were prepared using carbonized heterostructures (LTO-C) without adding more carbon to the composites and tested in sodium half-cell configurations. Higher capacities and improved capacity retention over 250 cycles, and lower impedance were observed as the carbon content of LTO-C heterostructures was increased from 0% (LTO nanosheets) to 30%. These results indicate that the self-assembly approach for 2D heterostructured electrode materials is a promising strategy to overcome electronic transport limitations of layered transition metal oxides and improve their electrochemical performance for next generation energy storage applications.

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Section: ■ Results and Discussionmentioning

confidence: 72%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Heterostructured Lepidocrocite Titanate-Carbon Nanosheets for Electrochemical Applications

Barım

Dhall

Arca

et al. 2021

ACS Appl. Nano Mater.

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Tailoring Stepped Layered Titanates for Sodium-Ion Battery Applications

Yin,

Ahn,

Barim

et al. 2024

Acc. Mater. Res.

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Metrics & MoreArticle Recommendations * sı Supporting Information CONSPECTUS: Concerns about sustainability and supply chain issues associated with lithium-ion batteries (LIBs) have led researchers and companies around the world to investigate alternative technologies. Of all the so-called "beyond LIBs", sodium-ion batteries (NIBs) are in the most advanced stage of development, and are being considered for grid storage applications as well as moderate-range electric vehicles. While graphite is the most commonly used anode material for LIBs, hard carbons are used in NIBs because sodium insertion into graphite does not occur to a useful extent. Other possibilities, based on cost and availability arguments, are titanates, which are generally denser than disordered carbons, meaning more material can be packed into a given volume, leading potentially to greater energy density. We have researched stepped layered titanates for use as anode materials, focusing on two types of structures. The first is "sodium nonatitanate" or NNT, with the composition NaTi 3 O 6 (OH)•2H 2 O having six Ti 4+ O 6 octahedra joined together in steps to form layers with sodium ions and water in-between. The lepidocrocite-type titanate structure, contains zigzag layers (or steps one Ti 4+ O 6 unit across). These exist in a wide range of compositions, and contain large exchangeable cations between the layers. An unusual feature of both NNT and the lepidocrocite titanates is the very low potentials (0.3−0.5 V vs Na + /Na) at which they insert sodium. This makes them particularly attractive for anode applications. Another interesting feature is the ability to tailor the electrochemical properties by various modifications, such as heat-treatment to remove water and change the structure, introduction of vacancies, ion-exchange, surface modifications, and carbon coating or graphene wrapping, all of which alter the electrochemical properties. Finally, heterostructuring (interleaving titanate layers with carbon) results in new materials with different redox properties. For all the titanates, the first cycle Coulombic efficiency (C.E.) is very sensitive to the binder used in the electrode fabrication and the electrolyte used. Because sodium insertion occurs at such a low potential, some electrolyte and binder are irreversibly reduced during the first cycle to form a protective solid electrolyte interphase (SEI). In a full cell, it is important to maximize the C.E. because all the cyclable sodium must come from the cathode, so cells must be overbuilt to compensate for these losses. Proper selection of binder and electrolyte results in improved cycling performance and minimal first cycle losses. Finally, examples of full cells containing some of the materials under discussion are provided.

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Lepidocrocite Titanate–Graphene Composites for Sodium-Ion Batteries

et al. 2022

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To overcome electronic transport issues of layered titanates in sodium-ion batteries, we have designed and synthesized composites of lepidocrocite titanates with reduced graphene oxide through a solution-based self-assembly approach. The parent lepidocrocite titanate (K 0.8 [Ti 1.73 Li 0.27 ]O 4 ) was exfoliated by a softchemical approach and mechanical shaking. Exfoliated layered titania sheets (LTO) were then combined with reduced graphene oxide (rGO) layers to assemble into composites through flocculation. Countercations (i.e., Mg 2+ ) were used for the selfassembly of negatively charged titania and rGO nanosheets via flocculation. The carbon content in the composites was tuned from 1 to 17% by changing the ratio of titania and rGO sheets in the mixed colloidal suspensions. Electrodes were processed with as-prepared LTO−rGO composites without any carbon additives and tested in sodium half-cell configurations. Mg + -coagulated LTO−rGO composite electrodes deliver higher capacities than electrodes prepared with coagulated titania sheets and 10% acetylene black in sodium half-cells and display good capacity retention after 50 cycles. Electrochemical impedance spectroscopy results indicate lower charge transfer resistance for LTO−14.5%rGO composites than that of coagulated titania sheets with 10% acetylene black. A power law analysis of cells containing the composites indicate a hybrid mechanism consisting of both surface and diffusional processes. A comparison with a similar system, that of dopaminederived LTO-C heterostructures, reveal significant differences. While capacities showed a strong dependence on carbon content for the dopamine-derived materials, this was not true for the LTO−rGO composites. Instead, the highest capacity was obtained for the 14.5% rGO sample, with a lower value obtained for the 17% rGO sample. A greater proportion of the redox processes were surface rather than diffusional in nature for the LTO−rGO composites as well.

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A layered nonstoichiometric lepidocrocite-type sodium titanate anode material for sodium-ion batteries

Cited by 5 publications

References 29 publications

Heterostructured Lepidocrocite Titanate-Carbon Nanosheets for Electrochemical Applications

Heterostructured Lepidocrocite Titanate-Carbon Nanosheets for Electrochemical Applications

Tailoring Stepped Layered Titanates for Sodium-Ion Battery Applications

Lepidocrocite Titanate–Graphene Composites for Sodium-Ion Batteries

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