Stoichiometry and volume dependent transport in lithium ion memristive devices

Orfanidou, C M; Ioannou, Panagiotis S.; Kyriakides, Evripides; Nicolaou, Christiana Th.; Mihailescu, Ion N.; Nguyen, Van Son; Van, Hoang Nguyen; Schneegans, Olivier; Giapintzakis, J.

doi:10.1063/1.5051568

Cited by 4 publications

(3 citation statements)

References 22 publications

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“…All transport curves were recorded at >2.5 V, beyond the Schottky barrier for nickel-contacted devices. From Figure a, we observe increased conductivity (σ) as lithium content decreases, consistent with previous reports for Li x CoO 2 . ,,, Our resistivities (ρ) tend to be ∼1–2 orders greater than most bulk measurements at 300 K, but are on par with similar thickness Li x CoO 2 films . This increased ρ is unsurprising, given the reduced dimensionality of our nanoflakes and the suggested surface scattering this includes.…”

Section: Results and Discussionsupporting

confidence: 89%

“…24,27,38,41 Our resistivities (ρ) tend to be ∼1−2 orders greater than most bulk measurements at 300 K, 19 but are on par with similar thickness Li x CoO 2 films. 47 This increased ρ is unsurprising, given the reduced dimensionality of our nanoflakes and the suggested surface scattering this includes. Additionally, a temperature-dependence scan was performed to assess transport in Li x CoO 2 .…”

Section: Contact Analysismentioning

confidence: 95%

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Electrical Characterization and Charge Transport in Chemically Exfoliated 2D Li_xCoO₂ Nanoflakes

et al. 2020

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Transition metal oxides often possess complex interactions between charge, spin, lattice, and orbital degrees of freedom, resulting in correlated electronic and magnetic phases. Li x CoO2, one of the most commonly used cathode choices in rechargeable batteries, is a prime example of this, evidencing numerous correlated effects evolving as a function of lithium content (x). Due to the strong electrostatic forces that govern the layered nature of this material, however, most investigations of these behaviors have been on bulk forms (>0.1 mm). In the two-dimensional (2D) limit, correlated effects are more easily tuned and studied; therefore, it is of fundamental importance to develop an experimental basis for investigation. Herein, a two-step process is utilized to chemically delithiate and exfoliate LiCoO2 single crystals and study nanoflakes 10–60 nm thick, with 0.37 < x < 0.8. An initial electrical characterization of this new form reflects bulk conduction properties, verifying the reliability of this new technique: temperature-dependent resistance measurements indicate an insulating 2D variable ranging hopping conduction for samples of x > 0.75, and metallic characteristics with a finite residual conductance for x < 0.75. However, these thin flakes also exhibit correlated characteristics less commonly observed and understood in Li x CoO2. An energy barrier upon contact formation is observed for all conditions, independent of lithium concentration and electrode work function, suggesting enhanced correlated effects due to reduced dimensionality. Additionally, charge-ordering phenomena in the temperature-dependent resistance occur under specific preparation conditions. These anomalies are markedly larger in magnitude than previous accounts in bulk systems and are also found in low lithium ranges of x < 0.5, matching theoretical predictions not commonly observed experimentally. This work utilizes a new approach to gain insight behind the complex transport phenomena inherent in Li x CoO2, providing a new opportunity to understand these correlated effects using a 2D, single-crystal form.

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Section: Results and Discussionsupporting

confidence: 89%

Section: Contact Analysismentioning

confidence: 95%

Electrical Characterization and Charge Transport in Chemically Exfoliated 2D Li_xCoO₂ Nanoflakes

et al. 2020

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“…To date, there has been only one report on the switching characteristics for the Li‐spinel LiFe 5 O 8 . Besides that, the scarce literature on Li‐based memristor architectures has focused on layered hexagonal Li x CoO 2 , layered LiNbO x and perovskite LiLaTiO 3 …”

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confidence: 99%

Lithium‐Battery Anode Gains Additional Functionality for Neuromorphic Computing through Metal–Insulator Phase Separation

et al. 2020

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Specialized hardware for neural networks requires materials with tunable symmetry, retention, and speed at low power consumption. The study proposes lithium titanates, originally developed as Li‐ion battery anode materials, as promising candidates for memristive‐based neuromorphic computing hardware. By using ex‐ and in operando spectroscopy to monitor the lithium filling and emptying of structural positions during electrochemical measurements, the study also investigates the controlled formation of a metallic phase (Li7Ti5O12) percolating through an insulating medium (Li4Ti5O12) with no volume changes under voltage bias, thereby controlling the spatially averaged conductivity of the film device. A theoretical model to explain the observed hysteretic switching behavior based on electrochemical nonequilibrium thermodynamics is presented, in which the metal‐insulator transition results from electrically driven phase separation of Li4Ti5O12 and Li7Ti5O12. Ability of highly lithiated phase of Li7Ti5O12 for Deep Neural Network applications is reported, given the large retentions and symmetry, and opportunity for the low lithiated phase of Li4Ti5O12 toward Spiking Neural Network applications, due to the shorter retention and large resistance changes. The findings pave the way for lithium oxides to enable thin‐film memristive devices with adjustable symmetry and retention.

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Tunable electrical field-induced metal-insulator phase separation in LiCoO2 synaptic transistor operating in post-percolation region

Zhang

Chen

et al. 2023

Nano Energy

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Stoichiometry and volume dependent transport in lithium ion memristive devices

Cited by 4 publications

References 22 publications

Electrical Characterization and Charge Transport in Chemically Exfoliated 2D Li_xCoO₂ Nanoflakes

Electrical Characterization and Charge Transport in Chemically Exfoliated 2D Li_xCoO₂ Nanoflakes

Lithium‐Battery Anode Gains Additional Functionality for Neuromorphic Computing through Metal–Insulator Phase Separation

Tunable electrical field-induced metal-insulator phase separation in LiCoO2 synaptic transistor operating in post-percolation region

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Stoichiometry and volume dependent transport in lithium ion memristive devices

Cited by 4 publications

References 22 publications

Electrical Characterization and Charge Transport in Chemically Exfoliated 2D LixCoO2 Nanoflakes

Electrical Characterization and Charge Transport in Chemically Exfoliated 2D LixCoO2 Nanoflakes

Lithium‐Battery Anode Gains Additional Functionality for Neuromorphic Computing through Metal–Insulator Phase Separation

Tunable electrical field-induced metal-insulator phase separation in LiCoO2 synaptic transistor operating in post-percolation region

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Electrical Characterization and Charge Transport in Chemically Exfoliated 2D Li_xCoO₂ Nanoflakes

Electrical Characterization and Charge Transport in Chemically Exfoliated 2D Li_xCoO₂ Nanoflakes