Voltage Hysteresis of Silicon Nanoparticles: Chemo‐Mechanical Particle‐SEI Model

Köbbing, Lukas; Latz, Arnulf; Horstmann, Birger

doi:10.1002/adfm.202308818

Cited by 14 publications

(4 citation statements)

References 101 publications

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“…Mechanical stress caused by the large volume expansion is often given as a reason. 37,38 Durdel et al 39 proposed another explanation based on the strong relaxation behavior of Si. According to this hypothesis, charge transfer requires large overpotentials even at low (de-)lithiation rates.…”

Section: Resultsmentioning

confidence: 99%

Active Material Lithiation in Gr/SiOx Blend Anodes at Increased C-Rates

Knorr,

Li,

Schamel

et al. 2024

J. Electrochem. Soc.

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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.

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Section: Resultsmentioning

confidence: 99%

Active Material Lithiation in Gr/SiOx Blend Anodes at Increased C-Rates

Knorr,

Li,

Schamel

et al. 2024

J. Electrochem. Soc.

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“…Silicon (Si) anode material is one of the most promising alternatives for graphite, since its high theoretical capacity of 3579 mAh/g for Li 15 Si 4 is about 10 times higher than that of graphite [5]. However, the disadvantages of the Si anode are low electrical conductivity and large volume changes on cycling, which leads to fast capacity fading and a poor cycle life [6][7][8]. Many studies have reported techniques for preparing silicon/carbon (Si/C) composites with different graphite or carbon precursors, which is an effective approach to suppress the severe capacity degradation of pure Si [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Effect of Graphene on the Performance of Silicon–Carbon Composite Anode Materials for Lithium-Ion Batteries

Ni,

Xia,

Liu

et al. 2024

Materials

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(Si/graphite)@C and (Si/graphite/graphene)@C were synthesized by coating asphalt-cracked carbon on the surface of a Si-based precursor by spray drying, followed by heat treatment at 1000 °C under vacuum for 2h. The impact of graphene on the performance of silicon–carbon composite-based anode materials for lithium-ion batteries (LIBs) was investigated. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) images of (Si/graphite/graphene)@C showed that the nano-Si and graphene particles were dispersed on the surface of graphite, and thermogravimetric analysis (TGA) curves indicated that the content of silicon in the (Si/graphite/graphene)@C was 18.91%. More bituminous cracking carbon formed on the surface of the (Si/graphite/graphene)@C due to the large specific surface area of graphene. (Si/Graphite/Graphene)@C delivered first discharge and charge capacities of 860.4 and 782.1 mAh/g, respectively, initial coulombic efficiency (ICE) of 90.9%, and capacity retention of 74.5% after 200 cycles. The addition of graphene effectively improved the cycling performance of the Si-based anode materials, which can be attributed to the reduction of electrochemical polarization due to the good structural stability and high conductivity of graphene.

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“…It has been suggested that this hysteresis could arise as a consequence of complex mechanical behavior involving the SEI under large strains. 22 We hypothesize that the hysteresis will decrease the driving force for overhang equalization to the point that it may not happen in Si electrodes. Considering Fig.…”

mentioning

confidence: 99%

“…Regardless of how slow the cell is cycled or how long the cell is allowed to rest, a sizable voltage gap will always exist (Fig. 2d), [22][23][24] and thus changes in lithium content will require very different potentials depending on the direction of change. It has been suggested that this hysteresis could arise as a consequence of complex mechanical behavior involving the SEI under large strains.…”

mentioning

confidence: 99%

Inactive Overhang in Silicon Anodes

O’Brien,

Trask,

Salpekar

et al. 2024

J. Electrochem. Soc.

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Li-ion batteries contain excess anode area to improve manufacturability and prevent Li plating. These overhang areas in graphite electrodes are active but experience decreased Li+ flux during cycling. Over time, the overhang and the anode portions directly opposite to the cathode can exchange Li+, driven by differences in local electrical potential across the electrode, which artificially inflates or decreases the measured cell capacity. Here, we show that lithiation of the overhang is less likely to happen in silicon anodes paired with layered oxide cathodes. The large voltage hysteresis of silicon creates a lower driving force for Li+ exchange as lithium ions transit into the overhang, rendering this exchange highly inefficient. For crystalline Si particles, Li+ storage at the overhang is prohibitive, because the low potential required for the initial lithiation can act as thermodynamic barrier for this exchange. We use micro-Raman spectroscopy to demonstrate that crystalline Si particles at the overhang are never lithiated even after cell storage at 45oC for four months. Because the anode overhang can affect the forecasting of cell life, cells using silicon anodes may require different methodologies for life estimation compared to those used for traditional graphite-based Li-ion batteries.

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Voltage Hysteresis of Silicon Nanoparticles: Chemo‐Mechanical Particle‐SEI Model

Cited by 14 publications

References 101 publications

Active Material Lithiation in Gr/SiOx Blend Anodes at Increased C-Rates

Active Material Lithiation in Gr/SiOx Blend Anodes at Increased C-Rates

Effect of Graphene on the Performance of Silicon–Carbon Composite Anode Materials for Lithium-Ion Batteries

Inactive Overhang in Silicon Anodes

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