Extreme Rate Capability Cycling of Porous Silicon Composite Anodes for Lithium‐Ion Batteries

Abstract

Silicon‐based anodes have the potential to increase the capacity of lithium‐ion batteries but suffer from irreversible damage due to their volume expansion. Capacity‐controlled cycling has emerged as a promising method for silicon‐based anodes; however, few studies have evaluated how high C‐rates affect cycle life under capacity‐controlled cycling. Here, we examine how a repetitive cycling at high C‐rates and long cycle numbers affects the electrochemical performance. This extreme rate capability test (cycling between C/5 and 8C for 560 cycles) illustrates the robustness of the silicon‐composite anodes and indicates that the anode continues to perform well at C/5 for another 120 cycles after the 560‐cycle‐testing at 8C. When the C‐rate increases, there is a drop in capacity, which can be attributed to an increase in the polarization resistance of the anode, which increases as the cell ages. The superior rate capability of silicon‐composite anodes is promising for applications requiring fast charge‐discharge rates.

Mechanism Study on Garnet-type Li6.4La3Zr1.4Ta0.6O12 Regulating the Solid Electrolyte Interphases of Si/C Anodes

“…The reduction peak at 0.01 V during the first cycle is observed, which is due to the conversion of crystalline silicon to amorphous silicon. In the second cycle, two reduction peaks at 0.01 and 0.15 V correspond to the formation of Li-Si alloy, and two oxidation peak at 0.35 and 0.53 V are assigned to dealloying process of the Li-Si alloy [21][22][23] . In addition, the rate performances of the half-cells of PP-10 μm-LLZTO and bare PP separators are compared (Fig.…”

Prelithiation Effects in Enhancing Silicon-Based Anodes for Full-Cell Lithium-Ion Batteries Using Stabilized Lithium Metal Particles

“…Galvanostatic intermittent titration technique (GITT) and cyclic voltammetry (CV) tests were performed on prelithiated and control Si/PPAN half-cells after 3 formation cycles at 0.15 A g –1 , with Li metal as the reference and counter electrodes. For GITT, each current pulse (0.15 A g –1 ) was applied for 360 s, followed by a relaxation for 4500 s during lithiation and delithiation between 0.01 and 1 V. The amount of Li alloying with Si was calculated for each current pulse by applying eq , normalΔ δ = M normalB italiczF m normalB I τ where M B is the atomic weight of Si (g mol –1 ), z is the valence of mobile species (Li + ), F is the Faraday’s constant (A s mol –1 ), m B is the mass of Si in the electrode (g), I is the current applied (A), and τ is the pulse duration (s). The apparent diffusion coefficient of Li was also calculated by eq , D normalL normali + = 4 π τ true( m normalB V normalm M normalB A true) 2 true( normalΔ E normals normalΔ E τ true) 2 where D is the diffusion coefficient (cm 2 s –1 ), V m is the molar volume (cm 3 mol –1 ), A is the electrode area (cm 2 ), Δ E s is the change in steady state voltage, and Δ E τ is the change in transit voltage during pulse without Ohmic drop.…”

“…For GITT, each current pulse (0.15 A g –1 ) was applied for 360 s, followed by a relaxation for 4500 s during lithiation and delithiation between 0.01 and 1 V. The amount of Li alloying with Si was calculated for each current pulse by applying eq , where M B is the atomic weight of Si (g mol –1 ), z is the valence of mobile species (Li + ), F is the Faraday’s constant (A s mol –1 ), m B is the mass of Si in the electrode (g), I is the current applied (A), and τ is the pulse duration (s). The apparent diffusion coefficient of Li was also calculated by eq , where D is the diffusion coefficient (cm 2 s –1 ), V m is the molar volume (cm 3 mol –1 ), A is the electrode area (cm 2 ), Δ E s is the change in steady state voltage, and Δ E τ is the change in transit voltage during pulse without Ohmic drop.…”

“…9,13,23 Galvanostatic intermittent titration technique (GITT) and cyclic voltammetry (CV) tests were performed on prelithiated and control Si/ PPAN half-cells after 3 formation cycles at 0.15 A g −1 , with Li metal as the reference and counter electrodes. For GITT, each current pulse (0.15 A g −1 ) was applied for 360 s, followed by a relaxation for 4500 s during lithiation and delithiation between 0.01 and 1 V. The amount of Li alloying with Si was calculated for each current pulse by applying eq 1 24,25…”