Study of the Relaxational Polarization Dynamics of the LiPON Solid Electrolyte

Determination of Diffusion Coefficients of Lithium in Solid Electrolyte LiPON

“…As was shown in [2], platinum electrodes contain a large amount of dissolved lithium and, depending on the polarity, extraction or insertion of lithium occurs. In addition, according to the results of [3], a Faraday process takes place on platinum electrodes, and the leakage current circuit is closed by the flow of the resulting lithium atoms. In other words, there are two oppositely directed diffusion flows: lithium ions and atoms.…”

“…Figure 2, along with the experimental Nyquist diagram, shows a diagram calculated by Equations (2) and (3) for the following values of the parameters of structural elements: R el = 180 Ω, R lk = 11,000 Ω, C dl = 2.1 × 10 −7 F, A W1 = 10 4 Ω•s −1/2 , and A W2 = 9 × 10 4 Ω•s −1/2 . The value R el = 180 Ω was obtained by the method described in [3] and was not used for fitting. The rest of the parameters were selected so that the deviation from the experimental curve, characterized by RSS (residual sum of squares), was minimal.…”

“…In [3], the relative dielectric permeability of LiPON was estimated as ε r ≈ 250, and the remaining parameters were d Li = 1.56 × 10 −10 m, δ = 10 −6 m, A W1 = 10 4 Ω•s −1/2 , and S = 6.4 × 10 −5 m 2 . Their substitution in Equation (5) gives the value of the diffusion coefficient D 1 = 1.5 × 10 −11 cm 2 /s, which is in good agreement with the data of [4,5].…”

“…where τ 0 is the relaxation time of the concentration of lithium ions due to reduction reactions at a cathode. In [3], the relaxation time during the discharge of Pt/LiPON/Pt through 1 MΩ was determined as τ 0 = 51.3 s. In this case, Equation ( 6) gives the concentration value in the near-cathode layer by C Li + = 2.1 × 10 22 cm −3 . For the obtained values of the concentration and mobility of lithium ions, the conductivity was σ =1.9 × 10 −6 S•cm −1 .…”

“…It should be noted that the specific capacity of SSLIB is significantly lower than the capacity of batteries with liquid electrolytes. Thus, in the SSLIB of electrochemical system Li x V 2 O 5 /LiPON/Si@O@Al [1], the specific capacity is 5.6 µA•h/cm 2 and 6.5 mA•h/cm 3 , while the thin-film cells of the same system with a liquid electrolyte have a maximum capacity of 200 µA•h/cm 2 and 20 mA•h/cm 3 . The decrease in capacity is due to the lower ionic conductivity of the solid LiPON electrolyte compared to the liquid electrolyte.…”