GITT量測設置範例

Reference :https://onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1002%2Fadma.201705580&file=adma201705580-sup-0001-S1.pdf

• A cell was charged or discharged at 30 mA g-1 rate for 20 min, followed by a 3 h open circuit step to allow relaxation back to equilibrium (defined as dE/dt < 0.2 mV h-1). 
• The procedure was continued until the charge (or discharge) voltage reached 1.8 V (0.2 V).
• The Zn2+ ion diffusion coefficients could be calculated using the following equation first outlined by Weppner and Huggins:

where, I is the current (A); 

Vm is the molar volume of the ZVO (cm3 mol-1); 

ZA is the charge number;

F is the Faraday’s constant (96485 C mol-1); 

S is the electrode/electrolyte contact area (cm2); 

dE/dδ is the slope of the coulometric titration curve, found by plotting the steady state

voltages E (V) measured after each titration step δ; 

dE/d√t is the slope of the linearized plot of the potential E (V) during the current pulse of duration t (s).

If sufficiently small currents are applied for short time intervals, so that dE/d√t can be considered linear and the coulometric titration curve can be also considered linear over the composition range involved in that step, the above equation can be simplified into:

Here, τ is the duration of the current pulse (s); 

nm is the number of moles (mol); 

Vm is the molar volume of the electrode (cm3 mol-1); 

S is the electrode/electrolyte contact area (cm2);

ΔEs is the steady-state voltage change, due to the current pulse and ΔEt is the voltage change during the constant current pulse, eliminating the iR drop.