$(20+$extra $\frac{5}{100}$ There are two eminent processes involved in lithiation of graphite $(L{i}^{+}$intercalation into graphite$)$ as shown below: $(1)L{i}^{+}$penetration into solid$-$electrolyte interface $($SEI$)$ layer, $(2)L{i}^{+}$in the SEI layer intercalated into graphite.

e$)$

To investigate the effect of an additive called VC$,$ two different half cells are built up$.$ Both of them consisted of graphite as a working electrode and lithium metal as a counter electrode with a lithium ion$-$containing electrolyte. The first cell as a control did not include VC in its electrolyte $(-$VC$)$ while the second one has VC$.$ Then, the following Nyquist plot was obtained with those cells.

ideal gas constant $(R)=8\mathrm{.}314\frac{J}{m}o\frac{l}{K}$

$R\frac{T}{F}$ at room temperature $=26mV$

$MW=27$ for $Al$ and $127$ for I.

Faraday constant $(F)=96500\frac{C}{m}$ole

$log(e)=0\mathrm{.}434$

$M=mo\frac{l}{L}={10}^{-3}mo\frac{l}{c}{m}^3$

ACE$312.$EChem.Hyun$-$Kon Song

final. $160614$

Name:

Based on the eminent processes described above, an equivalent circuit would be used to interpret the impedance data. The following equivalent circuit consists of two parts responsible for $(1)$ SEI penetration and $(2)$ intercalation.

where $R=$ resistor $($ohm$)$ and CPE or $W=$ constant phase element with $[T]=oh{m}^{-1}se{c}^P,[P]=$ no unit$).$

$(1)$ Guess values of parameters of each element without using software. Assume CPE can be replaced by a pure capacitor $($that is to say, $P=1).$ Fill out the table below. You should show how you can obtain your guess in your answer book.

$\backslash$table$[[,$VC$,+$VC$],[$Rs$,,],[$CPESE: T$,,],[$CPEsel: P$,,],[$RSEl$,,],[$CPEd: T$,,],[$CPE $1$ : P$,,],[$Rct$,,],[$Wct: T$,,],[$Wct: P$,,]]$

$(2)$ What is the effect or function of $VC?$ You can deduce your own conclusion from comparing the parameter values between $-VC$ and $+VC.$