Page 595 - Handbook of Battery Materials

17.4 Bulk Properties 569

Table 17.11 Values for E HOMO at HartreeFock level from Ref. [278] for several anions.

Anion E HOMO (eV)

HF/6-31G(d) HF/6-31 + G(d,p) HF/6-311 + G(2d,p)

− –9.548 –10.309 –10.327
BF 4
−
CF 3 BF 3 –7.780 –8.506 –8.499
− –7.774 –8.464 –8.451
C 2 F 5 BF 3
− –7.921 –8.595 –8.580
n-C 3 F 7 BF 3
− –8.063 –8.719 –8.702
n-C 4 F 9 BF 3
− –7.641 –8.312 –8.300
(CF 3 ) 2 BF 2
(CF 3 ) 3 BF − –8.436 –9.065 –9.044
(CF 3 ) 4 B − –9.241 –9.830 –9.804
(C 6 H 5 ) 4 B − –4.692 –4.978 –4.991
(C 6 F 5 ) 4 B − –6.550 –6.901 –
−
PF 6 –10.713 –11.268 –11.234
− –8.858 –9.441 –9.420
CF 3 PF 5
−
(CF 3 ) 2 PF 4 –9.008 –9.580 –9.580
− –8.089 –8.643 –8.632
(CF 3 ) 3 PF 3
−
(CF 3 ) 4 PF 2 –7.426 –7.972 –7.968
(CF 3 ) 5 PF − –7.503 –8.034 –8.027
(CF 3 ) 6 P − –7.578 –8.100 –8.089
− –8.314 –8.852 –8.836
(C 2 F 5 ) 3 PF 3
to vary both the computational method and the corresponding basis set. Starting
with an appropriate computational method and a minimal basis set, a systematic
enhancement of the latter should in an ideal case result in a convergence of the
orbital energies to a constant limit. Otherwise, one has to alter the computational
method and test all the basis sets again. It is possible that one will obtain different
constant limits of the orbital energies with different computational methods. In
this case it is not possible to select the ‘true’ value without experimental studies.

17.4.3
Passivation and Corrosion Abilities of Lithium Salt Electrolytes

Electrolytes in energy storage devices react not only with the active material, such
as activated carbon in double layer capacitors (DLCs) or carbon and metal oxides in
lithium-ion batteries on the anode and cathode respectively. The active material is
fixed on metal foils that serve as current collector. So the foil is also in contact with
the electrolyte and undergoes electrochemical reactions.
In energy storage investigations, corrosion and protection of aluminum are
of special interest. In lithium-ion batteries, the active material, for example, a
transition metal compound (LiMO 2 ,M = V, Cr, Fe, Co, Ni,...) [279–283], is fixed
on aluminum, forming the cathode. Due to its high conductance, high available