Advanced lithium and lithium-ion rechargeable batteries for automotive applications
Creators: name: Damen, Libero <1980>
Publisher: name: Alma Mater Studiorum - Università di Bologna
Year: 2011
Subjects: CHIM/02 Chimica fisica

description: The worldwide demand for a clean and low-fuel-consuming transport promotes the 
development  of  safe,  high  energy  and  power  electrochemical  storage  and  conversion 
systems.  Lithium-ion  batteries  (LIBs)  are  considered  today  the  best  technology  for  this 
application as demonstrated by the recent interest of automotive industry in hybrid (HEV) 
and electric vehicles (EV) based on LIBs. This thesis work, starting from the synthesis and 
characterization  of  electrode  materials  and  the  use  of  non-conventional  electrolytes, 
demonstrates that LIBs with novel and safe electrolytes  and electrode materials meet the 
targets of specific energy and power established by U.S.A. Department of Energy (DOE) 
for automotive application in HEV and EV. 
In  chapter  2  is  reported  the  origin  of  all  chemicals  used,  the  description  of  the 
instruments used for synthesis and chemical-physical characterizations,   the       electrodes 
preparation, the batteries configuration and the electrochemical characterization procedure 
of electrodes and batteries. 
Since  the  electrolyte  is  the  main  critical  point  of  a  battery,  in  particular  in  large-
format  modules,  in  chapter  3  we  focused  on  the  characterization  of  innovative  and  safe 
electrolytes  based  on  ionic  liquids  (characterized  by  high  boiling/decomposition  points, 
thermal and electrochemical stability and appreciable conductivity) and mixtures of ionic 
liquid with conventional electrolyte.  
In chapter 4 is discussed the microwave accelerated sol–gel synthesis of the carbon-
coated lithium iron phosphate (LiFePO 4 -C), an excellent cathode material for LIBs thanks 
to  its  intrinsic  safety  and  tolerance  to  abusive  conditions,  which  showed  excellent 
electrochemical performance in terms of speciﬁc capacity and stability.  
In    chapter    5    are    presented    the    chemical-physical    and    electrochemical 
characterizations of graphite and titanium-based anode materials in different electrolytes. 
We also characterized a new anodic material, amorphous SnCo alloy, synthetized with a 
nanowire morphology that showed to strongly enhance the electrochemical stability of the 
material during galvanostatic full charge/discharge cycling. 
Finally,  in  chapter  6,  are  reported  different  types  of  batteries,  assembled  using  the 
LiFePO 4 -C  cathode  material,  different  anode  materials  and  electrolytes,  characterized  by 
deep  galvanostatic  charge/discharge  cycles  at  different  C-rates  and  by  test  procedures  of the  DOE  protocol  for  evaluating  pulse  power  capability  and  available  energy.  First,  we 
tested a battery with the innovative cathode material LiFePO 4 -C and conventional graphite 
anode and carbonate-based electrolyte (EC DMC LiPF 6  1M) that demonstrated to surpass 
easily  the  target  for  power-assist  HEV  application.  Given  that  the  big  concern  of 
conventional lithium-ion batteries is the flammability of highly volatile organic carbonate-
based electrolytes, we made safe batteries with electrolytes based on ionic liquid (IL). In 
order  to  use  graphite  anode  in  IL  electrolyte  we  added  to  the  IL  10%  w/w  of  vinylene 
carbonate (VC) that produces a stable SEI  (solid electrolyte interphase)  and prevents the 
graphite exfoliation phenomenon. Then we assembled batteries with LiFePO 4 -C cathode, 
graphite anode and PYR 14 TFSI 0.4m LiTFSI with 10% w/w of VC that overcame the DOE 
targets for HEV application and were stable for over 275 cycles. We also assembled and 
characterized ―high safety‖ batteries with electrolytes based on pure IL, PYR 14 TFSI with 
0.4m  LiTFSI  as  lithium  salt,  and  on  mixture  of  this  IL  and  standard  electrolyte 
(PYR 14 TFSI 50% w/w and EC DMC LiPF 6  50% w/w), using titanium-based anodes (TiO 2  
and  Li 4 Ti 5 O 12 )  that  are  commonly  considered  safer  than  graphite  in  abusive  conditions. 
The batteries bearing the pure ionic liquid did not satisfy the targets for HEV application, 
but the batteries with Li 4 Ti 5 O 12  anode and 50-50 mixture electrolyte were able to surpass 
the  targets.  We  also  assembled  and  characterized  a  lithium  battery  (with  lithium  metal 
anode)     with     a     polymeric     electrolyte     based     on     poly-ethilenoxide     (PEO 20 –
LiCF 3 SO 3 +10%ZrO 2 ),  which  satisfied  the  targets  for  EV  application  and  showed  a  very 
impressive cycling stability. 
In conclusion, we developed three lithium-ion batteries of different chemistries that 
demonstrated  to  be  suitable  for  application  in  power-assist  hybrid  vehicles:  graphite/EC 
DMC LiPF 6 /LiFePO 4 -C, graphite/PYR 14 TFSI 0.4m LiTFSI with 10% VC/LiFePO 4 -C and 
Li 4 T i5 O 12 /PYR 14 TFSI  50%-EC  DMC  LiPF 6   50%/LiFePO 4 -C.  We  also  demonstrated  that 
an all solid-state polymer lithium battery as Li/PEO 20 –LiCF 3 SO 3 +10%ZrO 2 /LiFePO 4 -C is 
suitable for application on electric vehicles. Furthermore we developed a promising anodic 
material alternative to the graphite, based on SnCo amorphous alloy.