Development of structural stability and the electrochemical performances of ‘ La ’

substituted spinel LiMn2O4 cathode materials for rechargeable lithium-ion batteries

D. Arumugam, G. Paruthimal Kalaignan, P. ManisankarSolid State Ionics 179 (2010) 580 – 586

Sameh HamzawyAlagr Raj PaulrajMESC9

Outline Introduction

Experiment

Results and discussion

Conclusion

Introduction

Advantages Disadvantages

LiCoO2 High specific capacity High cost

Better cyclic performance Toxicity

LiMn2O4 Inexpensive, relatively. Poor cycle performance at high temperature.

Environmentally Capacity fading

Lithium-ion batteries have gained increasing importance as power sources due to their high working voltage, low self discharge rate, and long life.

Reducing the amount of Mn3+ in LiMn2O4 improve the cyclability of the materials.

Substitute Mn by some metal species such as :

LiNixMn2−xO4, LiCoxMn2 −xO, LiLaxMn2 −xO4 ????

Experiment: Spinel LiLaxMn2 – xO4 ,where x=0.00, 0.01, 0.03, 0.05 and 0.10 were synthesized by sol-gel method.

Results and discussion

X-ray diffraction pattern of the spinel LiMn2 O4 and lanthanum substituted LiLaxMn2− x O 4 powders prepared by sol – gel technique at 900 °C.

Single phase diffraction patterns for the 5 samples

Cubic spinel structure

The intensity of the diffraction peaks are enhanced after doping, indicating large crystal size.

Lattice parameters, unit cell volume, and intensity ratios of spinel LiLaxMn2 – xO4 , (x=0.00 to 0.10) cathode materials.

Increasing lanthanum doping , increases the lattice parameters

More lattice space for Li intercalation and deintercalation

Prevent lattice shrinking during the deintercalation

SEM image of LiMn2O4 and lanthanum substituted LiLaxMn2 – xO4 powders synthesized at 900 °C. a) LiMn2 O4, b) LiLa0.01Mn1.99O4 , c) LiLa0.03Mn1.97O4 , d) LiLa0.05Mn1.95O4 and e) LiLa0.10Mn1.90O4.

Raj’s part

Raman SpectroscopyLocal

symmetrical properties

Sensitive to the short range environment of cations and the coordinated oxygen ions.

Galvanostatic charge/discharge studies

Cycling was done between 2.75V to 4.5 V @ .1c Current density

Two plateaus one at4.05 &another 4.15

Cyclic Voltammetery

LiMn2O4

LiLa0.01Mn1.99O4

LiLa0.05Mn1.95O4LiLa0.10Mn1.90O4

Life Cycle Test

LiMn2O4

LiLa0.05Mn1.95O4

Rate capability of LiLa0.05Mn1.95O4

C Rate Intial stage capacity(mAh/g)

CapacityAfter 50 cycles(mAh/g)

.1c 127 115

.5 129 112

1 119 106

2 112 103

5 102 87

ConclusionThe LiLa x Mn 2 − x O 4 (x=0.00, 0.01, 0.03,

0.05 ,0.10) cathode materials were synthesized by low T sol-gel method.

single phase structure was conformed by XRD and Raman ,Higher dopant level impurity phases were present

LiLa0.05Mn1.95O4 has excellent capacity retention.

Thank you