Spinel LiMn2O4

Comparison of cathode materials

Materials Properties	LiCoO2	LiNiO2	LiMn2O4
Structure	Hexagonal a = 2.82 Å, c = 14.05 Å	Hexagonal a = 2.88 Å, c = 14.18 Å	Cubic (Spinel) a = 8.24 Å
Theoretical capacity (mAh/g)	274	275	148
Practical capacity (mAh/g)	120~130	120~150	100~120
O2 evolution during overcharging	Yes	Yes	No
Diffusion coefficient (cm2/s)	10-7~10-9	10-7~10-9	10-9~10-11
Conductivity (S/cm)	10-2	10-1	10-6
Cost of the metal (US$/kg)	50	8	2
Main advantages	Straight forward synthesis High cycle numbers Good capacity retention	Highest capacity	3V plateau can be used as lithium source for anode
Main drawbacks		Reversibility highly dependent on synthesis conditions Capacity fading upon long-term cycling	Synthesis is tricky Problems of capacity retention at high temperature (>50ºC)

Schematic illustration of Li atom stackings for Spinel LiMn2O4.

LiCoO2 Electron microscope photo

LiMn2O4 Electron microscope photo

LiNiO4 Electron microscope photo

C6+ LiMn2 O4↔ Lix C6+ Li1-x Mn2 O4, Schematic illustration of the discharge and charge processes of a lithium rechargeable battery
When the battery is charged, the lithium ions in the cathode material (lithium compound) migrate via a separator to between the layers of carbon material that form the anode, and a charging current flows.
When the battery is discharged, the lithium ions in the carbon material that form the anode migrate via a separator to the cathode material (lithium compound), and a discharging current flows.
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(a) Raw data of the applied voltage versus time at a constant current charging and discharging cycling,

(b) converted voltage versus capacity curve, the typical charging-discharging curve for a test cell using LixMn2O4 as the major cathode materials.

Li-ion mineral lamp, also call Miners Lamps, Mining Lamps, LED safety lamps, safety lamps,  etc
(Enlarge and see more details by clicking the photo)