Tuning the Activity of Oxygen in LiNi0.8Co0.15Al0.05O2Battery Electrodes.
Layered transition metal oxides such as LiNi0.8Co0.15Al0.05O2(NCA) are highly desirable battery electrodes. However, these materials suffer from thermal runaway caused by deleterious oxygen loss and surface phase transitions when in highly overcharged and overheated conditions, prompting serious safety concerns. Using in situ environmental transmission electron microscopy techniques, we demonstrate that surface oxygen loss and structural changes in the highly overcharged NCA particles are suppressed by exposing them to an oxygen-rich environment. The onset temperature for the loss of oxygen from the electrode particle is delayed to 350 °C at oxygen gas overpressure of 400 mTorr. Similar heating of the particles in a reducing hydrogen gas demonstrated a quick onset of oxygen loss at 150 °C and rapid surface degradation of the particles. The results reported here illustrate the fundamental mechanism governing the failure processes of electrode particles and highlight possible strategies to circumvent such issues.
NECCES, Binghamton University , Binghamton, New York 13902, United States.|Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States.
Khim
K
Karki
NECCES, Binghamton University , Binghamton, New York 13902, United States.
Yiqing
Y
Huang
Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States.
Sooyeon
S
Hwang
Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States.
Andrew D
AD
Gamalski
NECCES, Binghamton University , Binghamton, New York 13902, United States.
M Stanley
MS
Whittingham
NECCES, Binghamton University , Binghamton, New York 13902, United States.
Guangwen
G
Zhou
Center for Functional Nanomaterials, Brookhaven National Laboratory , Upton, New York 11973, United States.
Eric A
EA
Stach
chemical potential; lithium-ion battery; oxidation−reduction; transition metal oxides; transmission electron microscopy