TY - JOUR
T1 - Doubling Reversible Capacities in Epitaxial Li
4
Ti
5
O
12
Thin Film Anodes for Microbatteries
AU - Cunha, Daniel M.
AU - Hendriks, Theodoor A.
AU - Vasileiadis, Alexandros
AU - Vos, Chris M.
AU - Verhallen, Tomas
AU - Singh, Deepak P.
AU - Wagemaker, Marnix
AU - Huijben, Mark
PY - 2019
Y1 - 2019
N2 -
Despite the lower gravimetric capacity, Li
4
Ti
5
O
12
is an important alternative to graphite anodes, owing to its excellent high temperature stability, high rate capability, and negligible volume change. Although surfaces with lithium compositions exceeding Li
7
Ti
5
O
12
were observed previously during the first charge-discharge cycles, no stable reversible capacities were achieved during prolonged cycling. Here, structural engineering has been applied to enhance the electrochemical performance of epitaxial Li
4
Ti
5
O
12
thin films as compared to polycrystalline samples. Variation in the crystal orientation of the Li
4
Ti
5
O
12
thin films led to distinct differences in surface morphology with pyramidal, rooftop, or flat nanostructures for respectively (100), (110), and (111) orientations. High discharge capacities of 280-310 mAh·g
-1
were achieved due to significant surface contributions in lithium storage. The lithiation mechanism of bulk Li
4
Ti
5
O
12
thin films was analyzed by a phase-field model, which indicated the lithiation wave to be moving faster along the grain boundaries before moving inward to the bulk of the grains. The (100)-oriented Li
4
Ti
5
O
12
films exhibited the highest capacities, the best rate performance up to 30C, and good cyclability, demonstrating enhanced cycle life and doubling of reversible capacities in contrast to previous polycrystalline studies.
AB -
Despite the lower gravimetric capacity, Li
4
Ti
5
O
12
is an important alternative to graphite anodes, owing to its excellent high temperature stability, high rate capability, and negligible volume change. Although surfaces with lithium compositions exceeding Li
7
Ti
5
O
12
were observed previously during the first charge-discharge cycles, no stable reversible capacities were achieved during prolonged cycling. Here, structural engineering has been applied to enhance the electrochemical performance of epitaxial Li
4
Ti
5
O
12
thin films as compared to polycrystalline samples. Variation in the crystal orientation of the Li
4
Ti
5
O
12
thin films led to distinct differences in surface morphology with pyramidal, rooftop, or flat nanostructures for respectively (100), (110), and (111) orientations. High discharge capacities of 280-310 mAh·g
-1
were achieved due to significant surface contributions in lithium storage. The lithiation mechanism of bulk Li
4
Ti
5
O
12
thin films was analyzed by a phase-field model, which indicated the lithiation wave to be moving faster along the grain boundaries before moving inward to the bulk of the grains. The (100)-oriented Li
4
Ti
5
O
12
films exhibited the highest capacities, the best rate performance up to 30C, and good cyclability, demonstrating enhanced cycle life and doubling of reversible capacities in contrast to previous polycrystalline studies.
KW - battery anode
KW - crystal orientation
KW - epitaxial thin film
KW - Li Ti O
KW - surface capacity
UR - http://www.scopus.com/inward/record.url?scp=85065767061&partnerID=8YFLogxK
U2 - 10.1021/acsaem.9b00217
DO - 10.1021/acsaem.9b00217
M3 - Article
SN - 2574-0962
VL - 2
SP - 3410
EP - 3418
JO - ACS Applied Energy Materials
JF - ACS Applied Energy Materials
IS - 5
ER -