Li2TiSiO5: A Low Redox Potential and Large Capacity Titanium-Based

Anode Material for Lithium-Ion Batteries

Author list: Jingyuan Liu,a Wei Kong Pang,bd Tong Zhou,c Long Chen,a Yonggang Wang,a

Vanessa K. Peterson,bd Zhongqin Yang,*c Zaiping Guo,*b Yongyao Xia*a

a Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Institute

of New Energy, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Fudan University,

Shanghai 200433, China. E-mail: yyxia@fudan.edu.cn

b School of Mechanical, Materials, and Mechatronic Engineering, Institute for Superconducting & Electronic

Materials, Faculty of Engineering, University of Wollongong, Wollongong NSW 2522, Australia. E-mail:

zguo@uow.edu.au

c State Key Laboratory of Surface Physics and Key Laboratory for Computational Physical Sciences (MOE), and

Department of Physics and Collaborative Innovation Center of Advanced Microstructures, Fudan University,

Shanghai 200433, China. E-mail: zyang@fudan.edu.cn

d Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organization, Locked Bag

2001, Kirrawee DC NSW 2232, Australia

Electronic Supplementary Material (ESI) for Energy & Environmental Science.This journal is © The Royal Society of Chemistry 2017

Figure S1. Thermogravimetric analysis curve of as-prepared Li2TiSiO5 in oxygen. Since

Li2TiSiO5 is stable to high temperature, the mass loss is attributed to the carbon-

coating.

Figure S2 Scanning TEM (STEM) image (a), with corresponding EDX spectrum (d) and

EDX-mapping of oxygen (c, red), titanium (e, azure), and silicon (f, orange), with an

overlapped image showing each element (b).

Figure S3 Voltage-capacity plots for the first 2 cycles of uncoated Li2TiSiO5 with cut-

off potential of 0 V at a current density of 0.02 A g-1 (left) and 0.2 A g-1 (right).

Figure S4 Capacity-Voltage curves for the discharge process of Li2TiSiO5 (top-left) and

graphite (top-right); simulated irreversible capacity of Li2TiSiO5 (bottom-left) and

graphite (bottom-right).

Figure S5. dQ/dV versus voltage plots at different cut-off potentials of 0 V (up), 0.1 V

(middle), and 0.2 V (bottom). The profiles are calculated based on the

discharge/charge profiles shown in Fig. 4.

Figure S6. Reversibility of Li2TiSiO5 at different cut-off potentials. For ease of

comparison, the capacities for all three cut-off potentials are shown as relative to

the second cycle capacity.

Figure S7. TEM images of Li2TiSiO5 electrode before cycling (a) and after 100

discharge/charge cycles with cut-off potential of 0.1 V (c) and 0 V (e). SAED patterns

of Li2TiSiO5 electrode before cycling (b) and after 100 discharge/charge cycles with

cut-off potential of 0.1 V (d) and 0 V (f). All results in this figure were obtained from

electrodes charged back to 3 V. Discrete dots in the SAED pattern and larger particles

in the TEM image are observed for the 0.1 V electrode, while smaller particles in the

TEM image and more rings in the SAED pattern can be detected for the 0 V electrode,

supporting the argument that a slightly higher cut-off potential could provide some

protection of the electrode from amorphization and pulverization.

Figure S8. XRPD data for Li2TiSiO5 electrodes before and after 100 discharge/charge

cycles with cut-off potentials of 0.1 V and 0 V. Reflections of Li2TiSiO5 are indexed in

black and those of the Cu substrate in brown

Figure S9. a. Schematic illustration of possible lithium ion insertion into the 4e sites.

b. Schematic illustration of the intercalation mechanism occurring during the charge-

discharge process, with the voltage calculated by using DFT. The calculated average

potential is -8.4 V vs. Li+/Li, much lower than the measured potential, indicating that

the intercalation process does not occur during discharge of Li2TiSiO5.

Figure S10. XANES analysis of Li2TiSiO5 in different electrochemical states. The

dotted black line (dashed black line on right) is the XANES spectrum of pure titanium

metal foil, and was treated as Ti0. The left spectra are Li2TiSiO5 in various

discharge/charge states. From bottom to top: undischarged Li2TiSiO5 (treated as Ti4+),

Li2TiSiO5 discharged to 0.3 V (near the plateau voltage), Li2TiSiO5 discharged to 0 V,

Li2TiSiO5 charged to 0.3 V, and Li2TiSiO5 charged to 3 V. The right spectra are

enlargements of the indicated energy range and not offset, in order to show relative

intensities. All states were tested within the first discharge/charge cycle.

Figure S11. Schematic illustration of the conversion mechanism for the

electrochemical charge-discharge process, with voltage calculated using DFT.

Tables

Table S1. Calculated and experimental structure parameters. Structure parameters a,

b, and c are in Å, while α, β, γ are in °.

Calculation a b c α β γ

Li2TiSiO5 6.47 6.47 4.48 90.00 90.00 90.00

TiO 5.85 9.33 4.17 90.00 90.00 107.39

Li 3.44 3.44 3.44 90.00 90.00 90.00

Li4SiO4 11.63 6.13 16.85 90.00 99.05 90.00

Li2.5TiSiO5 6.62 6.62 4.49 90.74 90.74 90.34

Experiment a b c α β γ

Li2TiSiO5S1 6.44 6.44 4.40 90.00 90.00 90.00

TiOS2 5.86 9.34 4.14 90.00 90.00 107.53

LiS3 3.51 3.51 3.51 90.00 90.00 90.00

Li4SiO4S4 11.55 6.09 16.65 90.00 99.50 90.00

Li2.5TiSiO5 - - - - - -

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