Lithium Batteries with Nearly Maximum Metal. Storage Supporting Information

Transcription

1 Lithium Batteries with Nearly Maximum Metal Storage Supporting Information Abdul-Rahman O. Raji,, Rodrigo Villegas Salvatierra,, Nam Dong Kim, Xiujun Fan, Yilun Li, Gladys A. L. Silva, Junwei Sha and James M. Tour,,,* Department of Chemistry, Smalley-Curl Institute and The NanoCarbon Center, Department of Materials Science and NanoEngineering, Rice University, 6100 Main Street, Houston, Texas 77005, USA These authors contributed equally to this work. * S1

2 Current (A) Average R= 0.33 Thickness = 30 μm Area contact = μm 2 Average Conductivity = S m -1 Evaporated Metal Voltage (V) Figure S1. Current vs Voltage (I V) curves of GCNT carpet. IV curves were measured from the top of the CNT carpet (with evaporated Ni contact areas) to the Cu current collector. The conductivity were averaged over 5 measurements (red lines) between 0 and 1 V. S2

3 Capacity (mah cm -2 ) V vs (Li + /Li) Capacity (Ah g -1 GCNT ) Figure S2. Electrochemical characteristics of Li-ion-inserted GCNT as opposed to Li-metal. Charge/discharge profile of Li-ion inserted GCNT. Reports on CNT LIB electrodes to date show similar electrochemical behavior for Li-ion insertion and extraction with no flat voltage profile. 1-3 It is generally thought that the behavior is due to adsorption of Li ions on the CNTs external surfaces 1-3 and/or internal surfaces by diffusing through open ends or sidewall defects. 1,4-7 A large voltage gap exists between Li insertion and extraction curves. 1,3,8 The stored Li is not in the metallic form and the large voltage gap is attributed to the presence of impurities on the CNTs. 8 With charging up to only 1 V used for the GCNT-Li electrode, these Li-ions extracted from GCNT, which are not due to Li metal stripping, have a minimal capacity contribution of mah cm -2 (i.e. 129 mah g -1 GCNT or 6.5 μgli cm -2 ), which is negligible compared to plated Li-metal. S3

4 V (vs Li + /Li) Time (h) Figure S3. Electrochemical characteristics of the Li-metal deposited on CuG (no CNT). First cycle charge/discharge profile of CuG-Li. Intensity (a. u.) GCNT-Li (Kapton tape) Li foil (Kapton tape) Kapton tape Li metal o 36.1 o (110) S4

5 Figure S4. X-ray diffractogram (XRD) of Li-metal in GCNT-Li. The XRD of GCNT-Li was measured by first plating the equivalent amount of 4 mah cm -2, opening the half-cell and laminating with a polyimide (Kapton) tape inside a glove box. The same experiment was conducted with a pure Li foil. The laminated samples were removed from the glove box and the XRD was measured in air. Reference Li-metal file (American Mineralogist Crystal Structure Database, AMCSD# , lithium). The peak corresponding to (110) plane at 36.1 o has the same position as the bulk Li foil, matching the reference Li peak. The lower intensity of the GCNT- Li peak is consistent with the lower density of Li-metal in GCNT-Li compared with bulk Li foil. V (vs Li+/Li) 1 0 6th cycle 300th cycle Time (h) Figure S5. Voltage characteristics of the GCNT anode. Charge/discharge voltage profiles of GCNT-Li for the 6th and 300th cycles. The slightly higher Li extraction time for the 300th cycle corresponds to a slightly higher capacity and increased coulombic efficiency of 99.83% compared to 94.3% for the 6th cycle. The current density is 2 ma cm -2 (5.2 A g -1 GCNT-Li). S5

6 Figure S6. Electrochemical characteristics of the GCNT anode vs horizontal CNT anode. Schematics and voltage profiles of a) vertical and seamless GCNT grown on Cu and b) horizontal CNT deposited on graphene-covered Cu. S6

7 Figure S7. Comparison of Li plating on GCNT anode vs horizontal CNT anode. SEM images of CNT electrode (not GCNT) on copper foil (90% SWCNT-HiPco, 10% PVDF) and CNT-Li with mass loading of CNT of 0.31 mg cm -2. a-c) Cross-section SEM images of pure CNT electrode before Li plating. d-f) Cross-section SEM images of CNT-Li electrode with Li plated to an equivalent capacity of 4 mah cm -2. g-h) Top-view SEM image of CNT-Li with areal capacity of 4 mah cm -2. The Li plated on CNT-Li electrode presents a different morphology compared to GCNT-Li, in which the Li forms as a separate layer rather than an embedded structure as found in GCNT-Li structure. The compactness of the SWCNT electrode (~ 5 µm) is also different from the GCNT morphology, even having a higher mass loading (0.31 mg cm -2 ) compared to GCNT (~ 0.2 mg cm -2 ). S7

8 Figure S8. SEM images of GCNT and GCNT-Li. a-c) GCNT grown for 1, 2 and 5 min, respectively. d,e) GCNT-Li at an areal capacity of 4 mah cm -2 over a 17.8 µm GCNT grown for 1 minute. At a thickness of 25.2 µm, the GCNT-Li is only 45% thicker than the bare GCNT. S8

9 a b Coulombic Efficiency (%) Coulombic Efficiency (%) Cycles st cycle withou pre-lithiation method 1st cycle CE with pre-lithiation method Areal capacity (mah cm -2 ) mah cm mah cm mah cm mah cm -2 Figure S9. Cycling stability and CE of GCNT-Li with different areal capacities. a) The coulombic efficiency of cycling experiments of electrodes GCNT-Li-0.4 to GCNT-Li-4 are shown. The tests of GCNT-Li-0.7, GCNT-Li-1.3 and GCNT-Li-2.1 were tested at a current density of 2 ma cm -2, while the GCNT-Li-4 was tested at 1 ma cm -2. Inset shows expanded plot. b) Average 1 st cycle CE of GCNT-Li with different areal capacities with or without pre-lithiation method (see Methods for details on pre-lithiation procedure). S9

10 a Mass Loss (%) c Capacity (Ah g -1 ) SC Temperature ( o C) SC (0.2 C) Cycles e 3 60% Coulombic Efficiency b V (vs Li/Li + ) d V (vs Li/Li + ) C 17% Capacity (Ah g -1 ) SC (4 M LiFSI in DME) SC (1 M LiPF 6 in EC:DEC) 0.1 C Capacity (Ah g -1 ) 0.1 C V (vs Li/Li + ) % Capacity (Ah g -1 S ) Figure 10. Characterization of SC cathodes. a) Thermogravimetric (TG) curves of the SC powder with S mass loss only occurs after 700 C. The TG curves do not show a plateau at the end of the test, therefore the 60 wt% was calculated at the minimum mass loss. b) Charge/discharge curves of the SC half-cells in 4 M LiFSI/DME at 0.2 C. First discharge cycle is indicated by the arrow. First charge/discharge cycle has a CE of 83%, indicated by the irreversible capacity of 17% S10

11 (parallel dotted lines) on the first discharge. c) Cycling stability and CE plot of the half-cell SC in 4 M LiFSI/DME at 0.2 C. d) Comparison of the SC cathode half-cell tests in electrolytes 4 M LiFSI/DME and 1 M LiPF6 in EC:DEC (1:1 volume ratio). e) First cycle of FB using GCNT-Li and SC showing an overall CE of 70%. S11

12 Figure S11. Morphology of lithiated GCNT-Li and delithiated SC after 500 cycles in a fullcell with 2 mah cm -2 at 1 ma cm -2. a-c) SEM images of GCNT-Li by size-view showing the intact shape of the GCNT structure with plated Li. The left is the bottom with a Cu current collector. The thickness of the GCNT-Li is 88 μm. d-f) SEM images of GCNT-Li by top-view with no dendritic or mossy Li. g-i) SEM images of the delithiated SC by top-view showing the S12

13 intact shape of the electrode. The right is the bottom with a steel current collector. The thickness of the SC is 96 μm. j-l) SEM images of the delithiated SC by top-view. Gravimetric capacity of GCNT-Li anodes Table S1. Calculations of specific capacity using GCNT-Li electrodes Capacity GCNT or Li metal Lithiated Current Total mass Capacity carbon mass (per carbon Collector per g mass (per cm 2 ) mass (per cm 2 ) cm 2 ) GCNT-Li (one side) GCNT-Li (dual side) 4 mah cm mg ~ 1.05 mg mg 9.4 mg 8 mah cm mg ~ 2.1 mg mg 10.7 mg 426 mah g mah g -1 Graphite 8 mah cm mg & 8.05 mg 34.2 mg 233 mah g-1 LiC 6 (dual sided) Commercial standard 9 µm thick Cu foil; & Assuming 90 wt% of LiC 6 capacity ~ 305 mah g -1 S13

14 Energy density calculations and projections of GCNT-Li and SC based full batteries Table S2. Electrode masses for energy density calculations Anode (per cm 2 ) Cathode (per cm 2 ) Total Total Li mass (active GCNT CC a S mass Other CC c mass d mass e material) (active components b (active (electrodes, material) materials) no CC) 0.67 mg mg 2.13 mg mg 4.99 mg mg mg mg a current collector (CC) of anode, copper foil 30 µm b Carbon additives (CB) and binder c current collector (CC) of cathode, steel foil 30 µm d Total mass combined of active materials in the cathode and anode e Total mass of anode and cathode electrodes S14

15 Table S3. Energy calculations Total Energy delivered by GCNT-Li/SC FB Gravimetric Energy density (by active materials only) Gravimetric Energy density (by electrode mass) 3.76 mwh (at A g -1 ) a Wh kg Wh kg -1 a Current density is calculated based on mass of cathode active materials (S mass) References 1. Claye, A. S.; Fischer, J. E.; Huffman, C. B.; Rinzler, A. G.; Smalley, R. E. Solid-State Electrochemistry of the Li Single Wall Carbon Nanotube System. J. Electrochem. Soc. 2000, 147, Shimoda, H.; Gao, B. X.; Tang, P.; Kleinhammes, A.; Fleming, L.; Wu, Y.; Zhou, O. Lithium Intercalation into Opened Single-Wall Carbon Nanotubes: Storage Capacity and Electronic Properties. Phys. Rev. Lett. 2002, 88, Landi, B. J.; Ganter, M. J.; Cress, C. D.; DiLeo, R. A.; Raffaelle, R. P. Carbon Nanotubes for Lithium Ion Batteries. Energy Environ. Sci. 2009, 2, Landi, B. J.; Ganter, M. J.; Schauerman, C. M.; Cress, C. D.; Raffaele, R. P. Lithium Ion Capacity of Single Wall Carbon Nanotube Paper Electrodes. J. Phys. Chem. C 2008, 112, Garau, C.; Frontera, A.; Quinonero, D.; Costa, A.; Ballester, P.; Deya, P. M. Ab Initio Investigations of Lithium Diffusion in Single-Walled Carbon Nanotubes. Chem. Phys. 2004, 297, S15

16 6. Xing, W. R.; Dunlap, A. J.; Dahn, R. Studies of Lithium Insertion in Ballmilled Sugar Carbons. J. Electrochem. Soc. 1998, 145, Gao, B.; Bower, C.; Lorentzen, J. D.; Fleming, L.; Kleinhammes, A.; Tang, X. P.; McNeil, L. E.; Wu, Y.; Zhou, O. Enhanced Saturation Lithium Composition in Ball-Milled Single- Walled Carbon Nanotubes. Chem. Phys. Lett. 2000, 327, Carter, R.; Oakes, L.; Cohn, A. P.; Holzgrafe, J.; Zarick, H. F.; Chatterjee, S.; Bardhan, R.; Pint, C. L. Solution Assembled Single-Walled Carbon Nanotube Foams: Superior Performance in Supercapacitors, Lithium-Ion, and Lithium Air Batteries. J. Phys. Chem. C 2014, 118, S16