3-D binder-free graphene foam as cathode for high capacity Li-O2 batteries

To provide energy densities higher than those of conventional Li-ion batteries, a Li–O2 battery requires a cathode with high surface area to host large amounts of discharge product Li2O2. Therefore ...

The C 1s XPS spectra in Fig. S3 show that some decomposition products containing ether and carboxylate bonds formed on the surface of graphene electrode after the 1 st discharge.The results also revealed a noticeable contribution from carbonate (-CO 3 ) decomposition product to the C1s spectrum of the graphene electrode after the 7 th discharge.This feature can be correlated with the fact that the Li 2 CO 3

(a) (b)
side products have been formed after cycling.The 1 st and 7 th discharge samples contain one main peak at the binding energy of about 208 eV with the spin-orbit split doublets (Cl 2p 1/2 ) at 1.6 eV higher binding energy ascribed to LiClO 4 salt.The other component with lower intensity at about 198.5 eV could be assigned to Cl bonded to elements with low electronegativity (e.g.LiCl). 14A comparison of the spectra after the 1 st discharge and after the 7 th discharge shows a moderate increase of the Cl-Li feature, thereby suggesting that additional surface degradation species could have been formed by LiClO 4 salt decomposition.49.3±4.9 The data in Table S3 were acquired from GF@Al and SP electrodes at the current density of 100 mA g -1 .The Y Li2O2 values are calculated by using the following equation: The surface density and thickness of Li 2 O 2 on ideal single layer graphene surface after full discharge were calculated from the formula as follows: 2.31 × 10 3   -3

≈ 13𝑛𝑚
In which is the calculated mass of Li certainly appealing.We therefore feel that our work provides new insight to the oxygen electrode design and that the results presented here may also open up new routes for the fabrication of low-cost and binder-free electrodes for Li-O 2 cells.The tables were added to the supporting information.

Fig. S1 .
Fig. S1.Discharge-charge curves of Al foam in a Li-O 2 cell using 1 M LiClO 4 in DMSO as

Fig. S2 .
Fig. S2.(a) Charge-discharge curves and (b) cycling performance of GF@Al at a current

Fig. S5 the
Fig. S5 the discharge curve of SP and GF@Al cathode for titriation

Table S2 :
Battery properties for recently reported graphene cathode materials.often required in the post synthesis treatment processes.Economical factors or technical problems associated with up-scaled production of graphene-catalyzed cathode unfortunately can't be widely addressed.The possibility of utilizing the graphene foam for the design of facile, inexpensive and binder-free electrode described in the present work, is 12,13ulated from data reported in the reference.It should, however, be noted that different types of binder have been used in most of these graphene-catalyzed cathode materials.It has been shown that binders are unstable in Li-O 2 cells and increase the electrolyte decomposition during cycling, decrease the electrode porosity and the electrical conductivity, while lowering the O 2 -diffusion rate12,13.As shown in Table 1, high temperatures are also 2 O 2 with the given 2 e -/ Li 2 O 2 process during   2  2,  discharge, is the discharge capacity, is the mass of the Li 2 O 2 product on average graphene  ̅  surface and are the theoretical surface area and specific surface area of graphene, and ,     is the thickness of calculated Li 2 O 2 on graphene surface.  2  2,  = 52  Even with a multilayer structure graphene, the calculated Li 2 O 2 thickness is still at a reasonable range.