Furthermore, the cycling performances of 2D WB-based Li-S cells are investigated, and WB nanoparticles are acted as the comparison (3D WB). Those 2D and 3D WB-based Li-S cells (3.2 mA/cm
2) show the stabilized capacities of 720 and 440 mAh/g at 4.0 mg/cm
2 loading, retaining capacities of 620 and 380 mAh/g after 200 cycles with approximately 98% coulombic efficiency, respectively (
Fig. 5a). The SEM images (Figs. S3a and b in Supporting information) show the morphology of 3D WB material is irregular particles, and the crystal structure (Fig. S3c in Supporting information) of 3D WB is the standard tetragonal WB (JCPDS No. 35–0738). The corresponding first discharge plateau (
Fig. 5b) shows the S
82−/S
62− to S
42− in the long-chain polysulfide conversion (Δ
C1), the second discharge plateau is S
42− to S
22−/S
2− in the short-chain polysulfide conversion (Δ
C2), and the polarized voltage differences (Δ
V) are measured at approximately 20% depth of discharge/charge [
42-
44]. In
Fig. 5c, the Δ
V of 2/3D WB-based Li-S cells present 0.40/0.40, 0.37/0.42, 0.41/0.46 and 0.40/0.45 V at the 50
th, 100
th, 150
th and 200
th cycles, respectively. The stabilized Δ
V reveals the controllable polarization with the stable electrochemical reaction of polysulfide in the running 2D WB-based Li-S cell. Moreover, the (Δ
C2)/(Δ
C1 + Δ
C2) ratios of 2/3D WB-based Li-S cells reveal 65%/65%, 63%/63%, 66%/65% and 68%/66% after 50, 100, 150 and 200 cycles, respectively (
Fig. 5d). Those corresponding ratios of Δ
C2/Δ
C1 of 2/3D WB-based Li-S cells are 1.8/1.8, 1.7/1.7, 1.9/1.9 and 2.1/1.9 after 50, 100, 150 and 200 cycles, respectively [
42,
45]. The conversion processes (S
8 to Li
2S
4 to Li
2S
2/Li
2S) indicate the high barrier of solid-state diffusion (solid S
8 to liquid Li
2S
4) with sluggish phase evolution, causing the electrochemical reactions of polysulfides should be powered. The above-mentioned Δ
C2/Δ
C1 and (Δ
C2)/(Δ
C1 + Δ
C2) values show a slight difference in the different cycles, which indicates the enhanced electrochemical activity of polysulfide conversion [
42,
45,
46]. With further rate performances at 1.0, 2.0, 3.0, 4.0 and 5.0 mA/cm
2, the WB-based cell shows reversible capacities of 970, 810, 700, 650 and 410 mAh/g, respectively (
Fig. 5e). The corresponding discharge profiles have corresponded to S
8 to polysulfides and Li
2S
2/Li
2S, and the charge profiles are oxidation process from Li
2S
2/Li
2S to S
8 (
Fig. 5f). For comparison, the 3D WB-based Li-S cell shows reversible capacities of 650, 470, 320, 120 and 90 mAh/g (Fig. S3d in Supporting information), respectively, which is the corresponding current at 1.0, 2.0, 3.0, 4.0 and 5.0 mA/cm
2. In what follows, the high sulfur loading (8.0 mg/cm
2) of WB cathode delivers superior capacities of 7.7 mAh/cm
2, retains 5.8 mAh/cm
2 after 100 cycles at 3.2 mA/cm
2 (
Fig. 5g), where the performances of similar Li-S cells in the kinds of literature are summarized in
Figs. 5h-
i and Table S1 (Supporting information). Those WB-based Li
2S
6 cells show a better performance than other reported electrodes in the Li-S cells, and further reveal the efficient electrochemical kinetics of polysulfides. Furthermore, the electrochemical performance of 2D WB electrode is added in the electronic supplementary information (ESI), which is including CV curves (Figs. S4a-f in Supporting information) and the galvanostatic intermittent titration technique (GITT, Fig. S4g in Supporting information), and
in-situ XPS spectra (Figs. S4h-k in Supporting information).