Solid–Liquid–Gas Management for Low-Cost Hydrogen Gas Batteries

Abstract

Aqueous nickel-hydrogen gas (Ni-H 2 ) batteries with excellent durability (>10,000 cycles) are important candidates for grid-scale energy storage but are hampered by the high-cost Pt electrode with limited performance. Herein, we report a low-cost nickel-molybdenum (NiMo) alloy as an efficient bifunctional hydrogen evolution and oxidation reaction (HER/ HOR) catalyst for Ni-H 2 batteries in alkaline electrolytes. The NiMo alloy demonstrates a high HOR mass-specific kinetic current of 28.8 mA mg −1 at 50 mV as well as a low HER overpotential of 45 mV at a current density of 10 mA cm −2 , which is better than most nonprecious metal catalysts. Furthermore, we apply a solid−liquid−gas management strategy to constitute a conductive, hydrophobic network of NiMo using multiwalled carbon nanotubes (NiMo-hydrophobic MWCNT) in the electrode to accelerate HER/HOR activities for much improved Ni-H 2 battery performance. As a result, Ni-H 2 cells based on the NiMo-hydrophobic MWCNT electrode show a high energy density of 118 Wh kg −1 and a low cost of only 67.5 $ kWh −1 . With the low cost, high energy density, excellent durability, and improved energy efficiency, the Ni-H 2 cells show great potential for practical grid-scale energy storage.

Non-Noble Metal High-Entropy Alloy-Based Catalytic Electrode for Long-Life Hydrogen Gas Batteries

“…Figure b shows the XPS profile of Cu 2p. The two peaks located at 932.3 and 952.1 eV correspond to the 2p 3/2 and 2p 1/2 of Cu in the NNM-HEA catalyst. , The Ni 2p spectrum (Figure c) displays the coexistence of metallic Ni 0 (852.6 and 869.9 eV for Ni 0 2p 3/2 and Ni 0 2p 1/2 ) and Ni 2+ (854.5 and 871.8 eV for Ni 2+ 2p 3/2 and Ni 2+ 2p 1/2 ). , In the Mo 3d spectrum (Figure d), the peaks located at 228 eV, 229.4 eV, 230.3 eV, and 231.9 eV can be assigned to the 3d 5/2 of Mo 0 , Mo 4+ , Mo 5+ , and Mo 6+ , respectively. , The W 4f XPS spectrum is shown in Figure e, in which the peaks at 31.5 and 33.5 eV are attributed to W 0 4f 7/2 and W 0 4f 5/2 , respectively, and the peaks at 35.2 and 37.2 eV correspond to W 6+ 4f 7/2 and W 6+ 4f 5/2 , respectively. , For the Co 2p spectrum (Figure f), the peaks at 780.7 and 797.1 eV can be attributed to Co 2+ 2p 3/2 and Co 2+ 2p 1/2 , respectively. , The signals of the oxidation states of Ni, Mo, W, and Co are caused by the formation of surface oxides after exposure of the samples to air …”

“…40,41 The Ni 2p spectrum (Figure 3c) displays the coexistence of metallic Ni 0 (852.6 and 869.9 eV for Ni 0 2p 3/2 and Ni 0 2p 1/2 ) and Ni 2+ (854.5 and 871.8 eV for Ni 2+ 2p 3/2 and Ni 2+ 2p 1/2 ). 14,23 In the Mo 3d spectrum (Figure 3d), the peaks located at 228 eV, 229.4 eV, 230.3 eV, and 231.9 eV can be assigned to the 3d 5/2 of Mo 0 , Mo 4+ , Mo 5+ , and Mo 6+ , respectively. 17,20 The W 4f XPS spectrum is shown in Figure 3e, in which the peaks at 31.5 and 33.5 eV are attributed to W 0 4f 7/2 and W 0 4f 5/2 , respectively, and the peaks at 35.2 and 37.2 eV correspond to W 6+ 4f 7/2 and W 6+ 4f 5/2 , respectively.…”

“…34,44 The signals of the oxidation states of Ni, Mo, W, and Co are caused by the formation of surface oxides after exposure of the samples to air. 23 To test the electrocatalytic performance, the as-prepared NNM-HEA@CF catalytic electrode is used as the working electrode directly. The Ni foam and commercial 20 wt % Pt/C coated Cu foam (Pt/C@CF) are tested as controls.…”

“…Among non-noble metal (NNM) catalysts, Ni-based materials are widely considered as excellent candidates for the alkaline HER/HOR. − However, pristine Ni exhibits poor HER/HOR catalytic activity, which is usually modified by alloying with other elements, generating heterostructures, or adjusting structures . For instance, Ni-based alloys, such as MoNi, Ni 4 Mo, , and NiMoCo, , have been demonstrated to show excellent HER/HOR performance. In addition, Ni/V 2 O 3 , Ni 3 N/Ni/NF, Ni/Ni 3 N-C heterostructure catalysts and strain-engineered Ni nanoparticles (Ni-H 2 -2%) were also reported to exhibit good HER/HOR performance.…”

An All-Climate Nonaqueous Hydrogen Gas–Proton Battery

“…Due to the promotion of H 2 diffusion and mass transport, the limiting current density increases with the rotational speed. The Koutecky–Levich (K-L) diagram shown in Figure S4b yields a straight line with a slope of 4.06 cm 2 mA –1 s –1/2 , close to the theoretical value of 4.87 cm 2 mA –1 s –1/2 for the two-electron transfer of the HOR. , We further used the K-L equation to calculate the kinetic current density ( J k ) of the Pt/C catalyst. At an overpotential of 200 mV (vs RHE), a geometric J k value of 2.71 mA cm –2 was obtained, and the HOR mass activity of the Pt/C catalyst was 0.28 A mg –1 .…”