In Situ Engineering of Inorganic-Rich Solid Electrolyte Interphases via Anion Choice Enables Stable, Lithium Anodes.

The discovery of liquid battery electrolytes that facilitate the formation of stable solid electrolyte interphases (SEIs) to mitigate dendrite formation is imperative to enable lithium anodes in next-generation energy-dense batteries. Compared to traditional electrolyte solvents, tetrahydrofuran (THF)-based electrolyte systems have demonstrated great success in enabling high-stability lithium anodes by encouraging the decomposition of anions (instead of organic solvent) and thus generating inorganic-rich SEIs. Herein, by employing a variety of different lithium salts (i.e., LiPF6, LiTFSI, LiFSI, and LiDFOB), it is demonstrated that electrolyte anions modulate the inorganic composition and resulting properties of the SEI. Through novel analytical time-of-flight secondary-ion mass spectrometry methods, such as hierarchical clustering of depth profiles and compositional analysis using integrated yields, the chemical composition and morphology of the SEIs generated from each electrolyte system are examined. Notably, the LiDFOB electrolyte provides an exceptionally stable system to enable lithium anodes, delivering >1500 cycles at a current density of 0.5 mAh g-1 and a capacity of 0.5 mAh g-1 in symmetrical cells. Furthermore, Li//LFP cells using this electrolyte demonstrate high-rate, reversible lithium storage, supplying 139 mAh g(LFP) -1 at C/2 (≈0.991 mAh cm-2 , @ 0.61 mA cm-2 ) with 87.5% capacity retention over 300 cycles (average Coulombic efficiency >99.86%).

In-Situ-Grown Cu Dendrites Plasmonically Enhance Electrocatalytic Hydrogen Evolution on Facet-Engineered Cu2 O.

Herein, facet-engineered Cu2 O nanostructures are synthesized by wet chemical methods for electrocatalytic HER, and it is found that the octahedral Cu2 O nanostructures with exposed crystal planes of (111) (O-Cu2 O) has the best hydrogen evolution performance. Operando Raman spectroscopy and ex-situ characterization techniques showed that Cu2 O is reduced during HER, in which Cu dendrites are grown on the surface of the Cu2 O nanostructures, resulting in the better HER performance of O-Cu2 O after HER (O-Cu2 O-A) compared with that of the as-prepared O-Cu2 O. Under illumination, the onset potential of O-Cu2 O-A is ca. 52 mV positive than that of O-Cu2 O, which is induced by the plasmon-activated electrochemical system consisting of Cu2 O and the in-situ generated Cu dendrites. Incident photon-to-current efficiency (IPCE) measurements and the simulated UV-Vis spectrum demonstrate the hot electron injection (HEI) from Cu dendrites to Cu2 O. Ab initio nonadiabatic molecular dynamics (NAMD) simulations revealed the transfer of photogenerated electrons (27 fs) from Cu dendrites to Cu2 O nanostructures is faster than electron relaxation (170 fs), enhancing its surface plasmons activity, and the HEI of Cu dendrites increases the charge density of Cu2 O. These make the energy level of the catalyst be closer to that of H+ /H2 , evidenced by the plasmon-enhanced HER electrocatalytic activity.

Heterostructured Core-Shell Ni-Co@Fe-Co Nanoboxes of Prussian Blue Analogues for Efficient Electrocatalytic Hydrogen Evolution from Alkaline Seawater.

The rational construction of efficient and low-cost electrocatalysts for the hydrogen evolution reaction (HER) is critical to seawater electrolysis. Herein, trimetallic heterostructured core-shell nanoboxes based on Prussian blue analogues (Ni-Co@Fe-Co PBA) were synthesized using an iterative coprecipitation strategy. The same coprecipitation procedure was used for the preparation of the PBA core and shell, with the synthesis of the shell involving chemical etching during the introduction of ferrous ions. Due to its unique structure and composition, the optimized trimetallic Ni-Co@Fe-Co PBA possesses more active interfacial sites and a high specific surface area. As a result, the developed Ni-Co@Fe-Co PBA electrocatalyst exhibits remarkable electrocatalytic HER performance with small overpotentials of 43 and 183 mV to drive a current density of 10 mA cm-2 in alkaline freshwater and simulated seawater, respectively. Operando Raman spectroscopy demonstrates the evolution of Co2+ from Co3+ in the catalyst during HER. Density functional theory simulations reveal that the H*-N adsorption sites lower the barrier energy of the rate-limiting step, and the introduced Fe species improve the electron mobility of Ni-Co@Fe-Co PBA. The charge transfer at the core-shell interface leads to the generation of H* intermediates, thereby enhancing the HER activity. By pairing this HER catalyst (Ni-Co@Fe-Co PBA) with another core-shell PBA OER catalyst (NiCo@A-NiCo-PBA-AA) reported by our group, the fabricated two-electrode electrolyzer was found to achieve high output current densities of 44 and 30 mA cm-2 at a low voltage of 1.6 V in alkaline freshwater and simulated seawater, respectively, exhibiting remarkable durability over a 100 h test.