Suppressed Dissolution and Enhanced Desolvation in Core–Shell MoO₃@TiO₂ Nanorods as a High‐Rate and Long‐Life Anode Material for Proton Batteries

Abstract

of renewable energies need them to couple with energy storage devices. [1][2][3][4] Aqueous batteries stand out from many types of batteries, due to their intrinsic safe, low material costs, and facile manufacturing as well. [5][6][7] One of the typical examples is lead-acid batteries that have been commercialized and adopted in many fields. [8][9][10] However, the strong corrosion on cell components caused by highly concentrated acid, the unsatisfactory cycle life, and the high toxicity of Pb to organisms greatly limit the applications of lead-acid batteries. [10][11][12] Hence, aqueous metal-ion batteries based on alkali ions, alkaline-earth metal ions, and Zn 2+ are considered intensively to address these concerns. [13][14][15][16] However, their large ionic radii are very harmful to rate capability. Compared to these ions, protons as the charge carriers have the unique advantages, such as a small ion size, a low molar mass, and a high abundance in nature. [9,17,18] Moreover, benefited from Grotthuss mechanism, protons in aqueous electrolytes and in electrode materials would exhibit high ionic conductivity, facilitating the reaction kinetics and rate capability. [19][20][21] Up to now, metal oxides, prussian blue analogues (PBA), and organic materials have been explored as cathode materials of proton batteries. Gogotsi et al. reported the proton-intercalation chemistry in MnO 2 based on surface reactions. [22] Hu et al. [23] found that RuO 2 •xH 2 O nanotubes had a specific capacitance of 1300 F g −1 related to proton insertion/extraction. Ji et al. [20] demonstrated that one of Turnbull's blue, in which protons were transferred via Grotthuss mechanism, presented extraordinary rate performances up to 4000 C (380 A g −1 , 508 mA cm −2 ) and ultralong cycling about 0.73 million cycles. Compared with the case of cathode materials, the anode materials are rarely reported. [24][25][26][27] MoO 3 as one of the anode materials has promising perspectives, due to its high capacity, low cost, and layer structure. Yan and co-workers [25] prepared MoO 3 by calcining MoS 2 nanosheets in air, which showed a capacity of 152 mAh g −1 at 5 C in 1 m H 2 SO 4 . The capacity, however, went down to ≈68% of the initial data only after 100 cycles at 10 C or ≈67% at 50 C. It was attributed to the dissolution of MoO 3 and the formation of polyoxometalate, resulting in the capacity fading. Thus, Zhao et al. [26] used highly concentrated H 2 SO 4 (6 m) to inhibit the detrimental dissolution of MoO 3 . Although cycling stability Rechargeable proton batteries are attractive, because protons as a charge carrier have a small ionic radius, a lightest mass, and a high abundance on Earth. MoO 3 , as one of the promising anode materials in rechargeable proton batteries, suffers from the severe dissolution in acidic electrolytes upon cycling.Here, an ultrathin TiO 2 shell is coated on MoO 3 nanorods to suppress the detrimental dissolution during cycles. TiO 2 also lowers the desolvation energy of hydrated protons, promoting the reaction kinetics...

Pre‐Protonated Vanadium Hexacyanoferrate for High Energy‐Power and Anti‐Freezing Proton Batteries

“…[9,31] A lower proton diffusion barrier is represented by the smaller activation energy, which is also an important reason why H-VHCF has high-rate performance. [32,33] To examine the effect of protonation and deprotonation on the structure, the ex situ XRD spectra of the H-VHCF electrode in selected states were measured for the initial two discharge/charge cycles. Ex situ XRD spectra of the electrode show that the peaks of ( 200) and (400) shift to small angle during charging, and shift back during discharging.…”

Rational Design of Electrode–Electrolyte Interphase and Electrolytes for Rechargeable Proton Batteries

“…3 ) [ 24 ]. Another bottleneck for α -MoO 3 is the large interfacial energy barrier needed for complete desolvation of hydrated protons [ 62 ]. Therefore, rational design of electrode interphase can not only protect the electrode surface lattice, but also reduce the interface resistance leading to improved battery cycling lifespan and rate capability.…”

“…Wang and co-authors have coated an ultrathin TiO 2 shell on α -MoO 3 nanorods to suppress the detrimental dissolution of α -MoO 3 and facilitate the desolvation process of hydronium ions [ 63 ]. The TiO 2 coating is uniform, ultrathin (~ 5 nm), and amorphous, which was fabricated by the coating of the hydrolysis product of tetrabutyl titanate and the later calcination in air.…”

“…The fast desolvation process and superior interphase reaction kinetics plus the good electron/ion conductivity of TiO 2 , enable the MoO 3 @TiO 2 composite outstanding rate performance (171.0 mAh g −1 at 30 A g −1 ). Constructed with MnO 2 , the full cell holds a high energy density up to 252.9 Wh kg −1 and power density of 18.3 kW kg −1 [ 63 ].…”

Coupling W18O49/Ti3C2Tx MXene Pseudocapacitive Electrodes with Redox Electrolytes to Construct High‐Performance Asymmetric Supercapacitors

“…Due to the synergistic effects between metal oxides and the added functional materials, these composites exhibit improved capacitive performance, originating from enlarged pseudocapacitances of metal oxides as well as additional capacitances from the added functional materials. [26][27][28][29] Note here that physical synthesis of such composites might not be conductive to the formation of strong synergistic effects between metal oxides and the added functional materials. Among various binary/ternary metal oxides, tungsten oxides (WO x , 2 ≤ x ≤ 3) are the most promising pseudocapacitive electrode materials since they feature excellent intrinsic properties (e.g., environmental friendliness, outstanding electrochemical stability).…”