Unveiling the “Proton Lubricant” Chemistry in Aqueous Zinc‐MoS₂ Batteries

Abstract

Proton insertion chemistry in aqueous zinc‐ion batteries (AZIBs) is becoming a research hotspot owing to its fast kinetics and additional capacities. However, H+ storage mechanism has not been deciphered in the popular MoS2‐based AZIBs. Herein, we innovatively prepared a MoS2/poly(3,4‐ethylenedioxythiophene) (MoS2/PEDOT) hybrid, where the intercalated PEDOT not only increases the interlayer spacing (from 0.62 to 1.29 nm) and electronic conductivity of MoS2, but also activates the proton insertion chemistry. Thus, highly efficient and reversible H+/Zn2+ co‐insertion/extraction behaviors are demonstrated for the first time in aqueous Zn‐MoS2 batteries. More intriguingly, the co‐inserted protons can act as lubricants to effectively shield the electrostatic interactions between MoS2/PEDOT host and divalent Zn2+, enabling the accelerated ion‐diffusion kinetics and exceptional rate performance. This work proposes a new concept of “proton lubricant” driving Zn2+ transport and broadens the horizons of Zn‐MoS2 batteries.

Activated Proton Storage in Molybdenum Selenide through Electronegativity Regulation

“…[ 45 ] According to previous reports, the Se defects can improve conductivity and accelerate ion diffusion, which will effectively optimize electrochemical performance of MoSe 2 cathode. [ 34,45 ] The Raman results in Figure S10 (Supporting Information) show a redshifted A 1g peak of O‐MoSe 2 compared to pure MoSe 2 , which is arising from the weakened interaction between MoSe 2 layers owing to oxygen doping. [ 34,46,47 ] Furthermore, the effect of oxygen doping on specific surface area is characterized by the nitrogen adsorption‐desorption isotherm (Figure S11a, Supporting Information).…”

“…[ 34,45 ] The Raman results in Figure S10 (Supporting Information) show a redshifted A 1g peak of O‐MoSe 2 compared to pure MoSe 2 , which is arising from the weakened interaction between MoSe 2 layers owing to oxygen doping. [ 34,46,47 ] Furthermore, the effect of oxygen doping on specific surface area is characterized by the nitrogen adsorption‐desorption isotherm (Figure S11a, Supporting Information). The O‐MoSe 2 shows a higher a specific surface area (28.2744 m 2 g –1 ) than pure MoSe 2 (15.6021 m 2 g –1 ).…”

“…Transition metal dichalcogenides (TMDs) have been considered as promising cathode materials for AZBs due to the large interlayer spacing, small bandgap and high electronic conductivity. [ 33–35 ] Unfortunately, the H + ‐dominated insertion mechanism was not found in TMDs cathode materials in previous reports due to the high adsorption barrier between H + and host. In addition, the unmodified TMDs cathode such as MoS 2 generally shows a low specific capacity, which blocks their application in AZBs.…”

Vertical Graphene Film Enables High-Performance Quasi-Solid-State Planar Zinc-Ion Microbatteries

“…It is obvious that there are a pair of strong redox peaks (1.6 vs 1.35 V) and a pair of weak redox peaks (1.53 vs 1.23 V). The galvanostatic charge–discharge (GCD) curve at different current densities in Figure c displays a similar two-stage discharge voltage plateau at around 1.3 V, which could be attributed to the insertion/extraction mechanism of H + and Zn 2+ in MnO 2 . , The main reaction formulas can be summarized as follows: Cathode : MnO 2 + normalH + + normale − ↔ MnOOH Zn 2 + + 2MnO 2 + 2e − ↔ ZnMn 2 normalO 4 Anode : Zn ↔ Zn 2 + + 2e − …”

“…The galvanostatic charge−discharge (GCD) curve at different current densities in Figure 3c displays a similar two-stage discharge voltage plateau at around 1.3 V, which could be attributed to the insertion/extraction mechanism of H + and Zn 2+ in MnO 2 . 55,56 The main reaction formulas can be summarized as follows: 57 (2)…”