Pseudocapacitive Ti-Doped Niobium Pentoxide Nanoflake Structure Design for a Fast Kinetics Anode toward a High-Performance Mg-Ion-Based Dual-Ion Battery

Abstract

Magnesium-ion batteries (MIBs) have received increasing attention for next-generation energy storage recently because of the natural abundance, high capacity, and dendrite-free deposition of Mg. However, their applications are hindered by irreversible Mg anode plating in conventional electrolytes and the lack of cathode materials, demonstrating high working voltage, satisfactory Mg 2+ diffusivity, and long cycling life. In this work, we first developed a novel magnesium-ion based dual-ion battery (Mg-DIB) by utilizing expanded graphite as the cathode and Ti-doped niobium pentoxide nanoflakes (Ti−Nb 2 O 5 NFs) as the anode. The Ti−Nb 2 O 5 NFs showed hierarchical structures of microspheres with diameters of 4−5 μm assembled by nanoflakes. For the first time, the Mg-ion storage mechanism in Ti−Nb 2 O 5 NFs was investigated. Benefiting from the hierarchical structure design and pseudocapacitive intercalation behavior of Mg ions, the Ti−Nb 2 O 5 NF anode exhibited fast Mg-ion diffusion. Consequently, the Mg-DIB exhibited a high discharge capacity of 93 mA h g −1 at 1 C (1 C corresponding to 100 mA g −1 ), along with good long-term cycling performance with a capacity retention of 79% at 3 C after 500 cycles. The Mg-DIB also demonstrated a capacity retention of 77% at 5C, indicating its good rate performance. Moreover, the Mg-DIB exhibited a high discharge medium voltage of ∼1.83 V, thus enabling a high energy density of 174 W h kg −1 at 183 W kg −1 and 122 W h kg −1 at a high power density of 845 W kg −1 , among the best of the reported magnesium-ion full batteries. Our work provides a new strategy to improve the performance of MIBs and other rechargeable batteries.

Enabling Mg‐Based Ionic Liquid Electrolytes for Hybrid Dual‐Ion Capacitors

“…Recently, Yang et al . reported on a Mg‐based DIB cell using expanded graphite as cathode and Ti‐doped niobium pentoxide nanoflakes as fast kinetics anode [7i] …”

Synthesis of Metal Oxides@C (Metal = Ni, Fe) Based Prussian Blue Analogs as a High-performance Anode Material for Lithium-ion Battery

“…By calculating the b values of the three REDOX peaks, it is found that the three b values are all between 0.5 and 1, which means that the discharge capacity is jointly contributed by capacitor and electrochemical reaction during the charging and discharging process [31]. The b values corresponding to Peak1, Peak2 and Peak3 are 0.62, 0.53 and 0.51, respectively.…”

“…Previous studies on the charge storage mechanism in batteries have found that there is an electrochemical behavior of pseudocapacitance during charge and discharge. Pseudocapacitance refers to a supercapacitor in which highly reversible chemical absorption and REDOX reactions occur on the electrode surface, near the surface or in the bulk phase in two or quasi-two dimensions, and the relevant capacitance is generated [31,32]. In this pseudocapacitive charge storage behavior, the charge is stored on the surface of the material due to the faradaic reactions.…”

Organic Positive Materials for Magnesium Batteries: A Review

“…[28] Interestingly, with those advantages, Mg batteries can be regarded as a credible alternative for storage systems of the next generation. [29,30] The formation of dendrites when using liquid electrolytes presents a major safety issue in metal-anode batteries (Li or Na metal) because the thin metal needles can expand through the separator and induce a short circuit inside the battery, which can trigger exposure of harmful substances, flame, and explosions. [31][32][33] Nevertheless, Mg metal anode shows surprising dendrite-free behaviour during the stripping/plating process from low to medium current density or sometimes at high applied current density.…”

“…SHE, relatively higher than Li + /Li or Ca 2+ /Ca leading to a more favourable negative reduction potential [28] . Interestingly, with those advantages, Mg batteries can be regarded as a credible alternative for storage systems of the next generation [29,30] …”