Achieving High Stability and Rate Performance Using Spherical Nickel-Zinc Layered Double Hydroxide in Alkaline Solution

Abstract

Nickel layered double hydroxide, Ni(OH)2, has been widely used as the cathode for nickel based battery systems. However, the currently commercialized β-Ni(OH)2 is limited by its low capacity. In contrast, α-Ni(OH)2 can give higher capacity, but it is challenging to stabilize in alkaline solution due to the conversion to β-Ni(OH)2. Herein, we use zinc doped Ni(OH)2 and control its spherical morphology to strengthen the stability of α-Ni(OH)2 in a nickel metal hydride battery system. With an optimal zinc doping content of 3 mol% for the spherical α-Ni(OH)2 (Ni-Zn3), the cathode shows the highest discharge capacity of 351.3 mAh g–1 at a current density of 70 mA g–1 (0.2 C) and superior rate performance, which even delivers 271.5 mAh g–1 at 5 C. More importantly, the durability of the Ni-Zn3 cathode is significantly enhanced, which maintains 81.7% after cycling 360 times, almost twice as long as that of pure α-Ni(OH)2. Studies show that the stabilized Ni–O bond and suitable aperture structure are mainly responsible for the advanced electrochemical properties of the Ni-Zn3. The results show that proper zinc doping spherical α-Ni(OH)2 with low-cost and high performance is an promising cathode material for nickel-based battery systems.

Alkaline Ni−Zn Rechargeable Batteries for Sustainable Energy Storage: Battery Components, Deterioration Mechanisms, and Impact of Additives

“…β−Ni(OH) 2 phase is the widely used active material in commercial batteries. Its theoretical capacity is lower than of α‐ Ni(OH) 2 phase, however it is stable in the alkaline solution [80–82] . Ageing process, controlled by Oswald ripening, leads to a dissolution of this phase in the alkaline solution and β−Ni(OH) 2 is formed by reprecipitation from the solution.…”

“…[83] Cell performance is affected by both the cathode and the anode: irreversible capacity loss upon initial cycling occurs due to a capacity asymmetry of the electrodes and as Zn accumulation occurs over cycling and cannot be fully consumed upon discharge, the coulombic efficiency drastically drops. [80]…”

“…The cathode in the battery is based on a semiconductive Nickel Hydroxide as an active material, mixed with a binder and additional conductive materials, supported by current collector [10,78,79] . Generally, four distinct phases can be produced over the cycle lifetime of this cathode; β−Ni(OH) 2 , β−NiOOH, γ−NiOOH and α−Ni(OH) 2 [80] . The phase conversion is demonstrated in Figure 4(a).…”

“…Likewise for the anode, parasitic reactions on the cathode are also possible. Oxygen evolution reaction (OER) is the major one and dominant at a sufficient overpotential upon charging [10,80,85] . NiOOH demonstrates high catalytic activity toward OER.…”

Sulfonate compounds embraced from acid copper electroplating baths as innovative additives for alkaline Zn batteries

“…13,15 Simultaneously, the electrochemical process in the cathode comprises a transition from Ni(OH) 2 to NiOOH, with the b phase being the desired one due to both high reversibility and stability, while compromising capacity. [16][17][18][19] Finally, the aqueous alkaline electrolyte has a high solubility of ionic Zn species, 20,21 a high conductivity, 2,21,22 and a reduced volatility. 2 Even though this chemistry has previously been thoroughly explored, a breakthrough is still necessary to keep up with commercializing existing battery chemistries.…”