An innovative anode material of lithium-ion battery, Li ₃ VO ₄ /Ti ₃ C ₂ T x , was synthesized. The overall three-dimensional electronic and ionic transport pathways were formed in anode, which promoted both electron and ion transport during the lithiation and delithiation processes.

Micro zinc-air batteries (micro-ZABs) are a promising power source for miniature devices, attracting great attention due to their high energy density, biodegradability, and safety. Operating ZABs in an ultralean, minimum volume electrolyte regime is a productive approach to maximize energy density. However, an ultralean electrolyte ZAB is more susceptible to unfavorable reactions than one containing a larger amount of electrolyte. In particular, side reactions that result in hydroxide ion (OH⁻) consumption significantly hinder the electrochemical performance of the micro-ZAB. The mechanisms of such side reactions are studied through titrations and electrochemical impedance spectroscopy (EIS). The experimental results demonstrate that both carbonation and zincate accumulation contribute to the consumption of OH⁻ in ultralean alkaline hydrogel electrolytes and can significantly impact electrochemical performance. Under the conditions studied, for an alkaline polyvinyl alcohol (PVA) hydrogel electrolyte, the average consumption rate of OH⁻ due to carbonation is measured to be 5.22 × 10⁻⁷ mol min⁻¹ cm⁻². A diffusion-reaction model is developed to understand the carbonation process. Adopting parameters from the literature on aqueous systems, the model shows good agreement with experimental results, suggesting that the carbonation process of PVA alkaline hydrogel electrolytes is similar to that of alkaline aqueous electrolytes. The electrochemical performance of the micro-ZAB is modeled based on the consumption rates of the OH⁻ and is shown to be in good agreement with experimental data.

Small-scale quadrotors, typically defined as centimeter-scale in size and tens of grams in weight, are increasingly being utilized in applications such as agricultural monitoring or search and rescue operations. These vehicles are typically powered with lithium-ion batteries. However, vehicle operational efficiency and capability are often compromised by the limited energy density of these batteries, resulting in short operational duration. This work explores a high-energy chemistry, aluminum-air (Al-air), as a power source to significantly extend the operational duration of small-scale quadrotors. Rapid corrosion of the aluminum anode in existing Al-air systems has been a barrier to adoption in applications where long-term operation is required. However, corrosion is less of a concern in the small-scale quadrotor application, where the battery is typically under continuous use over a short period of time. The electrochemical and packaging design of a micro-Al-air pouch cell battery is optimized for two operating points: an energy density of 325 Wh/(kg_battery ) above a power density of 500 W/(kg_battery ), and an energy density of 240 Wh/(kg_battery ) above a power density of 800 W/(kg_battery ), both of which far surpass the performance of equivalent commercial lithium-ion batteries. A 3D-printed small-scale quadrotor platform is used to evaluate flight duration. The micro Al-air battery delivers 13.1 minutes of flight time, compared to the 4.5 minutes of flight time provided by the commercial micro lithium-ion battery. This work demonstrates the feasibility of Al-air batteries that simultaneously possess sufficiently high power density to achieve small-scale quadrotor flight, and sufficiently high energy density to achieve extended duration of that flight.

A significant challenge for power sources of small-scale quadrotors is the simultaneous need for high gravimetric energy density and high power density. While aluminum–air batteries (AABs) can provide the high energy density, achieving high power density typically necessitates expensive catalysts such as platinum, which can be a significant cost driver. We present microfabricated silver-based air-cathodes for high-power AABs that are suitable for small-scale quadrotor applications. Experimental results, supported by a diffusion–reaction model, indicate that the power performance of the Ag-based cathode is largely determined by the electrochemically active catalyst surface area. To maximize the surface area, we exploit a microfabrication technique involving co-sputtering of a silver–copper alloy on a carbon paper substrate, followed by selective etching of the copper. This process results in a Ag-based paper cathode that delivers a power density of 202 mW cm⁻² with 0.3 mg-silver cm⁻² catalyst loading. Under battery discharge conditions relevant to small-scale quadrotor operations, the discharge performance of the silver-based AAB is examined. The silver-based cathode achieves a discharge peak power density of 1000 W/kg_battery, which is 70% that of the platinum-based cathode. Notably, when discharging above the 800 W/kg_battery threshold required for the small-scale quadrotor, the silver-based cathode achieves a comparable discharge duration compared with the platinum-based cathode. The cost analysis reveals a significant economic advantage, with this high-power silver-based cathode being 460 times less expensive than the commercial platinum-based cathode on a materials basis.