Silicon-air Batteries Research Articles

Silicon-air batteries enabled by in-situ FeMn alloy-catalyzed nitrogen-doped carbon nanotube arrays as efficient air electrodes catalysts

Silicon-air batteries (SABs) have become promising candidates for energy conversion and storage devices due to their high theoretical energy density, cost-effectiveness, and inherent safety. However, the slow kinetics of the 4e− transfer in the oxygen reduction reaction (ORR) at the cathode during discharge, coupled with severe polarization, reduces the battery’s capacity and hinders the development of silicon-air batteries. The cathodes of currently developed SABs primarily rely on commercial Pt/C and MnO2, with limited research on low-cost, efficient, and stable air cathodes for SABs. To address this issue, we synthesized nitrogen-doped carbon nanotubes containing FeMn alloy particles (FeMn@NCNTs) as cathode ORR catalysts using a simple high-temperature pyrolysis method combined with chemical vapor deposition. In an alkaline medium, the catalyst’s half-wave potential (E1/2) reached 0.83 V. Moreover, the FeMn@NCNTs air cathode exhibited excellent compatibility with the silicon anode, and the constructed aqueous silicon-air battery demonstrated a high specific capacity (165 Ah kg−1) and power density (3.69 mW cm−2). Additionally, the quasi-solid-state SABs constructed with FeMn@NCNTs showed stable operation over a wide temperature range, providing a new solution for the development of low-cost, efficient silicon-air batteries suitable for a wide range of applications.

Enhanced performance of quasi-solid-state silicon-air batteries through light-assisted anodic reactions

Silicon-air batteries (SABs) offer a promising energy storage solution due to their high theoretical energy density, cost-effectiveness, and environmental friendliness. However, practical applications are hindered by limitations in maximum discharge current density and discharge voltage, stemming from intrinsic electrochemical properties of the silicon (Si) anode and surface oxidation kinetics. This study addressed the low maximum discharge current density of SABs by leveraging the Si semiconductor properties and employing a light-assisted strategy. Introducing light to the silicon anode generates photogenerated electron-hole pairs. Furthermore, introducing light to the Si anode allowed for the generation of photogenerated electron-hole pairs. The resulting holes reacted with OH- ions to form hydroxyl radical (OH), which efficiently oxidized the Si surface, thereby facilitating electrochemical reactions. This enhancement increased the anodic reaction kinetics, thereby enhancing the maximum discharge current density of SABs. Furthermore, through this strategy, light-assisted SABs exhibited significant performance improvements: under 1 sun illumination, maximum discharge current density increased by 50.0 %, discharge voltage by 10.0 %, and power density by 45.0 %. Under 3 suns illuminations, these metrics improved further, with maximum discharge current density increasing by 87.5 %, discharge voltage by 20 %, and power density by 200 %. Additionally, quasi-solid-state SABs (QSSSABs) according to this strategy exhibited versatility across various application scenarios, thereby significantly expanding the practical potential of SABs technology.

Quasi-solid-state silicon-air batteries with high capacities and wide-temperature adaptabilities

Silicon-air batteries (SABs) have emerged as significant energy conversion devices due to its high theoretical energy density and favorable energy-to-cost ratios. However, their application is limited by low anode utilization, electrolyte leakage and aqueous configuration. According, herein, a PAAK-M-ionic liquid (IL) hydrogel (PAAK-M-IL) has been developed using a hygroscopic IL, 1-ethyl-3-methylimidazolium chloride (EMImCl), as an additive for the twin-chain PAAK-M. This PAAK-M-IL demonstrates a high conductivity of 332 mS cm-1 and a significant water uptake of 1486 % at room temperature. Quasi-solid-state silicon-air batteries (QSSSABs) constructed based on the PAAK-M-IL exhibit a remarkable specific capacity of 184.47 Ah kg-1, achieving a lifespan of nearly 121 h. Crucially, the QSSSABs exhibit excellent stability and practicality across a wide temperature range (-10 °C to 60 °C) and under harsh conditions, such as water immersion, rinsing, and liquid nitrogen soaking. A QSSSAB is capable of powering a digital clock/a music player in extreme weather and adverse environments. This research marks a groundbreaking achievement in the development of high-performance, practical, and adaptable QSSSABs, effectively addressing the challenges of SABs application in practical scenarios and providing a robust technical foundation for their future advancement.

Reduced graphene oxide assembled on the Si nanowire anode enabling low passivation and hydrogen evolution for long-life aqueous Si-air batteries

Silicon-air batteries (SABs), a new type of semiconductor air battery, have a high energy density. However, some side reactions in SABs cause Si anodes to be covered by a passivation layer to prevent continuous discharge, and the anode utilization rate is low. In this work, reduced graphene oxide (RGO) fabricated via high-temperature annealing or L-ascorbic acid (L.AA) reduction was first used to obtain Si nanowires/RGO-1000 (Si NWs/RGO-1000) and Si nanowires/RGO-L.AA (Si NWs/RGO-L.AA) composite anodes for SABs. It was found that RGO suppressed the passivation and self-corrosion reactions and that SABs using Si NWs/RGO-L.AA as the anode can discharge for more than 700 hours, breaking the previous performance of SABs, and that the specific capacity was increased by 90.8% compared to bare Si. This work provides a new solution for the design of high specific capacity SABs with nanostructures and anode protective layers.

Optimization of the discharge performance of silicon–air batteries by aluminum doping

Optimization of the discharge performance of silicon–air batteries by aluminum doping

Uncovering the Mechanisms behind the Limited Discharge Duration of Silicon-Air Batteries with Alkaline Electrolytes

The demand for electronic devices with high storage capacities and long-lasting batteries has motivated the development of new battery systems. Metal-air and semiconductor-air batteries are particularly interesting due to their high capacity densities due to the use of air for the cathode reaction. The Si-air battery was introduced as a battery system that operated with a room-temperature ionic liquid or KOH as the electrolyte.[1,2] However, the practical capacity density is reduced to a fraction of the theoretical value in liquid electrolytes, and the passivation of the silicon anode in aqueous electrolytes is a major challenge.[3,4] Increasing the surface area of the Si electrode can reduce the local reaction rate and enable the dissolution of the reaction products, but it also increases the overall corrosion rate. A threshold temperature and the addition of fresh electrolyte solution can also extend the discharge duration.[3,5] Silicon-air batteries have the potential to become the next generation of batteries, as they are made from non-critical raw materials and have a high theoretical capacity. However, silicon-air batteries using alkaline electrolytes suffer from early passivation and termination of discharge. To understand this process, we investigated the correlation between dissolved silicon in the electrolyte and the discharge duration until passivation. Our findings revealed that silicate enrichment in the electrolyte reduces the flow of reaction products away from the silicon surface, leading to rapid oxidation and passivation of the surface.[6] We utilized various techniques, including electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM), to investigate this phenomenon further. Our results showed that the silicate concentration in the electrolyte plays a crucial role in determining the performance of silicon-air batteries. A lower concentration of silicates in the electrolyte leads to sustained discharge, while a higher concentration results in early passivation and termination of discharge.In conclusion, our investigation highlights the critical role of silicates in the performance of silicon-air batteries utilizing alkaline solutions. Our findings suggest that controlling the concentration of silicates in the electrolyte is crucial to ensure the sustained discharge of these batteries. This study provides essential insights into the mechanisms governing the passivation of silicon surfaces in alkaline electrolytes, which will aid in the development of more efficient and sustainable energy storage solutions.[1] G. Cohn, D. Starosvetsky, R. Hagiwara, D. D. Macdonald, Y. Ein-Eli, Electrochem. commun. 2009, 11, 1916–1918.[2] X. Zhong, H. Zhang, Y. Liu, J. Bai, L. Liao, Y. Huang, X. Duan, ChemSusChem 2012, 5, 177–180.[3] Y. E. Durmus, Ö. Aslanbas, S. Kayser, H. Tempel, F. Hausen, L. G. J. G. J. de Haart, J. Granwehr, Y. Ein-Eli, R.-A. A. Eichel, H. Kungl, Electrochim. Acta 2017, 225, 215–224.[4] Y. E. Durmus, S. Jakobi, T. Beuse, Ö. Aslanbas, H. Tempel, F. Hausen, L. G. J. de Haart, Y. Ein-Eli, R.-A. Eichel, H. Kungl, J. Electrochem. Soc. 2017, 164, A2310–A2320.[5] S. Sarwar, M. Kim, G. Baek, I. Oh, H. Lee, Bull. Korean Chem. Soc. 2016, 37, 997–1003.[6] R. Schalinski, S. L. Schweizer, R. B. Wehrspohn, ChemSusChem 2023, DOI 10.1002/cssc.202300077.

Inhibition of Corrosion in Alkaline Silicon–Air Batteries with Polyethylene Glycol

Silicon–air batteries (SABs) are attracting significant attention for their potential as high‐energy‐density electrochemical storage devices. One of the main limitations for the commercial use of alkaline SABs is the high corrosion, which results in a low conversion efficiency. Herein, the aim is to examine the influence of polyethylene glycol (PEG) on the conversion efficiency of SABs, shedding light on key factors affecting their performance. SABs using KOH as electrolyte at two concentrations, 0.5 and 2.0 mol L−1, are investigated. The results show that replacing part of the water in the alkaline electrolyte with PEG changes the etching behavior from anisotropic to polishing and increases the specific energy density by 53% and 123% in 0.5 and 2 mol L−1 KOH electrolytes, respectively.

The Role of Silicate Enrichment on the Discharge Duration of Silicon-Air Batteries.

Silicon-air batteries are candidates for next generation batteries from non-critical raw materials. However, current silicon-air batteries with alkaline electrolytes suffer from premature termination of the discharge process. To understand this process, we investigated the correlation of dissolved silicon in the electrolyte and the discharge duration until passivation. The air- and Si-electrode could be excluded as the source of the voltage drop, while the concentration of silicates in the electrolyte was identified as the decisive factor. A low silicate concentration in the electrolyte was found to be crucial for a sustained discharge of silicon-air batteries with alkaline electrolytes and full consumption of the silicon electrode used in these conditions was shown.

In/Ga-Doped Si as Anodes for Si-Air Batteries with Restrained Self-Corrosion and Surface Passivation: A First-Principles Study.

Silicon-air batteries (SABs) are attracting considerable attention owing to their high theoretical energy density and superior security. In this study, In and Ga were doped into Si electrodes to optimize the capability of Si-air batteries. Varieties of Si-In/SiO2 and Si-Ga/SiO2 atomic interfaces were built, and their properties were analyzed using density functional theory (DFT). The adsorption energies of the SiO2 passivation layer on In- and Ga-doped silicon electrodes were higher than those on pure Si electrodes. Mulliken population analysis revealed a change in the average number of charge transfers of oxygen atoms at the interface. Furthermore, the local device density of states (LDDOS) of the modified electrodes showed high strength in the interfacial region. Additionally, In and Ga as dopants introduced new energy levels in the Si/SiO2 interface according to the projected local density of states (PLDOS), thus reducing the band gap of the SiO2. Moreover, the I-V curves revealed that doping In and Ga into Si electrodes enhanced the current flow of interface devices. These findings provide a mechanistic explanation for improving the practical efficiency of silicon-air batteries through anode doping and provide insight into the design of Si-based anodes in air batteries.

Si protected by metal-organic segments as anodes in Si-air batteries

Silicon-air batteries have attracted attention because of their high theoretical energy densities. However, the practical application of Si-air batteries is limited by the corrosion of silicon anodes. In this work, metal-organic segments (MOSs) coating was used for the first time to protect anodes in silicon-air batteries and the effects of MOS coating on the electrochemical performance of silicon-air batteries have been systematically investigated. The surface morphology of Si@MOS composites can be well-controlled by changing solution concentrations. The potentiodynamic polarization curves and the theoretical calculation prove that the corrosion rate of the silicon anodes can be effectively inhibited by the MOS coating. The critical KOH solution concentration can be reduced from 1.9 M for bare silicon to 1.3 M for Si@MOS composite anode. The Si@MOS composite anode also exhibits a longer discharge time of about 430 h at 0.9 V with a specific capacity 114 mAh g−1, which is much higher than that of bare Si (250 h with a specific capacity of 71 mAh g−1). This work not only demonstrates a surface modification method to protect the Si anode, but also provides a novel idea to improve the performance of Si-air batteries.

Performance of silicon-air batteries using industrial silicon as anode

Performance of silicon-air batteries using industrial silicon as anode

Silicon–air batteries: progress, applications and challenges

Silicon–air battery is an emerging energy storage device which possesses high theoretical energy density (8470 Wh kg−1). Silicon is the second most abundant material on earth. Besides, the discharge products of silicon–air battery are non-toxic and environment-friendly. Pure silicon, nano-engineered silicon and doped silicon have been found potential candidate for anode. Meso-porous meso-cellular carbon having optimal pore size and imbibed with α-MnO2 nanowires catalyst is found the most promising cathode. Several technical, design and corrosion problems associated with Si–air battery system have to be resolved for its mass scale deployment. This review presents comprehensive information on Si–air battery technology. Graphic abstract

Feasibility study of polypropylene-based aluminium-air battery

The global economy depend on the fossil fuel to meet the daily power demands, ranging from electricity supply to transportation. It is estimated that more than 60% of the world power generation is depending on the fossil fuel. Therefore, the search for clean energy to replace fossil fuel has become the current research trend in the world. Metal-air battery featuring high energy density is projected as one of the promising candidate for the next generation energy storage system. There are various type of metal-air batteries available in the literature such as lithium-air battery, magnesium-air battery, silicon-air battery, aluminium-air battery, zinc-air battery, etc. However, aluminium-air batteries with its low cost and high energy density of 4300 Wh/kg show a great potential for future energy storage applications. In this study, the performance of the aluminium-air battery with polypropylene separator is being investigated. The battery is filled with 1M of Potassium Hydroxide electrolyte. Anode of the battery is made of Aluminium foil and carbon fibre cloth is used as cathode of the battery. The experimental results shown that, the maximum capacity of 23 mAh can be achieved using 6.25 mA of constant current discharge. By connecting the batteries in series, it is sufficient to power on a light-emitting diodes and charging a mobile phone.

Silicon and Iron as Resource-Efficient Anode Materials for Ambient-Temperature Metal-Air Batteries: A Review.

Metal-air batteries provide a most promising battery technology given their outstanding potential energy densities, which are desirable for both stationary and mobile applications in a “beyond lithium-ion” battery market. Silicon- and iron-air batteries underwent less research and development compared to lithium- and zinc-air batteries. Nevertheless, in the recent past, the two also-ran battery systems made considerable progress and attracted rising research interest due to the excellent resource-efficiency of silicon and iron. Silicon and iron are among the top five of the most abundant elements in the Earth’s crust, which ensures almost infinite material supply of the anode materials, even for large scale applications. Furthermore, primary silicon-air batteries are set to provide one of the highest energy densities among all types of batteries, while iron-air batteries are frequently considered as a highly rechargeable system with decent performance characteristics. Considering fundamental aspects for the anode materials, i.e., the metal electrodes, in this review we will first outline the challenges, which explicitly apply to silicon- and iron-air batteries and prevented them from a broad implementation so far. Afterwards, we provide an extensive literature survey regarding state-of-the-art experimental approaches, which are set to resolve the aforementioned challenges and might enable the introduction of silicon- and iron-air batteries into the battery market in the future.

New Insights into the Passivation Behavior of Silicon Electrodes in Silicon-Air Batteries with Alkaline Electrolytes

The chemical etching of silicon has been investigated thoroughly during the past 40 years to achieve a fast and controlled process for texturing surfaces. Nonetheless, still little is known about the electrochemical reaction of silicon with KOH for the use in batteries. The high theoretical capacity density of 3817 mAh cm-2 and potential of 2.09 V make the silicon-air system a promising candidate for energy storage. However, a crucial constraint to the use of an aqueous alkaline electrolyte, such as KOH, is related to the fact that the system discharges only once. Overpotentials reduce the practical potential to 1.4 V, and the competing chemical corrosion of the silicon leads to a strong self-discharge, resulting in a low conversion efficiency. The discharge ends with a sudden potential drop, due to the passivation of the silicon surface before the complete consumption of the electrode. We believe that understanding the mechanisms behind that potential drop and the processes that lead to it are essential to the further improvement of this silicon-air battery. Therefore, we studied cells with different KOH concentrations and with flat phosphor-doped silicon (100) wafers as the Si-electrodes. To investigate the potential drop and increase the conversion efficiency of silicon electrodes, we performed electrochemical measurements in a full cell setup. Galvanostatic discharge tests revealed that the ratio of electrochemical to chemical reaction is influenced by the KOH concentration when the battery is discharged till the passivation. While the highest etching rate for silicon in KOH solution reaches its maximum around 6 mol L-1 KOH, the electrochemical reaction seems to have a peak at 2 mol L-1 KOH in our experimental conditions. We compared the performance of cells with various concentrations of pre-dissolved silicon in KOH and we found a correlation between the silicon content in the electrolyte and the time before the potential drop occurred. The conductivity of the solution decreases with increasing silicon content, probably as a result of the presence of a network of silicate species, which might hinder the diffusion of the Si(OH)4 species. To prove this hypothesis, we tested different volumes of the electrolyte with the same cell parameters. The use of an excess of electrolyte solution enabled the complete consumption of the 500 μm Si-electrode in any KOH concentration used. During these experiments, the silicate species do not reach the critical concentration, and the reaction products can dissolve into the bulk electrolyte, not leading to the formation of a passivation layer. Figure 1

Ionic Liquid Based Electrolytes for Electrical Storage

Ionic liquids (ILs) – salts that are liquid at temperatures below 100°C – have gained big popularity over the past years and have become products of industrial interest, instead of just being lab curiosities. They show interesting combination of physical and chemical properties. A tunable viscosity and conductivity, chemical and thermal stability as well as large electrochemical windows and incombustibility at temperatures below their decomposition point makes them promising components for safe electrolytes in batteries, supercapacitors and other energy devices. In this talk we will present our latest results and developments in the field of ionic liquid based electrolytes for batteries and supercapacitors. In the latter cycling stability over 8 000 000 cycles has been achieved. The use of mixtures of ionic liquids and suitable additives in order to enhance performance and safety of zinc-air, aluminum-air and silicon-air batteries will also be discussed.

New insight into the discharge mechanism of silicon–air batteries using electrochemical impedance spectroscopy

The mechanism of discharge termination in silicon-air batteries, employing a silicon wafer anode, a room-temperature fluorohydrogenate ionic liquid electrolyte and an air cathode membrane, is investigated using a wide range of tools. EIS studies indicate that the interfacial impedance between the electrolyte and the silicon wafer increases upon continuous discharge. In addition, it is shown that the impedance of the air cathode-electrolyte interface is several orders of magnitude lower than that of the anode. Equivalent circuit fitting parameters indicate the difference in the anode-electrolyte interface characteristics for different types of silicon wafers. Evolution of porous silicon surfaces at the anode and their properties, by means of estimated circuit parameters, is also presented. Moreover, it is found that the silicon anode potential has the highest negative impact on the battery discharge voltage, while the air cathode potential is actually stable and invariable along the whole discharge period. The discharge capacity of the battery can be increased significantly by mechanically replacing the silicon anode.

Limitation of Discharge Capacity and Mechanisms of Air‐Electrode Deactivation in Silicon–Air Batteries

The electrocatalytical process at the air cathode in novel silicon-air batteries using the room-temperature ionic liquid hydrophilic 1-ethyl-3-methylimidazolium oligofluorohydrogenate [EMI⋅2.3 HF⋅F] as electrolyte and highly doped silicon wafers as anodes is investigated by electrochemical means, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) spectroscopy. The results obtained by XPS and EPR provide a model to describe the limited discharge capacity by means of a mechanism of air-electrode deactivation. In that respect, upon discharge the silicon-air battery's cathode is not only blocked by silicon oxide reduction products, but also experiences a major modification in the MnO₂ catalyst nature. The proposed modification of the MnO₂ catalyst by means of a MnF₂ surface layer greatly impacts the Si-air performance and describes a mechanism relevant for other metal-air batteries, such as the lithium-air. Moreover, the ability for this deactivation layer to form is greatly impacted by water in the electrolyte.

High‐Capacity Silicon–Air Battery in Alkaline Solution

High‐Capacity Silicon–Air Battery in Alkaline Solution

A silicon–air battery utilizing a composite polymer electrolyte

Gel polymer electrolytes (GPEs) made of blends of ionic liquids and polymer elements, are of high interest as electrolytes in batteries. They possess the high mechanical stability and non-fluidity of solids, together with the thermal and electrochemical stabilities of ionic liquids. In the present work we studied GPE, comprised of a EMI·(HF) 2.3F ionic liquid and 2-hydroxyethyl methacrylate polymer. Morphological characteristics, thermal, electrical, and electrochemical studies confirmed the ability of the GPE to serve as an electrolyte in an all solid Si–air battery. The ionic transport number, determined via the Wagner polarization technique, was found to be close to unity, suggesting ionic conduction domination over an electrical conduction. GPE containing 70 mol% ionic liquid showed a discharge voltage of 0.6 V over more than 850 h, in a discharge current of 0.1 mA cm −2. This work demonstrates the feasibility of using gel polymer electrolytes in silicon–air batteries that offer unprecedented specific energy for powering low power devices.