Mid Sweden University

Silicon-based anodes offer substantially higher theoretical capacities than graphite in lithium-ion batteries, but their practical deployment is hindered by severe volume changes that induce mechanical degradation and unstable interfacial chemistry. While nanoscaling strategies can mitigate these effects, they often suffer from low tapped density, complex synthesis, and limited scalability. Porous silicon microparticles provide a promising alternative by partially accommodating volume expansion while preserving processability and electrode-level integrity. Here, a HF-free urea-assisted etching strategy is employed to generate porous silicon microparticles under mild conditions, leveraging the coupled action of thermally induced structural disruption and chemically driven surface modification. Control experiments confirm that the combined action of these effects is essential to achieve BJH-resolved mesoporosity and increased surface area. The resulting porous silicon exhibits oxygen- and nitrogen-containing surface functionalities. Composite electrodes prepared with nanographite and sodium alginate binder at graphite:silicon:binder ratios of 8:1:1, 7:2:1, and 4.5:4.5:1 demonstrate improved electrochemical behavior. In half-cell testing, electrodes containing 10-20 wt % porous silicon deliver stable redox activity and retain 630-880 mAh g-1 after 100 cycles at 0.1 C, with Coulombic efficiencies of 98.8-99.7%, whereas higher silicon loadings lead to rapid capacity decay. Cycling-resolved impedance and differential-capacity analyses reveal the formation of a thicker yet mechanically resilient interphase that stabilizes charge-transfer kinetics, while rate capability tests show 65-74% capacity retention at 2 C.

Silicon materials are currently being explored for usage in lithium–ion battery anodes due to their high lithium storage capacity,but their practical application is hindered by severe volume expansion during cycling, leading to mechanical degradation andcapacity fading. This study introduces a novel two-pot method for synthesizing silicon nanoparticles (Si NPs) to address thesechallenges. The method decouples precursor decomposition and nanoparticles deposition enabling in situ growth of Si NPs onnanographite substrates. By replacing hazardous silane precursors with polyvinyl alcohol or hydrogen gas, we eliminate safetyrisks while simplifying production. Scanning electron microscopy and electrochemical characterization confirm uniform Si NPdeposition. The fabricated electrodes displayed stable electrochemical performance with a capacity of 503 mAh/g after 100 cyclesin a half-cell configuration. This approach offers a safe route for producing high-performance silicon-based anodes.

A recyclability perspective is essential in the sustainable development of energy storage devices, such as lithium-ion batteries (LIBs), but the development of LIBs prioritizes battery capacity and energy density over recyclability, and hence, the recycling methods are complex and the recycling rate is low compared to other technologies. To improve this situation, the underlying battery design must be changed and the material choices need to be made with a sustainable mindset. A suitable and effective approach is to utilize bio-materials, such as paper and electrode composites made from graphite and cellulose, and adopt already existing recycling methods connected to the paper industry. To address this, we have developed a concept for fabricating fully disposable and resource-efficient paper-based electrodes with a large-scale roll-to-roll coating operation in which the conductive material is a nanographite and microcrystalline cellulose mixture coated on a paper separator. The overall best result was achieved with coated roll 08 with a coat weight of 12.83(22) g/m2 and after calendering, the highest density of 1.117(97) g/cm3, as well as the highest electrical conductivity with a resistivity of 0.1293(17) m (Formula presented.) m. We also verified the use of this concept as an anode in LIB half-cell coin cells, showing a specific capacity of 147 mAh/g, i.e., 40% of graphite’s theoretical performance, and a good long-term stability of battery capacity over extended cycling. This concept highlights the potential of using paper as a separator and strengthens the outlook of a new design concept wherein paper can both act as a separator and a substrate for coating the anode material. 

Silicon materials are currently being explored for usage in lithium-ion battery anodes due to their high lithium storage capacity. We have developed a novel method, using a simple thermal treatment of low-cost silicon powder and nanographite, resulting in a composite where silicon nanoparticles are grown on the graphene surfaces. Electrodes fabricated from these Si-NG composites delivered a stable capacity of 489 mAh/g during 25 cycles, i.e. higher than conventional graphite anodes (theoretical capacity: 372 mAh/g). The method uses low-cost materials and avoids complex setups, thereby suggesting industrial scalability.

Porous silicon (Si) has gained significant interest in various applications due to its high surface area, tunable pore structure, excellent chemical reactivity, biocompatibility, and surface functionalization potential. Traditional methods for synthesizing porous Si often rely on hydrofluoric acid, a hazardous chemical that poses significant environmental and safety risks, limiting its scalability and sustainability. In this study, a green and scalable approach for synthesizing porous Si microparticles through urea-assisted etching is presented and evaluated as a function of temperature and container conditions (crucible vs. autoclave). The urea etching transformed pristine silicon microparticles, with a non-porous structure and a BET surface area of 2.3 m2/g, into porous silicon with surface areas as high as 26.7 m2/g. The highest porosity was achieved at 400 °C, while higher temperatures (600 °C and 800 °C) led to diminished porosity and surface restructuring. Quantitative analysis revealed a maximum etching yield of 17.5 %, etching rate of 14.6 mg/h, and a pore formation efficiency of ∼43 %. The crystalline structure of silicon remained intact across all treatments, with minor surface disorder observed at higher temperatures. The urea-assisted etching produced a temperature-and environment-dependent surface oxidation and nitrogen incorporation. At 220 °C and 400 °C, a thick oxide layer formed, particularly under high-‍pressure conditions, while oxidation was less pronounced at 600 °C and 800 °C, likely due to rapid thermal decomposition limiting sustained gas-solid interactions. Nitrogen incorporation was most significant in Si-220-HP, where multiple nitrogen environments were detected, including Si–N, NH2/NH3+, and NOx species. At higher temperatures, only stable Si–N bonds persisted, while other nitrogen species diminished. 

This study investigates the performance of silicon nanoparticles (Si NPs) and silicon nanographite (SiNG) composite-based anodes for lithium-ion batteries (LiBs). Si offers a promising alternative to traditional graphite anodes due to its higher theoretical capacity, despite encountering challenges such as volume expansion, pulverization, and the formation of a solid electrolyte interface (SEI) during lithiation. SiNPs anode exhibited initial specific capacities of 1568.9 mAh/g, decreasing to 1137.6 mAh/g after 100th cycles, with stable Li–Si alloy phases and high Coulombic efficiency (100.48%). It also showed good rate capability, retaining 1191.3 mAh/g at 8400 mA g−1 (2.82C), attributed to its carbon matrix structure. EIS indicated charge transfer with RB of 3.9 Ω/cm−2 and RCT of 11.4 Ω/cm−2. Contrastingly, SiNG composite anode had an initial capacity of 1780.7 mAh/g, decreasing to 1297.5 mAh/g after 100 cycles. Its composite structure provided cycling stability, with relatively stable capacities after 50 cycles. It exhibited good rate capability (1191.3 mAh/g at 8399.9 mA g−1), attributed to its carbon matrix structure. Electrochemical impedance spectroscopy showed higher resistances for RB of 4.2 Ω/cm−2 and RCT of 15.6 Ω/cm−2 compared to SiNPs anode. These findings suggest avenues for improving energy storage devices by selecting and designing suitable anode materials.

Silicon dioxide (SiO2 or Silica) is one of the most prevalent substances in the crust of the Earth. The main varieties of crystalline silica are quartz, cristobalite, and tridymite. When applied as a material for energy, it is affordable and eco-friendly. The SiO2 is considered as electrochemically inactive toward lithium. The SiO2 exhibits low activity for diffusion and inadequate electrical conductivity. As the particle size of SiO2 decreases, the diffusion pathway of Li-ions shortens, and the electrochemical activity is promoted. In investigation, Cost-effective synthesis approach was employed to produce crystalline cristobalite alpha low silicon dioxide nanoparticles (CCαL SiO2 NPs) derived from Oryza sativa (rice) husk using a solvent extraction modification technique. The objective was to fabricate an cost-effective future anode nanomaterial that could reduce the significant volume expansion growth, pulverization, and increase electrical conductivity of CCαL SiO2 NPs anode and develop high specific capacity for Lithium-ion battery (LiB). To study the phase and purity of the SiO2, a variety of characterization methods, including X-Ray Diffraction, Fourier Infra-Red Spectroscopy, Surface area analysis, Raman Shift analysis, Field Emission Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy, Contact angle measurement, Post-mortem X-ray diffraction, and Post-mortem field emission scanning electron microscopy were employed. This cost-effective synthesis of CCαL SiO2 NPs anode was first reported in this work.

Graphene-based 2D nanomaterials are gaining much interest in energy storage systems, specifically in ultracapacitors. Various electrolytes increase the performance of ultracapacitor (UC), Li-Ion capacitor (LIC), and Li-Ion battery (LIB). In the present work, we have successfully designed a "three-in-one" artificial method to engineer anode from a single precursor for high-performance UC, LIC, and LIB. In the present investigation, graphene oxide (GO) slurry was developed using the modified Hummers’ method. The effect of KOH, H2SO4, and KCl electrolytes on electrochemical performance of UC was demonstrated. The LiPF6 organic electrolyte solution on electrochemical performance of LIC and LIB is demonstrated. The GO deposited on stainless steel electrode achieved its highest specific capacitance of 422 F/g, energy density of 45.50 kWh/kg, and power density of 10,000 W/kg in 3.0 M in KCl, whereas GO as an anode material delivered a first discharge capacity of 456 mAh/g at 0.05 A/g current density with the efficiency of 100%.

Biometric signatures based on either the physiological or behavioural features of a person have been widely used for identification and authentication. However, few strategies have been developed that combine the two types of features in one signature. Here, we report a type of biometric signature based on the triboelectricity of the human body (TEHB) that combines these two types of features. This triboelectric biometric signature (TEBS) can be accomplished by anyone regardless of the physical condition, as it can be performed by many parts of the body. Different TEBS can be identified using a convolutional neural network (CNN) model with a test accuracy of up to 1.0. The TEBS has been further used for text encryption and decryption with a high sensitivity to changes. Moreover, a dual signed digital signature for enhanced security has been proposed. Our findings provide a new type of TEBS that can be generally used and demonstrated in applications. 

Silicon anodes are considered as promising electrode materials for next-generation high-capacity lithium-ion batteries (LIBs). However, the capacity fading due to the large volume changes (∼300%) of silicon particles during the charge−discharge cycles is still a bottleneck. The volume changes of silicon lead to a fracture of the silicon particles, resulting in the recurrent formation of a solid electrolyte interface (SEI) layer, leading to poor capacity retention and short cycle life. Nanometer-scaled silicon particles are the favorable anode material to reduce some of the problems related to the volume changes, but problems related to SEI layer formation still need to be addressed. Herein, we address these issues by developing a composite anode material comprising silicon nanoparticles and nano graphite. The method developed is simple, cost-efficient, and based on an aerogel process. The electrodes produced by this aerogel fabrication route formed a stable SEI layer and showed high specific capacity and improved cyclability even at high current rates. The capacity retentions were 92 and 72% of the initial specific capacity at the 171st and the 500th cycle, respectively.