Tin Anode Research Articles

(Invited) Solving the Energy Storage and Energy Conversion Conundrum – Materials to the Rescue

Energy storage systems have witnessed a meteoric rise ever since Sony commercialized the first Li-ion battery in 1994. Over the years, there have been a plethora of cathode, anode and electrolyte systems developed with stable cycle life and high coulombic efficiencies currently deployed in commercial electric vehicles. Similarly, alternate silicon and tin anodes were targeted as the next generation anodes to ubiquitous carbon. Recalcitrant volume expansion and ensuing solid electrolyte interphase (SEI) issues have reverted the focus back to the omnipresent high-energy density Li metal with efforts to overcome the ominous flammability and safety issues. Escalated impending demand for higher energy density have also made sulfur, an economic and common industrial effluent an attractive active material reverting attention back to Li-S batteries. Similarly, the portentous signs of global warming and the concomitant desire for developing green energy solutions have made hydrogen an imperative and attractive energy source providing the impetus for economic proton exchange membrane (PEM)-based water electrolysis (PEMWE) and fuel cells (PEMFCs). Like the energy storage field, PEMWE and PEMFCs have also witnessed intense research activity over the years following the early work on direct methanol fuel cells (DMFC). Developing high performance materials systems for energy storage and super responsive low-cost electrocatalysts still remain the major conundrum for developing high energy density and high-power density energy storage and conversion systems, respectively.This presentation will discuss the materials challenges that need to be overcome in Li-S batteries and PEM-based water electrolysis and fuel cells. Specifically, efforts aimed at achieving high-energy density cathodes and anodes as well as electrolyte additives for meeting the 500 Whkg-1 energy density targets for electric vehicle technology will be discussed. High sulfur (4-6 mg/cm2) loaded confined cathodes with unique ability to trap the pernicious polysulfide species combined with unique theoretical first principles calculations derived functional electrocatalysts exhibiting the propensity to reversibly catalyze the formation of Li2S and elemental S will be discussed. In tandem, progress made in generating new dendrite-free anodes and low-density current collectors exhibiting areal capacities as high as 15 mAh/cm2 with stable cycling over 100 cycles as well as electrolyte additives matching the cathode and anode performances will be outlined. Similarly, the journey into developing innovative low temperature chemical complexation approaches to novel bifunctional metallic nanostructured electrocatalysts first for DMFC systems and later how the unique approaches were modified targeting acid mediated PEMWE and PEMFCs comprising nanoscale metallic and complex ceramic doped oxide systems will be presented and discussed. Specifically, efforts made in the direction of realizing a unitized regeneration fuel cell (URFC) systems will be outlined and discussed in detail.

(Battery Student Slam 8 Award Winner) Evaluating Electrodeposited Tin and Antimony-Based Anodes for Sodium-Ion Batteries

The widescale adaption of intermittent renewable energy sources, such as wind and solar, must be accompanied by a grid storage network to store energy when it is abundant and redistribute it as needed for on-demand use. Short-term storage in the form of rechargeable batteries is an attractive avenue for meeting these storage needs. The dominant technology in today’s market, the lithium-ion battery (LIB), is cost-prohibitive due to the need for rare-earth materials. Using the same working principle as LIBs, sodium-ion batteries (NIBs) utilize earth-abundant, low-cost sodium compounds instead of lithium compounds. Tin (Sn) and antimony (Sb) alone are promising anode materials for sodium-ion batteries with high theoretical capacities (847 and 660 mAh/g for Sn and Sb with Na, respectively) relative to current LIB anode chemistry (372 mAh/g) [1,2]. When combined, SnSb has shown to have increased stability relative to Sn or Sb alone [3]. Here, we synthesized Sn-Sb thin films with varied Sn and Sb atomic ratios by co-electrodeposition from a deep eutectic solvent by modifying solution stoichiometry and electrodeposition parameters. Using a combination of X-ray photoelectron spectroscopy (XPS), X-ray diffraction, and energy dispersive X-ray spectroscopy (EDS), phases and compositions of Sn-Sb synthesized by electrodeposition were identified. Once synthesized, we sought to determine the influence of morphology, surface chemistry, and composition on the capacity retention and rate capabilities of Sn and Sb-based anodes in NIBs. An optimized electrode composition was identified using a carbonate-based electrolyte, which resulted in stable capacity retention cycling at a rate of C/2 for 270 cycles.[1] W. T. Jing, C. C. Yang, and Q. Jiang, Journal of Materials Chemistry A, 8, 2913–2933 (2020).[2] S. Megahed and B. Scrosati, Journal of Power Sources, 51, 79–104 (1994).[3] W. P. Kalisvaart, H. Xie, B. C. Olsen, E. J. Luber, and J. M. Buriak, ACS Applied Energy Materials, 2, 5133–5139 (2019).

Recovery of Crude Silver and Valuable Metals from Tin Anode Slime

Recovery of Crude Silver and Valuable Metals from Tin Anode Slime

Electrodeposition of Tin and Antimony-Based Anode Materials for Sodium-Ion Batteries

Tin antimonide (SnSb) is a promising alloying anode for sodium-ion batteries due to its high theoretical capacity and relative stability. The material is popular in the battery field, but, to our knowledge, few studies have been conducted on the influence of altering Sn and Sb stoichiometry on anode capacity retention and efficiency over time. Here, Sn-Sb electrodes were synthesized with compositional control by optimizing electrodeposition parameters and stoichiometry in solution and the alloys were cycled in sodium-ion half-cells to investigate the effects of stoichiometry on both performance and electrochemical phenomena. Higher concentrations of antimony deposited into the films were found to best maintain specific capacity over 270 cycles in the tin-antimony alloys, with each cell showing a slow, gradual decrease in capacity. We identified that a 1:3 ratio of Sn:Sb retained a specific capacity of 486 mAh g−1 after 270 cycles, highlighting a need to explore this material further. These results demonstrate how control over stoichiometry in Sn-Sb electrodes is a viable method for tuning performance.

Separation of arsenic from tin anode slime by vacuum distillation

Tin anode slime (TAS) is a high-value waste produced by electrolytic refining of crude tin. In order to reduce the discharge of harmful waste and realize rational recycling, a process of removing arsenic from TAS by vacuum distillation was proposed, and theoretical and experimental studies were carried out. The saturated vapor pressure of each element in TAS and the activation energy of arsenic evaporation during vacuum distillation was calculated. The evaporation temperature and holding time of vacuum distillation for arsenic removal were investigated. The effects of evaporation temperature and holding time on arsenic removal were discussed. The results showed that the residual arsenic content is 0.32–0.19%, and the removal rate of arsenic is 84.87–91.90% at 1153 K and the range of holding time is 30–120min. When the temperature is 1353 K and the holding time from 30 to 120 min, the residual arsenic content is 0.029–0.025% and the removal rate is 99.43–99.59%. The activation energy for the evaporation of arsenic from TAS in vacuum distillation is EAs = 52.76 kJ/mol. The removal of arsenic improves the recycling value of TAS, and provides ideas for treating harmful substances from industrial wastes and recovering valuable metals.

Decoupled tin-silver batteries with long cycle life and power output stability based on dendrite-free tin anode and halide insertion cathode chemistry.

Conventional Ag-Zn batteries have historically faced the challenge of poor cycling stability, rooting in issues associated with Ag cathode dissolution and Zn anode dendrites. Herein, we present a pioneering decoupled Sn-Ag cell, which features two chambers separated by a cation-exchange membrane, containing a dendrite-free Sn metal anode immersed in an alkaline anolyte, and an Ag nanowires/carbon nanotube 3D thick-network cathode in a neutral catholyte. Benefiting from the achieved high electroplating/stripping stability of the metallic Sn anode in the alkaline electrolyte and the electrochemical reversibility of the Ag/AgCl cathode redox couple in the neutral electrolyte, the assembled decoupled Sn-Ag cell demonstrates superior cycling stability, retaining 82.4% of its initial capacity even after 4000 cycles (2 mA cm-2), significantly outperforming both the contrastive decoupled Ag-Zn cell (1500 cycles) and conventional alkaline Ag-Zn batteries (<100 cycles). Furthermore, through the integration of the decoupled Sn-Ag battery with solar cells and power management circuits, an intelligent power system of photovoltaic charging and energy storage was designed, demonstrating its practical viability through maintenance-free charging-discharging during day-night cycles. This research not only significantly increases the lifespan of Ag-batteries with an ultra-flat voltage platform but also opens avenues for the decoupled design of a wide variety of aqueous battery systems.

Characterization of Nanostructured Tin Oxide Anodes Obtained By Electrolytic Oxidation for High-Energy Lithium-Ion Batteries

In recent years, the growing electric vehicle market has increased the need for cost efficient and high energy materials for batteries drastically. Tin and tin oxide materials bear great potential as anode materials for Li-Ion batteries due to low cost and high theoretical capacity. Nevertheless, the development of commercial tin anodes has so far been hindered due to several drawbacks related to high volume expansion during operation leading to fast cell degradation. To circumvent these issues, nanostructured electrodes can be applied to mitigate volume changes. Typically, the production process of such electrodes is challenging, leading to high cost and issues in terms of scalability. Electrochemical processes, such as the electrolytic oxidation of tin, has been found a promising alternative to fabricate nanostructured electrodes. The additive-free tin oxide anodes obtained from this process exhibit high gravimetric and volumetric capacity, excellent rate capability as well as promising cycle life. The morphology and microstructure have high impact on the rate capability and cycling stability of tin oxide anodes. Since structural properties can be precisely adjusted by controlling the electrochemical oxidation process, a deeper understanding of the structure-property relationship is needed to optimize the production process and pave the way for commercialization.Herein an in-depth characterization of nanostructured tin oxide anodes formed by electrochemical oxidation is presented. The rate capability and the cycling stability are investigated by means of electrochemical measurements in battery cells. Operando electrochemical dilatometry is used to investigate the thickness change of the anodes during cycling (cell breathing). In-situ XRD measurements are applied to elucidate the reaction mechanism. The anodes are carefully analyzed by SEM/EDS at different state of lithiation to understand the impact of volume changes on the inner porosity and morphology. Finally, the cycling stability of tin oxide anodes is improved by applying an electrochemical prelithiation step. Therefore, the impact of different prelithiation regimes on the cycling stability is evaluated in full cells. The results contribute to the understanding of electrochemical behavior of nanostructured tin oxide anodes and the derivation of optimal design criteria adjusted by electrochemical surface engineering.

Understanding the Phase Transitions in Tin Foil Electrodes for Sodium-Ion Batteries through Light Microscopy and Kinetic Analysis

Group IVA elements exhibit some interesting sodium capabilities via electrochemical alloying processes (except carbon). Among them, tin is believed to be the most promising anode candidate for sodium-ion batteries (SIBs) due to its simple fabrication and monolithic form (e.g., metallic foils).[1] Nevertheless, tin foil anodes usually fail prematurely after only a handful of cycles. This poor reversibility is reported to be largely associated with the structural collapse of tin electrodes caused by huge volume differences among various Na-Sn phases (up to ~420%).[2][3] The volume change and the number of stress-induced cracks during different phase transitions can be different, given that these intermediate sodium-containing tin phases have different crystal structures and mechanical properties.[4] To prolong the lifetime of tin foil electrodes, it is crucial to determine which phase transitions have a greater impact on crack formation in the tin electrode and deliberately mitigate the problematic phase transitions.In this work, the mechanisms and kinetics of the phase transitions that occur in the sodiation of tin foil are extensively investigated using operando light microscopy and robust electrochemical techniques. Ex situ X-ray diffraction (XRD) (Figure 1) reveals that the initial sodiation of tin foil begins with a significant crystalline to amorphous transition (i.e., c-Sn to a-NaSn), followed by the a-NaSn to c-Na9Sn4 and the c-Na9Sn4 to c-Na15Sn4 transitions. To further understand these transitions, we introduce a new battery configuration for light microscopy to observe the dynamic change of the cross-section macrostructure of tin foil electrodes during cycling. It is expected that the observation could partly quantify the volume expansion during different phase transitions, directly visualize the formation of cracks, and accurately estimate the sodium diffusion coefficient in tin foil electrodes. Moreover, the change of charge transfer resistance as a function of sodiation depth is measured using electrochemical impedance spectroscopy (EIS), shedding light on the degradation mechanism. Besides, potentiostatic intermittent titration technique (PITT) is also employed to determine the role of diffusion or interfacial charge transfer on the whole kinetics of tin anode at different depths of discharge. These investigations could yield fundamental insights into the sodiation mechanisms and kinetics of tin foil electrodes, and more importantly, provide guidance for the utilization of binder- and additive-free tin foil as a reliable SIB anode. Figure 1

Study on electrochemical properties of lead calcium tin anode for hydrometallurgy

This study aims to investigate the electrochemical properties of lead calcium tin (Pb–Ca(0.14%)–Sn(1.04%)) anode employed in hydrometallurgy. Various methods were employed, including cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS), to comprehensively characterize the behavior of this alloy under diverse operating conditions. The findings of this investigation indicate that the Pb–Ca(0.14%)–Sn(1.04%) anode demonstrates remarkable corrosion resistance and a lower oxygen evolution potential in comparison to conventional lead anodes. As a result, enhanced operational efficiency can be achieved. Furthermore, the incorporation of Ca and Sn in the alloy has a substantial positive effect on its mechanical properties, thereby rendering the anode more resilient in harsh operating environments. Consequently, this contributes to reduced maintenance costs. Overall, this study underscores the promising potential of lead calcium tin anodes in promoting more sustainable and efficient hydrometallurgical processes.

Understanding the Effect of Deposition Potential on the Electrodeposited Tin Anodes for Lithium-Ion Batteries

Tin (Sn) is an emerging anode candidate for Li-ion batteries. Due to its high availability and low cost, researchers are studying Sn anode as a next-generation anode alternative for Li-ion batteries (LIB). In this study, we have investigated the electroplated Sn anode obtained from the aqueous media. We have utilized the electrodeposition method for synthesizing pure tin anode on the copper current collector. Aqueous media comprised of tin salt, surface activator, adhesive agent, buffering, and the complexing agent was utilized for obtaining pure tin without using any binder and a conductive agent. Deposition potentials and their effect on the particle morphology and crystal structure were investigated. To enhance the electrochemical performance, we coated the tin anode with the conducting polymer coating and further analyzed the effect of the heat treatment on the polymer-coated tin anodes. The electrochemical performance and physicochemical properties of the electrodeposited Sn electrode were characterized by, Scanning electron microscopy, X-ray Diffraction, and electrochemical techniques. As the voltage of the coating potential increases, it has been observed that the tin particles further enlarge. No difference is observed in X-ray diffraction results for the tin electrodes obtained at different voltages. Coating voltage values of -0.8V and -0.9V have provided ideal electrochemical results. Although polymer coating has a positive effect on the initial capacity value, it has been observed that it does not have sufficient improvement in cycle life.

Boosted Surface‐Redox Pseudocapacitance in 2D Mesoporous TiN for High‐Power Sodium‐Ion Capacitors

Pseudocapacitive materials with surface‐redox reactions are capable of realizing high capacities at ultrahigh rates; however, it remains a challenge in the synthesis of active components with high surface area to boost surface‐redox sodiation but restrain side reactions. Herein, a two‐step, topochemical synthesis of 2D mesoporous TiN (2D‐meso‐TiN) with high surface area and rich mesoporosities is presented. It is demonstrated that the sodium‐ion storage mechanism of TiN anode is based on the existence of surficial titanium oxides via redox reactions between Ti4+ and Ti3+. The interconnected, highly conductive 2D‐meso‐TiN with high surface area largely increases the pseudocapacitive capacities, leading to a high capacity of 160/93 mAh g−1 at 0.1/10 A g−1, which is much higher than 2D‐TiN (120/72 mAh g−1) and commercial TiN nanoparticles (57/30 mAh g−1). The surface‐redox (de)sodiation undergoes no destruction of crystalline TiN, which enables high initial coulombic efficiency and long‐term cycles. Furthermore, a novel hybrid sodium‐ion capacitor consisting of 2D‐meso‐TiN anode and Na3V2(PO4)3 cathode is assembled without any presodiation treatments. The hybrid capacitor delivers both high energy density (94 Wh kg−1 at 64 W kg−1) and high power density (38 Wh kg−1 at 4.4 kW kg−1), as well as long cycling stability.

Passivation Evaluation of Tin Anode Containing Sb and Bi Assuming Tin Electrorefining

原材料のリサイクルへの取り組みが必須課題であり，エレクトロニクス実装分野で使用されるはんだ材料もリサイクルして使用していくことが望ましい。はんだに使用される合金組成は，低温はんだ・高温はんだなど多様化しておりリサイクル材の不純物元素の多様化・純度低下が予想される。

Tendency Regulation of Competing Reactions Toward Highly Reversible Tin Anode for Aqueous Alkaline Batteries.

Investigating dendrite-free stripping/plating anodes is highly significant for advancing the practical application of aqueous alkaline batteries. Sn has been identified as a promising candidate for anode material, but its deposition/dissolution efficiency is hindered by the strong electrostatic repulsion between Sn(OH)3 - and the substrate. Herein, this work constructs a nondense copper layer which serves as stannophile and hydrogen evolution inhibitor to adjust the tendency of competing reactions on Sn foil surface, thus achieving a highly reversible Sn anode. The interactions between the deposited Sn and the substrates are also strengthened to prevent shedding. Notably, the ratio of Sn redox reaction is significantly boosted from ≈20% to ≈100%, which results in outstanding cycling stability over 560 h at 10 mA cm-2 . A Sn//Ni(OH)2 battery device is also demonstrated with capacities from 0.94 to 22.4 mA h cm-2 and maximum stability of 1800 cycles.

Controllable hydrogen generation at low temperatures and safety evaluation for tin anode materials of spent lithium-ion batteries

Given the environmental pollution and thermal risks of lithium-ion batteries, it is necessary to recycle and evaluate the safety of spent lithium-ion batteries. Here, lithium tin alloys (LixSny) were prepared via mechanical alloying to simulate the tin anode materials at different lithium-embedded states. Among them, the Li22Sn5 alloy showed the optimum hydrolysis performance, releasing 351 mL g−1 hydrogen in 10 s at 293 K. The safety evaluation was carried out based on hydrolysis performance, maximum adiabatic temperature rise, and other parameters. The Li22Sn5 alloy required 738.8 mL of water to cool down to 303 K. Moreover, the reaction rates can be precisely controlled by tailoring the solution components, which effectively promoted the security and controllability for practical application. In addition, the hydrogen production of Li22Sn5 sample after hydrogenation increased to 624 mL g−1, even at a subzero temperature of 243 K, 510 mL g−1 hydrogen can be generated within 30 s. This study provides a new idea for the safety evaluation and recycling of tin anode materials in spent lithium-ion batteries.

High-Efficiency and High-Current GaN-Based Microwave Rectifier for Wireless Strain Sensing and Monitoring

In this article, a gallium nitride (GaN) Schottky barrier diode (SBD)-based microwave rectifier with high efficiency, current, and power bandwidth is proposed for wireless strain sensing and monitoring. Solutions including semiconductor devices, rectification circuits, and sensing mechanisms are discussed. A microwave rectifier working at 928 MHz is designed for wireless rectification strain sensing, with a measured power efficiency over 85% and a load resistance lower to 40 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> based on a customized quasi-vertical GaN SBD. The finger layout and TiN anode make the SBD series resistance reduced to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.81~\Omega $ </tex-math></inline-formula> , but saturation current enhanced to 11.8 nA, which significantly reduces rectification loss when the load resistance is small. Finally, a rectification strain sensor (RSS) is proposed by dielectric coupling the rectifier and a piezo-permittivity liquid metal elastomer foam (LMEF), with a measured relative output power variation and wireless working distance over 437%/mm and 3 m, respectively.

Anti-pulverization intermetallic Fe–Sn anchored on N-doped carbon anode boosted superior power and stable lithium storage

Tin (Sn) anode suffers from considerable volume deformation, generating vast dilatation-induced stresses leading to pulverization for lithium-ion batteries (LIBs). Herein, the Sn–Fe–C composite anode material with a jujube cake-like structure where Sn/FeSn2 metalcore anchored on an N-doped carbon matrix is constructed. During the lithiation process, the intermetallic Fe–Sn (FeSn2) generates Fe nanoparticles, which are uniformly distributed in the Sn matrix to relieve internal stress and create a conductive network, thus enhancing electron conduction and ion diffusion kinetics. In addition, the N-doped carbon matrix maintains the material structural integrity and improves overall conductivity. Consequently, the Sn–Fe–C anode delivers a high reversible 400 mAh g−1 over 1100 cycles at 5 A g−1 (capacity retention of up to 90.9%) and rate performance (237 mAh g−1 at 20 A g−1). Sn–Fe–C anode pairs with porous carbon (PC) cathode to assemble lithium-ion capacitors (Sn–Fe–C || PC LICs), which show a maximum energy density of 203.8 Wh kg−1, an excellent power density of 23925.3 W kg−1, and energy retention rate of 72.9% after 18,000 cycles at 1 A g−1. The Sn–Fe–C material as an anti-pulverization anode could be a potential application for high-performance LIBs and LICs in the future.

Low Temperature Behavior of Alloy Anodes for Lithium-Ion Batteries

Lithium-ion batteries are ubiquitous in most energy storage applications, but they fail completely below about -20 ºC, which hinders their use in low-temperature applications, like electric aviation and space exploration. Materials that alloy with lithium offer high specific capacities and have been researched thoroughly at room temperature, but their low temperature behavior is not well understood, despite indications that they may exhibit superior performance. In this work, we characterize the electrochemical and structural changes of antimony, tin, and silicon anodes at temperatures down to -40 ºC using a tailored ether electrolyte. Antimony anodes exhibit reversible cycling at -40 ºC, with a first cycle specific capacity of 450 mAh g-1, and tin and silicon can be cycled at -20 ºC with first cycle specific capacities far exceeding that of graphite. In addition, three-electrode coin-cell experiments reveal strong influences of the lithium metal counter electrode on the overall galvanostatic voltage profiles; these influences become dominant at low temperature and obscure the inherent behavior of the alloy anodes. This finding highlights the importance of using an appropriate reference electrode for low-temperature experiments, especially for sensitive experiments such as the galvanostatic intermittent titration technique (GITT). GITT experiments revealed the contributions of kinetic processes and thermodynamic hysteresis as a function of temperature in these materials, and they showed that the different materials feature different kinetic and hysteretic behavior at low temperature. The low temperature electrochemical behavior of silicon is seemingly more dependent on structural changes during the lithiation/delithiation transformations, while tin and antimony are more strongly impacted by kinetic effects at low temperatures. Finally, X-ray diffraction experiments on antimony anodes reveal difference in the average crystallite size and crystallite evolution at low temperature during cycling. Overall, these results are an important for understanding the fundamental behavior of alloy materials at low temperature and are an important step for the engineering of high-energy, low-temperature lithium-ion batteries.

(Digital Presentation) Elucidating Electrolyte-Induced Performance Decay in Sodium-Tin Batteries

Tin (Sn) anodes for sodium-ion batteries have recently been extensively investigated due to their high capacity (847 mAh/g), low average operating potential (~250 mV vs. Na/Na+), environmental benignity, and high abundance. Unfortunately, upon repeated charging/discharging, both the Sn electrode and Na metal suffers from large volume changes that rupture the solid electrolyte interphase (SEI) and initiate the onset of cell failure. To understand such complex and interrelated phenomena, we have designed a 3-electrode cell to track the evolution of the electrochemical signature of both the working and counter electrode. Additionally, we have compared the electrode morphology and electrode/electrolyte interface under different electrochemical conditions and probed these morphological/interfacial changes with cycling life performance to cultivate a holistic understanding of different types of failure mechanisms. In particular, we have discussed whether the primary reason for the shorter cycling life is the mesoscopic/macroscopic deformation of the Sn electrode caused by volume expansion/contraction or the continuous formation/breakdown of SEI. Furthermore, the effect of a localized electrochemical environment, which primarily depends on the choice of electrolytes (ether-based and carbonate-based), is also explored here.

Optimization of recess-free AlGaN/GaN Schottky barrier diode by TiN anode and current transport mechanism analysis

In this work, the optimization of reverse leakage current (I R) and turn-on voltage (V T) in recess-free AlGaN/GaN Schottky barrier diodes (SBDs) was achieved by substituting the Ni/Au anode with TiN anode. To explain this phenomenon, the current transport mechanism was investigated by temperature-dependent current–voltage (I–V) characteristics. For forward bias, the current is dominated by the thermionic emission (TE) mechanisms for both devices. Besides, the presence of inhomogeneity of the Schottky barrier height (qφ b) is proved by the linear relationship between qφ b and ideality factor. For reverse bias, the current is dominated by two different mechanisms at high temperature and low temperature, respectively. At high temperatures, the Poole–Frenkel emission (PFE) induced by nitrogen-vacancy (V N) is responsible for the high I R in Ni/Au anode. For TiN anode, the I R is dominated by the PFE from threading dislocation (TD), which can be attributed to the decrease of V N due to the suppression of N diffusion at the interface of Schottky contact. At low temperatures, the I R of both diodes is dominated by Fowler–Nordheim (FN) tunneling. However, the V N donor enhances the electric field in the barrier layer, thus causing a higher I R in Ni/Au anode than TiN anode, as confirmed by the modified FN model.

Facile preparation of low-cost multifunctional porous binder for silicon anodes in lithium-ion batteries

A novel multifunctional binder (P-ppCMC) with cross-linked and porous structure is simply prepared through partially protonation and template methods for silicon anodes to accommodate the large volume change of silicon and to enhance the lithium-ion diffusion during the charge/discharge process. In this binder, the cross-linked structure, formed through the carboxyl and hydroxyl groups in partially protonated carboxymethyl cellulose, increases the adhesion and mechanical property of binder, buffering the volume variation of silicon during repeated cycles. The porous structure, generated via template approach, enhances the lithium-ion diffusion and tolerates the volume variation of silicon. Therefore, the P-ppCMC binder significantly improves the cycling stability and rate performance of silicon anodes. The silicon anode with P-ppCMC displays a reversible capacity of 1835 mA h g−1 after 200 cycles at a current density of 0.5 A g−1, and a rate capability of 1707 mA h g−1 at 5 A g−1. The P-ppCMC binder also effectively increases the cycling stability of tin anodes.