Composite Anode Research Articles

Influence of Moisture on the Electrochemical Performance of Prelithiated Graphite/SiOx Composite Anodes for Li-Ion Batteries

Prelithiation is widely recognized as a promising technology to enable the use of high capacity anode active materials such as silicon. Numerous prelithiation techniques have been proposed over the years, with a handful successfully undergoing pilot scale testing. Nevertheless, new challenges arise when moving from optimizing single processes to integrating them into the process chain. A major concern is the stability of prelithiated electrodes against moisture. In this study, we investigate the influence of industrially-relevant moisture levels on the electrochemical performance of prelithiated graphite/SiOx composite anodes in 3-electrode half- and full-cells. We identify several indicators of electrode degradation such as an increase in open circuit potential, a decrease in graphite lithiation potential, and changes in specific charge/discharge capacity. The underlying degradation mechanisms are examined using electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry, which show increased solid electrolyte interphase (SEI)-related interfacial resistances but no clear evidence of SEI degradation. Based on the experimental results, we define a process window for the stability of the investigated electrodes as a function of dew point and exposure time. Our results indicate an encouragingly high stability at dew points up to −40 °C for a realistic exposure time of 1 h.

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.

Enhancing the oxygen evolution activity and stability of Pb anode in Mn2+-containing acidic solution by embedding MnCo2O4 particles

Due to the excellent activity and stability of MnCo2O4 toward the oxygen evolution reaction (OER) in acidic solution, a Pb–MnCo2O4 composite anode for zinc electrowinning was prepared by embedding dispersed MnCo2O4 particles into a Pb matrix in a powder metallurgy process. In this work, the phase structure, chemical composition, and morphology of the oxide layers formed on Pure-Pb and Pb–MnCo2O4 were analyzed by XRD, SEM, and EDS. Galvanostatic polorization, Tafel tests, and EIS measurements were performed to investigate the anodic potential variation and OER kinetics of the Pure-Pb and Pb–MnCo2O4 composite anodes. Compared with that on the Pure-Pb anode, the oxide layer on Pb–MnCo2O4 is thinner, more compact, and more stable in a 160 g L−1 H2SO4 solution containing 4 g L−1 Mn2+. Consequently, the Pb–MnCo2O4 composite anode exhibited a much lower anode slime production (8.7 mg) during 72 h of the simulated zinc electrowinning process. Despite the smaller surface area and lower PbO2 content of the oxide layer, the Pb–MnCo2O4 composite anode presented preferable OER kinetics with a lower OER charge transfer resistance (0.729 Ω cm2) and a smaller Tafel slope (90.74 mV dec−1), which contributed to a 70 mV reduction in the anodic potential compared with that of the Pure-Pb anode.

Self-mixing anti-corrosive Zn-In powder composite anode with ultra-long lifespan for aqueous zinc-ion battery

Appropriate design of electrode structure and chemistry for Zn metal anode is important to the kinetics and electrochemical stability of Zn in aqueous batteries. Herein, In modified Zn powder electrode with carbon nanofibers as the stable electric conductive matrix provides an effective approach to simultaneously enhance reaction kinetics and inhibit H2 generation reactions. The designed Zn–In powder electrode presents self-mixing In distribution within the electrode during cycling thus enabling superior anti-corrasion and stable conductive network that significantly alters the Zn deposition behavior. Instant 3D Zn deposition with super-fast interfacial kinetics is achieved due to favorable Zn nucleation and growth as well as suppressed side reactions. Stable cycling of over 6300 h is achieved, which is 30-fold longer lifespan than Zn foil anode. Even at 5 mA cm−2, 5 mAh cm−2 (depth of discharge: 31.1%), Zn–In powder anode still presents stable cycling of over 500 h and low polarization voltage. Ultra-long cycle life of over 20,000 cycles can be achieved for full cells using Zn–In powder electrode paired with V2O5 cathode. Modified composite Zn powder electrode provides an effective and practical approach to address the electrochemical stability of Zn-based anodes in rechargeable cells.

Investigation of The Failure Mechanisms of Li-Ion Pouch Cells with Si/Graphite Composite Negative Electrodes and Single Wall Carbon Nanotube Conducting Additive

Silicon-Graphite composite electrodes are a rapidly developing area of research and commercialization. Increasing the energy density of current Li-ion battery technology can be done by simply creating silicon-graphite composite electrodes. It is well known that the failure of these silicon-graphite composite electrodes stems from the expansion of the silicon during cycling that causes mechanical degradation, excessive SEI formation, and electrode shift loss. Here we explore the use and capacity loss mechanisms of a silicon-graphite composite anode employing CMC/SBR binder used in conjunction with single wall carbon nanotubes. These nanotubes are thought to be effective in increasing mechanical resiliency of the electrodes and increase the electrical connectivity between particles within the formed electrode. When the Si/graphite electrode cycles, it is believed that the SWCNTs help keep the active particles electrically connected and, hence, electrochemically active. Through dV/dQ analysis and in situ pressure monitoring, the pouch cells studied here are shown to exhibit minimal loss of active mass in the positive and negative electrodes but experience capacity loss due to continued negative electrode SEI growth leading to lithium inventory or shift loss.

Carbon nanotubes anchored SiOx composite anode for high cyclic stability lithium-ion batteries

Silicon suboxide (SiOx, 0 < x < 2) is one of the most promising anode materials because of its high lithium-ion storage capacity. However, the poor intrinsic conductivity and large volume change during cycling limits its practical application as lithium-ion battery anode materials. Herein, we propose a novel strategy to introduce carbon nanotubes (CNTs) on the SiOx particles, forming a conductive network and relieving the volume expansion effect, which possess improved reversible capacity and robust structure for long cycling stability. The SiOx/CNT composite anode delivers reversible capacity of 1533.8 mAh g−1 at the first cycle and maintains 599.6 mAh g−1 after 500 cycles with a high coulombic efficiency of 99.7 %. In this paper, SiOx composite anchored by CNTs was prepared, which is a simple and effective strategy to improve the conductivity of SiOx, relieve the volume effect and further promote its electrochemical performance benefit from the high conductivity and structural stability of CNTs. This research provides a significant reference for constructing the delicate structure of SiOx-based composites to enhance cyclic performance.

Ladderlike polysilsesquioxanes derived dual-carbon-buffer-shell structural silicon as stable anode materials for lithium-ion batteries

Silicon-carbon (Si/C) composite materials have been proven to be one of the most promising anode materials for the next generation of lithium-ion batteries (LIBs) due to their high theoretical capacity. However, the substantial volume changes during alloying/dealloying processes have posed significant challenges to the working lifespan of Si-based anodes. In this study, we designed a dual-carbon-layer-structured Si composite anode material (DCS-Si). Using ladderlike polysilsesquioxanes as a precursor, we employed a zinc thermal reaction to internally reduce the Si–O–Si framework to Si0. Simultaneously, the phenyl groups directly connected to Si atoms served as a carbon source for the internally dense coating layer. The obtained product underwent further coating controllable pyrolysis reactions to form an external carbon coating layer. As anode for LIBs, DCS-Si delivered a reversible specific capacity exceeding 1000 mAh g−1. Even after 1350 cycles at a current density of 0.3 A g−1, the specific capacity remained above 500 mAh g−1. Moreover, even under a high current density of 3 A g−1, after nearly 1000 cycles, the capacity retention rate still exceeded 70%. Further testing of the full cell also indicated that DCS-Si is a highly promising high-energy-density anode, with potential applications in future commercial lithium-ion batteries.

A Stable Matrix Assisting Highly Compatible and Maintainable Lithium-Garnet Interface for Solid-State Batteries.

Solid-state Li metal batteries (SSLMBs) are attractive due to their capability to simultaneously offer high energy density and high-level safety when combining Li metal anodes, solid-state electrolytes (SSEs), and high-voltage cathodes together. However, SSLMBs may well incur short circuits caused by Li dendrites penetrations, which mainly originate from the instability and poor contact between Li metal and SSEs. Herein, by taking full advantage of the reaction products of Li and Li1.3Al0.3Ti1.7(PO4)3 (LATP), a lithium-LATP composite anode (Li-LATP) is obtained, in which a stable matrix is formed to enhance the contact between Li and the garnet-type SSEs, alleviating the volume change and preserving an intact interface during the charge/discharge process. Consequently, the Li-LATP/garnet/Li-LATP symmetric cell displays a fairly low interfacial resistance of 6Ωcm2 and stable cycling performance for over 2500h with a low overpotential. Furthermore, the LiCoO2/garnet/Li-LATP full cell also shows a high discharge capacity of 159mAhg-1 and great cycling performance.

PDA-Fe3O4 decorated carbon felt anode enhancing electrochemical performance of microbial fuel cells: Effect of electrode materials on electroactive biofilm

Anode modification is an effective strategy for enhancing the electrochemical performance of microbial fuel cell (MFC). However, the impacts of the modified materials on anode biofilm development during MFC operation have been less studied. We prepared a novel PDA-Fe3O4-CF composite anode by coating original carbon felt anode (CF) with polydopamine (PDA) and Fe3O4 nanoparticles. The composite anode material was characterized by excellent hydrophilicity and electrical conductivity, and the anodic biofilm exhibited fast start-up, higher biomass, and more uniform biofilm layer after MFC operation. The MFC reactor assembled with the composite anode achieved a maximum power density of 608 mW m−2 and an output voltage of 586 mV, which were 316.4% and 72.4% higher than the MFC with the original CF anode, respectively. Microbial community analysis indicated that the modified anode biofilm had a higher relative abundance of exoelectrogen species in comparison to the unmodified anode. The PICRUSt data revealed that the anodic materials may affect the bioelectrochemical performance of the biofilm by influencing the expression levels of key enzyme genes involved in biofilm extracellular polymer (EPS) secretion and extracellular electron transfer (EET). The growth of the anodic biofilm would exert positive or negative influences on the efficiency of electricity production and electron transfer of the MFCs at different operating stages. This work expands the knowledge of the role that anodic materials play in the development and electrochemical performance of anodic biofilm in MFCs.

Short-Chain Sulfur Confined into Nitrogen-Doped Hollow Carbon Nanospheres for High-Capacity Potassium Storage.

Carbon-based materials are one of the ideal negative electrode materials for potassium ion batteries. However, the limited active sites and sluggish diffusion ion kinetics still hinder its commercialization process. To address these problems, we design a novel carbon composite anode, by confining highly reactive short-chain sulfur molecules into nitrogen-doped hollow carbon nanospheres (termed SHC-450). The formation process involves the controlled synthesis of hollow polyaniline (PANI) nanospheres as precursors via an Ostwald ripening mechanism and subsequent sulfuration treatment. The high content of constrained short-chain sulfur molecules (20.94 wt%) and considerable N (7.15 wt%) ensure sufficient active sites for K+ storage in SHC-450. Accordingly, the SHC-450 electrode exhibits a high reversible capacity of 472.05 mAh g-1 at 0.1 A g-1 and good rate capability (172 mAh g-1 at 2 A g-1). Thermogravimetric analysis shows that SHC-450 has impressive thermal stability to withstand a high temperature of up to 640 °C. Ex situ spectroscopic characterizations reveal that the short-chain sulfur provides high capacity through reversible formation of K2S. Moreover, its special hollow structure not only provides ample space for highly active short-chain sulfur reactants but also effectively mitigates volume expansion during the sulfur conversion process. This work offers new perspectives on enhanced K+ storage performance from an interesting anode design and the space-limited domain principle.

Ni-Co MOF-derived rambutan-like NiCo2O4/NC composite anode materials for high-performance lithium storage

Taking advantage of the large surface area and high porosity characteristic of metal-organic framework (MOF) materials, the synthesis of carbon-coated bimetallic transition metal oxides stands out as an effective strategy to reduce volume expansion, enhance cycling stability, and improve electronic conductivity at the active sites in lithium-ion batteries (LIBs). In this research, a novel rambutan-like Ni-Co MOF was successfully synthesized via a hydrothermal method followed by calcination to obtain nitrogen-doped carbon-stabilized hierarchical rambutan-like NiCo2O4 composites (NiCo2O4/NC). The resulting composites inherited the original rambutan-like structure of the Ni-Co MOF, which was characterized by uniform size, highly ordered porosity and large surface area, and showed excellent electrochemical Li+ storage performance. In particular, the NiCo2O4/NC-600 composite exhibited superior cyclic stability and rate capability, maintaining a remarkable reversible charge/discharge specific capacity of 1281.7/1292.7 mAh g−1 after 400 cycles at 0.5 A g−1. In addition, when paired with LiFePO4 in a full cell, it maintained a reversible discharge specific capacity of 143.9 mAh g−1 after 200 cycles at 0.1 A g−1, indicating commendable cyclic stability. Ex-situ analyses confirmed the pseudo-capacitive behavior of the NiCo2O4/NC composites. Furthermore, the nitrogen-doped carbon layer embedded in the NiCo2O4/NC composites effectively mitigated the volume expansion during repeated Li stripping/plating processes, thereby improving the structural integrity, conductivity, and specific capacitance. This study presents a practical approach for fabricating nitrogen-doped carbon-stabilized bimetallic oxide anodes in high-power LIBs through architectural engineering and compositional tailoring.

Detachment and flow behaviour of anode slimes in high nickel copper electrorefining

Most of the world’s copper is produced via copper electrorefining, where nickel is the most abundant impurity in the process. Previously it has been suggested that nickel affects the adhesion of anode slimes on the anode as well as the porosity of the slime layer that forms. This paper investigates the effects of nickel, oxygen, sulphuric acid and temperature on the detachment of anode slimes from the anode surface. The detachment of particles as a function of both anode and electrolyte composition was studied on laboratory scale using a camera connected to a Raspberry Pi, and particle detection and movement analysed using TrackPy. The results revealed four different slime detachment mechanisms: cloud formation, individual particle detachment, cluster detachment and avalanche. These were found to be dependent on the electrolyte (0, 10, 20, 30 g/dm3 Ni2+ &amp; 100, 200 g/dm3 H2SO4), with increasing nickel concentration promoting cluster detachment and increasing sulphuric acid concentration favouring detachment of individual particles. Anode composition (0.05-0.44 wt% O and 0.07-0.64 wt% Ni) was shown to affect the flow direction of anode slimes, with increasing nickel leading to more upward-flowing slimes. Typical particle movement velocities were from -0.5 to 1.0 mm/s regardless of the electrolyte and anode composition, and regardless of the operating temperature (25 °C &amp; 60 °C) for small particles (&lt;0.5 mm). The results also support previous findings that increasing the nickel concentration of the electrolyte leads to a more porous anode slime layer on the anode.

A self-assembled carbon nanotube/silicon composite battery anode stabilized with chemically reduced graphene oxide sheets

This study presents a streamlined fabrication process for lithium-ion battery (LIB) electrodes, involving the dispersion of carbon nanotubes (CNT), silicon (Si), and graphene oxide (GO) in an aqueous solution, followed by vacuum filtration to produce self-standing composite electrodes. Two reduction routes are employed to form reduced graphene oxide (rGO). The chemically reduced CNT/Si/rGO-5 %-Chem anode exhibits superior mechanical resilience compared to thermally reduced counterparts, which suffer from reduced strength and structural integrity. Chemical reduction also enhances electrochemical performance, increasing the initial capacity of the non-reduced CNT/Si/GO-5 % composite anode from 1,461 to 2,342 mAh g−1, with improved long-term cycling performance. Electrochemical impedance spectroscopy shows lower pre-cycle charge transfer resistance (148 Ω) and superior solid electrolyte interphase (SEI) resistance (43 Ω) for chemically reduced anodes compared to thermally reduced ones. After cycling, the chemically reduced composite anode exhibits reduced electrolyte resistance and charge transfer resistance, indicating stable electrochemical reactions. The composite structure undergoes adaptive rearrangements during cycling, optimizing active material utilization. In summary, CNTs accommodate silicon swelling, while chemically reduced rGO promotes stable SEI formation, highlighting the benefits of chemical reduction in enhancing mechanical durability and electrochemical performance, making the self-standing CNT/Si/rGO composite film a promising LIB anode.

Anchoring Active Li Metal in Oriented Channel by In Situ Formed Nucleation Sites Enabling Durable Lithium-Metal Batteries.

Lithium metal is the ultimate anode material for pursuing the increased energy density of rechargeable batteries. However, fatal dendrites growth and huge volume change seriously hinder the practical application of lithium metal batteries (LMBs). In this work, a lithium host that preinstalled CoSe nanoparticles on vertical carbon vascular tissues (VCVT/CoSe) is designed and fabricated to resolve these issues, which provides sufficient Li plating space with a robust framework, enabling dendrite-free Li deposition. Their inherent N sites coupled with the in situ formed lithiophilic Co sites loaded at the interface of VCVT not only anchor the initial Li nucleation seeds but also accelerate the Li+ transport kinetics. Meanwhile, the Li2Se originated from the CoSe conversion contributes to constructing a stable solid-electrolyte interphase with high ionic conductivity. This optimized Li/VCVT/CoSe composite anode exhibits a prominent long-term cycling stability over 3000h with a high areal capacity of 10 mAh cm-2. When paired with a commercial nickel-rich LiNi0.83Co0.12Mn0.05O2 cathode, the full-cell presents substantially enhanced cycling performance with 81.7% capacity retention after 300 cycles at 0.2 C. Thus, this work reveals the critical role of guiding Li deposition behavior to maintain homogeneous Li morphology and pave the way to stable LMBs.

Ultrafast synthesis of spinel AMn2O4 (A= Co, Mn, Zn) nanopolyhedras and their composites applied to lithium ion battery anode

Spinel oxide anode materials are hardly used for commercial lithium-ion batteries because of their evident volume expansion in the discharging process and poor electronic conduction. Preparing a composite material of nanostructured spinel bimetallic oxides and carbon will solve the above problems and achieve outstanding electrochemical performance. In this study, an ultrafast approach (only 10 min) to synthesize spinel AMn2O4 (A= Co, Mn, Zn) nanopolyhedras and their composites with GO was successfully developed. Integrating spinel CoMn2O4 nanopolyhedras with GO can profoundly inhibit the problem of volume expansion but also eminently upgrading conductivity. The CoMn2O4/GO composite anode displays competent cyclic life and rate capability for lithium ion battery, delivering a large capacity of 738 mAh g−1 after 340 cycles at 2 A g−1. The ultrafast approach and alluring electrochemical performance of this work will inevitably give impetus to the fast development and application of spinel oxides.

Enhanced performance of acridine degradation and power generation by microbial fuel cell with g-C3N4/PANI-DA/CF anode

Microbial fuel cell (MFC) has attracted much attention in treating organic wastewater due to its double functions of degrading organics and generating electricity with microorganisms as biocatalysts. Unfortunately, some organics with biological toxicity such as acridine could inhibit the growth and activity of the microorganisms on the anode so that the double functions of MFC would recede. Enhancing microbial activity by using new biocompatible materials as anodes is prospective to solve problem. A novel anode was achieved by electrodepositing g-C3N4 sheets to the carbon felt (CF) modified with polyaniline-dopamine composite film, and used to treat wastewater containing acridine for the first time. After the operation of 13 d, MFC loading with the composite anode showed a degradation efficiency of 98.3% in 150 mg L−1 acridine, while that of CF-MFC was 55.8%. Moreover, MFC loading the modified anode obtained a maximum power density of 1976 ± 47 mW m−2, 140.1% higher than that of CF-MFC. Further analysis revealed that the functional microorganisms associated with acridine degradation such as Achromobacter and Alcaligenes were enriched on the g-C3N4/PANI-DA/CF anode. Moreover, the composite anode could improve the activity of microorganisms and elicit them to generate conductive nanowires, which was beneficial to transferring electrons from microbes to anode over long distances, suggesting a promising prospect application in MFC.

Si Nanowires: From Model System to Practical Li-Ion Anode Material and Beyond.

Nanowire (NW)-based anodes for Li-ion batteries (LIBs) have been under investigation for more than a decade, with their unique one-dimensional (1D) morphologies and ability to transform into interconnected active material networks offering potential for enhanced cycling stability with high capacity. This is particularly true for silicon (Si)-based anodes, where issues related to large volumetric expansion can be partially mitigated and the cycle life can be enhanced. In this Perspective, we highlight the trajectory of Si NWs from a model system to practical Li-ion battery anode material and future prospects for extension to beyond Li-ion batteries. The study examines key research areas related to Si NW-based anodes, including state-of-the-art (SoA) characterization approaches followed by practical anode design considerations, including NW composite anode formation and upscaling/full-cell considerations. An outlook on the practical prospects of NW-based anodes and some future directions for study are detailed.

Standardized cycle life assessment of batteries using extremely lean electrolytic testing conditions

Despite the proposal of numerous advanced materials for batteries, there remains a notable lack of comprehensive assessment protocols that facilitate direct comparisons between laboratory-scale research and industrial trials. Here, we introduce a standardized method coined as extremely lean electrolytic testing (ELET), designed as a uniform framework for evaluating the performance across different battery systems. This approach replicates the cycling behaviour of larger pouch cells within the more manageable format of coin cells under ELET conditions. Employing ELET, we develop quantitative models to create contour maps that standardize cell performance metrics. To demonstrate the ELET efficacy, we explore the mitigation of electrolyte decomposition in lithium-ion batteries through applying polydopamine coatings on silicon/carbon composite anodes, achieving a 150% decrease in electrolyte decomposition compared to uncoated ones. Additionally, we employ the ELET method to compare the performance of various post-secondary and commercial batteries, demonstrating its full utility in battery evaluation.

High performance carboxymethyl cellulose- polyethylene oxide polymer binder for black phosphorus anode in lithium-ion batteries

Black phosphorus (BP) is regarded as a promising anode material due to its high theoretical specific capacity and fast charging safety. However, the problems of huge volume expansion and moderate electrical conductivity may restrict its performance. In this work, we present a novel 3D network binary polymer binder synthesized from carboxymethyl cellulose (CMC) and polyethylene oxide (PEO) for adapt to lithium-ion batteries of BP and graphite (G) composite anode (BP-G). There are the following characteristics of the binder: CMC and PEO are crosslinked through intermolecular forces; while CMC and PEO are connected to BP through strong intermolecular forces, respectively; BP and graphite are connected through PC and POC bonds to form composite anode. So as to form a sturdy structure and effectively accommodate the volume expansion of BP during charging-discharging processes, while avoiding loss of electrical contact between electrode components. Accordingly, the lithium-ion battery shown an excellent electrochemical performance, such as a high initial discharge capacity of 1602 mA h g−1 at 0.5 A/g.

Preparation and Electrochemical Properties of the CF-Ti/β-PbO2 Composite Anode for Zinc Electrowinning

This study focused on creating a unique CF-Ti/β-PbO2 composite anode through the combination of powder metallurgy and electrodeposition techniques. A study was conducted on how carbon fiber affects the properties of the anode in the process of zinc electrowinning. The addition of carbon fiber was discovered to enhance the performance of the electrode. When 3% carbon fiber is added, the cell voltage of the composite anode is reduced by 3.06 V, and the current efficiency is increased by 10.16% to 96.39%. Compared to the composite anode without carbon fiber, the corrosion rate of the composite anode containing carbon fiber is decreased by 67.35%. Moreover, the energy usage is reduced by 50%, leading to a potential conservation of 3313.87 kW·h per ton.