Silicon-based Lithium-ion Batteries Research Articles

Hydrogen Bond-Enabled High-ICE Anode for Lithium-Ion Battery Using Carbonized Citric Acid-Coated Silicon Flake in PAA Binder.

A silicon-based lithium-ion battery (LIB) anode is extensively studied because of silicon's abundance, high theoretical specific capacity (4200 mAh/g), and low operating potential versus lithium. Technical barriers to large-scale commercial applications include the low electrical conductivity and up to about 400% volume changes of silicon due to alloying with lithium. Maintaining the physical integrity of individual silicon particles and the anode structure is the top priority. We use strong hydrogen bonds between citric acid (CA) and silicon to firmly coat CA on silicon. Carbonized CA (CCA) enhances electrical conductivity of silicon. Polyacrylic acid (PAA) binder encapsulates silicon flakes by strong bonds formed by abundant COOH functional groups in PAA and on CCA. It results in excellent physical integrity of individual silicon particles and the whole anode. The silicon-based anode shows high initial coulombic efficiency, around 90%, and the capacity retention of 1479 mAh/g after 200 discharge-charge cycles at 1 A/g current. At 4 A/g, the capacity retention of 1053 mAh/g was achieved. A durable high-ICE silicon-based LIB anode capable of high discharge-charge current has been reported.

Dual-Salt Localized High-Concentration Electrolyte for Long Cycle Life Silicon-Based Lithium-Ion Batteries.

Silicon-based materials are considered the most promising anodes for next-generation lithium-ion batteries (LIBs) owing to their high specific capacity. However, poor interfacial stability due to enormous volume changes severely restricts their mass application in LIBs. Here, we design a fluoroethylene carbonate (FEC)-containing dual-salt (LiFSI-LiPF6) ether-based localized high-concentration electrolyte (D-LHCE-F) for enhancing the interfacial stability of silicon-based electrodes. It is revealed that the dominating LiFSI salt of superior chemical and thermal stability prevents the formation of corrosive HF, while the addition of FEC improves the interface stability by promoting the formation of protective LiF-rich SEI and increasing the flexibility of the interface. This robust and flexible SEI layer can adapt to substantial variations in the volume of silicon electrodes while preserving the integrity of the interface. The SiOx/C electrode using the unique D-LHCE-F retains up to 78.5% of its initial capacity after 500 cycles at 0.5C, well surpassing that of the control electrolyte (3.4% capacity retention). More notably, the cycle life of the SiOx/C||NCM90 (LiNi0.9Co0.05Mn0.05O2) full batteries is effectively enhanced thanks to the stabilized electrode/electrolyte interfaces. The key findings of this work offer crucial knowledge for rationally designing electrolyte chemistry to enable the practical application of high-energy-density LIBs adopting silicon-based anodes.

Recent advances in modification strategies of silicon-based lithium-ion batteries

Recent advances in modification strategies of silicon-based lithium-ion batteries

Mechanism study on the cycling stability of silicon-based lithium ion batteries as a function of temperature

Adapting to a wide operating temperature range is an inevitable trend in the development of rechargeable batteries. This work investigates the cycling stability of silicon (Si)-based half and full cells at a wide temperature range and the associated capacity fading mechanisms. Results show that compared with room temperature (25 °C), low temperature (0 °C) causes a decrease in capacity due to sluggish kinetics, and high temperature (60 °C) results in the lowest first Coulombic efficiency and the worst cycling stability with different capacity fading mechanisms in the half and full cells. In addition, composition and stability of solid-electrolyte interphase films are strongly temperature sensitive. Specifically, high temperature aggravates the dissolution of organic layer and the degradation of lithium hexafluorophosphate, and low temperature is not conducive to the formation of lithium carbonate. This work clearly reveals the problems that need to be solved to realize the application of Si anodes at a wide temperature range, which has important guiding significance for promoting the development and application of Si anodes in lithium ion batteries.

A stress-control charging method with multi-stage currents for silicon-based lithium-ion batteries: Theoretical analysis and experimental validation

Controlling mechanical stress in silicon-based anode has been proved to be an effective method in improving the cycling performance of silicon-based lithium-ion battery. This work is aimed at developing stress-control charging strategies from the stress analysis of a silicon particle. Using a mechanochemical model coupled with the free volume theory, we analyze the stress evolution in a silicon particle with multi-stage current strategies for a small charging rate (C-rate) at a low SOC and a large C-rate at a high SOC. The calculation results support the proposed strategies in reducing the stresses in the silicon particle. We perform experimental tests, including cycling test and SEM (scanning electron microscopy) analysis, and demonstrate the feasibility of the proposed strategies. Using multi-stage currents for lithiation and a constant current for delithiation can have a conspicuous effect on improving the cycling performance of silicon-based lithium-ion batteries.

Effects of transition metals for silicon-based lithium-ion battery anodes: A comparative study in electrochemical applications

The strength, conductivity, elasticity, inactivity against lithium, and tunability properties of transition metals (TMs) are the major reasons these metals are used to synthesize silicon-based lithium-ion battery (LIBs) composite anodes. This is because TMs significantly influence and improve the overall electrochemical performance of LIB electrodes by mitigating the undesired expansion of silicon. The effects of different elemental transition metals copper (Cu), titanium (Ti), nickel (Ni), and iron (Fe) on the electrochemical performance of silicon-based composites were compared, and the phases formed during milling were correlated to the behavior of the composites in which they are present. The excellent performance of these electrodes was attributed to the reaction mechanism of transition metals after the first conversion reaction during lithiation and remained inactive during the ensuing cycles. It was found that the strength and ductile nature of nickel accounts for relieving mechanical stress induced on Silicon during the insertion and extraction of lithium ions. All copper-containing composites showed high stability in cycling but low capacity, which is attributed to the high amounts of copper, contained in these composites and the reaction of copper with silicon during milling. The presence of titanium improved the electrical conductivity and mechanical strength of the electrodes. Iron-containing composites were observed to highly withstand deformation due to the strength of the matrix. Moreover, the addition of 10 wt. percentage carbon improved the cycle performance and rate capability of Cu-Fe-Si-C, Cu-Ni-Si-C, Ni-Fe-Si-C, and Ni-Ti-Si-C. These composites showed stable cycling performance of 654.42 mAh g–1, 686.16 mAh g–1, 657.56 mAh g–1, and 643.29 mAh g–1 respectively after 100 cycles capacity at 1 C.

Failure analysis and design principles of silicon-based lithium-ion batteries using micron-sized porous silicon/carbon composite

Significant progress has been made toward overcoming fundamental challenges in developing a silicon (Si) anode for lithium-ion batteries (LIBs). However, much less work has been reported on design and failure analysis of these batteries for practical applications. In this work, we analyzed the main factors that affect the performance of a Si anode and the energy density of pouch cells using micron-sized, nanoporous Si coated by pitch-derived carbon (p-Si/C). The volumetric energy density of the Si anode depends heavily on these factors, such as the loading of p-Si/C in the anode, the calendering density of the anode, the first-cycle coulombic efficiency, and the capacity density of the anode. The effects of other factors on the cycling performance were also revealed by postmortem analysis of cycled anodes. We found that a stable p-Si/C electrode structure is critical to avoid the disintegration of the anode structural integrity and lithium plating and enable long-term cycling. Moreover, prelithiation of Si anodes increases energy density, while the degree of prelithiation is another factor to balance with the cycle life of Si-based full cells. We propose pathways and strategies for adoption of micron-sized p-Si/C anodes in LIBs for their practical applications.

Inorganic crosslinked supramolecular binder with fast Self-Healing for high performance silicon based anodes in Lithium-Ion batteries

Capacity retention is one of the key factors affecting the performance of silicon (Si)-based lithium-ion batteries and other energy storage devices. Herein, a three dimension (3D) network self-healing binder (denoted as PVA + LB) consisting of polyvinyl alcohol (PVA) and lithium metaborate (LiBO2) solution is proposed to improve the cycle stability of Si-based lithium-ion batteries. The reversible capacity of the silicon electrode is maintained at 1767.3 mAh g−1 after 180 cycles when employing PVA + LB as the binder, exhibiting excellent cycling stability. In addition, the silicon/carbon (Si/C) anode with the PVA + LB binder presents superior electrochemical performance, achieving a stable cycle life with a capacity retention of 73.7% (858.3 mAh g−1) after 800 cycles at a current density of 1 A g−1. The high viscosity and flexibility, 3D network structure, and self-healing characteristics of the PVA + LB binder are the main reasons to improve the stability of the Si or Si/C contained electrodes. The novel self-healing binder shows great potential in designing the new generation of silicon-based lithium-ion batteries and even electrochemical energy storage devices.

Facile preparation of micron-sized silicon-graphite‑carbon composite as anode material for high-performance lithium-ion batteries

Silicon/carbon (Si/C) composites have become the mainstream anodes for silicon-based lithium-ion batteries (LIBs) with outstanding stability and high capacity, in which carbon can significantly stabilize the silicon anodes. Currently, most Si/C composites use nano‑silicon as raw materials, which suffer from low energy density, high price and preparation complexity. Here, we have developed a silicon-graphite‑carbon ternary composite (Si-G-C-15) with cheap micron-sized silicon as raw materials. It was prepared by ball-milling of micron silicon and graphite and subsequent carbonization of PAN, followed by NaOH selective etching. Electrochemical test results demonstrate that Si-G-C-15 can possess a reversible capacity of 965 mAh/g at 200 mA/g, with a capacity retention of 71.34% and 786 mAh/g at a high current density of 1 A/g after 100 cycles. Notably, this facile preparation process of silicon anodes with high rates and good capacity stability highlights the potential practical application.

Carboxymethylated tamarind polysaccharide gum as a green binder for silicon-based lithium-ion battery anodes

Binders pave the way for silicon (Si)-based lithium-ion batteries (LIBs) by alleviating excessive expansion of Si and offer an intriguingly high theoretical specific capacity (4200 mAh g−1), even with small amounts of additive. Here, we report a novel aqueous binder, carboxymethylated tamarind polysaccharide gum (1-CMT), created by modifying a low-cost, abundant, and non-toxic natural polysaccharide (tamarind kernel powder) under mild conditions. The Si@1-CMT electrode has a satisfactory specific capacity of 3626.7 mAh g−1 as well as a coulombic efficiency of 90.96% at the initial cycle; the Si mass loading is approximately 0.75 mg cm−2. A specific capacity of 1176 mAh g−1 is retained after 200 cycles at a strict current density of 2000 mA g−1; the corresponding value for a Si@CMC electrode is only 697 mAh g−1. The 1-CMT electrode has a specific capacity greater than 1600 mAh g−1 even under a current density of 4000 mA g−1. The unique branched chain structure and substantial number of free polarfunctionalgroups explain the outstanding electrochemical properties. Hence, 1-CMT acts as a premium binder in a Si-based anode that can be used to create high-performance batteries.

A Stress-Control Charging Method with Multi-Stage Currents for Silicon-Based Lithium-Ion Batteries: Theoretical Analysis and Experimental Validation

A Stress-Control Charging Method with Multi-Stage Currents for Silicon-Based Lithium-Ion Batteries: Theoretical Analysis and Experimental Validation

Litchi shell-derived porous carbon for enhanced stability of silicon-based lithium-ion battery anode materials

Litchi shell-derived porous carbon for enhanced stability of silicon-based lithium-ion battery anode materials

Nano-vault architecture mitigates stress in silicon-based anodes for lithium-ion batteries

Nanomaterials undergoing cyclic swelling-deswelling benefit from inner void spaces that help accommodate significant volumetric changes. Such flexibility, however, typically comes at a price of reduced mechanical stability, which leads to component deterioration and, eventually, failure. Here, we identify an optimised building block for silicon-based lithium-ion battery (LIB) anodes, fabricate it with a ligand- and effluent-free cluster beam deposition method, and investigate its robustness by atomistic computer simulations. A columnar amorphous-silicon film was grown on a tantalum-nanoparticle scaffold due to its shadowing effect. PeakForce quantitative nanomechanical mapping revealed a critical change in mechanical behaviour when columns touched forming a vaulted structure. The resulting maximisation of measured elastic modulus (~120 GPa) is ascribed to arch action, a well-known civil engineering concept. The vaulted nanostructure displays a sealed surface resistant to deformation that results in reduced electrode-electrolyte interface and increased Coulombic efficiency. More importantly, its vertical repetition in a double-layered aqueduct-like structure improves both the capacity retention and Coulombic efficiency of the LIB.

Case study of N-carboxyanhydrides in silicon-based lithium ion cells as a guideline for systematic electrolyte additive research

Incorporation of silicon into negative electrodes is pursued widely to increase the energy density of lithium ion batteries (LIBs). However, severe volume changes of silicon during (de)lithiation cause consumption of active lithium and electrolyte by continuous solid electrolyte interphase (SEI) formation, resulting in deterioration of cell performance. Electrolyte additives offer an unprecedented way to improve LIB cell performance by effective interphase formation. Here, we report a class of electrolyte additives based on substituted N -carboxyanhydrides ( N -CAs) designed to effectively tailor the SEI formed in LiNi 0.5 Co 0.2 Mn 0.3 O 2 ( NCM523) ∥ SiO x /C full cells, which are evaluated in pouch cells with application-relevant electrolyte per-cell capacity ratios. The working mechanism is elucidated systematically by use of complementary postmortem techniques, correlating cycling and storage performance data, gas formation, SEI composition, and electrolyte degradation. With successful additive functionalization, several N -CAs even outperform the state-of-the-art additive fluoroethylene carbonate in terms of capacity retention. Tailored design of N -carboxyanhydrides with synergistic functional moieties Significant performance improvements of NCM523 ∥ SiO x /graphite lithium ion cells Relevant performance data by a reduced ratio of electrolyte per cell capacity Analyses of electrolyte degradation and SEI and gas formation are a versatile approach Use of electrolyte additives is a straightforward approach to improve the performance of silicon-based lithium ion batteries (LIBs). Schmiegel et al. introduce a new class of electrolyte additives based on substituted N -carboxyanhydrides with synergistic functional moieties that significantly improve LIB cell performance by effective solid electrolyte interphase formation.

Dual functionality of over-lithiated NMC for high energy silicon-based lithium-ion batteries

Over lithiated Li1+xNMCO2 is introduced as a dual-functional lithium source and cathode material to increase the lithium inventory and significantly improve the energy density and cycle life of lithium-ion batteries with a Si-based anode.

Rational Design and Mechanical Understanding of Three-Dimensional Macro-/Mesoporous Silicon Lithium-Ion Battery Anodes with a Tunable Pore Size and Wall Thickness.

Silicon is regarded as one of the most promising next generation lithium-ion battery anodes due to its exceptional theoretical capacity, appropriate voltage profile, and vast abundance. Nevertheless, huge volume expansion and drastic stress generated upon lithiation cause poor cyclic stability. It has been one of the central issues to improve cyclic performance of silicon-based lithium-ion battery anodes. Constructing hierarchical macro-/mesoporous silicon with a tunable pore size and wall thickness is developed to tackle this issue. Rational structure design, controllable synthesis, and theoretical mechanical simulation are combined together to reveal fundamental mechanisms responsible for an improved cyclic performance. A self-templating strategy is applied using Stöber silica particles as a templating agent and precursor coupled with a magnesiothermic reduction process. Systematic variation of the magnesiothermic reduction time allows good control over the structures of the porous silicon. Finite element mechanical simulations on the porous silicon show that an increased pore size and a reduced wall thickness generate less mechanical stress in average along with an extended lithiation state. Besides the mechanical stress, the evolution of strain and displacement of the porous silicon is also elaborated with the finite element simulation.

Study on the Application of Carbon-coated Copper Foil as Negative Current Collector for Silicon-based Lithium-ion Batteries

Study on the Application of Carbon-coated Copper Foil as Negative Current Collector for Silicon-based Lithium-ion Batteries

A stress-based charging protocol for silicon anode in lithium-ion battery: Theoretical and experimental studies

Abstract The large mechanical deformation induced by the lithiation/delithiation of silicon can induce rapid capacity fading of silicon-based lithium-ion battery. This work is focused on the development of a feasible stress-based charging protocol that can control the stress and deformation of silicon anode during electrochemical cycling from the stress analysis in a silicon particle. The stress-based charging protocol provides an approach to suppress the mechanical stress in silicon anode with the control of the upper cut-off voltage for delithiation. The numerical results reveal that applying a small upper cut-off voltage for delithiation can reduce the mechanical stress and lower the capacity of the silicon electrode, while it likely improves the performance of the silicon-based lithium-ion battery. Experimental study of silicon-based lithium-ion half cells reveals that applying a moderate cut-off voltage (600 mV in this work) achieves high reversible capacity and good cycling performance for all the C-rates tested in the work, and applying a large cut-off voltage of 1000 mV leads to the formation of large surface cracks and rapid capacity loss. The experimental results support the stress-based charging protocol, which is developed from the numerical analysis, that tuning the cut-off voltage can reduce the structural degradation and enhance the electrochemical performances of silicon-based lithium-ion battery.

Poly(siloxane imide) Binder for Silicon-Based Lithium-Ion Battery Anodes via Rigidness/Softness Coupling.

Binders play a crucial role in maintaining mechanical integrity of electrodes in lithium-ion batteries. However, the conventional binders lack proper elasticity, and they are not suitable for high-performance silicon anodes featuring huge volume change during cycling. Herein, a poly(siloxane imide) copolymer (PSI) has been designed, synthesized, and utilized as a binder for silicon-based anodes. A rigidness/softness coupling mechanism is demonstrated by the PSI binder, which can accommodate volume expansion of the silicon anode upon lithiation. The electrochemical performance in terms of cyclic stability and rate capability can be effectively improved with the PSI binder as demonstrated by a silicon nanoparticle anode.

Dynamic bonded supramolecular binder enables high-performance silicon anodes in lithium-ion batteries

Silicon-based lithium ion battery is reckoned as an ideal choice owing to its ultrahigh theoretical capacity and rich natural resources. However, its practical application is largely hampered by the low Coulombic efficiency (CE) and fast capacity decay arising from the substantial volumetric variations and the unstable solid-electrolyte interphase (SEI). Herein, we propose a binder-based optimization, where a three-dimensional (3D) binder network is devised with organic polyvinyl alcohol (PVA) backbones cross-linked by a functional boric acid (BA). Apart from the improved mechanics, B–OH bond is able to set a chemical bridge between the binder and Si surface by dehydration with Si–OH group, which enables the coherent link with Si surface. More importantly, the electron deficient B element readily accepts electrons during the cell formation and thus facilitates the buildup of an effective SEI film. The obtained lithium borate species significantly reduce the interfacial side reactions and improve the initial Coulombic efficiency (ICE). After optimization of the key parameters, a high ICE (92.76%) with excellent rate capability (~2920.73 mAh g−1 at 10 C) is obtained. After 500 cycles, the Si anode retained a capacity of ~1883.7 mAh g−1, massively outperforming the pure PVA-based Si counterpart (~317.9 mAh g−1).