High-capacity Lithium-ion Batteries Research Articles

An optimized quantum particle swarm optimization–extended Kalman filter algorithm for the online state of charge estimation of high-capacity lithium-ion batteries under varying temperature conditions

An optimized quantum particle swarm optimization–extended Kalman filter algorithm for the online state of charge estimation of high-capacity lithium-ion batteries under varying temperature conditions

Advancing Lithium-Ion Batteries’ Electrochemical Performance: Ultrathin Alumina Coating on Li(Ni0.8Co0.1Mn0.1)O2 Cathode Materials

Ni-rich Li(NixCoyMnz)O2 (x ≥ 0.8)-layered oxide materials are highly promising as cathode materials for high-energy-density lithium-ion batteries in electric and hybrid vehicles. However, their tendency to undergo side reactions with electrolytes and their structural instability during cyclic lithiation/delithiation impairs their electrochemical cycling performance, posing challenges for large-scale applications. This paper explores the application of an Al2O3 coating using an atomic layer deposition (ALD) system on Ni-enriched Li(Ni0.8Co0.1Mn0.1)O2 (NCM811) cathode material. Characterization techniques, including X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, were used to assess the impact of alumina coating on the morphology and crystal structure of NCM811. The results confirmed that an ultrathin Al2O3 coating was achieved without altering the microstructure and lattice structure of NCM811. The alumina-coated NCM811 exhibited improved cycling stability and capacity retention in the voltage range of 2.8–4.5 V at a 1 C rate. Specifically, the capacity retention of the modified NCM811 was 5%, 9.11%, and 11.28% higher than the pristine material at operating voltages of 4.3, 4.4, and 4.5 V, respectively. This enhanced performance is attributed to reduced electrode–electrolyte interaction, leading to fewer side reactions and improved structural stability. Thus, NCM811@Al2O3 with this coating process emerges as a highly attractive candidate for high-capacity lithium-ion battery cathode materials.

Advancing Lithium-Ion Batteries' Electrochemical Performance: Ultrathin Alumina Coating on Li(Ni0.8Co0.1Mn0.1)O2 Cathode Materials.

Ni-rich Li(NixCoyMnz)O2 (x ≥ 0.8)-layered oxide materials are highly promising as cathode materials for high-energy-density lithium-ion batteries in electric and hybrid vehicles. However, their tendency to undergo side reactions with electrolytes and their structural instability during cyclic lithiation/delithiation impairs their electrochemical cycling performance, posing challenges for large-scale applications. This paper explores the application of an Al2O3 coating using an atomic layer deposition (ALD) system on Ni-enriched Li(Ni0.8Co0.1Mn0.1)O2 (NCM811) cathode material. Characterization techniques, including X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, were used to assess the impact of alumina coating on the morphology and crystal structure of NCM811. The results confirmed that an ultrathin Al2O3 coating was achieved without altering the microstructure and lattice structure of NCM811. The alumina-coated NCM811 exhibited improved cycling stability and capacity retention in the voltage range of 2.8-4.5 V at a 1 C rate. Specifically, the capacity retention of the modified NCM811 was 5%, 9.11%, and 11.28% higher than the pristine material at operating voltages of 4.3, 4.4, and 4.5 V, respectively. This enhanced performance is attributed to reduced electrode-electrolyte interaction, leading to fewer side reactions and improved structural stability. Thus, NCM811@Al2O3 with this coating process emerges as a highly attractive candidate for high-capacity lithium-ion battery cathode materials.

Anisotropic, free-standing anodic films with aligned anatase-bronze TiO2-integrated graphene for high-capacity lithium-ion batteries

The composition modification and structure manipulation of carbon-based battery electrodes is becoming an increasingly urgent need for safer, more reliable, and effective electric vehicles. Herein, we fabricate a free-standing hybrid anatase-bronze TiO2-grafted reduced graphene oxide (TiO2-rGO) through a one-pot solvothermal procedure. The TiO2-rGO composite was transformed into a film with an anisotropic alignment and assembled as an anode into lithium-ion batteries (LIBs) to enhance its performance. Our previously developed “Pulse Freezing” process, with modifications including: (1) dimensional and structural optimization for larger and faster film production and (2) optimal microfluidic condition for vertical porous alignment, is utilized for assembling this nanocomposite anodic film. During the microfluidic assembly process, we achieved the desirable flowrate, flow patterns, and alignments of the integrated TiO2-rGO layers while forming porous microstructures through freeze drying. The porous and aligned TiO2-integrated rGO film exhibits a significantly enhanced specific capacity of 400 mAh/g at 0.2 A/g, which is a drastic increase compared to traditional TiO2 and carbon black electrodes possessing <50 mAh/g capacity, attributed to the anisotropic alignment and porous microstructure of rGO in combination with TiO2 grafting. The developed TiO2-rGO composite film provides a promising application of Ti-based electrodes in LIBs for commercial battery industries.

Advanced-design cross-linked binder enables high-performance silicon-based anodes through in-situ crosslinking based on sodium carboxymethyl cellulose and poly-lysine

Practical employment of silicon (Si) electrodes in lithium-ion batteries (LIBs) is limited due to the severe volume changes suffered during charging-discharging process, causing serious capacity fading. Here, a composite polymer (CP-10) containing sodium carboxymethyl cellulose (CMC-Na) and poly-lysine (PL) is proposed for the binder of Si-based anodes, and a multifunctional strategy of “in-situ crosslinking” is achieved to alleviate the severe capacity degradation effectively. A cross-linked three-dimensional (3D) network is established through the strong hydrogen bonding interaction and reversible electrostatic interactions within CP-10, offering favorable mechanical tolerance for the extreme volume expansion of Si. Moreover, hydrogen bonding interaction along with ion-dipole interaction formed between CP-10 and Si surface enhance the bonding capability of Si-based anodes, promoting the maintenance of anodes' integrity. Consequently, over 800 cycles are achieved for the Si@CP-10 at 0.5C while maintaining a fixed discharge specific capacity of 1000 mAh g−1. Moreover, the Si/C@CP-10 can stably operate over 500 cycles with a capacity retention of 77.12 % at 1C. The prolonged cycling lifetime of Si/C and Si anodes suggests great potential for this strategy in promoting the implementation of high-capacity LIBs.

Lithium-electroactive peroxidase-like MnO2 nanomaterials as an ultrasensitive and selective sensing platform for carcinogenic 3,3′-diaminobenzidine and high-capacity lithium-ion batteries cathode materials

Lithium-electroactive peroxidase-like MnO2 nanomaterials as an ultrasensitive and selective sensing platform for carcinogenic 3,3′-diaminobenzidine and high-capacity lithium-ion batteries cathode materials

Mitigating Gas Evolution in Electron Beam-Induced Gel Polymer Electrolytes Through Bi-Functional Cross-Linkable Additives.

The current high-capacity lithium-ion batteries (LIBs), reliant on flammable liquid electrolytes (LEs) and nickel-rich cathodes, are plagued by safety hazards, especially the risk of hazardous gas release stemming from internal side reactions. To address these safety concerns, an electron beam (E-beam)-induced gel polymer electrolyte (E-Gel) is introduced, employing dipentaerythritol hexaacrylate (DPH) as a bi-functional cross-linkable additive (CIA). The dual roles of DPH are exploited through a strategically designed E-beam irradiation process. Applying E-beam irradiation on the pre-cycled cells allows DPH to function as an additive during the initial cycle, establishing a protective layer on the surface of the anode and cathode and as a cross-linker during the E-beam irradiation step, forming a polymer framework. The prepared E-Gel with CIA has superior interfacial compatibility, facilitating lithium-ion diffusion at the electrode/E-Gel interface. The electrochemical assessment of 1.2 Ah pouch cells demonstrates that E-Gel substantially reduces gas release by 2.5 times compared to commercial LEs during the initial formation stage and ensures superior reversible capacity retention even after prolonged cycling at 55°C. The research underscores the synergy of bifunctional CIA with E-beam technology, paving the way for large-scale production of safe, high-capacity, and commercially viable LIBs.

Structural Reversibility of Nanoscaled Sn Anodes.

Alloying-type anode materials provide high capacity for lithium-ion batteries; however, they suffer pulverization problems resulting from the volume change during cycling. Realizing the cycling reversibility of these anodes is therefore critical for sustaining their electrochemical performance. Here, we investigate the structural reversibility of Sn NPs during cycling at atomic-level resolution utilizing in situ high-resolution TEM. We observed a surprisingly near-perfect structural reversibility after a complete cycle. A three-step phase transition happens during lithiation, accompanied by the generation of a significant number of defects, grain boundaries, and up to 202% volume expansion. In subsequent delithiation, the volume, morphology, and crystallinity of the Sn NPs were restored to their initial state. Theoretical calculations show that compressive stress drives the removal of vacancies generated within the NPs during delithiation, therefore maintaining their intact morphology. This work demonstrates that removing vacancies during cycling can efficiently improve the structural reversibility of high-capacity anode materials.

Dilithium pyridine-2, 5-dicarboxylate as potential anode material for Li-ion battery

Amongst various small molecules with different functional groups, conjugated carbonyls are the most promising materials for lithium storage at low potential. This work reports lithium storage in dilithium pyridine-2, 5-dicarboxylate small molecule. We show here that dilithium pyridine-2, 5-dicarboxylate reversibly stores 2 mol of Li-ion per molecule, giving a reversible capacity of 307 mAh/g at an average voltage of 1.0 V. The capacity retention after 500 cycles at 1C rate is 69 %. This material shows impressive rate performance with a capacity retention of 140 mAh/g at 5C rate. The inclusion of electronegative nitrogen in the benzene ring helps in improving the storage performance compared to lithium terephthalate. Further ex-situ studies demonstrate possible mechanism for reversible lithium storage. Our findings showcase that the deliberately engineered organic electrode material facilitates the development of high capacity lithium-ion battery.

Polyoxovanadate Li7[V15O36(CO3)] and its derivative γ-LiV2O5 as superior performance cathode materials for aqueous zinc-ion batteries

Recently, many reports have been published about polyoxovanadates (POVs) with multiple electrons redox activity for energy storage. However, they are easily transformed into solid-state oxides after calcination. We noted that although dehydrated Li7[V15O36(CO3)] (Li7V15) exhibited a high capacity for lithium-ion batteries (LIBs), it was reported that the electrochemical behavior of the dehydrated sample same as γ-LiV2O5 (γ-LVO) which prepared by annealing the cluster and undehydrated Li7V15 was not redox-active. Interestingly, we were surprised to find that undehydrated Li7V15 and its derivative γ-LVO showed better electrochemical performance than LIBs when first proposed as the cathode to store Zn2+. Both Li7V15 and γ-LVO electrodes provided excellent rate performance and satisfied cyclability (135.0 and 214.1 mAh g−1 at 3 A g−1 after 1000 cycles, respectively). The fast kinetics of Li7V15 and γ-LVO were verified by pseudocapacitive analysis, GITT and EIS tests. Moreover, the Zn2+ storage mechanism and redox behavior of Li7V15 and γ-LVO were examined by ex-situ measurements. First-principles calculations revealed that the Zn2+ was chemisorbed on the clusters and physisorbed between the clusters. This work enriches the POVs cathode chemistry in aqueous energy storage.

Synergistic Protecting-Etching Synthesis of Carbon Nanoboxes@Silicon for High-Capacity Lithium-Ion Battery.

Silicon (Si) is considered as the most likely choice for the high-capacity lithium-ion batteries owing to its ultrahigh theoretical capacity (4200 mA h g-1) being over 10 times than that of traditional graphite anode materials (372 mA h g-1). However, its widespread application is limited by problems such as a large volume expansion and low electrical conductivity. Herein, we design a hollow nitrogen-doped carbon-coated silicon (Si@Co-HNC) composite in a water-based system via a synergistic protecting-etching strategy of tannic acid. The prepared Si@Co-HNC composite can effectively mitigate the volume change of silicon and improve the electrical conductivity. Moreover, the abundant voids inside the carbon layer and the porous carbon layer accelerate the transport of electrons and lithium ions, resulting in excellent electrochemical performance. The reversible discharge capacity of 1205 mA h g-1 can be retained after 120 cycles at a current density of 0.5 A g-1. In particular, the discharge capacity can be maintained at 1066 mA h g-1 after 300 cycles at a high current density of 1 A g-1. This study provides a new strategy for the design of Si-based anode materials with excellent electrical conductivity and structural stability.

Interface and Morphology Engineered Amorphous Si for Ultrafast Electrochemical Lithium Storage.

Ultrafast high-capacity lithium-ion batteries are extremely desirable for portable electronic devices, where Si is the most promising alternative to the conventional graphite anode due to its very high theoretical capacity. However, the low electronic conductivity and poor Li-diffusivity limit its rate capability. Moreover, high volume expansion/contraction upon Li-intake/uptake causes severe pulverization of the electrode, leading to drastic capacity fading. Here, interface and morphology-engineered amorphous Si matrix is being reported utilizing a few-layer vertical graphene (VG) buffer layer to retain high capacity at both slow and fast (dis)charging rates. The flexible mechanical support of VG due to the van-der-Waalsinteraction between the graphene layers, the weak adhesion between Si and graphene, and the highly porous geometry mitigated stress, while the three-dimensional mass loading enhanced specific capacity. Additionally, the high electronic conductivity of VG boosted rate-capability, resulting in a reversible gravimetric capacity of ≈1270mAhg-1 (areal capacity of ≈37µAhcm-2 ) even after 100 cycles at an ultrafast cycling rate of 20C, which provides a fascinating way for conductivity and stress management to obtain high-performance storage devices.

High mechanical strength Si anode synthesis with interlayer bonded expanded graphite structure for lithium-ion batteries

Despite advancements in silicon-based anodes for high-capacity lithium-ion batteries, their widespread commercial adoption is still hindered by significant volume expansion during cycling, especially at high active mass loadings crucial for practical use. The root of these challenges lies in the mechanical instability of the material, which subsequently leads to the structural failure of the electrode. Here, we present a novel synthesis of a composite combining expanded graphite and silicon nanoparticles. This composite features a unique interlayer-bonded graphite structure, achieved through the application of a modified spark plasma sintering method. Notably, this innovative structure not only facilitates efficient ion and electron transport but also provides exceptional mechanical strength (Vickers hardness: up to 658 MPa, Young’s modulus: 11.6 GPa). This strength effectively accommodates silicon expansion, resulting in an impressive areal capacity of 2.9 mA h cm−2 (736 mA h g−1) and a steady cycle life (93% after 100 cycles). Such outstanding performance is paired with features appropriate for large-scale industrial production of silicon batteries, such as active mass loading of at least 3.9 mg cm−2, a high-tap density electrode material of 1.68 g cm−3 (secondary clusters: 1.12 g cm−3), and a production yield of up to 1 kg per day.

Enhancing Electric Vehicle Battery Capacity through Anode Material Modification

With global attention to environmental protection and sustainable development, the demand for electric vehicles is rapidly increasing. The high energy density, long lifespan, and fast charging ability of high-capacity lithium-ion batteries (LIBs) make them an ideal choice for electric vehicles. They provide a longer range for electric vehicles and meet the needs of consumers for efficient and environmentally friendly modes of transportation. The electrode material has a crucial impact on the capacity of lithium-ion batteries. A battery’s capacity is the maximum quantity of electricity it can discharge under specific discharge circumstances, and electrode material is one of the key factors determining this performance. This article summarizes several methods for modifying LIBs electrode materials, including nanostructures, surface modification, and alloying, to reveal the pathways that can be applied to enhance lithium-ion battery performance. In addition, this article also explores the current challenges faced by LIBs technology and proposes potential avenues for future research, providing useful information to anyone who wants to support the advancement of lithium-ion battery technologies.

(Invited) Utilizing Conjugated Imine Polymers to Stabilize Nanoparticle Silicon Anodes

Silicon anodes provide a compelling route towards delivering high-capacity lithium-ion batteries, however they are notoriously difficult to stabilize in conventional liquid electrolytes that are compatible with high performance cathodes. Furthermore, the drastic changes in volume that occur as silicon is lithiated and delithiated can lead to rapid cell failure and innovative polymeric binders are required to help mitigate mechanical issues. We have recently developed a novel method to synthesize the conjugated binder polyphenylmethanimine (polyPMI) using an imine metathesis reaction. We have demonstrated that this polymer can be used to stabilize silicon nanoparticles to produce a composite lithium-ion battery anode that is electrochemically stable for hundreds of lithiation and delithiation cycles with a Coulombic efficiency that is greater than 99.95% in a traditional carbonate liquid electrolyte.1 This novel polymeric coating passivates silicon nanoparticles by shielding them from direct electrolyte contact while maintaining effective ionic and electronic transport and also imbues the electrodes with excellent mechanical resilience to the volumetric changes experienced during cycling. We will cover the structure/property relationship of polyPMI within the context of the unique mechanical and electrochemical requirements of nanoparticle silicon anodes. We will also discuss the electrochemical behavior of this polymer and how it also offers new opportunities as an organic lithium-coordinating material that can be used to stabilize a variety of other battery electrodes. More broadly, we will posit that this solution-processed, ionically conductive, and electronically conductive polymer is applicable for a variety of energy storage and conversion technologies. Finally, this work will demonstrate how this novel polymer chemistry provides additional opportunities for tuning electrode architecture to target high areal capacity electrodes that enable high gravimetric and volumetric capacity full cells.1. T. R. Martin et al., Adv. Energy Mater., 2203921 (2023).

Doped Micron Silicon and Mxene Based Composite Anodes for High-Performance Li-Ion Batteries

With the world's energy needs constantly increasing, renewable energy sources must be technologically advanced and integrated with energy storage devices to ensure their uninterrupted operation. In recent decades, researchers have devoted substantial efforts to improve the energy density of lithium-ion batteries (LIBs) [1]. While graphite remains the commercial anode in LIBs, it’s very low theoretical capacity (372 mAh g-1) restricts its use in high-energy applications. Silicon (Si), owing to its high theoretical capacity of 4200 mAh g-1, natural abundance, and appropriate Li uptake potential (0.4 V vs Li/Li+), is a promising anode material [2]. However, its massive volume expansion restricts its practical use.In this study, micron-sized Si particles are combined with graphite. Micron Si is less expensive, and the synthesis process is simpler. The well-ground mixture (Si-G) is mixed with a polymer solution to generate pyrolytic carbon (upon carbonising). This aids in the buffering of mechanical stresses caused by Si volume expansion. Furthermore, direct exposure of Si to the electrolyte is avoided, stabilising the solid electrolyte interphase (SEI). The addition of a dopant improves the intrinsic conductivity of the material, resulting in increased capacity by providing electron and Li-ion transport channels. To further enhance the composite's performance, synthesized Mxene is added to promote the charge transport between micron Si. Using various techniques such as SEM-EDAX, XRD, Raman, and XPS spectroscopy, the composite's morphology and structure is studied which reveals uniformly distributed Si, C, and Mxene sheets that retain the sheet architecture.As an anode, the composite exhibits outstanding electrochemical performance which was evident by its impressive lithium storage specific capacity of 2003 mAh g-1 (based on weight of Si) even after long term cycling (at 1C rate). Additionally, the composite demonstrates superior rate performance with a specific capacity of 2439 mAh g-1 at 10 C rate, highlighting its potential for high-power applications. Moreover, the electrode displayed a low charge transfer impedance and fast electron transport, which improved the electrochemical performance. The reason for this improved performance is the unique structure consisting of Mxene and doping, which significantly increased the Li ion diffusion and the active sites. Also, low-cost micron Si is used which has a high tap density. Thus, this work provides an approach to develop high-capacity LIBs based on silicon. Keywords: Lithium-ion battery, micron silicon anode, Mxene, doping. References Liu, L. Kang, J. Hu, E. Jung, J. Zhang, S.C. Jun, Y. Yamauchi, Unlocking the Potential of Oxygen-Deficient Copper-Doped Co 3 O 4 Nanocrystals Confined in Carbon as an Advanced Electrode for Flexible Solid-State Supercapacitors, ACS Energy Lett. 6 (2021) 3011–3019. https://doi.org/10.1021/acsenergylett.1c01373.Zhou, Y. Liu, C. Du, Y. Ren, T. Mu, P. Zuo, G. Yin, Y. Ma, X. Cheng, Y. Gao, Polyaniline-encapsulated silicon on three-dimensional carbon nanotubes foam with enhanced electrochemical performance for lithium-ion batteries, Journal of Power Sources. 381 (2018) 156–163. https://doi.org/10.1016/j.jpowsour.2018.02.009.

First-Principles Dynamics Investigation of Germanium as an Anode Material in Multivalent-Ion Batteries

Germanium, a promising electrode material for high-capacity lithium ion batteries (LIBs) anodes, attracted much attention because of its large capacity and remarkably fast charge/discharge kinetics. Multivalent-ion batteries are of interest as potential alternatives to LIBs because they have a higher energy density and are less prone to safety hazards. In this study, we probed the potential of amorphous Ge anodes for use in multivalent-ion batteries. Although alloying Al and Zn in Ge anodes is thermodynamically unstable, Mg and Ca alloys with Ge form stable compounds, Mg2.3Ge and Ca2.4Ge that exhibit higher capacities than those obtained by alloying Li, Na, or K with Ge, corresponding to 1697 and 1771 mA·h·g–1, respectively. Despite having a slightly lower capacity than Ca–Ge, Mg–Ge shows an approximately 150% smaller volume expansion ratio (231% vs. 389%) and three orders of magnitude higher ion diffusivity (3.0 × 10−8 vs. 1.1 × 10−11 cm2 s−1) than Ca–Ge. Furthermore, ion diffusion in Mg–Ge occurs at a rate comparable to that of monovalent ions, such as Li+, Na+, and K+. The outstanding performance of the Mg–Ge system may originate from the coordination number of the Ge host atoms and the smaller atomic size of Mg. Therefore, Ge anodes could be applied in multivalent-ion batteries using Mg2+ as the carrier ion because its properties can compete with or surpass monovalent ions. Here, we report that the maximum capacity, volume expansion ratio, and ion diffusivities of the alloying electrode materials can be understood using atomic-scale structural properties, such as the host–host and host–ion coordination numbers, as valuable indicators.

A review study of binary and ternary ZnO/C composites as anodes for high-capacity lithium-ion batteries

A review study of binary and ternary ZnO/C composites as anodes for high-capacity lithium-ion batteries

Co-Estimation of State-of-Charge and State-of-Health for High-Capacity Lithium-Ion Batteries

To address the challenges of efficient state monitoring of lithium-ion batteries in electric vehicles, a co-estimation algorithm of state-of-charge (SOC) and state-of-health (SOH) is developed. The algorithm integrates techniques of adaptive recursive least squares and dual adaptive extended Kalman filtering to enhance robustness, mitigate data saturation, and reduce the impact of colored noise. At 25 °C, the algorithm is tested and verified under dynamic stress test (DST) and Beijing bus DST conditions. Under the Beijing bus DST condition, the algorithm achieves a mean absolute error (MAE) of 0.17% and a root mean square error (RMSE) of 0.19% for SOC estimation, with a convergence time of 4 s. Under the DST condition, the corresponding values are 0.05% for MAE, 0.07% for RMSE, and 5 s for convergence time. Moreover, in this research, the SOH is described as having internal resistance. Under the Beijing bus DST condition, the MAE and the RMSE of the estimated internal resistance of the proposed approach are 0.018% and 0.075%, with the corresponding values of 0.014% and 0.043% under the DST condition. The results of the experiments provide empirical evidence for the challenges associated with the efficacious estimation of SOC and SOH.

Large-scale assembly of isotropic nanofiber aerogels based on columnar-equiaxed crystal transition

Ice-templating technology holds great potential to construct industrial porous materials from nanometers to the macroscopic scale for tailoring thermal, electronic, or acoustic transport. Herein, we describe a general ice-templating technology through freezing the material on a rotating cryogenic drum surface, crushing it, and then re-casting the nanofiber slurry. Through decoupling the ice nucleation and growth processes, we achieved the columnar-equiaxed crystal transition in the freezing procedure. The highly random stacking and integrating of equiaxed ice crystals can organize nanofibers into thousands of repeating microscale units with a tortuous channel topology. Owing to the spatially well-defined isotropic structure, the obtained Al2O3·SiO2 nanofiber aerogels exhibit ultralow thermal conductivity, superelasticity, good damage tolerance, and fatigue resistance. These features, together with their natural stability up to 1200 °C, make them highly robust for thermal insulation under extreme thermomechanical environments. Cascading thermal runaway propagation in a high-capacity lithium-ion battery module consisting of LiNi0.8Co0.1Mn0.1O2 cathode, with ultrahigh thermal shock power of 215 kW, can be completely prevented by a thin nanofiber aerogel layer. These findings not only establish a general production route for nanomaterial assemblies that is conventionally challenging, but also demonstrate a high-energy-density battery module configuration with a high safety standard that is critical for practical applications.