Generation Lithium-ion Batteries Research Articles

Facile fabrication of core-shell α-Fe2O3@PPy imbedded into porous biomass-derived carbon for enhanced lithium storage

Due to the large theoretical capacity (1007mAh/g) and unique electrochemical properties, α-Fe2O3 is regarded as an improved anode for next generation lithium-ion batteries (LIBs). Nevertheless, its numerous applications in lithium storage are constrained by its weak conductivity and large volume variation during cycling. Herein, the unique BPC/α-Fe2O3@PPy composite is synthesized by incorporating α-Fe2O3@PPy into three-dimensional hierarchical porous carbon, which can enhance charge transfer efficiency and decrease its volume variation. As anodes for LIBs, the BPC/α-Fe2O3@PPy electrode displays excellent cycle stability and exceptional high-rate performance. This work offers a sustainable approach of constructing economic and green α-Fe2O3-based composite as novel LIBs anode materials for renewable applications.

Synergetic effects of Na+-Mo6+ co-doping on layered Li1.2Mn0.54Ni0.13Co0.13O2 cathode for high performance lithium-ion batteries

The Li-rich Mn-based material, with high energy density, less toxicity and low cost, is regarded as one of the potential cathode candidates for the next generation lithium-ion batteries (LIBs). However, some issues need to be addressed before large-scale commercialized application, such as capacity attenuation, low initial coulomb efficiency and poor rate performance, caused by the structure defects and oxygen escape from the crystal lattice at high voltage. Here, the Na+ and Mo6+ dopants are introduced to Li1.2Mn0.54Ni0.13Co0.13O2 by sol-gel method, with slight Li+ displaced by Na+ and tiny Mo6+ substituting transition metal ions, respectively. The doping effects on the Li layer spacing, Li/Ni mixing and oxygen vacancy defects have been examined. Regarding the doped samples, the valence states of transition metal elements and electrochemical performance are systematically studied. The Na+ and Mo6+ co-doping not only expands the lithium layer spacing and reduces cationic disorder to promote the Li+ diffusion and enhance the rate capability, but also stabilizes the oxygen skeleton, inhibits oxygen loss, and suppresses the migration of transition metal ions to improve the cyclic performance. As a result, Li1.18Na0.02(Mn0.54Ni0.13Co0.13)0.98Mo0.02O2 delivers 122.8 mAh.g−1 at 5 C and 262.9 mAh.g−1 at 0.2 C, retaining 90% capacity after 150 cycles.

Multi‐Dimensional Characterization of Battery Materials

AbstractDemand for low carbon energy storage has highlighted the importance of imaging techniques for the characterization of electrode microstructures to determine key parameters associated with battery manufacture, operation, degradation, and failure both for next generation lithium and other novel battery systems. Here, recent progress and literature highlights from magnetic resonance, neutron, X‐ray, focused ion beam, scanning and transmission electron microscopy are summarized. Two major trends are identified: First, the use of multi‐modal microscopy in a correlative fashion, providing contrast modes spanning length‐ and time‐scales, and second, the application of machine learning to guide data collection and analysis, recognizing the role of these tools in evaluating large data streams from increasingly sophisticated imaging experiments.

Design and Construction of Porous Silicon Materials as Stable Anodes for Lithium-Ion Batteries

Silicon is considered to be the most promising anode material for the next generation of lithium-ion batteries (LIBs), but its application is limited by the severe capacity decline due to volume expansion of up to 300%. Considering the inward accumulation of the stress produced during the actual lithiation process and the stabilizing effect of oxygen element, structural design and surface oxygen content regulation work together to improve the cyclic stability of silicon. Herein, we report the design and construction of novel porous silicon materials with regulated pore structure and surface oxygen content. The facile strategy for the synthesis of the materials is using Mg2Si and tetraethyl orthosilicate (TEOS) as Si resource, and the oxygen in the feedstock is ingeniously used at the same time. A series of Si anode materials with different pore structure and surface oxygen content were obtained by adjusting the proportion of Mg2Si and TEOS. Using 0.5 g of Mg2Si and 1 g of TEOS to prepare the material, the electrode reaches the optimum electrochemical performance with a discharge capacity of 935.9 mAh g–1 after 100 cycles and 587.2 mAh g–1 after 300 cycles at 0.5 and 1 A g–1, respectively. This work provides a new strategy for the design and preparation to boost stable lithium ion storage of silicon anode materials.

Interfacial Interaction of Multifunctional GQDs Reinforcing Polymer Electrolytes For All-Solid-State Li Battery.

Solid-state polymer electrolytes are highly anticipated for next generation lithium ion batteries with enhanced safety and energy density. However, a major disadvantage of polymer electrolytes is their low ionic conductivity at room temperature. In order to enhance the ionic conductivity, here, graphene quantum dots (GQDs) are employed to improve the poly (ethylene oxide) (PEO) based electrolyte. Owing to the increased amorphous areas of PEO and mobility of Li+ , GQDs modified composite polymer electrolytes achieved high ionic conductivity and favorable lithium ion transference numbers. Significantly, the abundant hydroxyl groups and amino groups originated from GQDs can serve as Lewis base sites and interact with lithium ions, thus promoting the dissociation of lithium salts and providing more ion pathways. Moreover, lithium dendrite is suppressed, associated with high transference number, enhanced mechanical properties and steady interface stability. It is further observed that all solid-state lithium batteries assembled with GQDs modified composite polymer electrolytes display excellent rate performance and cycling stability.

Influence of electrode fabrication process on nanocrystalline tin oxide electrochemical behaviour for high voltage SnO2/LNMO full cell Li-ion battery

Tin oxide is one of the most promising anode materials to replace graphite in the next generation lithium-ion batteries thanks to its high theoretical specific capacity, low cost and large availability. Unfortunately, its large-scale application is still limited, due to marked capacity loss and poor cyclability. Recent findings demonstrated improved reversibility of the electrochemical reactions through the optimization of SnO2 particles size. In this frame, the sol-gel method has proved to be one of the most interesting synthesis processes to obtain mono and polycrystalline SnO2 particles, which guarantee higher reversibility of the conversion reaction. In this work, SnO2 nanoparticles was synthesized by sol-gel method, with an average size of 5–50 nm, depending on the post calcination temperature. Subsequently, the optimization of the electrode composition in terms of mass loading and binder allowed to achieve a specific capacity of 350 mAh g−1, with a Coulombic efficiency of 99.9 % after 100 cycles at high current rate of 0.75 A g−1. Finally, the optimized and pre-lithiated SnO2 anode was coupled with the high voltage LiNi0.5Mn1.5O4 (LNMO) cathode in full-cell configuration, and the contribution of the voltage window and formation step to the final cell capacity was studied to determine the optimum conditions at which high cycling stability can be obtained.

Fault data generation of lithium ion batteries based on digital twin: A case for internal short circuit

Battery accidents are emerging for various kinds of applications, such as commercial electronics, electric scooters, electric vehicle and energy storage stations. Effective early warning algorithm is essential for mitigating the damage caused by battery failure. An early warning algorithm needs to be trained by failure data. However, building battery failure data (such as internal short circuit) by experiment consumes so much time and cost that it cannot match the development requirement of new product. This work demonstrates the validity of using digital twin technique to generate battery failure data to train the online early warning algorithm. The digital twin is formed by a highly reliable thermal-electrical coupled battery model. The influential factors, e.g., load current, short circuit position, equivalent short resistance and environment temperature, which determine the performance of the early warning algorithm were discussed. The warning threshold that may judge the fault warning rate and response speed of the algorithm was also analyzed. The digital twin helps us find that there is a temperature difference between the sensor location and the failure (short circuit) point. The temperature difference enlarges under the cases that the failure point is far from the measurement point, thereby hindering the timely detection and alarm for fault. The temperature gap can be as high as 261.2 °C under the extreme case of 0.1 Ω short circuit resistance. Therefore, the mismatch of the failure point and the measurement will give us the illusion that the failure occurs suddenly, or the so-called sudden death. The thermal runaway boundary for battery module varies with the ambient temperature and the short resistance, helping the determination of the threshold of the detection algorithm for thermal runaway. At last, a guidance on how to develop fault diagnosis algorithm with the help of digital twin to judgement of fault diagnosis threshold is summarized, with clear discussion of the accuracy, cost and efficiency of the method. The proposed method paves a way for the application of the digital twin on the fast development of battery management algorithms.

Graphite-Based Composite Anodes with C-O-Nb Heterointerfaces Enable Fast Lithium Storage.

To better satisfy the increasing demands for electric vehicles, it is crucial to develop fast-charging lithium-ion batteries (LIBs). However, the fast-charging capability of commercial graphite anodes is limited by the sluggish Li+ insertion kinetics. Herein, we report a synergistic engineering of uniform nano-sized T-Nb2 O5 particles on graphite (Gr@Nb2 O5 ) with C-O-Nb heterointerfaces, which prevents the growth and aggregation of T-Nb2 O5 nanoparticles. Through detailed theoretical calculations and pair distribution function analysis, the stable existence of the heterointerfaces is proved, which can accelerate the electron/ion transport. These heterointerfaces endow Gr@Nb2 O5 anodes with high ionic conductivity and excellent structural stability. Consequently, Gr@10-Nb2 O5 anode, where the mass ratio of T-Nb2 O5 /graphite=10/100, exhibits excellent cyclic stability and incredible rate capabilities, with 100.5 mAh g-1 after 10000 stable cycles at an ultrahigh rate of 20 C. In addition, the synergistic Li+ storage mechanism is revealed by systematic electrochemical characterizations and in situ X-ray diffraction. This work offers new insights to the reasonable design of fast-charging graphite-based anodes for the next generation of LIBs.

Enhanced electrochemical performance of silicon anode materials with titanium hydride treatment

As a promising anode material for the next generation of lithium-ion batteries, silicon (Si) suffers from the main problems of severe volume expansion and poor electrical conductivity. Compounding Si-based materials with metal hydrides is one of the ways to overcome these problems. Herein, we proposed TiH2 decorated Si composites prepared by ball milling and subsequent high-temperature calcination to restrain the volume expansion of Si and enhance the electrical conductivity. The resulting Si-0.05TiH2 anode delivered a reversible discharge capacity of 766.1 mAh/g after 100 cycles at a current density of 100 mA/g and better rate capability than the Si anode. Additionally, the impedance measurements and the density functional theory (DFT) calculation demonstrated that the insertion of Ti after dehydrogenation of TiH2 enhanced the conductivity of the composite anode. The charge transfer resistance (Rct) of Si-0.05TiH2 and Si anodes were 43.03 Ω and 609.6 Ω, respectively, indicated that the charge transfer process of Si/TiH2 electrodes was faster. This study provides a new strategy for compounding metal hydrides with Si, and a further attempt to enhance the electrochemical properties of Si.

Edge-boron-functionalized coal-derived graphite nanoplatelets prepared via mechanochemical modification for enhanced Li-ion storage at low-voltage plateau

The low Li-ion storage and poor rate capability hinder the application of graphite anode in the next generation lithium-ion batteries. Among various carbonaceous anode materials, these endowed with high Li-ions storage performance at low operating voltage are still the focus. Herein, edge-boron-functionalized coal-derived graphite nanoplatelets (B-CGNs) are prepared by mechanochemical modification using anthracite as the precursor. The obtained B-CGNs have mildly-expanded and larger-sized graphitic layers with a lateral dimension of 1.0–2.0 μm, meanwhile the edges of nanoplatelets are functionalized by a small amount of boron atoms. The B-CGNs as anode for LIBs exhibit an enhanced Li-ions storage performance. In particular, it delivers superior specific capacity (530 mAh·g−1 at 0.05 A·g−1) and rate capability (335 and 145 mAh·g−1 at 2.0 and 5.0 A·g−1) in the low voltage window of 0.01–1.0 V, and excellent stability through long-term cycling up to 800 cycles (near 100% capacity retention). Theoretical calculation further demonstrates that mildly-expanded interlayer spacing and boron-functionalized edges in B-CGNs contribute to the improvement of the Li-ion storage capacity and diffusion ability.

Interfacial Issues and Modification of Solid Electrolyte Interphase for Li Metal Anode in Liquid and Solid Electrolytes

AbstractThe high energy density required for the next generation of lithium batteries will likely be enabled by a shift toward lithium metal anode from the conventional intercalation‐based anode such as graphite. However, several critical challenges for Li metal originate from its highly reactive nature and the hostless reaction of deposition and stripping impede the practical use of Li metal as an anode. The role of the solid electrolyte interphase (SEI) is very important for the Li metal anode where the SEI must protect the dynamically changing surface of the Li metal. Since the SEI‐generating reaction mechanisms for the two different electrolyte systems, liquid and solid, are considerably different, the SEI layers formed between the Li metal and the electrolytes in the two electrolyte systems have substantially different properties, causing different interfacial issues. Inhibition of the interfacial problems requires different strategies to reinforce the SEI layer for each of the electrolyte systems. However, the differences in the two electrolyte systems have not been clearly compared in the prior literature. In this report, the interfacial issues for the two different electrolyte systems are compared and different strategies for SEI modification are provided to overcome the issues.

Prussian blue analogue vigorously coupled to Ti3C2Tx MXene nanosheet toward high-performance Li-ion batteries with stable cycling stability

In this work, the Prussian-blue type FeFe(CN)6 (Fe-PBA)/Ti3C2Tx hybrids (Fe-PBA-CT) with improved reversible capacity and high stable cycling stability are synthesized by a hydrolytic process. The Fe–PBAs cubic nanoparticles effectively promote electrode/electrolyte contact, accelerate electron transfer and ion diffusion. The Ti3C2Tx MXenes conductive networks can not only facilitate the transmission and diffusion of electrons/ions, but also provide additional Li+ ions storage sites to increase the specific capacity, thereby improving the rate performance and reversible capacity. Benefiting from the synergistic effect of nano cubic Fe-PBA and layered Ti3C2Tx MXenes, compared with pristine Fe-PBA, the Fe-PBA-CT2 cathode with moderate content of Ti3C2Tx MXenes delivers a superior discharge capacity of 145.9 mAh g−1 at 0.1 C, remarkable rate performance and excellent cycling stability without capacity fading after 900 cycles at 1 C. The ex-situ X-ray diffraction test proves that the structure change of Fe-PBA-CT is highly reversible process during cycling. The as-prepared Fe-PBA-CT exhibits a promising potential as a cathode material for the next generation lithium-ion batteries with stable cycling stability.

Front Cover: Nanostructuring Strategies for Silicon‐based Anodes in Lithium‐ion Batteries: Tuning Areal Silicon Loading, SEI Formation/Irreversible Capacity Loss, Rate Capability Retention and Electrode Durability (Batteries & Supercaps 3/2023)

Graphical Abstract The Front Cover illustrates the hierarchical hybrid nanostructured electrode composed of vertically aligned carbon nanotubes decorated with silicon nanoparticles as anode for the next generation lithium-ion batteries. More information can be found in the Research Article by C.-S. Cojocaru and co-workers.

Review and Stress Analysis on the Lithiation Onset of Amorphous Silicon Films

This work aims to review and understand the behavior of the electrochemical lithiation onset of amorphous silicon (a-Si) films as electrochemically active material for new generation lithium-ion batteries. The article includes (i) a review on the lithiation onset of silicon films and (ii) a mechanochemical model with numerical results on the depth-resolved mechanical stress during the lithiation onset of silicon films. Recent experimental studies have revealed that the electrochemical lithiation onset of a-Si films involves the formation of a Li-poor phase (Li0.3Si alloy) and the propagation of a reaction front in the films. The literature review performed reveals peculiarities in the lithiation onset of a-Si films, such as (i) the build-up of the highest mechanical stress (up to 1.2 GPa) during lithiation, (ii) a linear increase in the mechanical stress with lithiation which mimics the characteristics of linear elastic deformation, (iii) only a minute volume increase during Li incorporation, which is lower than expected from the number of Li ions entering the silicon electrode, (iv) the largest heat generation appearing during cycling with only a minor degree of parasitic heat contribution, and (v) an unexpected enhanced brittleness. The literature review points to the important role of mechanical stresses in the formation of the Li-poor phase and the propagation of the reaction front. Consequently, a mechanochemical model consisting of two stages for the lithiation onset of a-Si film is developed. The numerical results calculated from the mechanochemical model are in good accord with the corresponding experimental data for the variations in the volumetric change with state of charge and for the moving speed of the reaction front for the lithiation of an a-Si film of 230 nm thickness under a total C-rate of C/18. An increase in the total C-rate increases the moving speed of the reaction front, and a Li-rich phase is likely formed prior to the end of the growth of the Li-poor phase at a high total C-rate. The stress-induced phase formation of the Li-poor phase likely occurs during the lithiation onset of silicon electrodes in lithium-ion battery.

Deep eutectic solvent electrolytes based on trifluoroacetamide and LiPF6 for Li-metal batteries

New generation lithium batteries require better performances, improved safety, and sustainability. Better performances can be obtained with lithium anodes and high-voltage cathodes, which in turn pose more pressure on the electrolyte stability, which is mandatory for safety. Deep Eutectic Solvents (DESs) are promising components for safer and more environmentally sustainable electrolytes. We investigate the physico-chemical properties of DESs made with 2,2,2-trifluoroacetamide (TFA) and LiPF6. The best composition is tested against Li metal and two cathode active materials: LiFePO4 (LFP) and high voltage LiNi1-x-yMnxCoyO2 (NMC). We obtain good electrochemical performance in a Li-metal cell with LFP. Accelerated rate calorimetry shows improved thermal stability of the Li|DES|NMC cell with respect to a commercial liquid electrolyte.

Limiting Factors Affecting the Ionic Conductivities of LATP/Polymer Hybrid Electrolytes

All-Solid-State Lithium Batteries (ASSLB) are promising candidates for next generation lithium battery systems due to their increased safety, stability, and energy density. Ceramic and solid composite electrolytes (SCE), which consist of dispersed ceramic particles within a polymeric host, are among the preferred technologies for use as electrolytes in ASSLB systems. Synergetic effects between ceramic and polymer electrolyte components are usually reported in SCE. Herein, we report a case study on the lithium conductivity of ceramic and SCE comprised of Li1.4Al0.4Ti1.6(PO4)3 (LATP), a NASICON-type ceramic. An evaluation of the impact of the processing and sintering of the ceramic on the conductive properties of the electrolyte is addressed. The study is then extended to Poly(Ethylene) Oxide (PEO)-LATP SCE. The presence of the ceramic particles conferred limited benefits to the SCE. These findings somewhat contradict commonly held assumptions on the role of ceramic additives in SCE.

Grid-like Fe3O4 nanocrystals enhance the performances of glass-ceramic anodes for lithium-ion batteries

Glasses hold great promise as high-energy anode materials in next generation lithium-ion batteries (LIBs). However, the electrochemical performances of the glass anodes still need to be greatly enhanced to meet the requirement for developing high energy density LIBs. Here we show that grid-like Fe3O4 nanocrystals enable a substantial enhancement of the electrochemical performances of iron borate glass ceramic anode for LIBs. We find that both Fe2O3 and Fe3O4 crystals precipitate in the glass matrix during melt-quenching if Fe2O3 content exceeds about 20 mol%. The ferrous/ferric ion ratio increases with Fe2O3 content, and thereby significantly raises the electronic conductivity of the Fe2O3-B2O3 glass-ceramics. The 90Fe2O3–10B2O3 anode exhibits the reversible capacity of ∼ 505 mA h g−1 at 1 A g−1 after 1000 cycles. The unique architecture of this anode, which involves grid-like arrangement of Fe3O4 nanocrystals in glass phase, provides more active sites for storing Li+ ions, and enhances Li+ ions transfer kinetics. This architecture prevents the propagation of microcracks in anode during lithiation/delithiation and thereby enhances the cycling stability.

Voltage-dependent formation of cathode–electrolyte interphase with independent metallic layer in LiNi0.8Mn0.1Co0.1O2 cathode for high-energy density lithium-ion batteries

Layered LiNi0.8Mn0.1Co0.1O2 (NMC811) has emerged as the promising cathode material for next generation lithium-ion batteries owing to its high capacity. The double redox reaction between Ni2+/Ni3+ and Ni3+/Ni4+ is the major source of the large capacity, but it often leads to the formation of an unstable cathode–electrolyte interphase (CEI) layer. Herein, the correct nature of the CEI layer for the NMC811 battery has been studied with a particular attention to the voltage dependency (4.3 V vs. 4.7 V). A CEI metallic layer consisting of transition metal (TM) composites (i.e. 54.9MnOx, 54.9MnF3, 58.7NiO, 58.7NiF3, 58.9CoOx, and 58.9CoF3) has been long considered as a part of inorganic layer. However, the present study found that the metallic layer can be present as an independent CEI layer depending on the cut-off voltages. To further understand the nature of the CEI formation with the cathode material, a density-functional theory was conducted. The Fermi level with respect to the redox couples of the TMs/oxygen orbitals and their covalency not only affect the cathode stability but also modulate the CEI property. It is also proposed that the covalency of TM(3d)-O(2p) is the key factor that determines the localization of the TM metallic layer.

Silicon/Graphite/Amorphous Carbon as Anode Materials for Lithium Secondary Batteries.

Although silicon is being researched as one of the most promising anode materials for future generation lithium-ion batteries owing to its greater theoretical capacity (3579 mAh g-1), its practical applicability is hampered by its worse rate properties and poor cycle performance. Herein, a silicon/graphite/amorphous carbon (Si/G/C) anode composite material has been successfully prepared by a facile spray-drying method followed by heating treatment, exhibiting excellent electrochemical performance compared with silicon/amorphous carbon (Si/C) in lithium-ion batteries. At 0.1 A g-1, the Si/G/C sample exhibits a high initial discharge capacity of 1886 mAh g-1, with a high initial coulombic efficiency of 90.18%, the composite can still deliver a high initial charge capacity of 800 mAh g-1 at 2 A g-1, and shows a superior cyclic and rate performance compared to the Si/C anode sample. This work provides a facile approach to synthesize Si/G/C composite for lithium-ion batteries and has proven that graphite replacing amorphous carbon can effectively improve the electrochemical performance, even using low-performance micrometer silicon and large size flake graphite.

Insight into the effect of fracture surfaces in graphdiyne on the anode performance for lithium ion batteries.

Two-dimensional (2D) materials are promising anode materials for the next generation of lithium ion batteries. While the Li storage and kinetics at the surface and intercalation sites of 2D materials are widely explored, the effects of the fracture surfaces (FSs) are rarely considered despite the fact that there are numerous FSs in real 2D materials. Herein, we investigate how the FSs in graphdiyne (GDY) affect the anode performance based on first-principles calculations. Results show that both the internal and external FSs have much lower binding energies to Li atoms than perfect GDY, meaning FSs are more active in storing Li atoms. Then, the diffusion barriers of Li atoms on the internal and external FSs are only 0.42 and 0.47 eV, respectively, close to the 0.315 eV of surface sites and lower than the 0.638 eV of intercalation sites, indicating a good kinetics of Li atoms. In addition, due to the new electronic states from the C atoms with dangling bonds, the FSs convert the semiconductor characteristics of perfect GDY to metallic ones, which is helpful to the electronic conductivity. Our work demonstrates that the FSs in 2D materials are beneficial to the anode performance, which may enlighten the design of anode materials.