Energy Density Lithium-ion Batteries Research Articles

Enhanced prelithiation performance of Li5FeO4 cathode additive and optimized solid electrolyte interface enabled by Mn substitution

In the pursuit of enhancing the energy density of lithium-ion batteries, cathode prelithiation emerges as a pivotal approach, introducing additional irreversible active lithium ions to augment performance. Li5FeO4 (LFO) stands out as an excellent option, boasting an impressive theoretical specific capacity and the additional advantages of cost-effectiveness in raw materials and low preparation cost. However, the impact of extra lithium incorporations on compositional changes at the electrode-electrolyte interface as well as on cell stability has impeded further researches. Herein, a Mn doping strategy is proposed and predicted by first-principles calculations to synthesize partially Mn-substituted Li5.125Fe0.875Mn0.125O4 (LFMO). And the prelithiation with LFMO improved the interfacial composition of LiFePO4 (LFP) batteries compared to LFO, achieving a charging capacity of 213 mAh∙g−1 in the first cycle at 0.05 C. The subsequent treatment demonstrated superior cycling stability, maintaining a discharge specific capacity as high as 155.3 mAh∙g−1 after 100 cycles at 0.2 C, and exhibiting a higher capacity retention in the full cell. These discoveries could contribute to enhancing the regulation of battery interface during the utilization of LFO, potentially promoting the development of cathode lithium additives.

Tuning the electrochemical performance of graphite electrodes in lithium-ion batteries: Thermodynamics versus kinetics

Improving the energy density of lithium-ion batteries is a goal pursued in state-of-the-art batteries, and the use of thick electrodes is one of the most direct and effective methods. However, thick electrodes are often accompanied by severe deterioration in electrochemical performance. Graphite is a widely used anode material and great efforts are made from kinetic parameters to improve the performance of thick electrodes, while the thermodynamic effects are ignored for a long time. Herein, this work focuses on elucidating the thermodynamic effects on electrode processes and revealing regulatory effects of the equilibrium potential on reaction. Kinetics can cause electrodes to react nonuniformly, while thermodynamics can rectify electrodes reacting nonuniformly, leading to fluctuations in the reaction rate. The competitive relationship between kinetics and thermodynamics is explored in detail. The results demonstrate that the electrode process is still dominated by thermodynamics at high rates for thin graphite electrodes, while thick graphite electrodes quickly tend to be dominated by kinetics as the rate increases. Finally, a favorable performance enhancement can be obtained by optimizing the thermodynamic properties of graphite. This work illustrates that the alleviation of kinetic constraints is limited, providing a completely new guideline for future electrode design of lithium-ion batteries.

Sulfur-containing soft Lewis base polymers for improved lithium-ion conductivity under polymer-in-salt conditions

Abstract Solid polymer electrolytes have been intensively studied to improve the safety and energy density of lithium-ion batteries (LiBs). Although high-rate performance of LiBs has been reported in electrolytes under polymer-in-salt conditions with an excess of lithium salts and polymers, effective conditions for achieving high ionic conductivity remain unresolved. In this study, we elucidate the mechanism and high Li-ion transportability of poly(sulfone-thioether) under polymer-in-salt conditions. In particular, the composition of the polymer with an asymmetric Li salt, lithium(fluorosulfonyl)(trifluoromethane sulfonyl)imide (LiFTFSI), induced a high ionic conductivity above 10−5 S/cm, which is higher than that of the poly(ethylene oxide) (PEO)-Li salt system. Under polymer-in-salt conditions, the enhanced conductivity of poly(sulfone-thioether) contrasts with the conductivity drop observed in the conventional PEO system. These results show the superiority of polymers with soft Lewis bases, such as sulfur donor atoms, for Li-ion transport under polymer-in-salt conditions.

Homogeneously dispersed silicon/graphite composite toward enhanced lithium-ion batteries

At present, silicon/graphite composite is the most promising anode material for high energy density lithium-ion batteries. However, during the preparation, nanoscale silicon will inevitably undergo agglomeration, which will cause serious volume changes and breakage during the charging/discharging process. How to achieve uniform dispersion of nanoscale silicon onto the surface of graphite becomes a great challenge. Here, by grafting functional groups on the surface of silicon, both the repulsive force between silicon particles and the binding force between silicon/graphite have been improved, thereby highly uniform dispersed silicon is achieved. After being coated with asphalt and etching off the functional groups, the conductivity and ion migration ability of the composite are further improved. Resultantly, the modified composite provides a high discharging capacity of 598.4 mAh·g−1 at 0.2C and can still maintain a high-capacity retention of 90.7 % and a small volume expansion rate of 30.8 % after 500 cycles.

Construction of Hierarchical Conductive Networks for LiNi0.8Mn0.1Co0.1O2 Cathode toward Stable Cycling at High Areal Mass Loadings.

Realizing high-performance thick electrodes is considered as a practical strategy to promote the energy density of lithium-ion batteries. However, establishing effective transport pathways for both lithium-ions and electrons in a thick electrode is very challenging. This study develops a hierarchical conductive network structure for constructing high-performance NMC811 (LiNi0.8Mn0.1Co0.1O2) cathode toward stable cycling at high areal mass loadings. The hierarchical conductive networks are composed of a Li+/e- mixed conducting interface (lithium polyacrylate/hydroxyl-functionalized multiwalled carbon nanotubes) on NMC811 particles, and a segregated network of single-walled carbon nanotubes in the electrode, without any additional binders or carbon black. Such strategy endows the NMC811 cathode (up to 250µm and 50mg cm-2) with low porosity/tortuosity, ultrahigh Li+/e- conductivities and excellent mechanical property at low carbon nanotube content (1.8 wt%). It significantly improves the electrochemical reaction homogeneity along the electrode depth, meanwhile effectively inhibits the side reactions at the electrode/electrolyte interface and cracks in the NMC particles during cycling. This work emphasizes the crucial role of the electronic/ionic cooperative transportation in the performance deterioration of thick cathodes, and provide guidance for architecture optimization and performance improvement of thick electrodes toward practical applications, not just for the NMC811 cathode.

Engineering Nano-Sized Silicon Anodes with Conductive Networks toward a High Average Coulombic Efficiency of 90.2% via Plasma-Assisted Milling.

Si-based anode is considered one of the ideal anodes for high energy density lithium-ion batteries due to its high theoretical capacity of 4200 mAh g-1. To accelerate the commercial progress of Si material, the multi-issue of extreme volume expansion and low intrinsic electronic conductivity needs to be settled. Herein, a series of nano-sized Si particles with conductive networks are synthesized via the dielectric barrier discharge plasma (DBDP) assisted milling. The p-milling method can effectively refine the particle sizes of pristine Si without destroying its crystal structure, resulting in large Brunauer-Emmett-Teller (BET) values with more active sites for Li+ ions. Due to their unique structure and flexibility, CNTs can be uniformly distributed among the Si particles and the prepared Si electrodes exhibit better structural stability during the continuous lithiation/de-lithiation process. Moreover, the CNT network accelerates the transport of ions and electrons in the Si particles. As a result, the nano-sized Si anodes with CNTs conductive network can deliver an extremely high average initial Coulombic efficiency (ICE) reach of 90.2% with enhanced cyclic property and rate capability. The C-PMSi-50:1 anode presents 615 mAh g-1 after 100 cycles and 979 mAh g-1 under the current density of 5 A g-1. Moreover, the manufactured Si||LiNi0.8Co0.1Mn0.1O2 pouch cell maintains a high ICE of >85%. This work may supply a new insight for designing the nano-sized Si and further promoting its commercial applications.

Recent Progress and Synthetic Methods for Single-crystalline Cathode in Lithium-ion Batteries

Ni-rich layered transition metal oxides have been regarded as the most feasible way for achieving high energy density of lithium-ion batteries. Conventional Ni-rich cathodes are composed of spherical secondary particles, consisting of numerous primary particles. Unfortunately, the grain boundaries in the polycrystalline structure are vulnerable to the pulverization, leading to microcracks during cycling. The newly exposed surface from the microcrack can induce undesirable side reactions with the electrolyte, which severely deteriorates the battery performance. On the other hand, single-crystalline Ni-rich cathodes have gained significant attention for industrial applications due to their robust mechanical strength, resulting from the elimination of grain boundaries. The improved mechanical properties of single-crystalline cathodes effectively mitigate the interfacial side reactions, thereby attaining superior structural, thermal, and electrochemical performance. Herein, we have introduced various synthetic methods of the single-crystalline cathode, encompassing not only high-temperature sintering and the molten-salt method for the Ni-rich cathode but also the other strategies for different single-crystalline cathode materials. This review aims to provide a comprehensive understanding of single-crystalline cathode synthesis, with implications for the development of high-performance cathode materials.

The total use of rice husk to create highly porous silicon and sulfur-doped activated carbon for the fabrication of high-performance silicon-anode lithium-ion capacitors

The promising advantages between the high energy density of lithium-ion batteries and the high power density of supercapacitors are hybridized to construct lithium-ion capacitors (LICs). The high capacity of anode materials is challenging for high-performance LICs. Simultaneously, the quest for sustainable and environmentally friendly energy storage materials has attracted attention. In this work, rice husk was treated with alkaline to separate silica and biochar, followed by magnesiothermic reduction and thermal activation to produce porous silicon (PSi) and sulfur-doped activated carbon (SAC), respectively. The PSi had high porosity for accommodating volumetric expansion during cycling, resulting in outstanding rate capability and cycling stability, whereas the SAC had a high surface area with micro- and mesopores (2511 m2 g−1), a high degree of graphitization, and excellent electrochemical performance. For the fabrication of half-cell lithium-ion batteries, PSi gave a specific capacity of 1005.3 mAh g−1 between 0.01 and 2 V, while SAC provided a specific capacity of 108 mAh g−1 (2.0–4.5 V), and showed a better electrochemical stability than the both commercial silicon and activated carbon. When a full-cell LIC was fabricated, the optimized P-Si//SAC LIC had a high energy density of 107 Wh kg−1 at a power density of 163 W kg−1 and a capacitance retention of 81.3 and 61.8% between a potential range of 2.0–4.5 V after 1000 and 3000 charge-discharge cycles, respectively. This study not only turned agricultural waste into valuable, high-performance LICs but also made significant progress toward the creation of environmentally responsible, long-lasting, and sustainable energy storage systems.

Large-scale production of graphene encapsulated silicon nanospheres as flexible anodes for lithium ion batteries

Silicon (Si) is regarded as the most promising anode candidate for the next high energy density lithium ion batteries (LIBs) owing to its highest theoretical specific capacity and low lithiation potential. However, the practical application of Si-based materials is severely limited due to their enormous volume expansion, which leads to the breakdown of the electrode structure and shortens the cycle life. Herein, we successfully fabricated a free-standing graphene encapsulated silicon nanospheres (Si/rGO) film through homogenizing nano-Si in the lyotropic liquid crystallinity of graphene oxide (GO), followed by coating on the PET substrate and hot pressing technology. For the first time during the preparation process, the dispersion of nano-Si in deionized water was quantitatively characterized through real-time measurements of zeta potential and average particle size. Benefiting from the highly ordered layer-to-layer stacking and dense framework, the as-prepared Si/rGO film shows a high initial discharge capacity of 1727.2 mAh/g at 200 mA/g and superior cycling stability (1024.2 mAh/g over 200 cycles). This straightforward and easy-to-implement method can be used for industrial-scale production through continuous feeding.

A bimetal strategy for suppressing oxygen release of 4.6V high-voltage single-crystal high-nickel cathode

High-voltage cathode materials, such as single-crystal high-nickel layered oxide materials, are a necessary condition for achieving high energy density lithium-ion batteries, but they have to be accompanied by the structural instability and irreversible release of lattice oxygen during operation, posing serious safety hazards. Here, to solve the lattice oxygen release issue of single-crystal high-nickel cathode, we propose an improved strategy for overall cathode by synchronously addressing interface and lattice instability, ensuring stable operation at a high voltage up to 4.6 V. By Al-doping, in the bulk phase, we intensify the charge transfer between transition metals and oxygen, and the columnar effect caused by doped atoms effectively alleviates internal strain, thereby significantly limiting lattice shrinkage and then suppressing oxygen release. On the other hand, the protective layer of LiNbO3 as the fast ion conductor formed at the cathode interface suppresses parasitic reactions and hinders lattice oxygen loss caused by dissolution of transition metals. Therefore, after 200 cycles at a cut-off voltage of 4.6 V, our cathode material still maintains a capacity retention rate of 89.1%. Density functional theory (DFT) calculations predict the effective suppression of oxygen release for the modified cathode materials, which has been further confirmed by differential electrochemical mass spectrometry (DEMS) tests. This work provides a new perspective for solving the problem of oxygen release under high cut-off voltage conditions for single crystal high nickel cathode.

Study on the Adsorption of Trace Water in N-Methyl-pyrrolidone Solvents by A-Type Molecular Sieves.

N-Methyl-pyrrolidone (NMP) is an important coating solvent for the production of lithium batteries, and its water content will greatly affect the coating quality and energy density of lithium batteries, which needs to be reduced to 200 ppm. The current vacuum distillation technology suffers from high operating costs and high energy consumption, whereas the pervaporation technology only achieves solvent dehydration up to 99.5%. Therefore, it is of great significance to carry out the study of trace water removal from NMP solvents. In this paper, the A-type molecular sieve adsorption method was used to remove trace water from the NMP solvent, and the effects of molecular sieve type, particle size, adsorption temperature, feeding amount, and contact time on the dehydration performance of NMP system were first investigated. Adsorbed at 25 °C for 240 min at a feeding amount of 120 g/L, 3A molecular sieves were able to reduce the water content of the NMP solvent from 5000 to 140 ppm. Second, Langmuir and Freundlich equations were used to fit the static isothermal adsorption data, and the results showed a better correlation of the Langmuir equation. Then, the adsorption kinetics and diffusion mechanism were analyzed by the kinetic model and the Crank single-pore diffusion model. The R2 of the pseudo-first-order kinetic model was 0.9993, which was more suitable for describing the process of adsorption of water from the NMP solvent by 3A molecular sieves, and the effective diffusion coefficient De = 2.986 × 10-8 cm2/s was calculated for the Crank single-pore adsorption model, which proved water molecules on the 3A molecular sieve. The diffusion of water molecules on the inner surface of the pores is the controlling step of the adsorption process. Finally, the fixed-bed dynamic penetration curves were investigated to obtain the experimental data of fixed-bed adsorption, and the experimental data were fitted using the Thomas and Yoon-Nelson models, which showed that both models could describe the adsorption behavior of trace water in NMP solvents on 3A molecular sieves. This study provides a new idea for the removal of trace water in NMP systems, and a series of model fitting parameters provide basic data for industrial scale-up.

Poly(Imide) Separator Functionalized by Melamine Phosphonic Acid for Regulating Structural and Thermal Stabilities of Lithium-ion Batteries

As the energy density of lithium-ion batteries (LIBs) continues to increase, various separators are being developed to with the aim of improving the safety performance. Although poly(imide) (PI)-based separators are widely used, it is difficult to control their pore size and distribution, and this may further increase the risk associated. Herein, a melamine phosphonic acid (MP)-coated PI separator that can effectively control the pore structure of the substrate is suggested as a remedy. After the MP material is embedded into the PI separator with a simple one-step casting process, it effectively clogs the large pores of the PI separator, preventing the occurrence of internal short circuits during charging. It is anticipated that the MP material can also suppress rapid thermal runaway upon cycling due to its ability to reduce the internal temperature of the LIB cell caused by the desirable endothermic behavior around 300°C. According to experiments, the MP-coated PI separator not only decreases the thermal shrinkage rate better than commercial poly(ethylene) (PE) separators but also exhibits a desirable Gurley number (109.6 s/100 cc) and electrolyte uptake rate (240%), which is unique. The proposed separator is electrochemically stable in the range 0.0–5.0 V (vs. Li/Li+), which is the typical working potential of conventional electrode materials. In practice, the MP-coated PI separator exhibits stable cycling performance in a graphite–LiNi0.83Co0.10Mn0.07O2 full cell without an internal short circuit (retention: 90.3%).

MOF-derived cobalt nanoparticles in silicon suboxide-based anodes for enhanced lithium storage

The ultra-high theoretical capacity of silicon-based (Si) materials makes them promising anode materials for high energy density lithium-ion batteries. Unfortunately, the dramatic volume change (∼300%) and low electrical conductivity of silicon have severely hindered the commercial use of silicon anodes. Silicon suboxide (SiOx) is one of the ideal candidates for high energy density batteries due to its reduced swelling and lower cost as compared to silicon. However, it remains a huge challenge to address the low conductivity, low (initial) coulombic efficiency and apparent volume effects of SiOx. In this paper, SiOx/Co@C composite anode materials loaded with metal Co nanoparticles were uniformly and efficiently prepared by using 3-aminopropyl triethoxysilane (APTES) as silicon source and Co-MOF as Co source via molecular self-assembly strategy. The experimental results and density functional theory (DFT) calculation showed that the catalytic action of embedded Co nanoparticles had activated the silico-oxygen bond of SiOx and the irreversible product Li2O, thereby improving the initial coulombic efficiency (ICE) and enhancing the reversible capacity. At the same time, the metal Co with mechanical rigidity and electrical conductivity alleviated the volume fluctuation during alloying and improved the charge transfer capacity and ion transport rate of the composite. When compared with SiOx@C anodes, SiOx/Co@C-600 composites showed higher initial CE, superior cyclic stability and good rate performance. In particular, the successful matching of the anode with the lithium iron phosphate (LFP) cathode in full cell systems validated the possibility of its practical application. This work provides important insights into the application of Si-based materials in lithium-ion battery electrode materials and the development of high energy density batteries.

Constructing a hierarchical porous nanotube In2O3 anode for high-performance lithium-ion batteries

With the rapid development of electric vehicles and various electronic products, higher energy density lithium-ion batteries are imperative to develop. As one of the key materials for lithium-ion batteries, anode materials with high energy density have become a research focus. Especially, In2O3 has received increasing attention due to its mature preparation technology, environmental protection, low work voltage, and high theoretical lithium storage capacity. However, the poor conductivity and serious volume change during the lithium removal/insertion process of In2O3 anode limit its performance. Based on this, a hierarchical porous nanotube In2O3 (HPNT-In2O3) anode is successfully prepared, in which the continuous one-dimensional nanotube structure of HPNT-In2O3 and abundant porous channels can provide the large specific surface area, accelerate the charge transfer rate, and supply a large number of Li+ storage active site. Moreover, the HPNT-In2O3 anode can maintain a higher reversible specific capacity of 470 mAh g−1 after 180 cycles at 0.1C, improve the cycling performance and rate performance, compared with a granular In2O3 anode. This work provides a new avenue to develop high performance anode materials for lithium-ion batteries.

Novel Aliphatic polycarbonate binders for Solvent‑free manufacturing High‑loading cathodes of high-performance lithium-ion batteries

To achieve high energy density lithium-ion battery depends on high area load of the active material in the cathode. However, it is challenging to attain high loading of active material by traditional wet coating method due to large amount of organic solvent used. A solvent-free manufacturing cathode that take advantages of viscous flow polymer binder under shearing force of ball-milling to bind the active materials and the conductive carbon uniformly on the current collector is an environment-friendly alternative and has attracted increasing attention. Herein, a solvent free manufacturing LiFeO4 cathode with thermoplastic polymer poly(lactide-co-propylene carbonate) as functional binder has high area loading up to 57 mg/cm2 of active material, and the battery assembled with such a LiFeO4 cathode and lithium metal anode can release a specific capacity of 135.5 mAh/g at 0.2C. In addition, the cathode using poly(propylene carbonate) or polycaprolactone functional binder can also be loaded with 40 mg/cm2 of active material, which expands the variety of binders for solvent free manufacturing electrodes. Solvent free manufacturing electrodes with such functional binders are expected to break through the technical bottleneck of lithium-ion battery with high energy density.

Improving Fast-Charging Capability of High-Voltage Spinel LiNi0.5 Mn1.5 O4 Cathode under Long-Term Cyclability through Co-Doping Strategy.

Co-free spinel LiNi0.5 Mn1.5 O4 (LNMO) is emerging as a promising contender for designing next generation high-energy-density and fast-charging Li-ion batteries, due to its high operating voltage and good Li+ diffusion rate. However, further improvement of the Li+ diffusion ability and simultaneous resolution of Mn dissolution still pose significant challenges for their practical application. To tackle these challenges, a simple co-doping strategy is proposed. Compared to Pure-LNMO, the extended lattice in resulting LNMO-SbF sample provides wider Li+ migration channels, ensuring both enhanced Li+ transport kinetics, and lower energy barrier. Moreover, Sb creating structural pillar and stronger TM─F bond together provides a stabilized spinel structure, which stems from the suppression of detrimental irreversible phase transformation during cycling related to Mn dissolution. Benefiting from the synergistic effect, the LNMO-SbF material exhibits a superior reversible capacity (111.4mAhg-1 at 5C, and 70.2mAhg-1 after 450cycles at 10C) and excellent long-term cycling stability at high current density (69.4% capacity retention at 5C after 1000cycles). Furthermore, the LNMO-SbF//graphite full cell delivers an exceptional retention rate of 96.9% after 300cycles, and provides a high energy density at 3C even with a high loading. This work provides valuable insight into the design of fast-charging cathode materials for future high energy density lithium-ion batteries.

Water-soluble Polypyrrole-Polybis(4-oxy benzene sulfonic acid)phosphazene Composites and Investigation of Their Performance as Cathode Binder in Li-ion Batteries.

Current electric storage systems eagerly focus on high-power and energy-dense Lithium-ion batteries to cope with increasing energy storage demands. Since cathode materials are one of the bottlenecks of these batteries, there is much interest in layered lithium-rich manganese oxide-based (LLMO) cathodes which can develop this technology. However, Initial Coulombic Efficiency (ICE) loss, poor rate performance and cycling instability issues are still persistent as problems to be solved for these materials. Recent research shows that water-soluble binders are effective in improving the performance of LLMO materials. Herein, we describe the synthesis, characterisation, and application of a series of water-soluble composites as a binder for LLMO cathodes. The PPy is introduced as part of the binder to improve the electronic conductivity and two different oxidants and various PPy to PSAP ratios were used to optimise the final properties. The electrochemical performance and morphology of the cathodes before and after cycling were investigated and compared with the conventional PVDF binder. The LLMO-2c electrode showed excellent charge-discharge performance, especially at 5 C and 10 C rates, and high cycling stability at 0.2 C whilst maintaining a final capacity of 184 mAh/g after 200 cycles, which is equal to 89.3 % capacity retention.

Smart-responsive sustained-release capsule design enables superior air storage stability and reinforced electrochemical performance of cobalt-free nickel-rich layered cathodes for lithium-ion batteries

Nickel-rich layered oxide stands as one of the most promising cathodes in demand for higher energy density of lithium-ion batteries (LIBs) in next generation. While increasing nickel content brings more capacity, it also makes this kind of cathode more vulnerable to the ambient, both the air outside the cell and the electrolyte inside, causing aggravated storage, structural and thermal instability. The cathode surface, as the first line of defense against the ambient attack, is the essential place to address these issues. Enlightened by the mechanism of “sustained-release capsule”, here we decorate the polydimethylsiloxane (PDMS), a skin with exceptional moisture-resistance and chemical stability, onto the surface of LiNi0.9Mn0.1O2. This PDMS skin demonstrated the smart response to the surrounding environment that the hydrophobic surface guarantees the ambient air storage stability by cutting off residual alkali accumulation and the protective role of coating could be relayed as another functional mechanism once entering the battery. The detrimental HF species generated from water-induced electrolyte decomposition are effectively captured and eliminated to defend cathode corrosion and enhance interfacial stability during long-term cycling. Attributed to the seamless protection from the outside to the inside of the battery, this well-capsuled Ni-rich cathode exhibits negligible capacity fading compared with fresh state even after long ambient exposure, and realizes superior cycling and thermal stability. This work demonstrates new guidelines to design smart-responsive coatings for cathode materials to reduce their susceptibility to the surrounding environment, towards improving both ambient storage stability and cycling stability.

PO43--doped layer @ spinel @ rGO sandwich-structured lithium-rich manganese-based cathode material with enhancing rate capability and cycle stability for Li-ion battery

The Li-rich Mn-based cathode (LRM) material faces challenges like low initial coulombic efficiency (ICE) and reduced capacity retention, which limit their commercial viability in high energy density lithium-ion batteries (LIBs). These challenges primarily arise from the irreversible migration of transition metal ions (TMn+) and the escape of lattice oxygen. Herein, this study proposes a novel approach to enhance Li-rich cathodes by implementing a PO43--doped layer @ spinel @ rGO sandwich structure, which effectively addresses the aforementioned challenges. Through the synergistic effects of PO43- doping and rGO surface modification, the modified samples demonstrate remarkable electrochemical properties. These include an impressive initial coulombic efficiency (ICE) of 87.54%, and a superior capacity of 187.12 mAhg−1 and 149.44 mAhg−1 at 25°C and 45°C, respectively, following 200 cycles at 1 C. Additionally, they exhibit an outstanding rate capability of 82.3 mAhg−1 at 10 C and a minimal voltage decrease of 0.504 V after 200 cycles. The synergetic strategy presented in this work serves as an inspiring source for the exploration of high energy density and long-cycle cathode materials.

Borate-Functionalized Disiloxane as Effective Electrolyte Additive for 4.5 V LiNi0.8Co0.1Mn0.1O2/Graphite Batteries.

Ni-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) is considered the most prominent cathode material to establish a practical high energy density of lithium-ion batteries (LIBs) for future electric vehicles. The energy density of LIBs is greatly determined by the capacity of electrode materials and the operating voltage of the cells. To further improve the cycle lifespan of NCM811 batteries to meet the requirement of driving range for the electric vehicle market, it is vital to design a novel electrolyte additive that can enhance the stability of the cathode/electrolyte interface at a wide range of voltage. Herein, a novel borate functionalized disiloxane compound, 1,1,1,3,3-pentamethyl-3-(3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)propyl) disiloxane (PMBPDS), is synthesized as cathode electrolyte interphase (CEI) film-forming additive to improve the cycling performance of NCM811 batteries. Systematic studies reveal that PMBPDS can construct a stable CEI film on the NCM811 surface and efficiently scavenge hydrofluoric acid (HF). The PMBPDS-derived CEI prevents the dissolution of transmission metals in the NCM811 cathode and enhances the capacity retention of NCM811/graphite cells from 68.3 to 70.6% after 200 cycles at 1 C in the voltage window of 3-4.5 V. This work provides more understanding on designing the molecular structure of additive compounds for improving the electrochemical performance of LIBs.