High Energy Density Lithium-ion Batteries Research Articles

An ultrathin LiF film coated on NCM electrode surface via magnetron sputtering for optimized structure stability and cycling performance

Nickel-riched layered oxide cathode is one of the most promising cathode materials for high energy density lithium-ion batteries, but the capacity decay and poor cycling stability due to the occurrence of side reactions at the electrode-electrolyte interface are huge obstacles preventing its performance. Surface coating is an effective method to solve this problem. In this paper, nanoscale LiF films were deposited on the surface of Ni0.83Co0.11Mn0.06O2 (NCM811) by magnetron sputtering, which effectively improved the electrochemical performance of NCM811 in half-cells. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) showed that LiF was uniformly deposited onto the electrode surface and was not embedded in the cathode particles. After 100 cycles at 0.5C, the discharge specific capacity of the coated modified NCM was 181.82 mAh/g with a retention rate of 93.95%, which was much higher than that of the original NCM811 at 160.84 mAh/g with a capacity retention rate of 83.11%, while the capacity remained basically unchanged. In addition, the modified rate capability was also significantly improved, with the discharge specific capacity of the modified sample at 5C being 167.26 mAh/g, which was 12.45% higher than that of the uncoated sample at 148.73 mAh/g. The deposited LiF film can protect the electrode interface, inhibit the decomposition of electrolyte and thus protect the positive electrode, and stabilize the structure of the particles.

Rich-Carbonyl Carbon Catalysis Facilitating the Li2CO3 Decomposition for Cathode Lithium Compensation Agent.

The active lithium loss of lithium-ion batteries can be well addressed by adding a cathode lithium compensation agent. Due to the poor conductivity and electrochemical activity, lithium carbonate (Li2CO3) is not considered as a candidate. Herein, an effective cathode lithium compensation agent, the recrystallized Li2CO3 combined with large specific surface area disordered porous carbon (R-LCO@SPC) is prepared. The screened SPC makes it easier for nano-sized Li2CO3 to adsorb and decompose on carbon substrate, meantime, exposing plenty of catalytic active sites of C═O, which can significantly improve the electrochemical activity and conductivity of Li2CO3, thus greatly reducing the decomposition potential of Li2CO3 (4.0V) and releasing high irreversible capacity (580mAhg-1) compared to the unmodified Li2CO3 (nearly no capacity above 4.6V). Meantime, the Li2CO3 can disappear completely without any by-product after the initial cycle accompanied by partially dissolved in electrolyte, optimizing the composition of SEI. The resultant lithium compensation agent applied to LMFP//graphite full cell exhibits a 19.1% increase in energy density, enhancing the rate and cycling performance, demonstrating great practical applications potential in high energy density lithium-ion batteries.

Electrophoretic assisted fabrication of additive-free WS2 nanosheet anodes for high energy density lithium-ion batteries.

2D WS2 nanosheets (NSs) are gaining popularity in the domain of Li-ion batteries (LIBs) due to their unique structures, which can enable reversible insertion and extraction of alkali metal ions. While synthesis methods have mostly relied on the exfoliation of bulk materials or direct growth on substrates, here we report an alternative approach involving colloidal hot-injection synthesis of 2D WS2 in 2H and 1T' crystal phases followed by their electrophoretic deposition (EPD) on the current collector. The produced 2D WS2 NSs' films do not require any additional additives during deposition, which boosts the energy density of the additive-free LIBs produced. The 1T' and 2H NSs exhibit long-term stable cyclic performance at C/5 for 600 cycles. At a high cycling rate (1C), the 2H NSs outperform the 1T' NSs, delivering a 1st cycle reversible capacity of 513 mA h g-1 with capacity retention of 73% after 100 cycles (compared to 205 mA h g-1, and 84 mA h g-1 respectively for NS-1T'). Post-cycling investigation confirms that there is no leaching or cracking of the active material on the surface of anodes after 100 cycles at C/5, which enables mechanical stability, and impressive battery performance of the WS2 NS electrodes.

Carbon-coated Ni0.5Mg0.5Fe1.7Mn0.3O4 nanoparticles as a novel anode material for high energy density lithium-ion batteries.

Lithium-ion batteries (LIBs) have gained considerable attention from the scientific community due to their outstanding properties, such as high energy density, low self-discharge, and environmental sustainability. Among the prominent candidates for anode materials in next-generation LIBs are the spinel ferrites, represented by the MFe2O4 series, which offer exceptional theoretical capacities, excellent reversibility, cost-effectiveness, and eco-friendliness. In the scope of this study, Ni0.5Mg0.5Fe1.7Mn0.3O4 nanoparticles were synthesized using a sol-gel synthesis method and subsequently coated with a carbon layer to further enhance their electrochemical performance. TEM images confirmed the presence of the carbon coating layer on the Ni0.5Mg0.5Fe1.7Mn0.3O4/C composite. The analysis of the measured X-ray diffraction (XRD) and Raman spectroscopy results confirmed the formation of nanocrystalline Ni0.5Mg0.5Fe1.7Mn0.3O4 before coating and amorphous carbon in the Ni0.5Mg0.5Fe1.7Mn0.3O4/C after the coating. The Ni0.5Mg0.5Fe1.7Mn0.3O4 anode material exhibited a much higher specific capacity than the traditional graphite material, with initial discharge/charge capacities of 1275 and 874 mA h g-1, respectively, at a 100 mA g-1 current density and a first coulombic efficiency of 68.54%. The long-term cycling test showed a slight capacity fading, retaining approximately 85% of its initial capacity after 75 cycles. Notably, the carbon-coating layer greatly enhanced the stability and slightly increased the capacity of the as-prepared Ni0.5Mg0.5Fe1.7Mn0.3O4. The first discharge/charge capacities of Ni0.5Mg0.5Fe1.7Mn0.3O4/C at 100 mA g-1 current density reached 1032 and 723 mA h g-1, respectively, and a first coulombic efficiency of 70.06%, with an increase of discharge/charge capacities to 826.6 and 806.2 mA h g-1, respectively, after 75 cycles (with a capacity retention of 89.7%), and a high-rate capability of 372 mA h g-1 at 2C. Additionally, a full cell was designed using a Ni0.5Mg0.5Fe1.7Mn0.3O4/C anode and an NMC811 cathode. The output voltage was about 2.8 V, with a high initial specific capacity of 755 mA h g-1 at 0.125C, a high rate-capability of 448 mA h g-1 at 2C, and a high-capacity retention of 91% after 30 cycles at 2C. The carbon coating layer on Ni0.5Mg0.5Fe1.7Mn0.3O4 nanoparticles played a crucial role in the excellent electrochemical performance, providing conducting, buffering, and protective effects.

Unveiling olivine cathodes for high energy-density lithium-ion batteries: a comprehensive review from the atomic level to the electrode scale

We propose unifying strategies for the development of high-energy, low-cost, long-lasting olivine cathodes through atomic to electrode level engineering, focusing on: (1) high energy densities, (2) kinetics, and (3) structural stabilities.

The Tuning of Strain in Layered Structure Oxide Cathodes for Lithium-Ion Batteries

Layered structure oxides have emerged as highly promising cathode materials for lithium-ion batteries. In these cathode materials, volume variation related to anisotropic lattice strain during Li + insertion/extraction, however, can induce critical structural instability and electrochemical degradation upon cycling. Despite extensive research efforts, solving the issues of lattice strain and mechanical fatigue remains a challenge. This perspective aims to establish the “structure–property relationship” between the degradation mechanism of the layered oxide cathode due to lattice strain and the structural evolution during cycling. By addressing these issues, we aim to guide the improvement of electrochemical performance, thereby facilitating the widespread adoption of these materials in future high-energy density lithium-ion batteries.

Enhancing the ultra-high rate capability of manganese-based olivine cathode by in situ catalytic growth of graphene carbon layer

Manganese-based olivine is a high energy and low-cost cathode material for lithium-ion batteries. However, its low electronic and ionic conductivity limits its further application. Herein the graphene-modified LiMn0.8Fe0.2PO4 (LMFP/C-Fe) composites are prepared by in-situ pyrolysis and catalytic graphitization through trace ferrocene as catalyst precursor. The average thickness of graphene carbon layer grown in situ is about 2–3 nm, which forms a dense and uniform carbon layer along the face of LMFP granules. It has been found that this unique structure can make a significant improvement to the electrical conductivity of LMFP. The as-prepared LMFP/C-Fe composite has a high discharge capacity of 155.9 mAh/g at 0.5C, and the capacity retention is 93.8 % after 300 charge-discharge cycles. In addition, the material can still provide reversible capacity of 94.4 mAh/g even at an ultra-high current rate of 30C. Therefore, this work offers new tactics for layout and preparation of long-life, low cost and high-energy density lithium-ion batteries, which will present a promising application in electric automobile and other applications.

Li-Rich Mn-Based Cathode Materials for Li-Ion Batteries: Progress and Perspective

The development of cathode materials with high specific capacity is the key to obtaining high-performance lithium-ion batteries, which are crucial for the efficient utilization of clean energy and the realization of carbon neutralization goals. Li-rich Mn-based cathode materials (LRM) exhibit high specific capacity because of both cationic and anionic redox activity and are expected to be developed and applied as cathode materials for a new generation of high-energy density lithium-ion batteries. Nevertheless, the difficulty of regulating anionic redox reactions poses significant challenges to LRM, such as low initial Coulombic efficiency, poor rate capability, and fast cycling capacity and voltage decay. To address the existing challenges of LRM, this review introduces their basic physicochemical characteristics in detail, analyzes the original causes of these challenges, focuses on the recent progress of the modification strategies, and then especially discusses the development prospects of LRM from different aspects.

(Invited) A Chemical Mechanism of Carbonate Electrolyte Failure at Silicon Anode Interface for New Electrolyte Design

Silicon (Si) anode has tremendous potential for the next-generation high energy density lithium-ion battery, but the development of devices with sufficient capacity retention and calendar life remains elusive. While numerous studies have characterized the composition and dynamics of the solid-electrolyte-interface (SEI) on silicon anodes, the chemical mechanisms that produce the identified species remain largely speculative and conflicting. In this presentation, we demonstrate the use of trimethylsilyllithium as a model compound to study the chemical mechanisms of electrolyte failure unique to silicon anodes. The insights from this mechanistic study led to the rational design of new electrolytes that outperform traditional EC-based carbonate electrolytes demonstrated in NMC811/Si full cells.

Towards Moisture Tolerant Lithium-Ion Batteries: A Systematic Investigation on the Effect of Moisture on Ni-Rich NMC Cathodes

In the ever-expanding lithium-ion battery (LIB) industry, lithium hexafluorophosphate (LiPF6) has been the most dominant lithium salt for preparing electrolytes. However, the challenges related to its moisture sensitivity (manifested by the formation of hydrofluoric acid) and thermal instability are yet to be addressed. Due to its improved ionic conductivity, reduced risk of producing hydrofluoric acid and better thermal and chemical stability, Lithium bis(fluorosulfonyl)imide (LiFSI) has been considered as a potential alternative salt to replace LiPF6. Nonetheless, LiFSI salt is currently not available in volumes relevant to industrial production; hindered by its high cost and the presence of trace quantities of chloride impurities. In addition, for operating cells at upper cut off voltages higher than 4.1~4.2 V, oxidative aluminum current collector corrosion [1] is a challenge.Among the high energy density LIB cathode materials, Nickel-rich LiNixMnyCozO2 (NMCs) are the most promising choices to fulfil the long mileage per charge requirements for powering electric vehicles [2]. In this study, the effect of moisture on the electrochemical performance of NMC622/Li and NMC622/graphite pouch cells was systematically investigated by adding water into 1 M LiFSI electrolyte. To better understand the interaction and effect of the added H2O with other electrolyte additives such as fluoroethylene carbonate (FEC), the electrochemical performance of the NMC622/Li half cells were tested with four different electrolytes; 1 M LiFSI in EC/DMC (50/50, v/v, control), 1 M LiFSI + 1000 ppm water, 1 M LiFSI + 10 wt% FEC, and 1 M LiFSI + 1000 ppm water + 10 wt% FEC. Double layered ultra-high molecular weight polyethylene separator (Solupor 3P07B) was used in all measurements. The water content in the electrolytes with 1000 ppm water was regularly monitored using the Karl-Fisher titration technique.It is intriguing that the addition of 1000 ppm water into the 1 M LiFSI electrolyte improved the specific discharge capacity and capacity retention of the NMC622/Li pouch cells. Furthermore, to investigate the morphological, microstructural, and chemical evolutions of the electrodes after short- and long-term cycling performance tests, postmortem characterizations such as ex situ XRD, S(T)EM, SEM/EDS, FTIR and XPS are being conducted.As expected, the oxidative aluminum current collector corrosion was scrutinized by running cyclic voltammetric measurements with the different electrolytes and the results were compared with that in 1 M LiPF6 (Figure 1a). It should be noted, however, that the voltammograms are obtained in the voltage range of 3.0 – 4.9 V. Ex situ SEM images of the cycled aluminum electrodes exhibited the formation of a thin film on the surface (Figure 1b, 1c), and the film formed on the aluminum electrode cycled with 10 wt% FEC was thicker compared to those with 1 M LiFSI and 1 M LiFSI + 1000 ppm H2O electrolytes. It was evident from the oxidative aluminum corrosion study that the current density and pitting corrosion were relatively smaller in the 10 wt% FEC containing electrolytes (Figure 1a). This is in agreement with the formation of relatively thicker films on the electrode surface with FEC containing electrolytes, as discussed above.Overall, it was evident from this study that addition of 1000 ppm water enhanced the discharge capacity and capacity retention of NMC622/Li pouch cells, and such moisture tolerant LiFSI based lithium-ion batteries can open new pathways which can ultimately enable the development of relatively higher dew point and less energy intensive dry rooms. However, for cell operations above ca. 4.3 V, proper prevention mechanisms are required for the oxidative aluminum current collector corrosion in such systems.

Interphase Regulation by Multifunctional Additive Empowering High Energy Lithium-Ion Batteries with Enhanced Cycle Life and Thermal Safety.

High energy density lithium-ion batteries (LIBs) adopting high-nickel layered oxide cathodes and silicon-based composite anodes always suffer from unsatisfied cycle life and poor safety performance, especially at elevated temperatures. Electrode /electrolyte interphase regulation by functional additives is one of the most economic and efficacious strategies to overcome this shortcoming. Herein, cyano-groups (-CN) are introduced into lithium fluorinated phosphate to synthesize a novel multifunctional additive of lithium tetrafluoro (1,2-dihydroxyethane-1,1,2,2-tetracarbonitrile) phosphate (LiTFTCP), which endows high nickel LiNi0.8 Co0.1 Mn0.1 O2 /SiOx -graphite composite full cell with an ultrahigh cycle life and superior safety characteristics, by adding only 0.5 wt % LiTFTCP into a LiPF6 -carbonate baseline electrolyte. It is revealed that LiTFTCP additive effectively suppresses the HF generation and facilitates the formation of a robust and heat-resistant cyano-enriched CEI layer as well as a stable LiF-enriched SEI layer. The favorable SEI/CEI layers greatly lessen the electrode degradation, electrolyte consumption, thermal-induced gassing and total heat-releasing. This work illuminates the importance of additive molecular engineering and interphase regulation in simultaneously promoting the cycling and thermal safety of LIBs with high-nickel NCMxyz cathode and silicon-based composite anode.

A Metal-Organic Framework-Derived Strategy for Constructing Synergistic N-Doped Carbon-Encapsulated NiCoP@N-C-Based Anodes toward High-Efficient Lithium Storage.

Transition metal phosphides (TMPs) have been regarded as the prospective anodes for lithium-ion batteries (LIBs). However, their poor intrinsic conductivity and inevitable large volume variation result in sluggish redox kinetics and the collapse of electrode structure during cycling, which substantially hinders their practical use. Herein, an effective composite electrodes design strategy of "assembly and phosphorization" is proposed to construct synergistic N-doped carbon-encapsulated NiCoP@N-C-based composites, employing a metal-organic frameworks (MOFs) as sacrificial hosts. Serving as the anodes for LIBs, one representative P-NCP-NC-600 electrode exhibits high reversible capacity (858.5mAhg-1, 120 cycles at 0.1Ag-1) and superior long-cycle stability (608.7mAhg-1, 500 cycles at 1Ag-1). The impressive performances are credited to the synergistic effect between its unique composite structure, electronic properties and ideal composition, which achieve plentiful lithium storage sites and reinforce the structural architecture. By accompanying experimental investigations with theoretical calculations, a deep understanding in the lithium storage mechanism is achieved. Furthermore, it is revealed that a more ideal synergistic effect between NiCoP components and N-doped carbon frameworks is fundamentally responsible for the realization of superb lithium storage properties. This strategy proposes certain instructive significance toward designable high-performance TMP-based anodes for high-energy density LIBs.

Dynamic hydrogen bond cross-linking binder with self-healing chemistry enables high-performance silicon anode in lithium-ion batteries

The structure instability and cycling decay of silicon (Si) anode triggered by stress buildup hinder its practical application to next-generation high-energy–density lithium-ion batteries (LIBs). Herein, a cross-linking polymeric network as a self-healing binder for Si anode is developed by in situ polymerization of tannic acid (TA) and polyacrylic acid (PAA) binder labelled as TA-c-PAA. The branched TA as a physical cross-linker complexes with PAA main chains through abundant dynamic hydrogen bonds, endowing the cross-linking TA-c-PAA binder with unique self-healing property and strong adhesion for Si anode. Benefiting from the mechanical robust and hard adhesion, the Si@TA-c-PAA electrode exhibits high reversible specific capacities (3250 mAh/g at 0.05C (1C = 4000 mA g−1)), excellent rate capability (1599 mAh/g at 2C), and impressive cycling stability (1742 mAh/g at 0.25C after 450 cycles). After Ex situ morphology characterization, in situ swelling analysis, and finite element simulation, it is found that the TA-c-PAA binder allows the Si anode to dissipate stress and prevent pulverization during lithiation and delithiation, thus the hydrogen bonds among interpenetrating network may be adaptable to the stress intensity. Our work paves a new avenue for the design of efficient and cost-effective binders for next-generation Si anode in LIBs.

Distinctive interphasial properties and high structural reversibility endowed by B-/CN– electrolyte additive and its superior electrochemical performance for graphite/LiCoO2 pouch cells

The exploration of high energy density batteries requires cathodes with a high specific capacity and high voltage. LiCoO2 (LCO), a prospective cathode material for lithium-ion batteries (LIBs), displays a decent capacity but without a compatible electrolyte to withstand its high voltage. To create an enduring cathode electrolyte interphase (CEI), a novel electrolyte additive, 2-cyanophenylboronic acid (CBB), which possesses both cyano (CN–) and boronic acid (B-) functional group, is firstly put forward to be applied in LCO/Li cells as well as graphite/LCO pouch cell. Data from experimental and theoretical research both reveal that CBB preferentially decomposes on LCO surface, constructing a thin, robust and homogeneous CEI film rich in B-F/B-O species with fast kinetics and low impedance, suppressing the LCO surface transformation upon cycling due to the alleviated Co dissolution. CBB additive can enhance the structural reversibility (in-situ X-ray diffraction), decrease the electrolyte decomposition and eliminate the HF formation, constructing a much smoother surface than base electrolyte. LCO/Li cells with 1% CBB deliver more excellent capacity retention (96%) and a much superior rate capability (145 mAh/g, 5C) than that of base electrolyte (67%, 115 mAh/g). Intriguingly, graphite/LCO pouch batteries containing 1% CBB for 300 cycles deliver more outstanding capacity retention of 80% than that of base electrolyte (2%). This work reveals that CBB can function as an efficient electrolyte additive for high voltage LCO cathode, of which its distinctive CEI modification on the LCO surface provides valuable perspectives for its commercial application towards high energy density LIBs.

Opportunities and Challenges of Layered Lithium-Rich Manganese-Based Cathode Materials for High Energy Density Lithium-Ion Batteries

Opportunities and Challenges of Layered Lithium-Rich Manganese-Based Cathode Materials for High Energy Density Lithium-Ion Batteries

Intergranular Shielding for Ultrafine-Grained Mo-Doped Ni-Rich Li[Ni0.96 Co0.04 ]O2 Cathode for Li-Ion Batteries with High Energy Density and Long Life.

Deploying Ni-enriched (Ni≥95 %) layered cathodes for high energy-density lithium-ion batteries (LIBs) requires resolving a series of technical challenges. Among them, the structural weaknesses of the cathode, vigorous reactivity of the labile Ni4+ ion species, gas evolution and associated cell swelling, and thermal instability issues are critical obstacles that must be solved. Herein, we propose an intuitive strategy that can effectively ameliorate the degradation of an extremely high-Ni-layered cathode, the construction of ultrafine-scale microstructure and subsequent intergranular shielding of grains. The formation of ultrafine grains in the Ni-enriched Li[Ni0.96 Co0.04 ]O2 (NC96) cathode, achieved by impeding particle coarsening during cathode calcination, noticeably improved the mechanical durability and electrochemical performance of the cathode. However, the buildup of the strain-resistant microstructure in Mo-doped NC96 concurrently increased the cathode-electrolyte contact area at the secondary particle surface, which adversely accelerated parasitic reactions with the electrolyte. The intergranular protection of the refined microstructure resolved the remaining chemical instability of the Mo-doped NC96 cathode by forming an F-induced coating layer, effectively alleviating structural degradation and gas generation, thereby extending the battery's lifespan. The proposed strategies synergistically improved the structural and chemical durability of the NC96 cathode, satisfying the energy density, life cycle performance, and safety requirements for next-generation LIBs.

Unlocking the Potential of Li-Rich Mn-Based Oxides for High-Rate Rechargeable Lithium-Ion Batteries.

Lithium-rich Mn-based oxides have gained significant attention worldwide as potential cathode materials for the next generation of high-energy density lithium-ion batteries. Nonetheless, the inferior rate capability and voltage decay issues present formidable challenges. Here, a Li-rich material equipped with quasi-three-dimensional (quasi-3D)Li-ion diffusion channels is initially synthesized by introducing twin structures with high Li-ion diffusion coefficients into the crystal and constructing a "bridge" between different Li-ion diffusion tunnels. The as-prepared material exhibits monodispersed micron-sized primary particles (MP), delivering a specific capacity of 303mAhg-1 at 0.1 C and an impressive capacity of 253mAhg-1 at 1 C. More importantly, the twin structure also serves as a "breakwater" to inhibit the migration of Mn ions and improve the overall structural stability, leading to cycling stability with 85% capacity retention at 1 Cafter 200 cycles. The proposed strategy of constructing quasi-3Dchannels in the layered Li-rich cathodes will open up new avenues for the research and development of other layered oxide cathodes, with potential applications in industry.

Scalable synthesis of high-performance Si/CNTs/C anodes for lithium-ion batteries based on recycling of silicon cutting waste

Si is expected to replace graphite anode materials in the next generation of high-energy–density lithium-ion batteries due to its high specific capacity and abundant resources. However, the poor electrical conductivity and the huge volume expansion during the lithiation and delithiation process hindering its further commercial application. In this work, silicon cutting waste（SCW）generated in the photovoltaic industry was recycled as raw material, and a slurry containing Si after sanding(S-Si) was obtained in the sanding machine, carbon nanotubes (CNTs) and polyvinylpyrrolidone (PVP) were added to the slurry, mixed homogeneously and then spray-dried and granulated, after high-temperature carbonization, Si/CNTs/C composite with high vibrational density, homogeneous particle size and excellent electrochemistry were obtained. The nano-sized Si can accommodate the volume expansion during the cycling process, and the CNTs are interspersed in the composite to construct a conductive network, thus enhancing the electronic conductivity of the composite. The as-synthesized Si/CNTs/C composite exhibited a residual capacity of more than 1000 mAh·g−1 after 500 cycles at a current of 1 A·g−1 and a capacity of 878 mAh·g−1 even at 10 A·g−1. Notably, full lithium-ion batteries with a Si/CNTs/C anode and LiFePO4 cathode delivered a stable capacity of 130 mAh·g−1 with an ICE of 88.1 %. Our work provides reference solutions for the recycling of waste materials in the photovoltaic industry as well as the preparation of low-cost, high-performance Si/C anodes for lithium-ion batteries.

Controlled roll to roll pre-lithiation by lithium vacuum vapor deposition for high performance silicon based lithium-ion battery

Silicon oxides (SiOx) anode has attracted great interest for high-energy–density lithium-ion battery due to its extremely abundant reserves, low cost, and easy synthesis. Despite these merits, its low initial columbic efficiency (ICE) and poor cycle ability severely hinder it from widely using. Pre-lithiation methods are considered to be the effective strategies to overcome low ICE concerns. However, current pre-lithiation methods are always limited by their own drawbacks, such as complicated process and uncontrollable pre-lithiation degree. In this work, we reported a controlled roll-to-roll pre-lithiation method with lithium vacuum vapor deposition. Our pre-lithiation method can not only achieve controllable and uniform pre-lithiation degree of SiOx anode, but also is a process simplified design appropriate for large-scale applications. The electrochemical performance of our pre-lithiated anode achieved 10 % ICE improvement and much stable cycle, demonstrating promising potential for commercial applications.

One thousandth of quaternity slurry additive enables one thousand cycle of 5V LNMO cathode

5 V high voltage LiNi0.5Mn1.5O4 (LNMO) is one of the most promising cathode candidates for high energy density lithium-ion batteries. However, the electrochemical performance of high voltage LNMO is significantly affected by the interfacial compatibility between cathode and electrolyte. High voltage leads to decomposition of electrolyte at the cathode-electrolyte interface (CEI), consuming electrolyte and forming an uneven, unstable, and unprotected CEI, and hindering Li+ diffusion and reducing electrochemical efficiency. At the same time, along with the dissolution of transition metals and irreversible crystal structure damage over cycles, its electrochemical performance is seriously impaired. To solve these problems, it is proposed to pre-form a stable passivation layer on the LNMO surface using tiny amount of quaternity slurry additive of potassium-nonafluoro-1-butanesulfonate (KPBS). The K+ in KPBS assists construction of uniform and stable electric field at the cathode particle surface together with the Li+, which induces uniform deposition of the CEI. The lithium-ion diffusion at the interface is accelerated due to existence of rich phase boundaries between KF and LiF species within the CEI. The sulfonic acid group of KPBS is capable of inhibiting transition metal dissolution via coordination boding with Ni/Mn cations. The nona fluoro butyl structure improves the interface compatibility with the poly(vinylidene difluoride) (PVDF) binder to enhance the structure robustness of the electrode. The quadruple effects exercised by the KPBS enable the LNMO almost no capacity decay after 1000 cycles at 1C and 5 V. This work has a great potential to boost significant advance of the high energy density lithium-ion battery technology.