Chemical Prelithiation of Negative Electrodes in Ambient Air for Advanced Lithium-Ion Batteries

In Situ Construction of Specific SEI Layer Affords Effective Prelithiation

Silicon-based anodes have been attracting attention due to their high theoretical specific capacity, but their low initial Coulombic efficiency (ICE) seriously hinders their commercial application. Direct contact prelithiation is considered to be one of the effective means of solving this problem. By means of prelithiation, a specific solid electrolyte interphase (SEI) was constructed, which inhibited the volume expansion of the SiO/C composite anode during prelithiation and reduced the local current generated when the lithium source was in contact with the anode. On the one hand, it can reduce the side reactions derived from the decomposition of electrolytes in the prelithiation process, and on the other hand, it can slow down the prelithiation process and inhibit the volume expansion of the SiO/C composite anode in the prelithiation process. The results of XPS, TOF-SIMS, and other tests show that the use of an electrolyte whose main component is LiTFSI can construct SEI film whose main component is LiF, which to a certain extent can slow down the rate of prelithiation, reduce the local current generated when the lithium source is in contact with the negative electrode, minimize the occurrence of side reactions, and inhibit the volume expansion of the negative electrode material. The full battery assembled with NCM111 positive electrode still exhibits 83.5% capacity retention after 500 cycles at 1 C current density. These studies provide some ideas to enhance the performance of silicon-based materials.

Controlled Growth Lateral/Vertical Heterostructure Interface for Lithium Storage

Artificial heterostructures with structural advancements and customizable electronic interfaces are fundamental for achieving high-performance lithium-ion batteries (LIBs). Here, a design idea for a covalently bonded lateral/vertical black phosphorus (BP)-graphdiyne oxide (GDYO) heterostructure achieved through a facile ball-milling approach, is designed. Lateral heterogeneity is realized by the sp2-hybridized mode P-C bonds, which connect the phosphorus atoms at the edges of BP with the carbon atoms of the terminal acetylene in GDYO. The vertical connection of the heterojunction of BP and GDYO is connected by P-O-C bond. Experimental and theoretical studies demonstrate that BP-GDYO incorporates interfacial and structural engineering features, including built-in electric fields, chemical bond interactions, and maximized nanospace confinement effects. Therefore, BP-GDYO exhibits improved electrochemical kinetics and enhanced structural stability. Moreover, through ex- and in-situ studies, the lithiation mechanism of BP-GDYO, highlighting that the introduction of GDYO inhibits the shuttle/dissolution effect of phosphorus intermediates, hinders volume expansion, provides more reactive sites, and ultimately promotes reversible lithium storage, is clarified. The BP-GDYO anode exhibits lithium storage performance with high-rate capacity and long-cycle stability (602.6 mAh g-1 after 1 000 cycles at 2.0 A g-1). The proposed interfacial and structural engineering is universal and represents a conceptual advance in building high-performance LIBs electrode.

Solution-Based Deep Prelithiation for Lithium-Ion Capacitors with High Energy Density

Lithium-ion capacitors (LICs) exhibit superior power density and cyclability compared to lithium-ion batteries. However, the low initial Coulombic efficiency (ICE) of amorphous carbon anodes (e.g., hard carbon (HC) and soft carbon (SC)) limits the energy density of LICs by underutilizing cathode capacity. Here, a solution-based deep prelithiation strategy for carbon anodes is applied using a contact-ion pair dominant solution, offering high energy density based on a systematic electrode balancing based on the cathode capacity increased beyond the original theoretical limit. Increasing the anode ICE to 150% over 100%, the activated carbon (AC) capacity is doubled by activating Li+ cation storage, which unleashes rocking-chair LIC operation alongside the dual-ion-storage mechanism. The increased AC capacity results in an energy density of 106.6 Wh kg-1 AC+SC, equivalent to 281% of that of LICs without prelithiation. Moreover, this process lowers the cathode-anode mass ratio, reducing the cell thickness by 67% without compromising the cell capacity. This solution-based deep chemical prelithiation promises high-energy LICs based on transition metal-free, earth-abundant active materials to meet the practical demands of power-intensive applications.

Advancing Li-ion capacitors through dual wet chemical prelithiation

Lithium-ion batteries (LIBs) and electrical double-layer capacitors (EDLCs) are widely used in commercial energy storage systems, but each has inherent limitations. To overcome these limitations, the lithium-ion capacitor (LIC) has emerged as a hybrid energy storage device, combining the benefits of LIBs and EDLCs. However, the introduction of active lithium into LICs poses challenges due to lithium's reactivity and instability. In this study, we propose a dual wet chemical prelithiation strategy to enhance LIC performance. By wet chemically prelithiating both the activated carbon cathodes and hard carbon anodes, significant improvements are achieved compared to traditional prelithiation methods. The dual prelithiation approach outperforms electrochemical prelithiation in terms of energy storage performance, cycle life, and process simplification. LICs with dual wet chemically prelithiated electrodes demonstrate the highest energy density and retain a substantial portion of reversible capacity even at high discharge rates. The strategy exhibits fast kinetics and wide operational stability. In contrast, LICs with metallic lithium anodes or electrochemically prelithiated hard carbon anodes exhibit inferior performance and limited cycle life. The dual wet chemical prelithiation strategy represents a breakthrough in LIC technology, offering superior performance, cycle stability, and scalability. It holds promise for alkali-ion energy storage systems and drives advancements in electrochemical energy storage technology.

Lithiophilic Chemistry Facilitated Ultrathin Lithium for Scalable Prelithiation

Prelithiation plays a crucial role in advancing the development of high-energy-density batteries, and ultrathin lithium (UTL) has been proven to be a promising anode prelithiation reagent. However, there remains a need to explore an adjustable, efficient, and cost-effective method for manufacturing UTL. In this study, we introduce a method for producing UTL with adjustable thicknesses ranging from 1.5 to 10 μm through blade coating of molten lithium on poly(vinylidene fluoride)-modified copper current collectors. By employing the transfer-printing method, prelithiated graphite and Si-C composite electrodes are prepared, which exhibit significantly improved initial Coulombic efficiencies of 99.60% and 99.32% in half-cells, respectively. Moreover, the energy densities of Li(NiCoMn)1/3O2 and LiFePO4 full cells assembled with the prelithiated graphite electrodes increase by 13.1% and 23.6%, respectively.

Critical Review of Emerging Pre-metallization Technologies for Rechargeable Metal-Ion Batteries

Low Coulombic efficiency, low-capacity retention, and short cycle life are the primary challenges faced by various metal-ion batteries due to the loss of corresponding active metal. Practically, these issues can be significantly ameliorated by compensating for the loss of active metals using pre-metallization techniques. Herein, the state-of-the-art development in various pr-emetallization techniques is summarized. First, the origin of pre-metallization is elaborated and the Coulombic efficiency of different battery materials is compared. Second, different pre-metallization strategies, including direct physical contact, chemical strategies, electrochemical method, overmetallized approach, and the use of electrode additives are summarized. Third, the impact of pre-metallization on batteries, along with its role in improving Coulombic efficiency is discussed. Fourth, the various characterization techniques required for mechanistic studies in this field are outlined, from laboratory-level experiments to large scientific device. Finally, the current challenges and future opportunities of pre-metallization technology in improving Coulombic efficiency and cycle stability for various metal-ion batteries are discussed. In particular, the positive influence of pre-metallization reagents is emphasized in the anode-free battery systems. It is envisioned that this review will inspire the development of high-performance energy storage systems via the effective pre-metallization technologies.

Interphase Engineering Enhanced Electro-chemical Stability of Prelithiated Anode

Prelithiation is an essential technology to compensate for the initial lithium loss of lithium-ion batteries due to the formation of solid electrolyte interphase (SEI) and irreversible structure change. However, the prelithiated materials/electrodes become more reactive with air and electrolyte resulting in unwanted side reactions and contaminations, which makes it difficult for the practical application of prelithiation technology. To address this problem, herein, interphase engineering through a simple solution treatment after chemical prelithiation is proposed to protect the prelithiated electrode. The used solutions are carefully selected, and the composition and nanostructure of the as-formed artificial SEIs are revealed by cryogenic electron microscopy and X-ray photoelectron spectroscopy. The electrochemical evaluation demonstrates the unique merits of this artificial SEI, especially for the fluorinated interphase, which not only enhances the interfacial ion transport but also increases the tolerance of the prelithiated electrode to the air. The treated graphite electrode shows an initial Coulombic efficiency of 129.4%, a high capacity of 170 mAh g-1 at 3 C, and negligible capacity decay after 200 cycles at 1 C. These findings not only provide a facile, universal, and controllable method to construct an artificial SEI but also enlighten the upgrade of battery fabrication and the alternative use of advanced electrolytes.

Electrolyte-assisted low-voltage decomposition of Li2C2O4 for efficient cathode pre-lithiation in lithium-ion batteries

Lithium oxalate (Li2C2O4) is an attractive cathode pre-lithiation additive for lithium-ion batteries (LIBs), but its application is hindered by its high decomposition potential (>4.7 V). Due to the liquid-solid synergistic effect of the NaNO2 additive and the LiNi0.83Co0.07Mn0.1O2 (NCM) cathode material, the decomposition efficiency of micro-Li2C2O4 reaches 100% at a low charge cutoff voltage of 4.3 V. Our work boosts the widespread practical application of Li2C2O4 by a simple and promising electrolyte-assisted cathode pre-lithiation strategy.

In Situ Prelithiation by Direct Integration of Lithium Mesh into Battery Cells

Silicon (Si)-based anodes are promising for next-generation lithium (Li)-ion batteries due to their high theoretical capacity (∼3600 mAh/g). However, they suffer quantities of capacity loss in the first cycle from initial solid electrolyte interphase (SEI) formation. Here, we present an in situ prelithiation method to directly integrate a Li metal mesh into the cell assembly. A series of Li meshes are designed as prelithiation reagents, which are applied to the Si anode in battery fabrication and spontaneously prelithiate Si with electrolyte addition. Various porosities of Li meshes tune prelithiation amounts to control the degree of prelithiation precisely. Besides, the patterned mesh design enhances the uniformity of prelithiation. With an optimized prelithiation amount, the in situ prelithiated Si-based full cell shows a constant >30% capacity improvement in 150 cycles. This work presents a facile prelithiation approach to improve battery performance.

Prelithiation of Lithium Peroxide for Silicon Anode: Achieving a High Activation Rate

The use of lithium peroxide (Li₂O₂) as a cost-effective low-weight prelithiation cathode additive was successfully demonstrated. Through a series of studies on the chemical stability of Li₂O₂ and the activation process of Li₂O₂ on the cathode, we revealed that Li₂O₂ is more compatible with conventional electrolyte and cathode laminate slurry than lithium oxide. Due to the significantly smaller size of commercial Li₂O₂, it can be used directly as a cathode additive. Moreover, the activation of Li₂O₂ on the cathode leads to the impedance growth of the cathode possibly resulting from the release of dioxygen and evacuation of Li₂O₂ inside the cathode. With the introduction of a new Li₂O₂ spread-coating technique on the cathode, the capacity loss was suppressed. Si||NMC full cells using Li₂O₂ spread-coated cathode demonstrated a highly promising activation rate of Li₂O₂ and significantly enhanced specific capacity and cycling stability compared to the uncoated full cells.

In Situ Mesopore Formation in SiOx Nanoparticles by Chemically Reinforced Heterointerface and Use of Chemical Prelithiation for Highly Reversible Lithium-Ion Battery Anode

SiO_x is a promising next-generation anode material for lithium-ion batteries. However, its commercial adoption faces challenges such as low electrical conductivity, large volume expansion during cycling, and low initial Coulombic efficiency. Herein, to overcome these limitations, an eco-friendly in situ methodology for synthesizing carbon-containing mesoporous SiO_x nanoparticles wrapped in another carbon layers is developed. The chemical reactions of vinyl-terminated silanes are designed to be confined inside the cationic surfactant-derived emulsion droplets. The polyvinylpyrrolidone-based chemical functionalization of organically modified SiO₂ nanoparticles leads to excellent dispersion stability and allows for intact hybridization with graphene oxide sheets. The formation of a chemically reinforced heterointerface enables the spontaneous generation of mesopores inside the thermally reduced SiO_x nanoparticles. The resulting mesoporous SiO_x -based nanocomposite anodes exhibit superior cycling stability (≈100% after 500 cycles at 0.5 A g^-1 ) and rate capability (554 mAh g^-1 at 2 A g^-1 ), elucidating characteristic synergetic effects in mesoporous SiO_x -based nanocomposite anodes. The practical commercialization potential with a significant enhancement in initial Coulombic efficiency through a chemical prelithiation reaction is also presented. The full cell employing the prelithiated anode demonstrated more than 2 times higher Coulombic efficiency and discharge capacity compared to the full cell with a pristine anode.

Local Electric Field Promoted Kinetics and Interfacial Stability of a Phosphorus Anode with Ionic Covalent Organic Frameworks

A phosphorus anode is a promising option for energy-storage applications because of its high theoretical specific capacity and safe lithiation potential. However, the multiphase phosphorus lithiation/delithiation reactions and soluble reaction intermediates cause sluggish reaction kinetics and loss of active materials. Herein, a novel local electric field (LEF) strategy is proposed to inhibit the intermediates dissolution and promote the reaction kinetics by optimizing ionic covalent organic frameworks (iCOFs). Among them, the LEF induced by the cationic covalent organic framework effectively enhances the electrochemical performance of the phosphorus anode. The strong electrostatic interaction between the polyphosphides and cationic covalent organic framework confines the dissolution of active materials and tailors the electronic structure of polyphosphides to accelerate the reaction kinetics. The cationic covalent-organic-framework-assisted phosphorus anode provides a high capacity of 1227.8 mAh g^-1 at 10.4 A g^-1 (8.6 C) and a high-capacity retention of 87% after 500 cycles at 1.3 A g^-1 . This work not only broadens the application of iCOFs for phosphorus anode but also inspires the great potential of the local electric field in battery technology.

Prelithiation Bridges the Gap for Developing Next-Generation Lithium-Ion Batteries/Capacitors

The ever-growing market of portable electronics and electric vehicles has spurred extensive research for advanced lithium-ion batteries (LIBs) with high energy density. High-capacity alloy- and conversion-type anodes are explored to replace the conventional graphite anode. However, one common issue plaguing these anodes is the large initial capacity loss caused by the solid electrolyte interface formation and other irreversible parasitic reactions, which decrease the total energy density and prevent further market integration. Prelithiation becomes indispensable to compensate for the initial capacity loss, enhance the full cell cycling performance, and bridge the gap between laboratory studies and the practical requirements of advanced LIBs. This review summarizes the various emerging anode and cathode prelithiation techniques, the key barriers, and the corresponding strategies for manufacturing-compatible and scalable prelithiation. Furthermore, prelithiation as the primary Li⁺ donor enables the safe assembly of new-configured "beyond LIBs" (e.g., Li-ion/S and Li-ion/O₂ batteries) and high power-density Li-ion capacitors (LICs). The related progress is also summarized. Finally, perspectives are suggested on the future trend of prelithiation techniques to propel the commercialization of advanced LIBs/LICs.

Prelithiation Reagents and Strategies on High Energy Lithium-Ion Batteries

Lithium-ion batteries (LIBs) have been widely employed in energy-storage applications owing to the relatively higher energy density and longer cycling life. However, they still need further improvement especially on the energy density to satisfy the increasing demands on the market. In this respect, the irreversible capacity loss (ICL) in the initial cycle is a critical challenge due to the lithium loss during the formation of solid electrolyte interphase (SEI) layer on the anode surface. The strategy of prelithiation was then proposed to compensate for the ICL in the anode and recover the energy density. Here, various methods of the prelithiation are summarized and classified according to the basic working mechanism. Further, considering the critical importance and promising progress of prelithiation in both fundamental research and real applications, this Review article is intended to discuss the considerations involved in the selection of prelithiation reagents/strategies and the electrochemical performance in full-cells. Moreover, insights are provided regarding the practical application prospects and the challenges that still need to be addressed.

Unblocked Electron Channels Enable Efficient Contact Prelithiation for Lithium-Ion Batteries

Contact prelithiation is strongly considered for compensating the initial capacity loss of lithium-ion batteries, exhibiting great potential for ultralong cycle life of working batteries and the application of large-scale energy-storage systems. However, the utilization of the sacrificial Li source for contact prelithiation is low (<65%). Herein the fundamental mechanism of contact prelithiation is described from the perspective of the Li source/anode interfaces by regulating the initial contact state, and a clear illustration of the pathogeny for capacity attenuation is successfully delivered. Specifically, creating plentiful electron channels is an access to making contact prelithiation with a higher Li utilization, as the mitigated local current density that reduces the etching of Li dissolution and SEI extension on electron channels. A vacuum thermal evaporation for depositing the Li film enables the contact interface to possess an adequate electron channel construction, rendering a Li utilization of 91.0%, and the dead Li yield is significantly reduced in a working battery.

Cryogenic Mechanical Prelithiation Reduces Porosity and Improves Battery Performance of an Alloy Foil Anode

Anode prelithiation could dramatically improve the initial Coulombic efficiency and battery life. Roll-to-roll mechanical prelithiation (MP) is an attractive option for achieving prelithiation in minutes. While our previous work on metallic-foil prelithiation revealed that an external pressure is necessary to achieve MP in a timely fashion, too high an applied pressure will cause severe damages in the form of porosity and cracking. Thus, gentler MP under smaller pressure, and surprisingly, cryogenic temperatures, while prepositioning prolific grain boundaries as lithium diffusion paths is critical. To this end, first, we developed an accumulative roll bonding (ARB) method to refine the grain size of Sn-5Sb foil for denser grain boundaries. After ARB of 12 cycles (ARB-12), the grain size of Sn-5Sb foil decreased from 20-50 to 0.5-1.5 μm. Then, MP was performed under a mild condition of 0.5 MPa and -20 °C. Thereby, the porosity of prelithiated ARB-12 was reduced to 1.8% from thickness measurement, significantly minimizing the prelithiation damage. As a result, due to grain refinement, we achieved lower interface impedance and better rate performance. The ARB-12 Sn-5Sb foil with a proper prelithiation design exhibited 180 and 110 stable cycles when pairing with commercial LFP and NCM811 cathodes. Furthermore, it also depletes less electrolyte and keeps higher capacity retention under -10 °C than that of the graphite anode.

A Review on Recent Advances for Boosting Initial Coulombic Efficiency of Silicon Anodic Lithium Ion batteries

Rechargeable silicon anode lithium ion batteries (SLIBs) have attracted tremendous attention because of their merits, including a high theoretical capacity, low working potential, and abundant natural sources. The past decade has witnessed significant developments in terms of extending the lifespan and maintaining high capacities of SLIBs. However, the detrimental issue of low initial Coulombic efficiency (ICE) toward SLIBs is causing more and more attention in recent years because ICE value is a core index in full battery design that profoundly determines the utilization of active materials and the weight of an assembled battery. Herein, a comprehensive review is presented of recent advances in solutions for improving ICE of SLIBs. From design perspectives, the strategies for boosting ICE of silicon anodes are systematically categorized into several aspects covering structure regulation, prelithiation, interfacial design, binder design, and electrolyte additives. The merits and challenges of various approaches are highlighted and discussed in detail, which provides valuable insights into the rational design and development of state-of-the-art techniques to deal with the deteriorative issue of low ICE of SLIBs. Furthermore, conclusions and future promising research prospects for lifting ICE of SLIBs are proposed at the end of the review.

Preparation and controllable prelithiation of core–shell SnOx@C composites for high-performance lithium-ion batteries

The carbon coated SnOx with adjustable composition and coating thickness was firstly prepared. The initial coulombic efficiency and cycle stability were improved by chemical prelithiation and the full-cell showed better cycling and rate performance.

Understanding of the Mechanism Enables Controllable Chemical Prelithiation of Anode Materials for Lithium-Ion Batteries

By compensating the irreversible loss of lithium ions during the first cycle, prelithiations can solve the issue of insufficient initial Coulombic efficiency for various anodes. Recently, the chemical prelithiation using organolithium compounds has attracted increasing attention because of its uniform and fast reaction, safety, and easily adjustable degree of prelithiation. However, the nature and activity of organolithium involved in chemical prelithiations have not been deeply explored yet. Here, by monitoring the electrical conductivity change in the lithiation solution in the duration of its formation, we have demonstrated the essential role of lithium radical anions for chemical prelithiation and compared the prelithiation activity of dissociated species and aggregates of lithium radical anions. The mechanistic understanding of the nature of the lithiation solution leads to controllable chemical prelithiation, as demonstrated in full cells of prelithiated hard carbon and LiFePO₄.

Weakly Solvating Solution Enables Chemical Prelithiation of Graphite-SiOx Anodes for High-Energy Li-Ion Batteries

Although often overlooked in anode research, the anode's initial Coulombic efficiency (ICE) is a crucial factor dictating the energy density of a practical Li-ion battery. For next-generation anodes, a blend of graphite and Si/SiO_x represents the most practical way to balance capacity and cycle life, but its low ICE limits its commercial viability. Here, we develop a chemical prelithiation method to maximize the ICE of the blend anodes using a reductive Li-arene complex solution of regulated solvation power, which enables a full cell to exhibit a near-ideal energy density. To prevent structural degradation of the blend during prelithiation, we investigate a solvation rule to direct the Li⁺ intercalation mechanism. Combined spectroscopy and density functional theory calculations reveal that in weakly solvating solutions, where the Li⁺-anion interaction is enhanced, free solvated-ion formation is inhibited during Li⁺ desolvation, thereby mitigating solvated-ion intercalation into graphite and allowing stable prelithiation of the blend. Given the ideal ICE of the prelithiated blend anode, a full cell exhibits an energy density of 506 Wh kg^-1 (98.6% of the ideal value), with a capacity retention after 250 cycles of 87.3%. This work highlights the promise of adopting chemical prelithiation for high-capacity anodes to achieve practical high-energy batteries.

Pre-Lithiation Strategies for Next-Generation Practical Lithium-Ion Batteries

Next-generation Li-ion batteries (LIBs) with higher energy density adopt some novel anode materials, which generally have the potential to exhibit higher capacity, superior rate performance as well as better cycling durability than conventional graphite anode, while on the other hand always suffer from larger active lithium loss (ALL) in the first several cycles. During the last two decades, various pre-lithiation strategies are developed to mitigate the initial ALL by presetting the extra Li sources to effectively improve the first Coulombic efficiency and thus achieve higher energy density as well as better cyclability. In this progress report, the origin of the huge initial ALL of the anode and its effect on the performance of full cells are first illustrated in theory. Then, various pre-lithiation strategies to resolve these issues are summarized, classified, and compared in detail. Moreover, the research progress of pre-lithiation strategies for the representative electrochemical systems are carefully reviewed. Finally, the current challenges and future perspectives are particularly analyzed and outlooked. This progress report aims to bring up new insights to reassess the significance of pre-lithiation strategies and offer a guideline for the research directions tailored for different applications based on the proposed pre-lithiation strategies summaries and comparisons.

Recent Advances in Silicon-Based Electrodes: From Fundamental Research toward Practical Applications

The increasing demand for higher-energy-density batteries driven by advancements in electric vehicles, hybrid electric vehicles, and portable electronic devices necessitates the development of alternative anode materials with a specific capacity beyond that of traditional graphite anodes. Here, the state-of-the-art developments made in the rational design of Si-based electrodes and their progression toward practical application are presented. First, a comprehensive overview of fundamental electrochemistry and selected critical challenges is given, including their large volume expansion, unstable solid electrolyte interface (SEI) growth, low initial Coulombic efficiency, low areal capacity, and safety issues. Second, the principles of potential solutions including nanoarchitectured construction, surface/interface engineering, novel binder and electrolyte design, and designing the whole electrode for stability are discussed in detail. Third, applications for Si-based anodes beyond LIBs are highlighted, specifically noting their promise in configurations of Li-S batteries and all-solid-state batteries. Fourth, the electrochemical reaction process, structural evolution, and degradation mechanisms are systematically investigated by advanced in situ and operando characterizations. Finally, the future trends and perspectives with an emphasis on commercialization of Si-based electrodes are provided. Si-based anode materials will be key in helping keep up with the demands for higher energy density in the coming decades.

Prelithiation: A Crucial Strategy for Boosting the Practical Application of Next-Generation Lithium Ion Battery

With the urgent market demand for high-energy-density batteries, the alloy-type or conversion-type anodes with high specific capacity have gained increasing attention to replace current low-specific-capacity graphite-based anodes. However, alloy-type and conversion-type anodes have large initial irreversible capacity compared with graphite-based anodes, which consume most of the Li⁺ in the corresponding cathode and severely reduces the energy density of full cells. Therefore, for the practical application of these high-capacity anodes, it is urgent to develop a commercially available prelithiation technique to compensate for their large initial irreversible capacity. At present, various prelithiation methods for compensating the initial irreversible capacity of the anode have been reported, but due to their respective shortcomings, large-scale commercial applications have not yet been achieved. In this review, we have systematically summarized and analyzed the advantages and challenges of various prelithiation methods, providing enlightenment for the further development of each prelithiation strategy toward commercialization and thus facilitating the practical application of high-specific-capacity anodes in the next-generation high-energy-density lithium-ion batteries.

Enabling SiOx/C Anode with High Initial Coulombic Efficiency through a Chemical Pre-Lithiation Strategy for High-Energy-Density Lithium-Ion Batteries

Carbon-coated SiO_x microparticles (SiO_x/C) demonstrate attractive potential for anode use in high-energy-density lithium-ion batteries due to high capacity and proper cycling stability. However, the excessive irreversible consumption of Li ions during the initial cycling remains a serious challenge arising from the limited lithium in full cells. Here, we endow SiO_x/C anode with high initial Coulombic efficiency using the chemical pre-lithiation strategy. The lithium silicate is uniformly pregenerated in SiO_x/C microparticles, which could effectively counteract the irreversible consumption of Li ions and avoid the complicated pre-lithiation process. Moreover, this strategy guarantees the structural integrity and processability of anode materials because of the homogeneous Li-organic complex solution pre-lithiation and high-temperature calcination process. The obtained SiO_x/C microparticles can be applied as anode materials by directly mixing with commercial graphite, which demonstrates proper specific capacity, high initial Coulombic efficiency, and excellent cycling performance. Furthermore, the pouch cells using LiNi_0.8Co_0.1Mn_0.1O₂ cathodes and the as-prepared anodes exhibit high energy density (301 Wh kg^-1) and satisfactory cycling stability (93.3% capacity retention after 100 cycles).

Controlled Prelithiation of SnO2/C Nanocomposite Anodes for Building Full Lithium-Ion Batteries

SnO₂ is an attractive anodic material for advanced lithium-ion batteries (LIBs). However, its low electronic conductivity and large volume change in lithiation/delithiation lead to a poor rate/cycling performance. Moreover, the initial Coulombic efficiencies (CEs) of SnO₂ anodes are usually too low to build practical full LIBs. Herein, a two-step hydrothermal synthesis and pyrolysis method is used to prepare a SnO₂/C nanocomposite, in which aggregated SnO₂ nanosheets and a carbon network are well-interpenetrated with each other. The SnO₂/C nanocomposite exhibits a good rate/cycling performance in half-cell tests but still shows a low initial CE of 45%. To overcome this shortage and realize its application in a full-cell assembly, the SnO₂/C anode is controllably prelithiated by the lithium-biphenyl reagent and then coupled with a LiCoO₂ cathode. The resulting full LIB displays a high capacity of over 98 mAh g^-1_LCO in 300 cycles at 1 C rate.

Fast and Controllable Prelithiation of Hard Carbon Anodes for Lithium-Ion Batteries

Hard carbon has been extensively investigated as anode materials for high-energy lithium-ion batteries owing to its high capacity, long cycle life, good rate capability, and low cost of production. However, it suffers from a large irreversible capacity and thus low initial coulombic efficiency (ICE), which hinders its commercial use. Here, we developed a fast and controllable prelithiation method based on a chemical reaction using a lithium-containing reagent (1 M lithium biphenylide dissolved in tetrahydrofuran). The prelithiation extent can be easily controlled by tuning the reaction time. An SEI layer is formed during chemical prelithiation, and the ICE of prelithiated hard carbon in half-cell format can be increased to ∼106% in 30 s. When matched with a LiNi_1/3Co_1/3Mn_1/3O₂ cathode, the full cell with the prelithiated hard carbon anode exhibits a much improved ICE (90.2 vs 75%) and cycling performance than those of the pristine full cell. This facile prelithiation method is proved to be a practical solution for the commercial application of hard carbon materials.

Chemically Prelithiated Hard-Carbon Anode for High Power and High Capacity Li-Ion Batteries

Hard carbons (HC) have potential high capacities and power capability, prospectively serving as an alternative anode material for Li-ion batteries (LIB). However, their low initial coulombic efficiency (ICE) and the resulting poor cyclability hinder their practical applications. Herein, a facile and effective approach is developed to prelithiate hard carbons by a spontaneous chemical reaction with lithium naphthalenide (Li-Naph). Due to the mild reactivity and strong lithiation ability of Li-Naph, HC anode can be prelithiated rapidly in a few minutes and controllably to a desirable level by tuning the reaction time. The as-formed prelithiated hard carbon (pHC) has a thinner, denser, and more robust solid electrolyte interface layer consisting of uniformly distributed LiF, thus demonstrating a very high ICE, high power, and stable cyclability. When paired with the current commercial LiCoO₂ and LiFePO₄ cathodes, the assembled pHC/LiCoO₂ and pHC/LiFePO₄ full cells exhibit a high ICE of >95.0% and a nearly 100% utilization of electrode-active materials, confirming a practical application of pHC for a new generation of high capacity and high power LIBs.

A new high-capacity and safe energy storage system: lithium-ion sulfur batteries

Lithium-ion sulfur batteries as a new energy storage system with high capacity and enhanced safety have been emphasized, and their development has been summarized in this review. The lithium-ion sulfur battery applies elemental sulfur or lithium sulfide as the cathode and lithium-metal-free materials as the anode, which can be divided into two main types. One is anode-type, where elemental sulfur is applied as the cathode, and the anode provides lithium ions. The other one is cathode-type, where lithium sulfide as the cathode provides lithium ions, and lithium-metal-free materials (e.g., graphite, silicon/carbon) function as the anode. Recently, some new lithium-ion sulfur battery systems have also been proposed, and are discussed in this review as well. The lithium-ion sulfur batteries not only maintain the advantage of high energy density because of the high capacities of sulfur and lithium sulfide, but also exhibit the improved safety of the batteries due to a non-lithium-metal in the anode. This review paper aims to track the recent progress in the development of lithium-ion sulfur batteries and summarize the challenges and the approaches for improving their electrochemical performances, including the lithiation methods to prepare lithium-metal-free anodes in anode-type lithium-ion sulfur batteries and the lithium sulfide cathode modification approaches in cathode-type lithium-ion sulfur batteries. Furthermore, the challenges and perspectives for future research and commercial applications have also been enumerated.

High-Performance Lithiated SiOx Anode Obtained by a Controllable and Efficient Prelithiation Strategy

Silicon-based electrodes are promising and appealing for futuristic Li-ion batteries because of their high theoretical specific capacity. However, massive volume change of silicon upon lithiation and delithiation, accompanied by continual formation and destruction of the solid-electrolyte interface (SEI), leads to low Coulombic efficiency. Prelithiation of Si-based anode is regarded as an effective way for compensating for the loss of Li⁺ in the first discharging process. Here, a high-performance lithiated SiO_x anode was prepared by using a controllable, efficient, and novel prelithiation strategy. The lithiation of SiO_x is homogeneous and efficient in bulk due to well-improved Li⁺ diffusion in SiO_x. Moreover, the in situ formed SEI during the process of prelithiation reduces the irreversible capacity loss in the first cycle and thus improves the initial Coulombic efficiency (ICE). Half-cells and full cells based on the as-prepared lithiated SiO_x anode prominently increase the ICE from 79 to 89% and 68 to 87%, respectively. It is worth mentioning that the homogeneously lithiated SiO_x anode achieves stable 200 cycles in NCM622//SiO_x coin full cells. These exciting results provide applicable prospects of lithiated SiO_x anode in the next-generation high-energy-density Li-ion batteries.