Bridging silicon materials and electrode engineering for high energy density lithium ion battery anodes

1 Introduction

The global transition toward electric vehicles (EVs) and the growing need for energy storage systems for data and AI centers have intensified the demand for rechargeable batteries with substantially higher energy density, high power capability, and fast-charging performance (Hong et al., 2024). While graphite has been the dominant anode material in commercial lithium-ion batteries (LIBs), its low theoretical specific capacity of 372 mAh g^-1 poses a fundamental limitation to further improvements in battery performance (Dong et al., 2025). Silicon (Si) has attracted considerable attention as a promising alternative because of its exceptionally high theoretical capacity of over 3,600 mAh g^-1 at room temperature (Su et al., 2014). However, the commercial implementation of Si anodes remains challenging because of several intrinsic drawbacks. In particular, the severe volume expansion of silicon during lithiation, up to 300%, results in particle pulverization, electrical isolation, and continuous rupture and reformation of the solid electrolyte interphase (SEI), which ultimately lead to rapid capacity decay and cell failure (Figure 1) (Choi and Aurbach, 2016).

Over the past decade, remarkable progress has been made at the material level through nanostructuring (Sung et al., 2021), alloying (Ruttert et al., 2020), and the development of composite materials such as SiOx and silicon-carbon composites (Son et al., 2015) to mitigate severe degradation. However, the transition from tightly controlled model electrodes with extremely low loading, often based on simplified systems in which Si is the sole active material, to high-loading, commercially relevant batteries continues to expose a persistent gap between laboratory-scale material successes and the practical requirements of electrode engineering. Addressing the barriers to the commercial implementation of silicon anodes requires a paradigm shift from purely material-centric design to an integrated strategy that simultaneously optimizes the active material, inactive components such as binders, conductive agents, functional additives, and surface interlayers, as well as the overall electrode architecture. This Perspective highlights the critical synergy between silicon material design and holistic electrode engineering, with a particular focus on our group’s recent contributions, to realize stable, high-energy-density Si anodes under practical operating conditions.

2 Advanced silicon materials design

To harness the capacity of silicon while suppressing its severe mechanical degradation, structural engineering of the active material has been a foundational strategy. Current interventions focus on buffering volume expansion and maintaining distinct microscopic electrical contacts. In this regard, carbon-based materials are particularly attractive because their high electrical conductivity and mechanical ductility can effectively compensate for the intrinsic limitations of silicon. Over the past decade, the field has witnessed notable contributions from multiple leading groups. Cui and coworkers demonstrated that well-ordered graphene coatings on Si particles-engineered via thermal oxidation followed by CVD-preserve structural integrity far more effectively than disordered carbon coatings (Kim et al., 2022). Furthermore, Cho’s group has continuously advanced scalable implementations; for instance, they engineered sub-nanometer silicon anodes (<1 nm) via a crystal growth inhibition mechanism, successfully demonstrating extreme particle size reduction and structural stability in practical prototype battery packs (Sung et al., 2021).

In our recent studies have demonstrated that robust nano-carbon platforms, such as graphene nanoribbon-based conductive networks, can simultaneously enhance microstructural homogeneity and mechanical robustness in silicon-carbon composite anodes (Kim et al., 2025). Likewise, the incorporation of 2D structured graphite into Si-based composites provides a resilient structural framework that accommodates the anisotropic swelling of silicon domains while maintaining inter-particle connectivity (Figure 2a) (Kim et al., 2024).

Metal oxide-based materials also represent promising coating candidates for silicon because of their excellent structural and electrochemical stability. In particular, advanced coating materials such as mixed-valence titanium oxide/oxynitride composites (TiO_2-x/TiO_1-yN_y) offer high ionic and electronic conductivity while mechanically protecting active silicon during repeated deep cycling (Figure 2b) (Wang et al., 2022; Wang et al., 2023).

While nanostructured Si materials have shown remarkable lab-scale cycling stability, a critical assessment reveals that most demonstrations rely on low areal loadings (<1 mAh/cm²) and flooded electrolyte conditions that do not reflect practical cell constraints. Furthermore, the scalability and cost-effectiveness of many nanostructuring approaches-such as the templated synthesis of porous Si or chemical vapor deposition of conformal carbon coatings-remain significant barriers to commercialization. This discrepancy between laboratory performance and industrial feasibility underscores the necessity of our co-design philosophy, which prioritizes bridging material innovations with scalable electrode engineering from the outset.

3 Electrode architecture and engineering

Although advanced silicon material designs provide the foundation for improved anode performance, their advantages cannot be sustained in practical cells without deliberate engineering of the electrode architecture. Realizing stable, high-energy-density silicon anodes therefore requires holistic optimization of the electrode matrix, including binders, conductive agents, interfacial chemistry, and processing methods, which collectively determine mechanical robustness, charge-transport continuity, and electrochemical stability.

3.1 Functional conductive networks and binders

In high-capacity Si anodes, particularly in thick and high-density electrode configurations, conductive agents are required not only to maintain electronic conduction pathways, but also to serve additional functions that support stable electrode operation. For instance, polyanion-assisted ionic-electronic conductive agents developed for high-density Si-based anodes can preserve electrical percolation pathways even under severe electrode breathing. They also facilitate electrolyte penetration throughout the electrode, thereby alleviating internal resistance and improving overall electrochemical performance (Kwon et al., 2022).

Accordingly, the role of the binder has evolved from a passive adhesive to an active structural component. In Si anodes, binders must now accommodate significant mechanical stress and preserve electrode integrity throughout repetitive volume fluctuations. To address the electrode cracking induced by these volume changes, various systems - such as pulley and self-healing binders - have been introduced (Wang et al., 2013; Choi et al., 2017). Extending this trajectory, we propose multifunctional network binders featuring mechanically robust crosslinked frameworks, which substantially enhance the structural stability of Si anodes (Figure 3A) (Park et al., 2023). This design concept becomes even more critical in all-solid-state batteries, where interfacially reinforced crosslinked binders can alleviate severe contact-loss issues at solid-solid interfaces (Lee C. et al., 2026).

3.2 Dry electrode processing and electrolyte additives

Because silicon anodes are typically commercialized in blended configurations with graphite, the implementation of thick-film electrodes is essential for maximizing their practical capacity and energy density (Sim et al., 2023). In this context, dry electrode processing has emerged as a promising manufacturing technology because it mitigates solvent-induced binder migration, one of the major bottlenecks of conventional wet-based processing for high-loading anodes. However, dry-processed anodes also present unique interfacial challenges, particularly those associated with binder decomposition (Han et al., 2024; Choi et al., 2025). Electrolyte additives, which have played a critical role in improving the cycling stability of conventional Si anodes (Choi et al., 2006; Etacheri et al., 2012), also provide an effective solution in dry-processed systems. In particular, tailored electrolyte additive designs are vital for suppressing initial irreversibility in dry-processed electrode matrices, thereby significantly enhancing electrochemical stability in full-cell configurations (Figure 3b) (Han et al., 2025). These benefits are not limited to dry-processed systems, as electrolyte additives remain equally important in conventional Si anodes. For example, chemical modifiers such as carboxy silanes can direct robust SEI formation and ensure stable operation even under high areal capacity (3.5 mAh cm^-2) condition (Lim et al., 2024).

3.3 Pre-lithiation strategies

Moreover, overcoming the inherently low initial Coulombic efficiency (ICE) of Si anodes, which largely originates from extensive SEI formation, requires electrode-level pre-lithiation engineering. Our earlier work showed that the incorporation of silicon-stabilized lithium metal powder (SLMP) composites enables controlled in situ prelithiation (Jang et al., 2023). More recently, we extended this concept to scalable fully dry manufacturing. To address the limitations of conventional dry-processed thick anodes, our group developed a lithium-metal-underlayer-based Li/Cu prelithiation strategy. In this simple one-step dry process, the lithium underlayer compensates for initial lithium loss in thick-film anodes while promoting the bottom-up formation of a uniform F-rich SEI (Figure 3c) (Lee H. -W. et al., 2026).

4 Bridging the gap: Co-design strategies for overcoming practical limitations

The gap between localized material design and macroscopic electrode fabrication continues to hinder the practical implementation of Si anodes. Addressing these life-cycle limitations requires a co-design strategy that integrates active materials, inactive electrode components, and interfacial chemistry.

In this context, co-design has been pursued through matrix engineering and surface/interfacial stabilization. Mechanochemically activated additives strengthen interactions within Si/C composite electrodes, enabling uniform dispersion, a robust matrix that tolerates severe volumetric stress, and improved SEI stability during cycling (Lee D. et al., 2025). Building on this concept, interface-stabilizing anion-anchoring additives (ISAA) were developed to address non-uniform Li⁺ flux and localized overpotentials arising from tortuous Li⁺ transport pathways (Kim et al., 2026). Through sulfonate-driven electrostatic stabilization and interfacial anion anchoring, ISAA creates a Li⁺-enriched interfacial environment that homogenizes Li⁺ flux and directs SEI evolution toward a thin, robust, LiF-rich inorganic interphase.

Equally important is the construction of a robust anode surface. Surface-engineering strategies that induce LiF-rich interphases, including the synergistic hybrid interlayer termed “Anode SHIELD,” enhance interfacial stability by mechanically isolating the active surface while increasing the Li⁺ transference number and promoting facile Li-ion transport (Figure 4) (Lee S. et al., 2025). These protective interlayers can also mitigate dendrite growth and short-circuit risks under abnormal cell behavior. Notably, this interfacial co-design strategy is not limited to conventional LIBs, but can be extended to pure silicon anodes in high-power lithium-ion capacitors, underscoring its broader versatility across device platforms (Ju O et al., 2024). Overall, these studies demonstrate that coupling mechanochemical formulation with targeted interfacial chemistry offers a viable route toward practical and scalable silicon-anode design.

5 Conclusion and perspectives

Silicon anodes remain among the most compelling candidates for next-generation lithium-ion batteries because of their exceptionally high theoretical capacity. However, their practical implementation continues to be limited by severe volume expansion, unstable interfacial reactions, low initial Coulombic efficiency, and the difficulty of translating promising material-level advances into commercially relevant electrode systems. As highlighted throughout this Perspective, overcoming these barriers requires moving beyond a purely material-centric view toward an integrated framework that connects active-material design with electrode architecture, interfacial chemistry, and scalable processing strategies.

From this perspective, recent progress in silicon anodes can be understood as the result of advances across multiple length scales. At the material level, structural engineering through carbon frameworks, composite design, and functional coatings has significantly improved the mechanical and electrochemical resilience of silicon-based active materials. At the electrode level, conductive agents, binders, electrolyte additives, and prelithiation strategies have evolved into active design parameters that govern charge transport, structural integrity, and interfacial stability under realistic operating conditions. Importantly, these developments show that the performance of advanced silicon materials can only be sustained when they are incorporated into an optimally engineered electrode matrix.

A key message emerging from our recent work is that co-design provides an effective pathway for bridging the long-standing gap between laboratory-scale material innovation and practical battery implementation. Mechanochemically activated additives, interface-stabilizing anion-anchoring additives, LiF-rich surface hybrid interlayers, and dry-process-compatible prelithiation strategies collectively illustrate that stable silicon-anode operation cannot be achieved by addressing mechanical, transport, or interfacial challenges independently. Rather, these factors must be coordinated in a way that simultaneously regulates composite-matrix robustness, Li-ion flux homogeneity, SEI chemistry, and manufacturability. In this sense, practical silicon-anode design is not the sum of isolated optimizations, but the outcome of a tightly integrated electrode system.

Looking ahead, the next stage of silicon-anode development must transition from fundamental proof-of-concept to solving specific industrial pain points (Figure 5). First, future research should prioritize high-loading, thick-film electrodes (>5.0 mAh/cm²) specifically optimized for extreme fast charging (XFC). This requires addressing the localized polarization and Li-plating risks that arise when high current densities are applied to high-resistance Si/C composites, with a target of achieving 80% state-of-charge in under 15 min. Second, interfacial engineering must extend to solid-state battery (SSB) configurations, where the primary challenge shifts to maintaining chemo-mechanical contact. Future research and development should focus on “breathable” interfaces that can accommodate Si expansion without delaminating from solid electrolytes or forming voids during stripping. Third, scalable processing routes, particularly dry manufacturing and integrated prelithiation strategies, should be refined to ensure that prelithiation and binder distribution remain uniform at the industrial scale, targeting a production throughput comparable to current graphite-based lines. Finally, to satisfy the demanding performance requirements of diverse applications such as electric vehicles, robotics, and urban air mobility (UAM), the field must establish a quantitative roadmap targeting at least 1,000 EOL (End of Life) cycles and energy densities exceeding 400 Wh/kg and 800 Wh/L at the cell level.

Overall, the future of silicon anodes will depend not simply on discovering better silicon materials, but on establishing a holistic design philosophy that unifies material innovation, electrode engineering, and scalable manufacturing. By bridging these traditionally separated domains, silicon anodes can move closer to practical realization in high-energy-density batteries capable of meeting the demands of electric vehicles, fast charging, and emerging large-scale energy storage applications.

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Footnotes

Edited by: Xingcheng Xiao, General Motors, United States

Reviewed by: Zhiya Zhang, Lanzhou University, China