Formulating Electron Beam-Induced Covalent Linkages for Stable and High-Energy-Density Silicon Microparticle Anode.

High-capacity silicon (Si) materials hold a position at the forefront of advanced lithium-ion batteries. The inherent potential offers considerable advantages for substantially increasing the energy density in batteries, capable of maximizing the benefit by changing the paradigm from nano- to micron-sized Si particles. Nevertheless, intrinsic structural instability remains a significant barrier to its practical application, especially for larger Si particles. Here, a covalently interconnected system is reported employing Si microparticles (5 µm) and a highly elastic gel polymer electrolyte (GPE) through electron beam irradiation. The integrated system mitigates the substantial volumetric expansion of pure Si, enhancing overall stability, while accelerating charge carrier kinetics due to the high ionic conductivity. Through the cost-effective but practical approach of electron beam technology, the resulting 500 mAh-pouch cell showed exceptional stability and high gravimetric/volumetric energy densities of 413 Wh kg-1, 1022 Wh L-1, highlighting the feasibility even in current battery production lines.

Printable and Free-Standing Silicon-Based Anode for Current Collector-Free Lithium-Ion Batteries.

The evolution of Li-ion rechargeable batteries has driven a demand for systems exceeding the energy density and shape diversity of conventional lithium-ion batteries. Silicon (Si)-based materials, suitable for high-energy-density applications, have been restricted in practical use due to their inherent structural instability and poor conductivities upon electrochemical cycling. Here, we propose a fully printable and free-standing anode, composed of hollow SiOx/C (H-SiOx/C) composite material and an MXene conductive binder, exhibiting high specific capacity, structural reliability, and superior ionic conductivity without any current collector. The hollow structure of H-SiOx/C accommodates volume changes during cycling, while the MXene binder forms a three-dimensional interconnected conducting structure for maintaining the structural integrity of electrodes without a current collector. Furthermore, the printability and free-standing nature of the H-SiOx/C/MXene anode are validated in both coin-type full cell and heart-shaped pouch cell configurations through a straightforward stencil printing technique. This work establishes a foundation for advanced Si-based anodes, enhancing performance and design flexibility and potentially contributing to practical printable battery systems.

Constructing Pure Si Anodes for Advanced Lithium Batteries.

ConspectusWith the escalating demands of portable electronics, electric vehicles, and grid-scale energy storage systems, the development of next-generation rechargeable batteries, which boasts high energy density, cost effectiveness, and environmental sustainability, becomes imperative. Accelerating these advancements could substantially mitigate detrimental carbon emissions. The pursuit of main objectives has kindled interest in pure silicon as a high-capacity electroactive material, capable of further enhancing the gravimetric and volumetric energy densities compared with traditional graphite counterparts. Despite such promising attributes, pure silicon materials face significant hurdles, primarily due to their drastic volumetric changes during the lithiation/delithiation processes. Volume changes give rise to severe side effects, such as fracturing, pulverization, and delamination, triggering rapid capacity decay. Therefore, mitigating silicon particle fracture remains a primary challenge. Importantly, nanoscale silicon (below 150 nm in size) has shown resilience to stresses induced by repeated volume changes, thereby highlighting its potential as an anode-active material. However, the volume expansion stress not only affects the internal structure of the particle but also disrupts the solid-electrolyte interphase (SEI) layer, formed spontaneously on the outer surface of silicon, causing adverse side reactions. Therefore, despite silicon nanoparticles offering new opportunities, overcoming the associated issues is of paramount importance.Thus, this Account aims to spotlight the significant strides made in the development of pure silicon anodes with particular attention to feature size. From the emergence of nanoscale silicon, the following nanotechnology played a crucial role in growing the particle through nano/microstructuring. Similarly, bulk silicon microparticles gradually surfaced with the post-engineering methods owing to their practical advantages. We briefly discuss the special characteristics of representative examples from bulk silicon engineering and nano/microstructuring, all aimed at overcoming intrinsic challenges, such as limiting large volume changes and stabilizing SEI formation during electrochemical cycling. Subsequently, we outline guidelines for advancing pure silicon anodes to incorporate high mass loading and high energy density. Importantly, these advancements require superior material design and the incorporation of exceptional battery components to ensure compatibility and yield synergistic effects. By broadening the cooperative strategies at the cell and system levels, we anticipate that this Account will provide an insightful analysis of pure silicon anodes and catalyze their practical applications in real battery systems.