Electrochemical performance and surface chemistry of nanoparticle Si@SiO 2 Li-ion battery anode in LiPF 6 -based electrolyte

Engineering of Silicon Core-Shell Structures for Li-ion Anodes

The amount of silicon in anode materials for Li-ion batteries is still limited by the huge volume changes during charge-discharge cycles. Such changes lead to the loss of electrical contacts, as well as mechanical and surface electrolyte interphase (SEI) instabilities, strongly reducing the cycle life. Core-shell structures have attracted a vast research interest due to the possibility of modifying some properties with a judicious choice of the shell. It is, for example, possible to improve the electronic conductivity and ionic diffusion, or buffer volume variations. This review gives a comprehensive overview of the recent developments and the different strategies used for the design, synthesis and electrochemical performance of silicon-based core-shells. It is based on a selection of the main types of silicon coatings reported in the literature, including carbon, inorganic, organic and double-layer coatings, Finally, a summary of the advantages and drawbacks of these different types of core-shells as anode materials for Li-ion batteries and some insightful suggestions in regards to their use are provided.

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.

A Scalable Cathode Chemical Prelithiation Strategy for Advanced Silicon-Based Lithium Ion Full Batteries

A silicon anode with ultra-high specific capacity has motivated tremendous exploration for high-energy-density lithium ion batteries while it still faces serious issues of irreversible lithium loss, unstable electrode electrolyte interface (SEI), and huge volume expansion. Prelithiation is a crucial technology to alleviate the harm of active lithium loss of silicon-based full-cell systems. Herein, we reported a cathode prelithiation method using Li₂S-PAN as a lithium "donor", which was synthesized via chemical reaction between sulfurized polyacrylonitrile and Li-biphenyl complex. The Li₂S-PAN with an initial charging capacity of 668 mAh g^-1 (2.5-4.0 V) is loaded on the LiFePO₄ electrode, and the LiFePO₄/Li₂S-PAN composite electrode displays a high initial charge capacity of 206 mAh g^-1, which is 22.3% higher than the pristine LiFePO₄. With a silicon/graphite/carbon (Si/G/C) composite anode, the Si/G/C||LiFePO₄/Li₂S-PAN full cell exhibits a reversible capacity of 123 and 107 mAh g^-1 in the 1st and 10th cycle, which is 15.5 and 24.5% higher than the Si/G/C||LiFePO₄ battery, respectively. The SEI layer of the silicon anode in the Si/G/C||LiFePO₄/Li₂S-PAN cell contains abundant conductive LiF species, which can enhance the interfacial stability and reaction kinetics of the cells. The proposed cathode prelithiation process is compatible with the industrial roll-to-roll electrode preparation process, exhibiting a promising application prospect.

Polymer electrolytes for metal-ion batteries

The results of studies on polymer electrolytes for metal-ion batteries are analyzed and generalized. Progress in this field of research is driven by the need for solid-state batteries characterized by safety and stable operation. At present, a number of polymer electrolytes with a conductivity of at least 10−4 S cm−1 at 25 °C were synthesized. Main types of polymer electrolytes are described, viz., polymer/salt electrolytes, composite polymer electrolytes containing inorganic particles and anion acceptors, and polymer electrolytes based on cation-exchange membranes. Ion transport mechanisms and various methods for increasing the ionic conductivity in these systems are discussed. Prospects of application of polymer electrolytes in lithium- and sodium-ion batteries are outlined.

The bibliography includes 349 references.

Lithium Dendrite Suppression with a Silica Nanoparticle-Dispersed Colloidal Electrolyte

Developing a safe and long-lasting lithium (Li) metal battery is crucial for high-energy applications. However, its poor cycling stability due to Li dendrite formation and excessive Li pulverization is the major hurdle for its practical applications. Here, we present a silica (SiO₂) nanoparticle-dispersed colloidal electrolyte (NDCE) and its design principle for suppressing Li dendrite formation. SiO₂ nanoclusters in the NDCE play roles in enhancing the Li⁺ transference number and increasing the Li⁺ diffusivity in the vicinity of the Li-plating substrate. The NDCE enables less-dendritic Li plating by manipulating the nucleation-growth mode and extending Sand's time. Moreover, SiO₂ can interplay with the electrolyte components at the Li-metal surface, enriching fluorinated compounds in the solid electrolyte interface layer. The initial control of the Li plating morphology and SEI structure by the NDCE leads to a more uniform and denser Li deposition upon subsequent cycling, resulting in threefold enhancement of the cycle life. The efficacy of the NDCEs has been further demonstrated by the practical battery design, featuring a commercial-level cathode and thin Li-metal (40 μm) anode.

Silicon-nanoparticle-based composites for advanced lithium-ion battery anodes

Lithium-ion batteries (LIBs) play an important role in modern society. The low capacity of graphite cannot meet the demands of LIBs calling for high power and energy densities. Silicon (Si) is one of the most promising materials instead of graphite, because of its high theoretical capacity, low discharge voltage, low cost, etc. However, Si shows low conductivity of both ions and electrons and exhibits a severe volume change during cycles. Fabricating nano-sized Si and Si-based composites is an effective method to enhance the electrochemical performance of LIB anodes. Using a small size of Si nanoparticles (SiNPs) is likely to avoid the cracking of this material. One critical issue is to disclose different types and electrochemical effects of various coupled materials in the Si-based composites for anode fabrication and optimization. Hence, this paper reviews diverse SiNP-based composites for advanced LIBs from the perspective of composition and electrochemical effects. Almost all kinds of materials that have been coupled with SiNPs for LIB applications are summarized, along with their electrochemical influences on the composites. The integrated materials, including carbon materials, metals, metal oxides, polymers, Si-based materials, transition metal nitrides, carbides, dichalcogenides, alloys, and metal-organic frameworks (MOFs), are comprehensively presented.