Lithium-ion batteries have witnessed meteoric advancement the last two decades. The anode area has seen unprecedented research activity on Si and Sn, the two anode alternatives to currently used carbon following the initial seminal work by Fuji on tin oxide nanocomposites. Recent reports on silicon nanowires, porous Si, and amorphous Si coatings on graphite nanofibers (GNF) have been very encouraging. High capacity and long cycle life anodes are still, however, elusive and much needed to meet the ever increasing energy storage demands of modern society. Herein, we report for the first time the synthesis of novel 1D heterostructures comprising vertically aligned multiwall CNTs (VACNTs) containing nanoscale amorphous/nanocrystalline Si droplets deposited directly on VACNTs with clearly defined spacing using a simple two-step liquid injection CVD process. A hallmark of these single reactor derived heterostructures is an interfacial amorphous carbon layer anchoring the nanoscale Si clusters directly to the VACNTs. The defined spacing of nanoscale Si combined with their tethered CNT architecture allow for the silicon to undergo reversible electrochemical alloying and dealloying with Li with minimal loss of contact with the underlying CNTs. The novel heterostructures thus exhibit impressive reversible stable capacities approximately 2050 mAh/g with very good rate capability and an acceptable first cycle irreversible loss approximately 20% comparable to graphitic anodes indicating their promise as high capacity Li-ion anodes. Although warranting further research, particularly with regard to long-term cycling, it can be envisaged that optimization of this simple approach could lead to reversible high capacity next generation Li-ion anodes.

http://ma.ecsdl.org/content/MA2010-01/5/352.full.pdf

Nanostructured Hybrid Silicon/Carbon Nanotube Heterostructures: Novel Reversible High-Capacity Lithium-Ion Anodes

Rechargeable aqueous metal-ion batteries are very promising as alternative energy storage devices during the post-lithium-ion era because of their green and safe inherent features. Among the different aqueous metal-ion batteries, aqueous zinc-ion batteries (ZIBs) have recently been studied extensively due to their unique and outstanding benefits that hold promise for large-scale power storage systems. However, zinc anode problems in ZIBs, such as zinc dendrites and side reactions, severely shorten the ZIB's cycle lifetime, thus restricting their practical application. Here, we sum up in detail the recent progress on general strategies to suppress zinc dendrites and zinc anode side reactions based on advanced materials and structure design, including the modification of the planar zinc electrode surface layer, internal structural optimization of the zinc bulk electrode, modification of the electrolyte and construction of the multifunctional separator. The various functional materials, structures and battery efficiencies are discussed. Finally, the challenges for ZIBs are identified in the production of functional zinc anodes.

Challenges in the material and structural design of zinc anode towards high-performance aqueous zinc-ion batteries

The development of low-cost and high-safety zinc-ion batteries (ZIBs) has been extensively discussed and reviewed in recent years, but the work on the comprehensive discussion and perspectives in developing zinc-ion electrolytes is still relatively lacking. Faced with critical challenges and bottlenecks practically, the viability of ZIBs critically depends on the development of suitable electrolytes and their practical considerations. In this review, a systematic summary with regard to the basic characteristics of zinc-ion electrolytes facing different issues from optimization strategies to the fundamental science of electrolyte/electrode interfaces (EEIs), particularly in the feasible modifications and advanced characterizations of EEIs, has been put forward. Due to the lack of consideration of the practical issues in major academic studies, we have particularly highlighted aspects that mainly focus on the choice of the electrolyte system, dosage of liquid and fluid electrolytes, status of gel and all-solid electrolytes, together with other concerns related to the electrolytes. The final section proposes significant perspectives to guide and promote the development of zinc-ion electrolytes.

Fundamentals and perspectives in developing zinc-ion battery electrolytes: a comprehensive review

Strategies for the Stabilization of Zn Metal Anodes for Zn‐Ion Batteries

Rechargeable aqueous zinc (Zn) ion-based energy storage systems have been reviving recently because of their low cost and high safety merits; however, they still suffer from the problems of corrosion and dendrite growth on Zn metal anodes that cause gas generation and early battery failure Unfortunately, the corrosion problem has not received sufficient attention until now Here, it is pioneeringly demonstrated that decorating the Zn surface with a dual-functional metallic indium (In) layer, acting as both a corrosion inhibitor and a nucleating agent, is a facile but effective strategy to suppress both drastic corrosion and dendrite growth Symmetric cells assembled with the treated Zn electrodes can sustain up to 1500 h of plating/stripping cycles with an ultralow voltage hysteresis (54 mV), and a 5000 cycle-life is achieved for a prototype full cell This work will instigate the further development of aqueous metal-based energy storage systems

A Corrosion-Resistant and Dendrite-Free Zinc Metal Anode in Aqueous Systems

Aqueous zinc (Zn) batteries (AZBs) are widely considered as a promising candidate for next-generation energy storage owing to their excellent safety features. However, the application of a Zn anode is hindered by severe dendrite formation and side reactions. Herein, an interfacial bridged organic-inorganic hybrid protection layer (Nafion-Zn-X) is developed by complexing inorganic Zn-X zeolite nanoparticles with Nafion, which shifts ion transport from channel transport in Nafion to a hopping mechanism in the organic-inorganic interface. This unique organic-inorganic structure is found to effectively suppress dendrite growth and side reactions of the Zn anode. Consequently, the Zn@Nafion-Zn-X composite anode delivers high coulombic efficiency (ca. 97 %), deep Zn plating/stripping (10 mAh cm-2 ), and long cycle life (over 10 000 cycles). By tackling the intrinsic chemical/electrochemical issues, the proposed strategy provides a versatile remedy for the limited cycle life of the Zn anode.

An Interface-Bridged Organic-Inorganic Layer that Suppresses Dendrite Formation and Side Reactions for Ultra-Long-Life Aqueous Zinc Metal Anodes.

Quasi-solid single Zn-ion conductor with high conductivity enabling dendrite-free Zn metal anode

Double the Capacity of Manganese Spinel for Lithium-Ion Storage by Suppression of Cooperative Jahn–Teller Distortion

Employing conductive binders in silicon (Si) anode has been considered as a fundamental solution to the pulverization of Si particles. Therefore, it is still a great challenge to improve the charge transfer capability of the conductive binder. Herein, a copolymer (PFPQ-COONa) is synthesized, characterized, and electrochemically tested as conductive binder for Si anode. It is found that PFPQ-COONa exhibits not only excellent cycling stability, but also satisfactory rate performance with relatively high areal loading, which outperforms currently reported single-component conductive binders. The superior electrochemical performance can be attributed to the molecular-level contact between binder and Si particles and to the enhanced intrinsic conductivity of PFPQ-COONa at reductive potential. This method provides a fresh perspective to design and develop conductive binder for high-capacity battery anode.

Zhibo Song

Papers

An Interface-Bridged Organic-Inorganic Layer that Suppresses Dendrite Formation and Side Reactions for Ultra-Long-Life Aqueous Zinc Metal Anodes.

Quasi-solid single Zn-ion conductor with high conductivity enabling dendrite-free Zn metal anode

Double the Capacity of Manganese Spinel for Lithium-Ion Storage by Suppression of Cooperative Jahn–Teller Distortion

Conductive Binder for Si Anode with Boosted Charge Transfer Capability via n-Type Doping.

Constructing a Highly Efficient Aligned Conductive Network to Facilitate Depolarized High-Areal-Capacity Electrodes in Li-Ion Batteries