Dealloying technique in the synthesis of lithium-ion battery anode materials

Constructing Three-Dimensional Architectures to Design Advanced Copper-Based Current Collector Materials for Alkali Metal Batteries: From Nanoscale to Microscale

Alkali metals (Li, Na, and K) are deemed as the ideal anode materials for next-generation high-energy-density batteries because of their high theoretical specific capacity and low redox potentials. However, alkali metal anodes (AMAs) still face some challenges hindering their further applications, including uncontrollable dendrite growth and unstable solid electrolyte interphase during cycling, resulting in low Coulombic efficiency and inferior cycling performance. In this regard, designing 3D current collectors as hosts for AMAs is one of the most effective ways to address the above-mentioned problems, because their sufficient space could accommodate AMAs' volume expansion, and their high specific surface area could lower the local current density, leading to the uniform deposition of alkali metals. Herein, we review recent progress on the application of 3D Cu-based current collectors in stable and dendrite-free AMAs. The most widely used modification methods of 3D Cu-based current collectors are summarized. Furthermore, the relationships among methods of modification, structure and composition, and the electrochemical properties of AMAs using Cu-based current collectors, are systematically discussed. Finally, the challenges and prospects for future study and applications of Cu-based current collectors in high-performance alkali metal batteries are proposed.

Engineering CoP Alloy Foil to a Well-Designed Integrated Electrode Toward High-Performance Electrochemical Energy Storage

Nanostructured integrated electrodes with binder-free design show great potential to solve the ever-growing problems faced by currently commercial lithium-ion batteries such as insufficient power and energy densities. However, there are still many challenging problems limiting practical application of this emerging technology, in particular complex manufacturing process, high fabrication cost, and low loading mass of active material. Different from existing fabrication strategies, here using a CoP alloy foil as a precursor  a simple neutral salt solution-mediated electrochemical dealloying method to well address the above issues is demonstrated. The resultant freestanding mesoporous np-Co(OH)_x /Co₂ P product possesses not only active compositions of high specific capacity and large electrode packing density (>3.0 g cm^-3 ) to meet practical capacity requirements, high-conductivity and well-developed nanoporous framework to achieve simultaneously fast ion and electron transfer, but also interconnected ligaments and suitable free space to ensure strong structural stability. Its comprehensively excellent electrochemical energy storage (EES) performances in both lithium/sodium-ion batteries and lithium-ion capacitors can further illustrate the effectiveness of the integrated electrode preparation strategy, such as remarkable reversible specific capacities/capacitances, dominated pseudo-capacitive EES mechanism, and ultra-long cycling life. This study provides new insights into preparation and design of high-performance integrated electrodes for practical applications.

Dealloyed Nanoporous Materials for Rechargeable Post-Lithium Batteries

Nanoporous materials (NPMs) made by dealloying have been well recognized as multifunctional electrodes for lithium-ion batteries (LIBs). In recent years, there are ever-increasing demands on grid-scale energy storage devices composed by earth-abundant elements such as Na, K, Mg, Al, and Zn. Compared to LIBs, these electrochemical cells face critical challenges such as slow kinetics of redox reactions and structural instability owing to large ion size and/or multiple-electron process. Much interest has been focused on NPMs to address these issues with great success. This Minireview discusses the recent research progresses on these novel electrode materials in the emerging post-lithium batteries, including the rational-design of NPMs, structure-performance correlation in each battery system, and insights into future development of this rapidly growing field.

Deterministic Design of Chemistry and Mesostructure in Li-Ion Battery Electrodes

All battery electrodes have complex internal three-dimensional architectures that have traditionally been formed through the random packing of the electrode components. What is now emerging is a new concept in battery electrode design, where the important electronic and ionic pathways, as well as the chemical interactions between the components of the electrode, are deterministically designed. Deterministic design enables far better properties than are possible through random packing, including dramatic improvements in both power and energy. Such a design approach is particularly attractive for emerging high-energy-density materials, which require available free volume as they swell during cycling. In addition to controlled structure, another important facet of the design of such systems is the stable chemical linkages between the active material and the conductive network that survive the lithiation and delithiation processes. In this Perspective, we discuss and provide our views on deterministically designed battery electrodes.

Three-Dimensional Binder-Free Nanoarchitectures for Advanced Pseudocapacitors

The ever-increasing energy demands for electrification of transportation and powering of portable electronics are driving the pursuit of energy-storage technologies beyond the current horizon. Pseudocapacitors have emerged as one of the favored contenders to fill in this technology gap, owing to their potential to deliver both high power and energy densities. The high specific capacitance of pseudocapacitive materials is rooted in the various available oxidation states for fast surface or near-surface redox charge transfer. However, the practical implementation of pseudocapacitors is plagued by the insulating nature of most pseudocapacitive materials. The wealth of the research dedicated to addressing these critical issues has grown exponentially in the past decade. Here, we briefly survey the current progress in the development of pseudocapacitive electrodes with a focus on the discussion of the recent most exciting advances in the design of three-dimensional binder-free nanoarchitectures, including porous metal/graphene-based electrodes, as well as metal-atom/ion-doping-enhanced systems, for advanced supercapacitors with comparable energy density to batteries, and high power density.

Extending Wireless Rechargeable Sensor Network Life without Full Knowledge

When extending the life of Wireless Rechargeable Sensor Networks (WRSN), one challenge is charging networks as they grow larger. Overcoming this limitation will render a WRSN more practical and highly adaptable to growth in the real world. Most charging algorithms require a priori full knowledge of sensor nodes’ power levels in order to determine the nodes that require charging. In this work, we present a probabilistic algorithm that extends the life of scalable WRSN without a priori power knowledge and without full network exploration. We develop a probability bound on the power level of the sensor nodes and utilize this bound to make decisions while exploring a WRSN. We verify the algorithm by simulating a wireless power transfer unmanned aerial vehicle, and charging a WRSN to extend its life. Our results show that, without knowledge, our proposed algorithm extends the life of a WRSN on average 90% of what an optimal full knowledge algorithm can achieve. This means that the charging robot does not need to explore the whole network, which enables the scaling of WRSN. We analyze the impact of network parameters on our algorithm and show that it is insensitive to a large range of parameter values.