There are growing concerns over the environmental, climate, and health impacts caused by using non-renewable fossil fuels. The utilization of green energy, including solar and wind power, is believed to be one of the most promising alternatives to support more sustainable economic growth. In this regard, lithium-ion batteries (LIBs) can play a critically important role. To further increase the energy and power densities of LIBs, silicon anodes have been intensively explored due to their high capacity, low operation potential, environmental friendliness, and high abundance. The main challenges for the practical implementation of silicon anodes, however, are the huge volume variation during lithiation and delithiation processes and the unstable solid-electrolyte interphase (SEI) films. Recently, significant breakthroughs have been achieved utilizing advanced nanotechnologies in terms of increasing cycle life and enhancing charging rate performance due partially to the excellent mechanical properties of nanomaterials, high surface area, and fast lithium and electron transportation. Here, the most recent advance in the applications of 0D (nanoparticles), 1D (nanowires and nanotubes), and 2D (thin film) silicon nanomaterials in LIBs are summarized. The synthetic routes and electrochemical performance of these Si nanomaterials, and the underlying reaction mechanisms are systematically described.

Silicon-based Nanomaterials for Lithium-Ion Batteries - A Review

Alloying anodes such as silicon are promising electrode materials for next-generation high energy density lithium-ion batteries because of their ability to reversibly incorporate a high concentration of Li atoms. However, alloying anodes usually exhibit a short cycle life due to the extreme volumetric and structural changes that occur during lithium insertion/extraction; these transformations cause mechanical fracture and exacerbate side reactions. To solve these problems, there has recently been significant attention devoted to creating silicon nanostructures that can accommodate the lithiation-induced strain and thus exhibit high Coulombic efficiency and long cycle life. In parallel, many experiments and simulations have been conducted in an effort to understand the details of volumetric expansion, fracture, mechanical stress evolution, and structural changes in silicon nanostructures. The fundamental materials knowledge gained from these studies has provided guidance for designing optimized Si electrode structures and has also shed light on the factors that control large-volume change solid-state reactions. In this paper, we review various fundamental studies that have been conducted to understand structural and volumetric changes, stress evolution, mechanical properties, and fracture behavior of nanostructured Si anodes for lithium-ion batteries and compare the reaction process of Si to other novel anode materials.

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25th anniversary article: Understanding the lithiation of silicon and other alloying anodes for lithium-ion batteries

This paper gives a comprehensive review about the most recent progress in synthesis, characterization, fundamental understanding, and the performance of graphene and graphene oxide sponges. Practical applications are considered including use in composite materials, as the electrode materials for electrochemical sensors, as absorbers for both gases and liquids, and as electrode materials for devices involved in electrochemical energy storage and conversion. Several advantages of both graphene and graphene oxide sponges such as three dimensional graphene networks, high surface area, high electro/thermo conductivities, high chemical/electrochemical stability, high flexibility and elasticity, and extremely high surface hydrophobicity are emphasized. To facilitate further research and development, the technical challenges are discussed, and several future research directions are also suggested in this paper.

A review of graphene and graphene oxide sponge: material synthesis and applications to energy and the environment

With the increased demand in energy resources, great efforts have been devoted to developing advanced energy storage and conversion systems. Graphene and graphene-based materials have attracted great attention owing to their unique properties of high mechanical flexibility, large surface area, chemical stability, superior electric and thermal conductivities that render them great choices as alternative electrode materials for electrochemical energy storage systems. This Review summarizes the recent progress in graphene and graphene-based materials for four energy storage systems, i.e., lithium-ion batteries, supercapacitors, lithium-sulfur batteries and lithium-air batteries.

Graphene and graphene-based materials for energy storage applications.

Deformation and stress in electrode materials for Li-ion batteries

Improved cycling stability of silicon thin film electrodes through patterning for high energy density lithium batteries

Vertically aligned graphene electrode for lithium ion battery with high rate capability

A porous polymer sheet or membrane is provided with a thin coating of an electrically non-conductive ceramic composition and the coating conforms to all surfaces, including the pore surfaces, of the membrane. Such a coated membrane serves well, for example, as an intra-cell separator in a lithium ion battery. The coating increases the mechanical properties and thermal stability of the separator in battery operation and retains electrolyte. The coating may be formed by a two-step vapor-phase process in which atoms of one or more metals such as aluminum, calcium, magnesium, titanium, silicon and/or zirconium are deposited in a conformal layer on a workpiece surface. The metal atoms may then be reacted with ammonia, carbon dioxide, and or water to form their respective non-conductive nitrides, carbides, and/or oxides on the surface. The two-step process is repeated as necessary to obtain a ceramic material coating of desired thickness.

Lithium-ion batteries with coated separators

We have constructed a negative-electrode material system that provides an abrupt voltage change near the end of discharge, providing a clear marker for the voltage vs state of charge (SOC) relationship. Distinctive voltage features during the operation of a battery enable an accurate state estimation of the cell, and thus efficient energy and power management as well as health assessment. The approach we have developed should be useful for lithium-ion batteries with cell voltages remaining nearly constant over a large SOC range such as cells constructed with graphite negative electrodes and iron phosphate positive electrodes. Specifically, we describe the incorporation of a lithium titanate (LTO) material into a substantially graphitic negative electrode so as to provide a distinctive voltage change at a preselected SOC. A simple analytic procedure based on juxtaposing open-circuit potential curves is shown to represent well the combined system open-circuit potential, thereby confirming the efficacy of the approach. Fabricated full cells comprising lithium iron phosphate positive and carbon-LTO negative electrodes are used to demonstrate the effectiveness of the concept in a battery.

Composite Titanate-Graphite Negative Electrode for Improved State-of-Charge Estimation of Lithium-Ion Batteries

Es wird eine porose Polymerfolie oder -membran mit einer dunnen Beschichtung aus einer elektrisch nicht-leitenden keramischen Zusammensetzung bereitgestellt, und die Beschichtung passt sich an alle Oberflachen, einschlieslich der Porenoberflachen, der Membran an. Eine derartige beschichtete Membran dient zum Beispiel als Intrazellenseparator in einer Lithium-Ionen-Batterie. Die Beschichtung erhoht die mechanischen Eigenschaften und die thermische Stabilitat des Separators im Batteriebetrieb und halt Elektrolyt zuruck. Die Beschichtung kann durch ein Zwei-Stufen-Dampfphasen-Verfahren gebildet werden, bei dem Atome eines Metalls oder mehrerer Metalle, zum Beispiel Aluminium, Calcium, Magnesium, Titan, Silicium und/oder Zirkonium, in einer konformen Schicht auf einer Werkstuckoberflache abgeschieden werden. Die Metallatome konnen dann mit Ammoniak, Kohlendioxid und/oder Wasser unter Bildung ihrer entsprechenden nicht-leitfahigen Nitride, Carbide und/oder Oxide auf der Oberflache umgesetzt werden. Das Zwei-Stufen-Verfahren wird bei Bedarf wiederholt, um eine Beschichtung aus keramischem Material in gewunschter Dicke zu erhalten.

Mark W. Verbrugge

Papers

Improved cycling stability of silicon thin film electrodes through patterning for high energy density lithium batteries

Vertically aligned graphene electrode for lithium ion battery with high rate capability

Lithium-ion batteries with coated separators

Composite Titanate-Graphite Negative Electrode for Improved State-of-Charge Estimation of Lithium-Ion Batteries

Lithium-Ionen-Batterien mit beschichteten Separatoren