Building a Better Battery
10 Dec 2010-Science (American Association for the Advancement of Science)-Vol. 330, Iss: 6010, pp 1485-1486
TL;DR: An ingenious in situ transmission electron microscope experiment that uses a low–vapor pressure ionic liquid electrolyte to allow imaging of a SnO2 nanowire electrode in an “open” electrochemical cell raises the question of whether such one-dimensional phase transformations can be induced in other materials.
Abstract: Innovations in the battery field are infrequent and hard-won. New electrochemical systems (a new positive or negative electrode, electrolyte, or combination thereof) reach the marketplace only once every few years, and the energy density of lithium-ion batteries as a class has increased on average by only 8 to 9% per year since the early 1990s. Thus, in the burgeoning field of nanoscale electrode materials, skepticism regarding new claims is perhaps not surprising because of the many requirements that any battery electrode must simultaneously meet to be commercialized. One route by which battery performance can be compromised is by mechanical failure due to the large volume changes associated with the charge-discharge cycle. On page 1515 of this issue, Huang et al. ( 1 ) report an ingenious in situ transmission electron microscope (TEM) experiment that uses a low–vapor pressure ionic liquid electrolyte to allow imaging of a SnO2 nanowire electrode in an “open” electrochemical cell. They observe a reaction mechanism in the SnO2 nanowires that progresses sequentially along the nanowire from end to end, allowing them to accommodate a ∼250% volume change without fracturing and at practical charging rates. These intriguing results raise the question of whether such one-dimensional phase transformations can be induced in other materials.
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TL;DR: This review aims to summarize major developments in the field of lithium-sulfur batteries, starting from an overview of their electrochemistry, technical challenges and potential solutions, along with some theoretical calculation results to advance the understanding of the material interactions involved.
Abstract: Due to their high energy density and low material cost, lithium–sulfur batteries represent a promising energy storage system for a multitude of emerging applications, ranging from stationary grid storage to mobile electric vehicles. This review aims to summarize major developments in the field of lithium–sulfur batteries, starting from an overview of their electrochemistry, technical challenges and potential solutions, along with some theoretical calculation results to advance our understanding of the material interactions involved. Next, we examine the most extensively-used design strategy: encapsulation of sulfur cathodes in carbon host materials. Other emerging host materials, such as polymeric and inorganic materials, are discussed as well. This is followed by a survey of novel battery configurations, including the use of lithium sulfide cathodes and lithium polysulfide catholytes, as well as recent burgeoning efforts in the modification of separators and protection of lithium metal anodes. Finally, we conclude with an outlook section to offer some insight on the future directions and prospects of lithium–sulfur batteries.
1,816 citations
TL;DR: It is shown that the problem of sulfur loss can be effectively diminished by controlling the sulfur as smaller allotropes in the confined space of a conductive microporous carbon matrix.
Abstract: The lithium–sulfur battery holds a high theoretical energy density, 4–5 times that of today’s lithium-ion batteries, yet its applications have been hindered by poor electronic conductivity of the sulfur cathode and, most importantly, the rapid fading of its capacity due to the formation of soluble polysulfide intermediates (Li2Sn, n = 4–8). Despite numerous efforts concerning this issue, combatting sulfur loss remains one of the greatest challenges. Here we show that this problem can be effectively diminished by controlling the sulfur as smaller allotropes. Metastable small sulfur molecules of S2–4 were synthesized in the confined space of a conductive microporous carbon matrix. The confined S2–4 as a new cathode material can totally avoid the unfavorable transition between the commonly used large S8 and S42–. Li–S batteries based on this concept exhibit unprecedented electrochemical behavior with high specific capacity, good cycling stability, and superior rate capability, which promise a practicable bat...
1,443 citations
TL;DR: Recent progress in functional materials applied in the currently prevailing rechargeable lithium-ion, nickel-metal hydride, lead acid, vanadium redox flow, and sodium-sulfur batteries is reviewed.
Abstract: There is an ever-growing demand for rechargeable batteries with reversible and efficient electrochemical energy storage and conversion. Rechargeable batteries cover applications in many fields, which include portable electronic consumer devices, electric vehicles, and large-scale electricity storage in smart or intelligent grids. The performance of rechargeable batteries depends essentially on the thermodynamics and kinetics of the electrochemical reactions involved in the components (i.e., the anode, cathode, electrolyte, and separator) of the cells. During the past decade, extensive efforts have been dedicated to developing advanced batteries with large capacity, high energy and power density, high safety, long cycle life, fast response, and low cost. Here, recent progress in functional materials applied in the currently prevailing rechargeable lithium-ion, nickel-metal hydride, lead acid, vanadium redox flow, and sodium-sulfur batteries is reviewed. The focus is on research activities toward the ionic, atomic, or molecular diffusion and transport; electron transfer; surface/interface structure optimization; the regulation of the electrochemical reactions; and the key materials and devices for rechargeable batteries.
1,384 citations
TL;DR: In this article, a review of recent progress in the research and development of redox flow battery technology, including cell-level components of electrolytes, electrodes, and membranes, is reviewed.
Abstract: With the increasing need to seamlessly integrate renewable energy with the current electricity grid, which itself is evolving into a more intelligent, efficient, and capable electrical power system, it is envisioned that energy-storage systems will play a more prominent role in bridging the gap between current technology and a clean sustainable future in grid reliability and utilization. Redox flow battery technology is a leading approach in providing a well-balanced solution for current challenges. Here, recent progress in the research and development of redox flow battery technology, including cell-level components of electrolytes, electrodes, and membranes, is reviewed. The focus is on new redox chemistries for both aqueous and non-aqueous systems.
1,216 citations
TL;DR: In this article, a three-dimensional (3D) holey-graphene/niobia (Nb2O5) composite for ultra-high-rate energy storage at high mass loading was proposed.
Abstract: Nanostructured materials have shown extraordinary promise for electrochemical energy storage but are usually limited to electrodes with rather low mass loading (~1 milligram per square centimeter) because of the increasing ion diffusion limitations in thicker electrodes. We report the design of a three-dimensional (3D) holey-graphene/niobia (Nb2O5) composite for ultrahigh-rate energy storage at practical levels of mass loading (>10 milligrams per square centimeter). The highly interconnected graphene network in the 3D architecture provides excellent electron transport properties, and its hierarchical porous structure facilitates rapid ion transport. By systematically tailoring the porosity in the holey graphene backbone, charge transport in the composite architecture is optimized to deliver high areal capacity and high-rate capability at high mass loading, which represents a critical step forward toward practical applications.
1,099 citations
References
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TL;DR: It is reported that electrodes made of nanoparticles of transition-metal oxides (MO), where M is Co, Ni, Cu or Fe, demonstrate electrochemical capacities of 700 mA h g-1, with 100% capacity retention for up to 100 cycles and high recharging rates.
Abstract: Rechargeable solid-state batteries have long been considered an attractive power source for a wide variety of applications, and in particular, lithium-ion batteries are emerging as the technology of choice for portable electronics. One of the main challenges in the design of these batteries is to ensure that the electrodes maintain their integrity over many discharge-recharge cycles. Although promising electrode systems have recently been proposed, their lifespans are limited by Li-alloying agglomeration or the growth of passivation layers, which prevent the fully reversible insertion of Li ions into the negative electrodes. Here we report that electrodes made of nanoparticles of transition-metal oxides (MO, where M is Co, Ni, Cu or Fe) demonstrate electrochemical capacities of 700 mA h g(-1), with 100% capacity retention for up to 100 cycles and high recharging rates. The mechanism of Li reactivity differs from the classical Li insertion/deinsertion or Li-alloying processes, and involves the formation and decomposition of Li2O, accompanying the reduction and oxidation of metal nanoparticles (in the range 1-5 nanometres) respectively. We expect that the use of transition-metal nanoparticles to enhance surface electrochemical reactivity will lead to further improvements in the performance of lithium-ion batteries.
7,404 citations
TL;DR: The theoretical charge capacity for silicon nanowire battery electrodes is achieved and maintained a discharge capacity close to 75% of this maximum, with little fading during cycling.
Abstract: There is great interest in developing rechargeable lithium batteries with higher energy capacity and longer cycle life for applications in portable electronic devices, electric vehicles and implantable medical devices. Silicon is an attractive anode material for lithium batteries because it has a low discharge potential and the highest known theoretical charge capacity (4,200 mAh g(-1); ref. 2). Although this is more than ten times higher than existing graphite anodes and much larger than various nitride and oxide materials, silicon anodes have limited applications because silicon's volume changes by 400% upon insertion and extraction of lithium which results in pulverization and capacity fading. Here, we show that silicon nanowire battery electrodes circumvent these issues as they can accommodate large strain without pulverization, provide good electronic contact and conduction, and display short lithium insertion distances. We achieved the theoretical charge capacity for silicon anodes and maintained a discharge capacity close to 75% of this maximum, with little fading during cycling.
6,104 citations
TL;DR: A tin-based amorphous composite oxide (TCO) was synthesized in this paper to replace the carbon-based lithium intercalation materials currently in extensive use as the negative electrode (anode) of lithium-ion rechargeable batteries.
Abstract: A high-capacity lithium-storage material in metal-oxide form has been synthesized that can replace the carbon-based lithium intercalation materials currently in extensive use as the negative electrode (anode) of lithium-ion rechargeable batteries. This tin-based amorphous composite oxide (TCO) contains Sn(II)-O as the active center for lithium insertion and other glass-forming elements, which make up an oxide network. The TCO anode yields a specific capacity for reversible lithium adsorption more than 50 percent higher than those of the carbon families that persists after charge-discharge cycling when coupled with a lithium cobalt oxide cathode. Lithium-7 nuclear magnetic resonance measurements evidenced the high ionic state of lithium retained in the charged state, in which TCO accepted 8 moles of lithium ions per unit mole.
2,470 citations
TL;DR: Because lithiation-induced volume expansion, plasticity, and pulverization of electrode materials are the major mechanical effects that plague the performance and lifetime of high-capacity anodes in lithium-ion batteries, these observations provide important mechanistic insight for the design of advanced batteries.
Abstract: We report the creation of a nanoscale electrochemical device inside a transmission electron microscope--consisting of a single tin dioxide (SnO(2)) nanowire anode, an ionic liquid electrolyte, and a bulk lithium cobalt dioxide (LiCoO(2)) cathode--and the in situ observation of the lithiation of the SnO(2) nanowire during electrochemical charging. Upon charging, a reaction front propagated progressively along the nanowire, causing the nanowire to swell, elongate, and spiral. The reaction front is a "Medusa zone" containing a high density of mobile dislocations, which are continuously nucleated and absorbed at the moving front. This dislocation cloud indicates large in-plane misfit stresses and is a structural precursor to electrochemically driven solid-state amorphization. Because lithiation-induced volume expansion, plasticity, and pulverization of electrode materials are the major mechanical effects that plague the performance and lifetime of high-capacity anodes in lithium-ion batteries, our observations provide important mechanistic insight for the design of advanced batteries.
1,398 citations
TL;DR: In this paper, a method was described in which crystalline silicon can be used as a practical anode material for lithium-ion batteries, and a cycling method was demonstrated in which the silicon is first partially converted to amorphous silicon, in situ, during conditioning cycles.
Abstract: A method is described in which crystalline silicon can be used as a practical anode material for lithium-ion batteries. Commercial lithium-ion cells are typically charged at a constant current to a fixed voltage and then are held by the charger at constant voltage until the current decreases to a certain value (also known as constant current/constant voltage or CCCV charging). It is first shown that CCCV charging can be used to reversibly cycle crystalline silicon and limit its capacity. A cycling method is then demonstrated in which crystalline silicon is first partially converted to amorphous silicon, in situ, during conditioning cycles. After the conditioning cycles the silicon can be cycled normally, using CCCV cycling limits, with good coulombic efficiency and little overlithiation during the first cycle.
1,049 citations