Metal Oxides and Oxysalts as Anode Materials for Li Ion Batteries

Despite the imminent commercial introduction of Li-ion batteries in electric drive vehicles and their proposed use as enablers of smart grids based on renewable energy technologies, an intensive quest for new electrode materials that bring about improvements in energy density, cycle life, cost, and safety is still underway. This Progress Report highlights the recent developments and the future prospects of the use of phases that react through conversion reactions as both positive and negative electrode materials in Li-ion batteries. By moving beyond classical intercalation reactions, a variety of low cost compounds with gravimetric specific capacities that are two-to-five times larger than those attained with currently used materials, such as graphite and LiCoO(2), can be achieved. Nonetheless, several factors currently handicap the applicability of electrode materials entailing conversion reactions. These factors, together with the scientific breakthroughs that are necessary to fully assess the practicality of this concept, are reviewed in this report.

Beyond Intercalation-Based Li-Ion Batteries: The State of the Art and Challenges of Electrode Materials Reacting Through Conversion Reactions

Coaxial manganese oxide/carbon nanotube (CNT) arrays deposited inside porous alumina templates were used as cathodes in a lithium battery. Excellent cyclic stability and capacity of MnO2/CNT coaxial nanotube electrodes resulted from the hybrid nature of the electrodes with improved electronic conductivity and dual mechanism of lithium storage. The reversible capacity of the battery was increased by an order compared to template grown MnO2 nanotubes, making them suitable electrodes for advanced Li ion batteries.

https://www.pkusz.edu.cn/uploadfile/2012/1018/20121018031647238.pdf

Coaxial MnO2/Carbon Nanotube Array Electrodes for High-Performance Lithium Batteries

The possibility of achieving high-energy, long-life storage batteries has tremendous scientific and technological significance. An example is the Li-S cell, which can offer a 3-5-fold increase in energy density compared with conventional Li-ion cells, at lower cost. Despite significant advances, there are challenges to its wide-scale implementation, which include dissolution of intermediate polysulphide reaction species into the electrolyte. Here we report a new concept to mitigate the problem, which relies on the design principles of drug delivery. Our strategy employs absorption of the intermediate polysulphides by a porous silica embedded within the carbon-sulphur composite that not only absorbs the polysulphides by means of weak binding, but also permits reversible desorption and release. It functions as an internal polysulphide reservoir during the reversible electrochemical process to give rise to long-term stabilization and improved coulombic efficiency. The reservoir mechanism is general and applicable to Li/S cathodes of any nature.

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Stabilizing lithium-sulphur cathodes using polysulphide reservoirs

Electrospinning is attracting close interest as a versatile fabrication method for one dimensional mesostructured organic, inorganic and hybrid nanomaterials of controlled dimensions prepared as random or oriented continuous nanofibres with possibilities of ordered internal morphologies such as core–sheath, hollow or porous fibre, or even multichannelled microtube arrangements. The dimensionality, directionality and compositional flexibility of electrospun nanofibres and mats are increasingly being investigated for the targeted development of electrode and electrolyte materials, where the specific properties associated with nanoscale features such as high surface area and aspect ratios, low density and high pore volume allow performance improvements in energy conversion and storage devices. We present here a review on the application of electrospinning for the design and fabrication of architectured, nanofibrous materials for dye sensitised solar cells, fuel cells, lithium ion batteries and supercapacitors, with particular emphasis on improved energy and power density imparted by performance improvement to, inter alia, ionic conductivity, cyclability, reversibility, interfacial resistance and electrochemical stability, as well as mechanical strength, of electrospun electrode and electrolyte components.

/pdf/electrospinning-designed-architectures-for-energy-conversion-24f2e62jrc.pdf

Electrospinning: designed architectures for energy conversion and storage devices

The electrochemical performance of 3d metal oxide (MO) electrode materials for Li-ion batteries was studied in the form of Li/CoO(Co 3 O 4 ) half-cells. Reversible capacity in the 750-1000 mAh/g range was achieved and sustained over numerous charge-discharge cycles both at room temperature and at 55°C. The studied oxides were then used as negative-electrode active materials to assemble larger plastic MO/LiCoO 2 Li-ion cells, which exhibited an average output voltage of 2 V and a stable reversible specific energy of 120 Wh/kg during extended cycling at ambient and elevated temperatures. This value can be compared to 180 Wh/kg obtained for similar C/LiCoO 2 Li-ion cells. Based on modeling, several scenarios involving material considerations present the optimum method for boosting the energy density of such MO/LiCoO 2 Li-ion systems.

F. Badway

Papers

Metal oxides as negative electrode materials in Li-ion cells