Dominic Bresser

ZnFe2O4-C/LiFePO4-CNT: A Novel High-Power Lithium-Ion Battery with Excellent Cycling Performance.

An innovative and environmentally friendly battery chemistry is proposed for high power applications. A carbon-coated ZnFe2O4 nanoparticle-based anode and a LiFePO4-multiwalled carbon nanotube-based cathode, both aqueous processed with Na-carboxymethyl cellulose, are combined, for the first time, in a Li-ion full cell with exceptional electrochemical performance. Such novel battery shows remarkable rate capabilities, delivering 50% of its nominal capacity at currents corresponding to ≈20C (with respect to the limiting cathode). Furthermore, the pre-lithiation of the negative electrode offers the possibility of tuning the cell potential and, therefore, achieving remarkable gravimetric energy and power density values of 202 Wh kg−1 and 3.72 W kg−1, respectively, in addition to grant a lithium reservoir. The high reversibility of the system enables sustaining more than 10 000 cycles at elevated C-rates (≈10C with respect to the LiFePO4 cathode), while retaining up to 85% of its initial capacity.

An Advanced Lithium-Air Battery Exploiting an Ionic Liquid-Based Electrolyte

A novel lithium-oxygen battery exploiting PYR14TFSI-LiTFSI as ionic liquid-based electrolyte medium is reported. The Li/PYR14TFSI-LiTFSI/O2 battery was fully characterized by electrochemical impedance spectroscopy, capacity-limited cycling, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. The results of this extensive study demonstrate that this new Li/O2 cell is characterized by a stable electrode-electrolyte interface and a highly reversible charge-discharge cycling behavior. Most remarkably, the charge process (oxygen oxidation reaction) is characterized by a very low overvoltage, enhancing the energy efficiency to 82%, thus, addressing one of the most critical issues preventing the practical application of lithium-oxygen batteries.

Enabling LiTFSI‐based Electrolytes for Safer Lithium‐Ion Batteries by Using Linear Fluorinated Carbonates as (Co)Solvent

In this Full Paper we show that the use of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as conducting salt in commercial lithium-ion batteries is made possible by introducing fluorinated linear carbonates as electrolyte (co)solvents. Electrolyte compositions based on LiTFSI and fluorinated carbonates were characterized regarding their ionic conductivity and electrochemical stability towards oxidation and with respect to their ability to form a protective film of aluminum fluoride on the aluminum surface. Moreover, the investigation of the electrochemical performance of standard lithium-ion anodes (graphite) and cathodes (Li[Ni1/3 Mn1/3 Co1/3 ]O2 , NMC) in half-cell configuration showed stable cycle life and good rate capability. Finally, an NMC/graphite full-cell confirmed the suitability of such electrolyte compositions for practical lithium-ion cells, thus enabling the complete replacement of LiPF6 and allowing the realization of substantially safer lithium-ion batteries.

Secondary lithium-ion battery anodes: From first commercial batteries to recent research activities: Addressing the challenges in rechargeable lithium-ion battery technologies

Following the development of commercial secondary lithium-ion batteries (LIBs), this article illustrates the progress of therein-utilised anode materials from the fi rst successful commercialisation to recent research activities. First, early scientifi c achievements and industrial developments in the fi eld of LIBs, which enabled the remarkable evolution within the last 20 years of this class of batteries, are reviewed. Afterwards, the characteristics of state-of-the-art commercially available anode materials are highlighted with a particular focus on their lithium storage mechanism. Finally, a new class of anode active materials exhibiting a different storage mechanism, namely combined conversion and alloying, is described, which might successfully address the challenges and issues lithiumion battery anodes are currently facing.

Interphase Evolution of a Lithium-Ion/Oxygen Battery

A novel lithium-ion/oxygen battery employing Pyr14TFSI-LiTFSI as the electrolyte and nanostructured LixSn-C as the anode is reported. The remarkable energy content of the oxygen cathode, the replacement of the lithium metal anode by a nanostructured stable lithium-alloying composite, and the concomitant use of nonflammable ionic liquid-based electrolyte result in a new and intrinsically safer energy storage system. The lithium-ion/oxygen battery delivers a stable capacity of 500 mAh g(-1) at a working voltage of 2.4 V with a low charge-discharge polarization. However, further characterization of this new system by electrochemical impedance spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy reveals the progressive decrease of the battery working voltage, because of the crossover of oxygen through the electrolyte and its direct reaction with the LixSn-C anode.

Challenges of “Going Nano”: Enhanced Electrochemical Performance of Cobalt Oxide Nanoparticles by Carbothermal Reduction and In Situ Carbon Coating

The electrochemical performance of nano- and micron-sized Co(3)O(4) is investigated, highlighting the substantial influence of the specific surface area on the obtainable specific capacities as well as the cycling stability. In fact, Co(3)O(4) materials with a high surface area (i.e. a small particle size) show superior specific features, which are, however, accompanied by a rapid capacity fading, owing to the increased formation of an insulating polymeric surface film that results from transition-metal-catalyzed electrolyte decomposition. The simultaneous coating with carbon of Co(3)O(4) nanoparticles and in situ reduction of the Co(3)O(4) by a carbothermal route yields a CoO-Co-C nanocomposite. The formation of this material substantially enhances the long-term cycling stability and coulombic efficiency of the lithium-ion active material used. Although the metallic cobalt enhances the electronic conductivity within the electrode and remains electrochemically inactive (as revealed by in situ powder X-ray diffraction analysis), it might have a detrimental effect on the long-term cycling stability by catalytically inducing continuous electrolyte decomposition.

A New, High Energy Sn–C/Li[Li0.2Ni0.4/3Co0.4/3Mn1.6/3]O2 Lithium-Ion Battery

In this paper we report a new, high performance lithium-ion battery comprising a nanostructured Sn-C anode and Li[Li0.2Ni0.4/3Co0.4/3Mn1.6/3]O2 (lithium-rich) cathode. This battery shows highly promising long-term cycling stability for up to 500 cycles, excellent rate capability, and a practical energy density, which is expected to be as high as 220 Wh kg(-1) at the packaged cell level. Considering the overall performance of this new chemistry basically related to the optimized structure, morphology, and composition of the utilized active materials as demonstrated by XRD, TEM, and SEM, respectively, the system studied herein is proposed as a suitable candidate for application in the lithium-ion battery field.

Polyacrylonitrile Block Copolymers for the Preparation of a Thin Carbon Coating Around TiO2 Nanorods for Advanced Lithium-Ion Batteries

Herein, a new method for the realization of a thin and homogenous carbonaceous particle coating, made by carbonizing RAFT polymerization derived block copolymers anchored on anatase TiO2 nanorods, is presented. These block copolymers consist of a short anchor block (based on dopamine) and a long, easily graphitizable block of polyacrylonitrile. The grafting of such block copolymers to TiO2 nanorods creates a polymer shell, which can be visualized by atomic force microscopy (AFM). Thermal treatment at 700 °C converts the polyacrylonitrile block to partially graphitic structures (as determined by Raman spectroscopy), establishing a thin carbon coating (as determined by transmission electron microscopy, TEM, analysis). The carbon-coated TiO2 nanorods show improved electrochemical performance in terms of achievable specific capacity and, particularly, long-term cycling stability by reducing the average capacity fading per cycle from 0.252 mAh g(-1) to only 0.075 mAh g(-1) .

Precursor Polymers for the Carbon Coating of Au@ZnO Multipods for Application as Active Material in Lithium-Ion Batteries

The synthesis of statistical and block copolymers based on polyacrylonitrile, as a source for carbonaceous materials, and thiol-containing repeating units as inorganic nanoparticle anchoring groups is reported. These polymers are used to coat Au@ZnO multipod heteroparticles with polymer brushes. IR spectroscopy and transmission electron microscopy prove the successful binding of the polymer onto the inorganic nanostructures. Thermogravimetric analysis is applied to compare the binding ability of the block and statistical copolymers. Subsequently, the polymer coating is transformed into a carbonaceous (partially graphitic) coating by pyrolysis. The obtained carbon coating is characterized by Raman spectroscopy and energy-dispersive X-ray (EDX) spectroscopy. The benefit of the conformal carbon coating of the Au@ZnO multipods regarding its application as lithium-ion anode material is revealed by performing galvanostatic cycling, showing a highly enhanced and stabilized electrochemical performance of the carbon-coated particles (still 831 mAh g(-1) after 150 cycles) with respect to the uncoated ones (only 353 mAh g(-1) after 10 cycles).

Ionic Liquid-based Electrolytes for Li Metal/Air Batteries: A Review of Materials and the New 'LABOHR' Flow Cell Concept

The Li-O2 battery has been attracting much attention recently, due to its very high theoretical capacity compared with Li-ion chemistries. Nevertheless, several studies within the last few years revealed that Li-ion derived electrolytes based on alkyl carbonate solvents, which have been commonly used in the last 27 years, are irreversibly consumed at the O2 electrode. Accordingly, more stable electrolytes are required capable to operate with both the Li metal anode and the O2 cathode. Thus, due to their favorable properties such as non volatility, chemical inertia, and favorable behavior toward the Li metal electrode, ionic liquid-based electrolytes have gathered increasing attention from the scientific community for its application in Li-O2 batteries. However, the scale-up of Li-O2 technology to real application requires solving the mass transport limitation, especially for supplying oxygen to the cathode. Hence, the ‘LABOHR’ project proposes the introduction of a flooded cathode configuration and the circulation of the electrolyte, which is then used as an oxygen carrier from an external O2 harvesting device to the cathode for freeing the system from diffusion limitation.