Fabio La Mantia

Highly conductive paper for energy-storage devices

Paper, invented more than 2,000 years ago and widely used today in our everyday lives, is explored in this study as a platform for energy-storage devices by integration with 1D nanomaterials. Here, we show that commercially available paper can be made highly conductive with a sheet resistance as low as 1 ohm per square (Ω/sq) by using simple solution processes to achieve conformal coating of single-walled carbon nanotube (CNT) and silver nanowire films. Compared with plastics, paper substrates can dramatically improve film adhesion, greatly simplify the coating process, and significantly lower the cost. Supercapacitors based on CNT-conductive paper show excellent performance. When only CNT mass is considered, a specific capacitance of 200 F/g, a specific energy of 30–47 Watt-hour/kilogram (Wh/kg), a specific power of 200,000 W/kg, and a stable cycling life over 40,000 cycles are achieved. These values are much better than those of devices on other flat substrates, such as plastics. Even in a case in which the weight of all of the dead components is considered, a specific energy of 7.5 Wh/kg is achieved. In addition, this conductive paper can be used as an excellent lightweight current collector in lithium-ion batteries to replace the existing metallic counterparts. This work suggests that our conductive paper can be a highly scalable and low-cost solution for high-performance energy storage devices.

Thin, Flexible Secondary Li-Ion Paper Batteries

There is a strong interest in thin, flexible energy storage devices to meet modern society needs for applications such as interactive packaging, radio frequency sensing, and consumer products. In this article, we report a new structure of thin, flexible Li-ion batteries using paper as separators and free-standing carbon nanotube thin films as both current collectors. The current collectors and Li-ion battery materials are integrated onto a single sheet of paper through a lamination process. The paper functions as both a mechanical substrate and separator membrane with lower impedance than commercial separators. The CNT film functions as a current collector for both the anode and the cathode with a low sheet resistance (∼5 Ohm/sq), lightweight (∼0.2 mg/cm(2)), and excellent flexibility. After packaging, the rechargeable Li-ion paper battery, despite being thin (∼300 μm), exhibits robust mechanical flexibility (capable of bending down to <6 mm) and a high energy density (108 mWh/g).

Carbon nanofiber supercapacitors with large areal capacitances

We develop supercapacitor (SC) devices with large per-area capacitances by utilizing three-dimensional (3D) porous substrates. Carbon nanofibers (CNFs) functioning as active SC electrodes are grown on 3D nickel foam. The 3D porous substrates facilitate a mass loading of active electrodes and per-area capacitance as large as 60 mg/cm2 and 1.2 F/cm2, respectively. We optimize SC performance by developing an annealing-free CNF growth process that minimizes undesirable nickel carbide formation. Superior per-area capacitances described here suggest that 3D porous substrates are useful in various energy storage devices in which per-area performance is critical.

An Aqueous Zinc‐Ion Battery Based on Copper Hexacyanoferrate

A new zinc-ion battery based on copper hexacyanoferrate and zinc foil in a 20 mM solution of zinc sulfate, which is a nontoxic and noncorrosive electrolyte, at pH 6 is reported. The voltage of this novel battery system is as high as 1.73 V. The system shows cyclability, rate capability, and specific energy values near to those of lithium-ion organic batteries based on Li4 Ti5 O12 and LiFePO4 at 10 C. The effects of Zn(2+) intercalation and H2 evolution on the performance of the battery are discussed in detail. In particular, it has been observed that hydrogen evolution can cause a shift in pH near the surface of the zinc electrode, and favor the stabilization of zinc oxide, which decreases the performance of the battery. This mechanism is hindered when the surface of zinc becomes rougher.

Batteries for lithium recovery from brines

Here, we report a new battery capable of efficiently recovering lithium from brines that is composed of a lithium-capturing cationic electrode (LiFePO4) and a chloride-capturing anionic electrode (Ag). It can convert a sodium-rich brine (Li : Na = 1 : 100) into a lithium-rich solution (Li : Na = 5 : 1) by consuming 144 W h per kg of lithium recovered.

Quantification of Oxygen Loss from Li1 + x ( Ni1 / 3Mn1 / 3Co1 / 3 ) 1 − x O2 at High Potentials by Differential Electrochemical Mass Spectrometry

Li 1+x (Ni 1/3 Mn 1/3 Co 1/3 ) 1―x O 2 (NMC) oxides are believed to be among the most promising positive electrode materials for future lithium-ion batteries. Differential electrochemical mass spectrometry (DEMS) experiments on the NMC oxides revealed oxygen evolution for overlithiated NMC compounds (x = 0.1) at potentials positive to 4.5 V vs Li/Li + . No oxygen evolution was detected for the stoichiometric NMC compound (x = 0). An analytical procedure for the quantitative analysis of the DEMS data was developed and applied to the oxygen evolution from overlithiated NMC compounds in acetonitrile (AcN) and ethylene carbonate/ dimethylcarbonate-based electrolytes. The analysis of DEMS data acquired in the AcN-based solution was used to quantify the oxygen loss from the structure of the overlithiated compounds. A hypothesis on the origin of the considerably irreversible specific charge observed in the first cycle of the galvanostatic cycling experiments on the overlithiated compounds was formulated.

Synthesis and Electrochemical Performance of a Lithium Titanium Phosphate Anode for Aqueous Lithium-Ion Batteries

Lithium-ion batteries that use aqueous electrolytes offer safety and cost advantages when compared to today’s commercial cells that use organic electrolytes. The equilibrium reaction potential of lithium titanium phosphate is �0.5 V with respect to the standard hydrogen electrode, which makes this material attractive for use as a negative electrode in aqueous electrolytes. This material was synthesized using a Pechini type method. Galvanostatic cycling of the resulting lithium titanium phosphate showed an initial discharge capacity of 115 mAh/g and quite good capacity retention during cycling, 84% after 100 cycles, and 70% after 160 cycles at a 1 C cycling rate in an organic electrolyte. An initial discharge capacity of 113 mAh/g and capacity retention of 89% after 100 cycles with a coulombic efficiency above 98% was observed at a C/5 rate in pH-neutral 2 M Li2SO4. The good cycle life and high efficiency in an aqueous electrolyte demonstrate that lithium titanium phosphate is an excellent candidate negative electrode material for use in aqueous lithium-ion batteries. The high power output and energy density of lithium-ion batteries have led to their widespread use as power sources for portable electronics. Most commercial lithium-ion cells rely on a highly flammable organic electrolyte. Concerns about the safety of these cells have largely precluded their adoption on larger scales. Improvement of the safety of lithium-ion batteries must occur if they are to be utilized for applications such as electric vehicles and industrial-scale energy storage. The replacement of the organic electrolytes found in commercial lithium-ion cells with an aqueous electrolyte would resolve the safety concerns surrounding these devices. Aqueous lithium-ion batteries could therefore be used for applications that require excellent safety.

Selectivity of a Lithium‐Recovery Process Based on LiFePO4

The demand for lithium will increase in the near future to 713,000 tonnes per year. Although lake brines contribute to 80% of the production, existing methods for purification of lithium from this source are expensive, slow, and inefficient. A novel electrochemical process with low energy consumption and the ability to increase the purity of a brine solution to close to 98% with a single-stage galvanostatic cycle is presented.

Ammonia-Annealed TiO2 as a Negative Electrode Material in Li-Ion Batteries: N Doping or Oxygen Deficiency?

Improving the chemical diffusion of Li ions in anatase TiO2 is essential to enhance its rate capability as a negative electrode for Li-ion batteries. Ammonia annealing has been used to improve the rate capability of Li4 Ti5 O12 . Similarly, ammonia annealing improves the Li-ion storage performance of anatase TiO2 in terms of the stability upon cycling and the C-rate capability. In order to distinguish whether N doping or oxygen deficiencies, both introduced upon ammonia annealing, are more relevant for the observed improvement, a systematic electrochemical study was performed. The results suggest that the creation of oxygen vacancies upon ammonia annealing is the main reason for the improvement of the stability and C-rate capability.

Mechanistic Studies of Fc‐PNA(⋅DNA) Surface Dynamics Based on the Kinetics of Electron‐Transfer Processes

N-Terminally ferrocenylated and C-terminally gold-surface-grafted peptide nucleic acid (PNA) strands were exploited as unique tools for the electrochemical investigation of the strand dynamics of short PNA(⋅DNA) duplexes. On the basis of the quantitative analysis of the kinetics and the diffusional characteristics of the electron-transfer process, a nanoscopic view of the Fc-PNA(⋅DNA) surface dynamics was obtained. Loosely packed, surface-confined Fc-PNA single strands were found to render the charge-transfer process of the tethered Fc moiety diffusion-limited, whereas surfaces modified with Fc-PNA⋅DNA duplexes exhibited a charge-transfer process with characteristics between the two extremes of diffusion and surface limitation. The interplay between the inherent strand elasticity and effects exerted by the electric field are supposed to dictate the probability of a sufficient approach of the Fc head group to the electrode surface, as reflected in the measured values of the electron-transfer rate constant, k(0). An in-depth understanding of the dynamics of surface-bound PNA and PNA⋅DNA strands is of utmost importance for the development of DNA biosensors using (Fc-)PNA recognition layers.