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The massive use of lithium batteries in industries, such as automotive and electrical network accumulation, requires the development of safer electrolytes, economic and possibly made from renewable resources using eco-friendly processes. In this work, we reported the synthesis and the physico-chemical and functional characterization of a polymer gel electrolyte (GPE) based on a skeleton of polyhydroxyalkanoate obtained from biomass by means of an easy and environmentally friendly chemical process. The GPE has an ionic conductivity of 0.8 mS cm−1 at room temperature, is thermally stable up to over 100 °C and is not flammable. The electrochemical stability window is higher than 5 V. The cell Li/GPE/LiFePO4 shows specific capacity of 100 mAhg−1 at 3C with 100% coulombic efficiency. These results demonstrate that the GPE based on polyhydroxyalkanoate is very promising for use in lithium batteries of high power density.

The safety issues of lithium-ion batteries require the substitution of volatile and flammable organic components of the electrolyte. In this context, deep eutectic solvents (DESs) represent an interesting alternative to conventional ionic liquids as green solvents to dissolve common lithium salts. This paper explores two eutectics: i) ethylene glycol/choline chloride (EG/ChCl, 3:1 mol/mol), and ii) L-(+)-lactic acid/choline chloride (LA/ChCl, 2:1 mol/mol). The lithium salts added in both cases were LiN(CF3SO2)2 and LiPF6, both in concentration of either 0.5 M or 1 M. They still retain their liquid properties despite the addition of relatively high molar contents (up to 1.0 M) of lithium salts. The 0.5 M LiPF6/EG:ChCl electrolyte, in particular, displays ionic conductivity of 7.95 mS cm−1 at room temperature, and is thus very promising as a green and cheap electrolyte.

Al-ion batteries technology is receiving growing attention thanks to the high natural abundance of aluminum and to the high energy density that can be obtained with a three-electron redox process. In this work, the physicochemical properties of the room temperature ionic liquid composed of aluminum chloride and 1-ethyl-3-methylimidazolium chloride ([EMIm]Cl) were systematically investigated by varying the molar ratio AlCl3/[EMIm]Cl in the range 1.11.7. The combined use of multinuclear (Al-27, C-13, H-1) NMR, electrochemical impedance spectroscopy, and thermal analysis allowed us to shed light on the structureproperties relationships of this complex system, also resolving some controversial conclusions of previous literature. We showed that the 1.2 molar ratio is the best compromise between high ionic conductivity and the use of the highly toxic AlCl3. This electrolyte was tested in a standard Al-ion cell and gave promising results even at very high current densities (i > 200 mA g(-1))

One of the primary targets of current research in the field of energy storage and conversion is the identification of easy, low-cost approaches for synthesizing cell active materials. Herein, we present a novel method for preparing nanometric slabs of Na 0.44 MnO 2 , making use of the eco-friendly urea within a solution synthesis approach. This kind of preparation greatly reduces the time of reaction, decreases the thermal treatment temperature, and allows the obtaining of particles with smaller dimensions compared with those obtained through conventional solid-state synthesis. Such a decrease in particle size guarantees improved electrochemical performance, particularly at high current densities, where kinetic limitations become relevant. Indeed, the materials produced via solution synthesis outperform those prepared via solid-state synthesis both at 2 C, (95 mA h g −1 vs. 85 mA h g −1 , respectively) and 5 C, (78 mA h g −1 vs. 68.5 mA h g −1 , respectively). Additionally, the former material is rather stable over 200 cycles, with a high capacity retention of 75.7%.

The implementation of aqueous electrode processing of cathode materials is a key for the development of greener Na-ion batteries. Herein, the development and optimization of the aqueous electrode processing for the ecofriendly Na0.44MnO2 (NMO) cathode material, employing carboxymethyl cellulose (CMC) as binder, are reported for the first time. The characterization of such an electrode reveals that the performances are strongly affected by the employed electrolyte solution, especially, the sodium salt and the use of electrolyte's additives. In particular, the best results are obtained using the 1 M solution of NaPF6 in EC/DEC (ethylene carbonate/diethyl carbonate) 3:7 (v/v) + 2 wt % FEC (fluoroethylene carbonate). With this electrolyte, the outstanding capacity of 99.7 mA h g-1 is delivered by the CMC-NMO cathode after 800 cycles at a 1C charge/discharge rate. On the basis of this excellent long-Term performance, a full sodium cell, composed of a CMC-based NMO cathode and hard carbon from biowaste (corn cob), has been assembled and tested. The cell delivers excellent performances in terms of specific capacity, capacity retention, and long-Term cycling stability. After 75 cycles at a C/5 rate, the capacity of the NMO in the full-cell approaches 109 mA h g-1 with a Coulombic efficiency of 99.9%.

Zinc oxide nanoarchitectures may be employed as binder-free, high specific capacity anodes for lithium batteries. By means of simple and low-impact wet chemistry approaches, we synthesized 1D (nanorods), 2D (single- and multi-layered nanosheets), and 3D (nanobrushes) ZnO arrays. These nanoarchitectures were compared as far as concerns their electrochemical properties and the structural modifications upon lithiation/delithiation. The best results were offered by 2D nanosheets, which showed reversible capacity of the order of 400 mAhg −1 after 100 cycles at 1 Ag −1 . This was due to: i) small nanoparticles, with average diameter of about 10 nm, which maximize the array specific surface area and favor the formation of the LiZn alloy; ii) the presence of a mesoporous texture, which allows larger space for accommodating the volume changes upon lithiation/delithiation. However, also these 2D structures showed large irreversible capacity losses. Our work highlights the need for more efficient buffering solutions in ZnO binder-free nanostructured anodes.

Mixed ionic-electronic conductors (MIEC) are of growing interest for fuel cells, batteries and sensors. Here, by exploiting the unique properties of Li 4 C 60 2D fulleride and poly(ethylene oxide) (PEO), we demonstrate the feasibility of a MIEC where the nature of transport can be tuned from ionic, to mixed, to almost entirely electronic, simply by changing the weight ratio of the two basic components. By coupling 7 Li MAS-NMR, electrochemical impedance spectroscopy and open circuit voltage (OCV) measurements of a Li/composite/LiFePO 4 cell we demonstrate that: i) a fraction of Li + ions is extracted by Li 4 C 60 and confined into PEO amorphous strands similarly to what happens in PEO-salt systems; ii) a transition between prevalently ionic and electronic conductivity takes place at 33 wt% Li 4 C 60 . This new class of MIEC is very promising for the design of both chemically and electrochemically stable semi-cells and interfaces which can be employed in batteries and supercapacitors.

ZnO is one of the materials of choice as anode for lithium batteries, due to its high theoretical capacity, natural abundance, low toxicity, and low cost. At present, however, its industrial exploitation is impeded by massive capacity fading, and by cycling instability due to the drastic volume expansions during the electrochemical lithiation/delithiation process. Herein, we present a novel graphite coated-ZnO anode for LiBs based on films of nanosheets, coated with graphite. The electrode is obtained by a simple and inexpensive solution hydrothermal synthesis, whereas the graphite is deposited by thermal evaporation, which is easier to perform than a wet chemistry technique. Our approach leads to a substantial increase of the permanent specific capacity, obtaining values of 600 mAhg-1 after 100 cycles at a high specific current of 1 Ag-1. This represents the best performance for long-cycled, ZnO-based anodes obtained so far. Such result derives from the peculiar porous structure of the nanosheets film (pore diameter < 1 nm), as well as by the graphite coating that works as a dimensional buffer and preserves its morphology during cycling. This appears a very promising strategy for designing more stable ZnO-based anodes for Li batteries and microbatteries.