Ionic liquids (ILs) are important electrolytes for applications in electrochemical devices. An emerging trend in ILs research is their hybridization with solid matrices, named ionogels. These ...ionogels can not only overcome the fluidity of ILs but also exhibit high mechanical strength of the solid matrix. Therefore, they show promise for applications in building lithium batteries. In this review, various types of solid matrices for confining ILs are summarized, including nonmetallic oxides, metal oxides, IL‐tethered nanoparticles, functionalized SiO2, metal–organic frameworks, and other structural materials. The synthetic strategies for ionogels are first documented, focusing on physical confinement and covalent grafting. Then, the structure, ionic conductivity, thermal stability, and electrochemical stability of ionogels are addressed in detail. Furthermore, the authors highlight the potential applications of state‐of‐art ionogels in lithium batteries. The authors conclude this review by outlining the remaining challenges as well as personal perspectives on this hot area of research.
Ionogels are a new class of hybrid materials made by the immobilization of ionic liquids in solid matrix. They are a promising quasi‐solid electrolyte for high‐performance lithium batteries. This review summarizes recent advances in rational design of ionogel electrolytes, with a particular emphasis on their preparation methods, structures, thermal and electrochemical properties, as well as potential applications in lithium batteries.
Lithium–air batteries are promising devices for electrochemical energy storage because of their ultrahigh energy density. However, it is still challenging to achieve practical Li–air batteries ...because of their severe capacity fading and poor rate capability. Electrolytes are the prime suspects for cell failure. In this Review, we focus on the opportunities and challenges of electrolytes for rechargeable Li–air batteries. A detailed summary of the reaction mechanisms, internal compositions, instability factors, selection criteria, and design ideas of the considered electrolytes is provided to obtain appropriate strategies to meet the battery requirements. In particular, ionic liquid (IL) electrolytes and solid‐state electrolytes show exciting opportunities to control both the high energy density and safety.
Performance enhancers: Electrolytes for Li–air batteries include non‐aqueous liquid electrolytes, solid‐state electrolytes, aqueous electrolytes, and hybrid electrolytes. This Review shows the importance of electrolytes to the mechanisms and performance of lithium–air batteries and provides a basis for selecting suitable electrolytes. The existing challenges, solutions, as well as guidance for the future direction of this field are also considered.
As the largest developing country, China has been changing rapidly over the last three decades and its economic expansion is largely driven by the use of fossil fuels, which leads to a dramatic ...increase in emissions of both ambient air pollutants and greenhouse gases (GHGs). China is now facing the worst air pollution problem in the world, and is also the largest emitter of carbon dioxide. A number of epidemiological studies on air pollution and population health have been conducted in China, using time-series, case-crossover, cross-sectional, cohort, panel or intervention designs. The increased health risks observed among Chinese population are somewhat lower in magnitude, per amount of pollution, than the risks found in developed countries. However, the importance of these increased health risks is greater than that in North America or Europe, because the levels of air pollution in China are very high in general and Chinese population accounts for more than one fourth of the world's totals. Meanwhile, evidence is mounting that climate change has already affected human health directly and indirectly in China, including mortality from extreme weather events; changes in air and water quality; and changes in the ecology of infectious diseases. If China acts to reduce the combustion of fossil fuels and the resultant air pollution, it will reap not only the health benefits associated with improvement of air quality but also the reduced GHG emissions. Consideration of the health impact of air pollution and climate change can help the Chinese government move forward towards sustainable development with appropriate urgency.
► China may face the worst air pollution problem in the world, and is also the largest emitter of carbon dioxide. ► Sufficient evidence shows that ambient air pollutants have a wide range of adverse health effects in China. ► Some evidence suggests that climate change poses significant health risks to the population in China. ► Consideration of the health impact of air pollution and climate change simultaneously can help the Chinese government move forward towards sustainable development with appropriate urgency.
Optical irradiation accompanied by spontaneous anti-Stokes emission can lead to cooling of matter, in a phenomenon known as laser cooling, or optical refrigeration, which was proposed by Pringsheim ...in 1929. In gaseous matter, an extremely low temperature can be obtained in diluted atomic gases by Doppler cooling, and laser cooling of ultradense gas has been demonstrated by collisional redistribution of radiation. In solid-state materials, laser cooling is achieved by the annihilation of phonons, which are quanta of lattice vibrations, during anti-Stokes luminescence. Since the first experimental demonstration in glasses doped with rare-earth metals, considerable progress has been made, particularly in ytterbium-doped glasses or crystals: recently a record was set of cooling to about 110 kelvin from the ambient temperature, surpassing the thermoelectric Peltier cooler. It would be interesting to realize laser cooling in semiconductors, in which excitonic resonances dominate, rather than in systems doped with rare-earth metals, where atomic resonances dominate. However, so far no net cooling in semiconductors has been achieved despite much experimental and theoretical work, mainly on group-III-V gallium arsenide quantum wells. Here we report a net cooling by about 40 kelvin in a semiconductor using group-II-VI cadmium sulphide nanoribbons, or nanobelts, starting from 290 kelvin. We use a pump laser with a wavelength of 514 nanometres, and obtain an estimated cooling efficiency of about 1.3 per cent and an estimated cooling power of 180 microwatts. At 100 kelvin, 532-nm pumping leads to a net cooling of about 15 kelvin with a cooling efficiency of about 2.0 per cent. We attribute the net laser cooling in cadmium sulphide nanobelts to strong coupling between excitons and longitudinal optical phonons (LOPs), which allows the resonant annihilation of multiple LOPs in luminescence up-conversion processes, high external quantum efficiency and negligible background absorption. Our findings suggest that, alternatively, group-II-VI semiconductors with strong exciton-LOP coupling could be harnessed to achieve laser cooling and open the way to optical refrigeration based on semiconductors.
•Environmental recycling of mixed cathode materials with organic citric acid.•Leaching efficiencies of Li, Co, Ni and Mn exceeded 95% at optimal conditions.•A new formula is proposed to study the ...mechanism and kinetics of leaching process.•Re-synthesized LiNi1/3Co1/3Mn1/3O2 exhibits good performances.
A “grave-to-cradle” process for the recycling of spent mixed-cathode materials (LiCoO2, LiCo1/3Ni1/3Mn1/3O2, and LiMn2O4) has been proposed. The process comprises an acid leaching followed by the resynthesis of a cathode material from the resulting leachate. Spent cathode materials were leached in citric acid (C6H8O7) and hydrogen peroxide (H2O2). Optimal leaching conditions were obtained at a leaching temperature of 90 °C, a H2O2 concentration of 1.5 vol%, a leaching time of 60 min, a pulp density of 20 g L−1, and a citric acid concentration of 0.5 M. The leaching efficiencies of Li, Co, Ni, and Mn exceeded 95%. The leachate was used to resynthesize new LiCo1/3Ni1/3Mn1/3O2 material by using a sol–gel method. A comparison of the electrochemical properties of the resynthesized material (NCM-spent) with that synthesized directly from original chemicals (NCM-syn) indicated that the initial discharge capacity of NCM-spent at 0.2 C was 152.8 mA h g−1, which was higher than the 149.8 mA h g−1 of NCM-syn. After 160 cycles, the discharge capacities of the NCM-spent and NCM-syn were 140.7 mA h g−1 and 121.2 mA h g−1, respectively. After discharge at 1 C for 300 cycles, the NCM-spent material remained a higher capacity of 113.2 mA h g−1 than the NCM-syn (78.4 mA h g−1). The better performance of the NCM-spent resulted from trace Al doping. A new formulation based on the shrinking-core model was proposed to explain the kinetics of the leaching process. The activation energies of the Li, Co, Ni, and Mn leaching were calculated to be 66.86, 86.57, 49.46, and 45.23 kJ mol−1, respectively, which indicates that the leaching was a chemical reaction-controlled process.
A hydrometallurgical method involving natural organic acid leaching has been developed for recovery of lithium and cobalt from the cathode active materials in spent lithium-ion batteries. Succinic ...acid is employed as leaching agent and H2O2 as reductant. The cobalt and lithium contents from the succinic acid-based treatment of spent batteries are determined by inductively coupled plasma-optical emission spectroscopy to calculate the leaching efficiency. The spent LiCoO2 samples after calcination and the residues after leaching are characterized by X-ray diffraction and scanning electron microscopy. The results show that nearly 100% of cobalt and more than 96% of lithium are leached under optimal conditions: succinic acid concentration of 1.5 mol L−1, H2O2 content of 4 vol.%, solid-to-liquid ratio of 15 g L−1, temperature of 70 °C, and reaction time of 40 min. Results are also given for fitting of the experimental data to acid leaching kinetic models.
•A new hydrometallurgical method is designed to recover spent Li-ion batteries.•Succinic acid is employed as leaching agent and H2O2 as reductant.•Nearly 100% of cobalt and more than 96% of lithium are leached.•Results are given for fitting of experimental data to acid leaching kinetic models.
An economical effective method is developed for recycling spent LiNi1/3Co1/3Mn1/3O2 cathodes, where more than 98% Li, Co, Ni and Mn can be leached out with different organic acids, and resynthesized ...to LiNi1/3Co1/3Mn1/3O2. The leaching mechanism is investigated at macro- and micro-scales. The particles undergo a loosening-breaking-shrinking change for two acids, while the FTIR and UV-vis spectra indicate different coordination reactions. The performance of LiNi1/3Co1/3Mn1/3O2 resynthesized from the leachate of the acetic acid leaching (NCM-Ac) and maleic acid leaching (NCM-Ma) are compared. The first discharge capacity of NCM-Ma and NCM-Ac at 0.2C are 151.6 and 115.0 mA h g−1, respectively. The much better performance of NCM-Ma than NCM-Ac results from the different coordination of the two acids in the sol-gel process, where the maleic acid can esterify to establish a stable network to chelate metal ions, while the weak chelation of acetic acid leads to the formation of impurities. The economics analysis including the cost of leaching acid and energy consumption shows that the price of organic acids and reducing agents, short leaching time, low temperature and high-valued products are the effective way to increase recycling and environmental benefits, which shows advantages in terms of resources cost and added value.
•An economical recycling process for spent lithium-ion batteries is proposed.•The leaching mechanism is investigated at macro- and micro-scales.•Environmental and economic analysis of the leaching process is investigated.
Owing to the high volumetric capacity and low redox potential, zinc (Zn) metal is considered to be a remarkably prospective anode for aqueous Zn‐ion batteries (AZIBs). However, dendrite growth ...severely destabilizes the electrode/electrolyte interface, and accelerates the generation of side reactions, which eventually degrade the electrochemical performance. Here, an artificial interface film of nitrogen (N)‐doped graphene oxide (NGO) is one‐step synthesized by a Langmuir–Blodgett method to achieve a parallel and ultrathin interface modification layer (≈120 nm) on Zn foil. The directional deposition of Zn crystal in the (002) planes is revealed because of the parallel graphene layer and beneficial zincophilic‐traits of the N‐doped groups. Meanwhile, through the in situ differential electrochemical mass spectrometry and in situ Raman tests, the directional plating morphology of metallic Zn at the interface effectively suppresses the hydrogen evolution reactions and passivation. Consequently, the pouch cells pairing this new anode with LiMn2O4 cathode maintain exceptional energy density (164 Wh kg−1 after 178 cycles) at a reasonable depth of discharge, 36%. This work provides an accessible synthesis method and in‐depth mechanistic analysis to accelerate the application of high‐specific‐energy AZIBs.
A facile Langmuir–Blodgett approach is used to construct an ultrathin and parallel nitrogen‐doped graphene protective layer on zinc (Zn) foil. The artificial interfacial film regulates the directional deposition of metallic Zn and inhibits the side reactions, thus achieving high‐energy‐density aqueous Zn‐ion batteries.
Aqueous batteries are promising devices for electrochemical energy storage because of their high ionic conductivity, safety, low cost, and environmental friendliness. However, their voltage output ...and energy density are limited by the failure to form a solid‐electrolyte interphase (SEI) that can expand the inherently narrow electrochemical window of water (1.23 V) imposed by hydrogen and oxygen evolution. Here, a novel (Li4(TEGDME)(H2O)7) is proposed as a solvation electrolyte with stable interfacial chemistry. By introducing tetraethylene glycol dimethyl ether (TEGDME) into a concentrated aqueous electrolyte, a new carbonaceous component for both cathode−electrolyte interface and SEI formation is generated. In situ characterizations and ab initio molecular dynamics (AIMD) calculations reveal a bilayer hybrid interface composed of inorganic LiF and organic carbonaceous species reduced from Li+2(TFSI−) and Li+4(TEGDME). Consequently, the interfacial films kinetically broaden the electrochemical stability window to 4.2 V, thus realizing a 2.5 V LiMn2O4−Li4Ti5O12 full battery with an excellent energy density of 120 W h kg−1 for 500 cycles. The results provide an in‐depth, mechanistic understanding of a potential design of more effective interphases for next‐generation aqueous lithium‐ion batteries.
A novel “ether‐in‐water” electrolyte is demonstrated by introducing the non‐aqueous co‐solvent TEGDME into an aqueous electrolyte. The designed Li4(TEGDME)(H2O)7 solvation sheath structure with stable interfacial chemistry dynamically expands the electrochemical stability window to 4.2 V. Meanwhile, the high‐quality solid electrolyte interphase (SEI) and cathode–electrolyte interface (CEI) derived from the reduction of Li+2(TFSI−) and Li+4(TEGDME) effectively suppress hydrogen/oxygen evolution and electrode dissolution.
Highlights
This review summarizes recent progresses in pristine metal–organic frameworks (MOFs), MOF composites, and their derivatives for next-generation rechargeable batteries including ...lithium–sulfur batteries, lithium–oxygen batteries, sodium-ion batteries, potassium-ion batteries, Zn-ion batteries, and Zn–air batteries.
The design strategies for MOF-based materials as the electrode, separator, and electrolyte are outlined and discussed.
The challenges and development strategies and of MOF-related materials for battery applications are highlighted.
Metal–organic framework (MOF)-based materials with high porosity, tunable compositions, diverse structures, and versatile functionalities provide great scope for next-generation rechargeable battery applications. Herein, this review summarizes recent advances in pristine MOFs, MOF composites, MOF derivatives, and MOF composite derivatives for high-performance sodium-ion batteries, potassium-ion batteries, Zn-ion batteries, lithium–sulfur batteries, lithium–oxygen batteries, and Zn–air batteries in which the unique roles of MOFs as electrodes, separators, and even electrolyte are highlighted. Furthermore, through the discussion of MOF-based materials in each battery system, the key principles for controllable synthesis of diverse MOF-based materials and electrochemical performance improvement mechanisms are discussed in detail. Finally, the major challenges and perspectives of MOFs are also proposed for next-generation battery applications.
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