Clean energy technologies are significantly hindered by limitations in materials science. From low activity to poor stability, and from low efficiency to high cost, the current materials are not able to cope with the challenges of clean energy technologies. However, recent advances in the materials preparation involving electrochemical process are providing hope for a better, cleaner energy generation. The present paper reviews the materials development conducted in our group in the past two years and highlights the role of electrochemical processes in a wide range of clean technologies, including enhancing the activity of cathodes in solid oxide fuel cell, increasing the stability of superalloy operating at high temperature, reducing the defect-induced failure in metal electrode in corrosive environment, and electrochemical preparation of reflective layer to produce high efficiency solar cells. The better understanding of electrochemical process plays a significant role to achieve the most challenging energy generation systems where the activity and efficiency maintains high with enhanced stability.

Given the massive shifts facing the future energy paradigm, it is pertinent to evaluate the centrality of battery applications in the evolving scenario. This paper will look into aspects of energy storage in the electric grid, transportation, renewable energy, microelectronics and internet of things. A number of factors including future projections, current research trajectories and a global strategies issues will be considered.

Lithium sulfur battery is one of the most promising rechargeable batteries with high theoretical energy density. Usually, sulfur-carbon composites are used as cathode materials to improve electrical conductivity and restrain dissolution of lithium polysulfide. It is noteworthy that loading amount of sulfur in a sulfur-carbon composite cathode material is very vital to obtain finally high energy density of a lithium-sulfur battery. Therefore, it is an important question how to achieve a high coefficient of utilization of sulfur in a cathode material with high sulfur loading. In our works, several kinds of sulfur-carbon composites with different sulfur loading are discussed on utilization coefficient of sulfur. A sulfur-carbon composite with a sulfur content of 81.7 wt% prepared with a hybrid carbon substrate as sulfur immobilizer delivers a high initial capacity of 837.3 and 685.9 mA h g-1 (composite) at the current densities of 80 and 160 mA g-1, respectively. After 150 cycles at the current density of 160 mA g-1, the discharge capacity remains at 554.4 mA h g-1, indicating a low capacity fading.

Coming Soon

Coming Soon

Coming Soon

To progress commercial application in a mobile device and energy storage, batteries with higher energy storage density than existing lithium-ion batteries need to be developed. Lithium sulfur battery thus would be an optimal choice, because it can deliver high energy density (2600 Wh/kg) and offer low-cost and environment-friendly characteristics. However, the sulfur cathode suffers from long-chain lithium polysulfides dissolution, volume variation and poor conductivity issues, leading to low active material use and low coulombic efficiency during charge/discharge cycles. Although advanced research has helped understand important relations between confinement and performance, effective and economical strategies to improve sulfur cathode cycling remain elusive. Here, we show that encapsulate sulfur in graphene nanosheets helps isolate sulfur from the electrolyte and facilitates electrons conductivity. The unique graphene nanosheets with multilateral structure show high specific surface (638.308 m2/g) and interconnected pores, which can effectively prevent the dissolution of polysulfides and accommodate the volume change between S and Li2S. High capacity and excellent cycle performance show the as-prepared sulfur/ multilateral graphene nanosheets nanocomposite can be a promising cathode for lithium-sulfur batteries.

Electrochemical energy storage devices can offer a number of great potentials for meeting future energy demands, such as of renewable energy, electric vehicles, portable electronics, that require high energy density, high power density and long cycle life. Among the various electrode materials available for energy storage devices, graphene, a one-atom thick two-dimensional (2D) sp2 carbon structure, has attracted considerable interest as a next-generation carbon material owing to its large surface area, high electrical conductivity and good mechanical/chemical stability. Currently, one obvious research is to utilize 2D graphene as either an electro-active material itself or a conductive carbon template for nano-hybrid electrode materials for energy storage devices such as supercapacitors and Li-ion batteries.
The key points in the research and application of graphene-based electrodes are as follow; At first, high-quality graphene should be synthesized to possess large specific surface area with high electrical conductivity similar to the pristine graphene. Then, the surface area of graphene should be maintained even after the electrode fabrication process, in order to achieve the large electrochemically active surface area. In addition, the conductive networks, as well as pore channels between graphene nanosheets, should be effectively developed in the electrode for fast ions/electrons transfer. Therefore the graphene-based materials should be designed to possess suitable nano-/macro-structure in the electrode for achieving these aims. In the case of the nano-hybrid materials, besides the above-described key points, the active materials should be effectively anchored or wrapped/entrapped between the graphene nanosheets to provide highly conducting network/buffering matrix to the active materials.
From this point of view, in this presentation, we report on the strategies to effectively exploit graphene-based electrode materials for energy storage devices. More details will be discussed at the meeting.

Exploration of novel electrochemical storage/conversion devices has been driven by the demand of electric transportation and grid storage, leading to materials and system design innovations.Currently, intensive research has mainly focused on improving the performance of high-energy-density lithium-ion batteries (LIBs) and high-power-density supercapacitors (SCs). Herein, a novel energy storage system is proposed, for which an N-doped carbon interlayer, made up of N-doped graphene or highly nitrogen carbon (HNC), is inserted between the iodine cathode and separator of Li-I2 battery, and the schematic representation are given in Figure below. As present, iodine ions can be generated first through a conversion reaction happening in the cathode, and then dissolve into the electrolytes and be restricted in the interlayer regions to proceed reversible and fast surface reaction between I3-, I- and I2, thus producing a high energy and power battery density.

In terms of sustainable development and environmental issues, the design and fabrication of efficient energy storage devices will be more critical in the future than at any time in the past. L-S batteries are promising candidates for such a purpose due to their high specific capacity and low environmental impact.
In our previous work, the summary of typical strategies in S cathode engineering and the corresponding characteristics and properties are illustrated. Clearly, morphology and porosity control are essential for constructing matrices with high S loadings, fast ion and electron transfer, confinement of PS and buffering of volume variation.

Fig Timeline for the advances in Li-S batteries and typical strategies in S cathode.
In our research work of constructing matrices with confinement of PS, we designed novel S@PTh composites with Core-shell structures via an in situ chemical oxidative polymerization method. The conductive PTh shell acts as a conducting additive and a porous adsorbing agent, enhancing the capacity and cycle life of the S cells to a large degree. In order to improve the utilization and rate capability, we further developed the novel concept of dual core-shell composites and investigated the effects of different conductive polymer coatings on the electrochemical performance of MWCNT@S composites. In Graphene based 2D/3D composites, we incorporated 1D core-shell MWCNT@S composites into the interlayer galleries of graphene (GS) through a facile solutionassembly process. The unique 3D sandwich-type architecture of the GS-MWCNT@S composite brought advantages in electron/ ion transfer, the confinement of PS and the accommodation of volume variation. We proposed a systematic modification of cathode and separator with polydopamine to synergistically mitigate the shuttle effect and improve the performance of lithium sulfur batteries. This systematic modification yields excellent capacity retention, high capacity, and high Coulombic efficiency.

Polymer electrolytes have a potential for use in next generation lithium and sodium batteries. Replacing the liquid electrolyte currently used has several advantages: it allows the use of high energy density solid lithium as the anode, removes toxic solvents, improves safety, and eliminates the need for heavy casings. Despite their advantages, the conductivity of solid polymer electrolytes is not sufficient for use in batteries. As a result, considerable effort towards improving conductivity and understanding mechanisms of lithium transport has taken place over the last 30 years. This talk considers the use of high ion content polymers as Na battery electrolytes. Polymer electrolytes do not conduct efficiently enough for practical application because ion motion is coupled to polymer motion. However, slow polymer motion (and thus stiffness) is critical for preventing dendrite formation that limits the use of Na or Li metal anodes. Here we demonstrate, with a combination of simulation, synthesis, and characterization, that polymer motion and ion motion decouple at high ion contents. To achieve this result, we use an anion-containing polymer with free Na cations. We design the polymer such that the ions self-assemble into chain-like aggregates. As percolation is reached, conduction remains high because stable ion chains transport free cations regardless of polymer motion.

Depleted lead paste materials from both the positive and negative grids of discarded lead-acid batteries as well as by-products derived from the gradual loss of these components through normal operation, known as shedding, were obtained from industry for leaching and recycling experiments. The main goal of this work is to develop an environmentally sustainable process to recycle spent lead paste materials consisting of PbO, PbO2 and PbSO4 in a cost effective manner.
The phase purity of precursor materials and crystal structure of products were determined by XRD. The thermal decomposition characteristics were investigated using TGA with SEM and EDX used to elucidate the microstructure and elemental distribution of each synthesised sample. Acid reactivity and BET/BJH analysis were conducted to determine the effects of various thermal processing methods on the microstructure of leached by-products and its corresponding relationship on reactivity and absorption.
An optimum stoichiometric reagent precursor to waste ratio was determined to obtain efficient and effective leaching of all depleted materials from industry. By-products from combustion-calcination experiments of leached materials were found to be nanostructured leady oxide. The degree of acid reactivity/absorption of generated nanostructured PbO varied greatly depending on the thermal processing method. The results obtained suggests a more complex interplay between acid reactivity/absorption and PbO microstructure than merely one that is dictated by surface area and particle size.

HEVs application has brought a novel and drastic challenge to current secondary batteries, namely, High Rate Partial State of Charge (HRPSoC). Under HRPSoC duty, conventional Valve Regulated Lead-Acid Battery (VRLA) suffered from an inevitable and irreversible sulfation, leading to a premature failure. To prolong the HRPSoC cycle performance of VRLA, carbon additives incorporated into a negative active material (NAM) have been proven an effective strategy to impede progressive sulfation. In this paper, serial concentrations (from 0% to 1.8%) of VULCAN 72, an accessible and cost-effective carbon additive, was introduced into NAM of VRLA.The consequence of initial capacity at various current density and HRPSoC cycle demonstrated that a relatively low fraction of VULCAN 72 in NAM, as many authoritative experts used to suggest, not exceed 0.5%, can slightly promote both initial capacity and HRPSoC cycle performance. However, a greater concentration of VULCAN 72, about 1.2%, accomplished five times longer HRPSoC cycle life with subtle decreased initial capacity. The microstructure of negative plate has been modified with well-shaped spherical VULCAN 72 particles performing as the skeleton, nonconducting large scale lead sulfate bulk has been partially eliminated. Thus, porous and spherical microstructure was constructed, which could provide enhanced resistance to irreversible sulfation and improve charge acceptance further. Based on this research, a rather high VULCAN 72 content, approximately 1.2%, is the optimum content of VULCAN 72 for a negative plate of VRLA under HRPSoC duty.

Today the Lithium ion batteries are spread in our society, utilized for our consumer electronics, start to be deployed in the automotive market, in energy distribution system, housing and several other applications. The lifestyle of the 21st century needs portable power sources with high energy and power. Today is mandatory increase batteries energy density and reduce their cost, as well as utilize recyclable materials which are easy to mining and abundant on our planet. Advanced energy storage systems that used new concepts and chemistries beyond lithium-ion batteries are currently under development, to name a few; Sodium ion Batteries, Sulfur Batteries, Magnesium Batteries, Metal air Batteries. The present talk will describe energy systems current under investigation, highlighting merit and demerit of each technology, and factors that hinder their commercialization, while trace a technology roadmap for the next five to ten years.

The hydrometallurgical process for lead recovery is being developed as the global lead consumption increasing in recent years, especially in China as the popularity of electric bicycle. Since the negative impact of impurities on the battery performance, the removal of Fe, Ba and other impurities is a big challenge of the hydrometallurgical process for lead recovery. A novel hydrometallurgical process is investigated to prepare high purity lead oxide from spent lead pastes in this paper. The ¦A-PbO can be obtained via desulphurization, acid leaching and liquid-phase synthesis process. The lead recovery rate can be as high as 92% of the overall process. In addition, more than 99% of Fe and 99% of Ba can be removed under the optimal conditions. Fe and Ba content in the PbO obtained was less than 40 ppm and 1ppm respectively. The lead oxide prepared presented a granular structure and can be used as the positive materials for lead acid battery.

A lithium-sulfur (Li-S) battery has a high theoretical capacity of 1675 mAh g-1 of elemental sulfur and a high nominal energy density of 2600 Wh kg-1 of cell weight. But it is plagued with problems of low active material utilization, poor cycle life and low rate performance, which arising from highly insulating nature of sulfur, the high solubility/diffusivity of lithium polysulfides in the organic electrolyte and volumetric expansion of sulfur during lithiation.
In response to such challenges, it is important to maintain the electrical conductivity network providing envelope for lithium sulfide reduction and oxidation within a liquid solvent electrolyte without loss of fluidity, while minimising shuttling away of sulfur and avoiding or controlling the deposition of insoluble sulfides which can block the conducting paths. Herein, the design and preparation of a series of unique carbon materials, based on metal organic framework (MOF)-derived hierarchical porous carbon, graphene-wrapped microporous carbon composite, few-layer graphene foam and carbon nanotube forest, have been demonstrated for sulfur loading to fabricate cathode scaffolds for Li-S batteries. In addition, chemical adsorption, which is a stronger interaction than physical adsorption, can be used to restrict the dissolution of polysulfides from sulfur cathodes. Therefore, nitrogen, sulfur-codoped (N,S-codoped) sponge-like graphene and B2O3/carbon microtube composite are used as electroactive interlayer for Li-S batteries to control the diffusion of polysulfides.
1. Nano Energy, 2015, 12, 538-546
2. Nanoscale, 2014, 6, 5746-5753.
3. APL Materials, 2014, 2(12), 124109
4. Chemical Communications, 2013, 49, 2192-2194.
5. Journal of Power Sources 2016, 303, 22-28.
6. Journal of Materials Chemistry A 2016, 4 (22), 8541-8547.
7. ACS applied materials & interfaces 2015, 7(43), 23885-23892.
8. Nano Energy 2015, 16, 152-162.

With the boom of consumer electronics (CE) and electric vehicle (EV), a large number of spent lithium-ion batteries (LIBs) have been generated worldwide. Resource depletion and environmental concern driven from the sustainable industry of CE and EV have motivated the urgent recycling of spent LIBs. Hydrometallurgical treatment is the favored technology for recycling of the metals from LIBs compared with pyrometallurgical processes, because it offers such advantages as low energy consumption, less toxic air emissions, and completely recovery of valuable components with high purity. Acid leaching plays a key role in the hydrometallurgical techniques for recovering metals, and strong inorganic acid is the most widely used in the past. However, toxic gases are released during leaching and the waste acid after leaching is a threat to the environment. From an environmental and healthy viewpoint, our group has investigated different organic acids as alternative leaching agents including citric acid, DL-malic acid, ascorbic acid and succinic acid. The leaching efficiencies of valuable metals by these organic acids are comparable with even higher than strong acid and avoid the secondary pollution introduced from strong inorganic acids. The kinetics analyses are also performed for a better understanding of the leaching process. The recycling process we studied with organic acid leaching is highly efficient and environmentally friendly, which can be advanced beyond the laboratory scale to achieve large-scale reclamation of spent LIB.

A citric acid and sodium citrate buffer solution based lead acid battery paste recycling process has been advanced by our group. It was found that the intermediate recycling products, lead citrate, could be used as precursors to produce hierarchical porous carbon monoliths and lead/carbon composites. Lead/carbon composite with nanosized lead particles anchored on porous carbon monolith could be produced by paralyzing of lead citrate precursors under Ar atmosphere at various temperatures. The size of lead particles was controlled by applying different pyrolysis procedures. By coating lead citrate precursors with PVP gel, the size of lead particles reached to as low as several nanometers. The lead particles inside the lead/carbon composite can be used to produce other lead containing compounds like PbS, PbI and PbO for energy materials application by taking advantage of the high activity of its nanosize. In addition, by washing away the nanosized lead particles, porous carbon materials with high specific surface area and hierarchical porous nanostructure was produced. The as prepared carbon materials can also be used as energy materials in new energy storage systems.

Recent developments indicate that Solid Oxide Fuel Cells could potentially be operated in reverse mode under selected conditions without significant performance degradation. This has generated significant industrial and academic interest and reversible SOFC systems are being developed by several organizations. Their potential applications may range from small scale domestic systems to large scale industrial systems for electricity, heat and fuel production. These systems are also expected to help with grid balancing in the future as electricity production from the intermittent renewable energy sources is expected to increase. This paper will present the current status with the development of reversible SOFCs and their several potential applications.

High-energy rechargeable lithium-sulfur batteries are a promising energy storage system that has the potential to meet the ever-rising demand of our energy-consuming world. With elemental sulfur (S) as a cathode and lithium (Li) metal as an anode, Li-S batteries offer a theoretical specific energy of 2600 Wh kg-1, which is about five times that of the state-of-art lithium ion batteries. However, their commercialization has not come true yet due to the issues with the dissolution and diffusion of polysulfides in liquid organic electrolytes, which cause serious capacity degradation and low Coulombic efficiency. In addition, the insulating nature of S and lithium sulfide (Li2S), the final discharge product, also intrinsically lead to poor electrochemical activity and thus low active material utilization. And the volume change arising from the conversion between S and Li2S is also a concern, in terms of cycle stability. To solve the aforementioned problems, our group has designed multi-functional sulfur matrix for a cathode and hierarchical interlayers for novel batteries configurations based on nano-structured carbon and metal oxides. Specifically, a polygonal nano carbon particles derived from a microporous zeolitic imidazolate framework (ZIF-8) was chosen as S-matrix, which was further wrapped by ultra-thin graphene to form a sandwich-like architecture. By taking advantages of the synergistic effect of hybrid conductive carbon and half-closed nano-scale design, stable cycle performance was achieved. To further advance the development of Li-S for practical application, we propose a conceptual design of a bio-inspired polysulfides brush by integration of polar metal oxide and inter-connected conductive frameworks. After the incorporation of this bio-inspired interlayer, excellent cycle and rate performance have been achieved for cathode with a high S loading. We strongly believe the design of chemi-functional interlayers with a brush-like nano-architecture opens a new direction for advancing high-performance Li-S batteries.

With the increasing demand for electronic devices, more rechargeable batteries are attractive for energy storage systems. In our work, three novel rechargeable aluminium-ion batteries are proposed. The first one is a rechargeable Ah-level soft-package aluminum-ion battery which is fabricated using carbon paper cathode, high-purity aluminum foil anode and an ionic liquid electrolyte consisting of AlCl3 and 1-ethyl-3-methylimidazalium chloride ([EMIm]Cl). It is the prototype battery with providing a maximal charge of 1.3 Ah at a current density of 10 mA g-1, can light an LED lamp for 14 hours, and can drive a super mini kart steadily. The second one is Al|AlCl3-NaCl|Cn high temperature (above 100 ¡æ) storage battery, which specific capacity is about 120 mA h g-1 at a current density of 1000 mA g-1 and remains stable at 60 mA h g-1 withstand more than 9000 cycles at a current density of 4000 mA g-1. And the third one is a novel rechargeable aluminium-ion battery which based on Al3+ and fabricated with MxSy(M=Ni, Cu, Ti) composites as a cathode material and high-purity Al foil as an anode. The discharge capacity remains over 60~80 mA h g-1 and coulombic efficiency of 99% after a few hundred cycles. Such rechargeable aluminium-ion batteries are to be low cost and safety, and represent a step forward in the development of aluminium-ion battery.

The reaction mechanism of a high capacity lithium- and manganese-rich metal oxide has been investigated. High-resolution synchrotron X-ray powder diffraction (HRPD) and X-ray absorption spectroscopy (XAS) were used, respectively, to evaluate the electrochemical charge and discharge reactions in terms of local and bulk structural changes, and variations in the oxidation states of the transition metal ions. Ni K-edge XAS data indicate the participation of nickel in reversible redox reactions, whereas Mn K-edge absorption spectra show that the manganese ions do not participate in the electrochemical reactions. Rietveld refinements of the oxygen occupancy during charge and discharge provide evidence of reversible oxygen contribution by the host structure; this unique oxygen participation is likely the main reason for the anomalously high capacity of these electrodes. The HRPD data also show that during the early cycles, characteristic peaks of the Li2MnO3 component disappear when charged to 4.7 V, but reappear on discharge to 2.5 V, consistent with a reversible lithium and oxygen extraction process. The results provide new insights into the charge compensation mechanisms that occur when high capacity, lithium- and manganese-rich electrode materials are electrochemically cycled � a topic that is currently being hotly debated in the literature. The reaction mechanism of abnormal capacity for anode materials will be also discussed in the meeting.

CNTs have been widely studied for a various field such as hydrogen storage, field emission materials and electrode materials for energy storage devices due to physical and chemical properties. We suggest unzipped CNTs with high specific surface area (1123 m2 g-1) and total pore volume (2.38 cm3 g-1) and a trimodal (micro-meso-macro) pore structure through alkali activation for energy storage devices. After severe alkali activation (in our study, CNT (C)/KOH = 1:10 (w/w) at 1000 °C), various pores were initially formed on the surface. Subsequently, a longitudinally unzipped structure was obtained as the individual pores connected. In contrast with other methods to prepare unzipped and porous CNTs, this method is economical and scalable because it enables a one-step synthesis of unzipped and porous CNTs. As per the non-localized density functional theory (NL-DFT), the distribution of micro-meso pores showed evidence of unzipping because the peak for pore sizes <1 nm, measured from the partially opened tips of the pristine CNTs, was broadened. Since the tips were perfectly opened after activation, this means that the micropores on the unzipped structure increased. In addition, the results showed that the unzipped porous CNTs had a trimodal pore structure. This structure resulted in increased specific surface area, as well as energy storage and adsorption capacities. Thus, we applied the unzipped CNTs for energy storage devices including lithium-sulfur (Li-S) secondary batteris and ultracapacitors. At the results, initial specific capacity is obtained over 950 mA g-1 (50% of theoretical specific capacity) in Li-S secondary batteries and the maximum energy density of the unzipped porous CNTs in ultracapacitors based on an organic electrolyte was 50 W h kg-1. Thus, the method is suitable for fabrication of unzipped porous CNTs, which show potential as energy efficient materials.

« Back To Technical Program