The growing electric vehicle (EV) market necessitates the pursuit of cathode materials with enhanced energy density and economic viability. Currently, widely utilized cathode materials include LiMnxNiyCo1-x-yO2 (NMC), LiNixCoyAl1-x-yO2, and LiFePO4 (LFP). Despite nickel’s recognition as an abundant element, concerns have arisen regarding its demand and supply chain stability, potentially posing challenges to the cost-effectiveness of high-nickel cathodes.1 Conversely, while LiFePO4 exhibits cost-effective manufacturing, its limited energy density remains a bottleneck for enhancing EV range.2 Thus, there persists a substantial demand for the development of high energy density cathodes utilizing abundant elements. Mn stands out as an earth-abundant elements with significantly lower costs compared to Ni and Co. The history of Mn-based cathode development is notably extensive, including noteworthy examples like the spinel-structured LiMn2O4 and the layered lithium manganese rich cathode (LMR-NMC). These achievements collectively make Mn-based cathodes immensely appealing. Nevertheless, the traditional spinel-structured LiMn2O4 suffers from low operatable capacity due to the Jahn-Teller distortion caused by reduced Mn ions which hinders its further application. Although the LMR-NMC cathode exhibit impressively high capacity, it also suffers from voltage hysteresis and fading which inhibits the energy density and making it hard to control by the energy management system (EMS). Thus, there is still an imperative demand for development of next generation high energy density Mn rich cathode material.3 In 2021, our group have reported a novel Co-free lithium-excess spinel (LxS) structure cathode material denoted as LxS-Li2MnNiO4. The unique LxS-structured Li2MnNiO4 surpasses conventional spinels such as LiMn2O4 and LiMn1.5Ni0.5O4 by doubling the Li concentration in its pristine state, while maintaining its cubic symmetry. The Li/LxS-L2MnNiO4 cell exhibits remarkable performance, delivering ~225 mAh/g capacity from 2.5 – 5.0 V, with nearly 96% retention after 50 cycles. The exceptional electrochemical performance of LxS-Li2MnNiO4 is attributed to the stable spinel framework and the inherent 3D Li-ion diffusion pathways, facilitating rapid Li-ion diffusion.4 Recently, we synthesized a new series of Mn-rich LxS cathodes. These newly developed Mn-rich compounds exhibit an even better electrochemical performance, showcasing exceptional structural stability. The successful synthesis of high-performance Mn-rich LxS-LMNO not only broadens the compositional space of LxS materials but also positions them as promising, high-energy density, and cost-effective next generation cathode materials. (1) Wang, L.; Wang, J.; Wang, L.; Zhang, M.; Wang, R.; Zhan, C. A critical review on nickel-based cathodes in rechargeable batteries. International Journal of Minerals, Metallurgy and Materials 2022, 29 (5), 925-941. (2) Wang, Y.; He, P.; Zhou, H. Olivine LiFePO4: development and future. Energy & Environmental Science 2011, 4 (3), 805-817, 10.1039/C0EE00176G. DOI: 10.1039/C0EE00176G. (3) Gutierrez, A.; Tewari, D.; Chen, J.; Srinivasan, V.; Balasubramanian, M.; Croy, J. R. Earth-Abundant, Mn-Rich Cathodes for Vehicle Applications and Beyond: Overview of Critical Barriers. Journal of The Electrochemical Society 2023. (4) Shi, B.; Gim, J.; Li, L.; Wang, C.; Vu, A.; Croy, J. R.; Thackeray, M. M.; Lee, E. LT-LiMn 0.5 Ni 0.5 O 2: a unique co-free cathode for high energy Li-ion cells. Chemical Communications 2021, 57 (84), 11009-11012.

This communication addresses the debate about the composition and structure of a lithium-rich manganese oxide electrode with a fully disordered Li-Mn-O rock salt component that was first reported as Li4Mn2O5 (Li2O•2LiMnO2), by Freire et al. in 2015. When prepared at 800 C, it has been determined that the formula of this compound can be designated more accurately as Li4Mn2O4.5, alternatively Li2O•Li0.667Mn1.333O2, or close thereto. The cubic, disordered Li0.667Mn1.333O2 (or Li0.333Mn0.667O) rock salt component, in which the manganese ions adopt an average oxidation state of 2.5+, transforms to a clearly-defined spinel configuration during electrochemical cycling. The electrochemical activation process during the initial charge reaction appears to include the oxidation of the manganese ions by oxygen released by the Li2O component between 4.5 and 4.6 V. In complete contrast, nickel-substituted electrodes, such as Li2O•2LiMn0.5Ni0.5O2 and Li2O•2LiMn0.475Ni0.475Co0.050O2, in which the manganese ions adopt a tetravalent state, have disordered rock salt components that are electrochemically inactive.

This paper addresses the debate about the composition and structure of a lithium-rich manganese oxide electrode with a fully disordered rock salt component, Li4Mn2O5 (or Li2O2LiMnO(2)), first reported by Freire et al. in 2016; it is typically prepared by a high-energy ball milling procedure. It has now been demonstrated that, when prepared at 800 degrees C, the formula of this compound is Li4Mn2O4.5, alternatively Li2OLi0.667Mn1.333O2, or close thereto. The cubic, disordered Li0.667Mn1.333O2 (or Li0.333Mn0.667O) rock salt component, in which the manganese ions adopt an average oxidation state of 2.5+, transforms to a clearly-defined spinel configuration during electrochemical cycling. The electrochemical activation process that occurs during the initial charge reaction includes the oxidation of the manganese ions by oxygen released by the Li2O component between 4.5 and 4.6 V. In complete contrast, nickel- and nickel-cobalt-substituted electrodes, such as Li2O2LiMn(0.5)Ni(0.5)O(2) (Li4MnNiO5) and Li2O2LiMn(0.475)Ni(0.475)Co(0.050)O(2) (Li4Mn0.95Ni0.95Co0.10O5), in which the manganese ions adopt a tetravalent state, have completely disordered rock salt components that are electrochemically inactive. (c) 2024 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.

Sodium-ion batteries have received extensive attention in recent years with the growing demand for sustainable energy storage systems. As a low-cost alternative to lithium-ion batteries, achieving secure, economical, and diverse materials supply chains is necessary for the successful market penetration of the technology. This presentation will introduce research and development efforts at Argonne National Laboratory aimed at advancing sodium-ion batteries that are based on earth-abundant elements. Synthesis, structure, and properties of Nax(Ni,Mn,Fe)O2 layered cathodes will be presented and some key commercialization challenges and insights will be discussed.

Dense and uniform Li6.25Al0.25La3Zr2O12 (Al-doped LLZO) solid-electrolyte film of similar to 24 mu m thickness is successfully fabricated by room temperature aerosol deposition (AD) method. The process optimization study revealed that careful control of particle size and morphology is one of critical determinants in the development of a compact AD membrane. Notably, our method facilitated an impressive ionic conductivity of approximately 10(-5) S cm(-1), bypassing the necessity for post-annealing processes, a milestone in itself. However, it is hypothesized that the attained conductivity is somewhat restrained by factors such as smaller grain size and potential surface degradation due to moisture exposure during fabrication, indicating avenues for further research. Looking forward, detailed investigations into the film's microstructure and its impact on transport properties will be a focal point, alongside potential enhancements through post-annealing and particle coating strategies. This research hints at a promising trajectory for the development of high-efficiency solid-state battery technology.

There has been a concerted effort over the past several years to design and develop manganese-rich lithium-metal-oxide cathodes for the lithium-ion battery industry. The prime motivation for this endeavor is to identify more cost effective and high energy electrode materials that can compete with today's Ni-rich (NMC) and LiFePO4 (LFP) systems. This presentation will cover recent developments at Argonne National Laboratory, highlighting the progress made in developing, characterizing and understanding disordered rocksalt- and lithiated-spinel electrode materials with a high manganese content, with a particular focus on cobalt-free systems.

The collaborative evaluation of electrode materials across multiple research entities requires standardized electrochemical testing protocols to produce reliable, one-to-one comparisons between different systems of interest. Similar to the work done by Long et al. on protocol standardization for coin-cell testing with graphite anodes [J. Electrochem. Soc., 163, A2999, (2016)], we introduce two standardized testing protocols designed to quickly evaluate important electrochemical properties of cathode materials using lithium-metal anodes. The two protocols measure kinetic and thermodynamic capacity losses, rate- and voltage-dependent cycling capacities, instabilities at high voltage and high cycling rate, and overpotentials at various states of charge. We then apply these protocols to four commercially available cathode materials to establish benchmark performance metrics that can be used to screen and evaluate new cathode materials.

Alkaline Earth free spinel oxides provide a potential benefit over Sr-doped perovskite-based materials commonly used as electrodes in high-temperature electrochemical energy conversion devices, e.g., solid oxide fuel cells (SOFCs). Sr-segregation is a known issue leading to performance degradation. In this study, CuxMn3-xO4 (x = 1, 1.2, and 1.5) porous electrodes were examined as SOFC cathodes using electrochemical impedance spectroscopy to investigate the oxygen reduction reaction (ORR) kinetics in relation to the material's intrinsic conductivity, the extrinsic electrode structure, and the cell test design. Similar to the electronic conducting (La,Sr)MnO3 SOFC cathodes, the ORR kinetics of CuxMn3-xO4 spinel electrodes was governed by the oxygen adsorption and diffusion at the particle surface as well as the charge transfer at the triple phase boundaries. The overall electrode polarization resistance was highly dependent on contact density with the metallic current collector, active material particle connectivity, electrode thickness, and the intrinsic electronic materials conductivity. We describe the importance of effective electronic charge transport parallel to the electrode surface in maximizing the electrochemically active electrode volume and enhancing electrode performance. We discuss an approach to optimize cell and electrode design with respect to active materials properties. This aspect is critical to ensure reliable evaluation of new materials, since laboratory-scale button-cells typically exhibit a high degree of electrode microstructure (e.g. porosity, thickness) and electrical contact density variation from sample to sample.& COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Over the past decade, designing advanced, high energy density lithium-ion batteries has become necessary because of the increasing demand for electric vehicles and energy storage devices. Research efforts have focused largely on developing layered, Ni-rich cathode materials due to their high specific capacity. However, their structural and thermal instability and the relatively high cost of nickel raises a concern about their long-term viability.1 Developing next generation cathode materials, based on earth abundant elements such as manganese and iron, has therefore attracted much research interest.2 In the late 1990s, the Mn-based spinel cathode, LiMn2O4 (LMO), dominated the early development of Li-ion batteries for the electric vehicle market. The 3-D network of channels provided by the Mn2O4 spinel framework for Li+-ion diffusion channels enables a good rate performance. However, the operational capacity of Li1-xMn2O4 spinel cathodes in a lithium cell at ~4 V over the range 01+xMn2O4, 0£x£1), a rapid fade of capacity occurs as a result of a severe crystallographic (Jahn Teller) distortion, which prevents the use of the lower voltage reaction in commercial cells. In this presentation, a novel LT-LiMn0.5Ni0.5O2 (LT-LMNO) cathode material with unique electrochemical properties will be reported, where LT refers to its low synthesis temperature (400 °C). In striking contrast to a layered electrode with the same composition, HT-LiMn0.5Ni0.5O2 (where HT = high temperature synthesis, ~850 °C), LT-LMNO has a composite configuration with structurally-integrated lithiated spinel- and layered-like components.3, 4 It provides an electrochemical capacity almost twice that of LMO. This discovery provides a new strategy for developing next-generation. Mn-rich spinel-based cathodes. References Bianchini, M.; Roca-Ayats, M.; Hartmann, P.; Brezesinski, T.; Janek, J., There and Back Again - The Journey of LiNiO2 as a Cathode Active Material. Chem. Int. Ed. Engl. 2019, 58 (31), 10434-10458. Croy, J. R.; Gutierrez, A.; He, M.; Yonemoto, B. T.; Lee, E.; Thackeray, M. M., Development of Manganese-rich Cathodes as Alternatives to Nickel-rich Chemistries. Power Sources 2019, 434, 226706. Thackeray, M. M.; Lee, E.; Shi, B.; Croy, J. R., Review: From LiMn2O4 to Partially-Disordered Li2MnNiO4: The Evolution of Lithiated-Spinel Cathodes for Li-Ion Batteries. Electrochem. Soc. 2022, 169 (2), 020535. Shi, B.; Gim, J.; Li, L.; Wang, C.; Vu, A.; Croy, J. R.; Thackeray, M. M.; Lee, E., LT-LiMn5Ni0.5O2: A Unique Co-free Cathode for High Energy Li-ion Cells. Chem. Comm. 2021, 57 (84), 11009-11012.

Recently, our group has reported a novel Li-ion battery cathode, ‘LT-LiMn0.5Ni0.5O2’, where LT refers to its relatively low synthesis temperature (400 °C). By collecting high energy X-ray diffraction and high-angle, annular-dark-field (HAADF) scanning-transmission electron microscopy (STEM) data, we confirm that the LT-LiMn0.5Ni0.5O2 features a unique partially disordered rock salt structure with predominant lithiated-spinel-like character. The electrochemical data indicates that the Li/LT-LiMn0.5Ni0.5O2 cells shows good cycle stability when operate between 2.5-5.0V. The 1st cycle specific discharge capacity was determined to be 225mAh/g. Two distinct voltage plateaus can be identified at approximately at ~4.6 V and ~3.5 V during discharge. The ~1 voltage separation of the plateaus is caused by the octahedral and tetrahedral site energy difference during lithium extraction and insertion.1 The discovery of LT-LiMn0.5Ni0.5O2 not only expand the compositional space for the known lithated-spinel family but also provide a practical way to increase the operational capacity of traditional spinels such like LiMn2O4 and LiMn1.5Ni0.5O2.2-5 It is well known that when synthesized at 900°C, LiMn0.5Ni0.5O2 features a layered structure.6 The existence of lithated-spinel like LiMn0.5Ni0.5O2 at low temperature (400°C) immediately raise another question: How does the synthesis temperature affect the structure and electrochemical performance of LiMn0.5Ni0.5O2? We synthesized a series of different temperature of LiMn0.5Ni0.5O2 powders. By collecting high energy X-ray diffraction and high-resolution transmission electron microscopy (HR-TEM) data, we confirm that, the LiMn0.5Ni0.5O2 exhibits a lithated spinel → disordered layered → ordered layered structure transformation as temperature increase from 400-900 °C. The Rietveld refinements results also reveals a gradual decrease of the Li/Ni exchange ratio accompanied by the synthesis temperature changes. The evolution of specific discharge capacity for different temperature LiMn0.5Ni0.5O2 shows a parabola-like curve behavior with the lowest discharge capacity at 700 °C. This unique behavior is likely to be related to the diffusion channels reconstruction along with the structure changes. 3D diffusion channels are incorporated with 2D diffusion channels at low temperature (400°C) for lithated-spinel LiMn0.5Ni0.5O2. Within the middle temperature range (500°C-700°C), the 3D channels destroy rapidly while 2D diffusion channels are not well established due to the highly disorder ratio resulting in a decrease of capacity. At higher temperature (800-900°C), the 2D diffusion channels are more well established enabling an increase of the capacity. Shi, B.; Gim, J.; Li, L.; Wang, C.; Vu, A.; Croy, J. R.; Thackeray, M. M.; Lee, E., LT-LiMn 0.5 Ni 0.5 O 2: a unique co-free cathode for high energy Li-ion cells. Chemical Communications 2021, 57 (84), 11009-11012. Thackeray, M. M.; Lee, E.; Shi, B.; Croy, J. R., Review–From LiMn2O4 to Partially-Disordered Li2MnNiO4: The Evolution of Lithiated-Spinel Cathodes for Li-Ion Batteries. Journal of The Electrochemical Society 2022, 169 (2), 020535. Gummow, R.; Thackeray, M.; David, W.; Hull, S., Structure and electrochemistry of lithium cobalt oxide synthesised at 400 C. Materials research bulletin 1992, 27 (3), 327-337. Lee, E.; Blauwkamp, J.; Castro, F. C.; Wu, J.; Dravid, V. P.; Yan, P.; Wang, C.; Kim, S.; Wolverton, C.; Benedek, R., Exploring lithium-cobalt-nickel oxide spinel electrodes for≥ 3.5 V Li-ion cells. ACS applied materials & interfaces 2016, 8 (41), 27720-27729. Lee, E.; Kwon, B. J.; Dogan, F.; Ren, Y.; Croy, J. R.; Thackeray, M. M., Lithiated Spinel LiCo1–x Al x O2 as a Stable Zero-Strain Cathode. ACS Applied Energy Materials 2019, 2 (9), 6170-6175. Yang, X.-Q.; McBreen, J.; Yoon, W.-S.; Grey, C. P., Crystal structure changes of LiMn0. 5Ni0. 5O2 cathode materials during charge and discharge studied by synchrotron based in situ XRD. Electrochemistry communications 2002, 4 (8), 649-654

LiMn0.5Ni0.5O2 has been plagued by the structural failure driven by the irreversible phase change upon subsequent cycling and the structural degradation caused by the seemingly unavoidable Li/Ni exchange. This begs for a better understanding of the correlation between lithium local structures, synthesis conditions, and overall electrochemical properties of materials. In this study, we use density functional theory (DFT) to assist experimental Li-6 solid-state magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy to understand the nature and change in lithium local structures with extended annealing times (168 vs 15 h) synthesized at 900 degrees C. To correlate the NMR peak changes after different synthesis conditions, we calculated the NMR spectra of representative low-energy model configurations of LiMn0.5Ni0.5O2 composition-zigzag, row, and flower structures-as well as the influence of Ni/Mn ordering and Li/Ni exchange on each spectrum using a supercell that is large enough to allow us to consider the effect of different relative configurations of adjacent transition metal (TM) layers. The analysis based on a combination of the calculated NMR and the experimental spectra suggests that most configurations contributing to the experimental spectra are in fact composed of a blend of configurations higher in energy than the classical well-ordered ground-state structures. The extended annealing of LiMn0.5Ni0.5O2 slightly enhances Ni/Mn and Li/Mn orderings while reducing the Li/Ni mixing ratio. This study shows how DFT calculations are crucial in providing a better understanding of the experimental characterization data and therefore local environments and domain structures in oxide materials, such as Li-ion battery cathodes.

A new Li-ion battery cathode, ‘LT-LiMn0.5Ni0.5O2’, where LT refers to its relatively low synthesis temperature (400 oC), has been identified. Electrochemical data indicate that Li/LT-LiMn0.5Ni0.5O2 cells operate between 5.0 and 2.5 V with good cycling stability, yielding a cathode capacity of 225 mAh/g. The electrochemical reactions occur in two distinct steps centered at ~3.75 V and ~4.7 V during charge, and at ~4.6 V and ~3.5 V during discharge. High-angle, annular-dark-field (HAADF) scanning-transmission electron microscopy (STEM) provide evidence that LT-LiMn0.5Ni0.5O2 consists of a unique, partially-disordered LiMn0.5Ni0.5O2 structure with predominant lithiated-spinel- and layered-like character. Structural analysis of LT-LiMn0.5Ni0.5O2 with synchrotron X-ray diffraction data shows, surprisingly, that lithiated-spinel and layered models with approximately 16% (~1/6) disorder between the lithium and manganese/nickel ions, yield an identical fit to the data, complicating the determination of the exact nature and level of disorder in each structural model. We believe that this is the first report of a Mn-stabilized, lithium-nickel-oxide spinel-related structure in which the redox reactions occur almost entirely on the nickel ions, with the likelihood that oxygen redox also contributes to some capacity above 4.7 V.

Ultrafiltration membranes, that respond to an external magnetic field and local temperature have been developed. Surface-initiated activator-generated electron transfer (AGET) atom transfer radical polymerization (ATRP) has been used to graft poly(N-isopropylacrylamide) (PNIPAm) from the surface of 300 kDa regenerated cellulose membranes. The polymerization initiator was selectively attached to the entire membrane surface, only the outer membrane surface or only the inner pore surface. A superparamagnetic nanoparticle was attached to the end of the polymer chain. The DI water flux as well as the flux and rejection of bovine serum albumin were investigated in the absence and presence of a 20 and 1000 Hz oscillating magnetic field. In an oscillating magnetic field, the tethered superparamagnetic nanoparticles can cause movement of the PNIPAm chains or induce heating. A 20 Hz magnetic field maximizes movement of the chains. A 1000 Hz magnetic field leads to greater induced heating. PNIPAm displays a lower critical solution temperature at 32 °C. Heating leads to collapse of the PNIPAm chains above their Lower Critical Solution Temperature (LCST). This work highlights the versatility of selectively grafting polymer chains containing a superparamagnetic nanoparticle from specific membrane locations. Depending on the frequency of the oscillating external magnetic field, membrane properties may be tuned.

Magnetically responsive ultrafiltration membranes were prepared by grafting poly(2-hydroxyethyl methacrylate) chains from the outer surface of 100-kDa regenerated cellulose ultrafiltration membranes. Surface-initiated atom transfer radical polymerization was used to graft the polymer chains. Grafting from the internal pore surface was suppressed by using glycerol as a pore-filling solvent during initiator immobilization at varied densities. Glycerol suppresses the initiator attachment to the pore surface. Polymerization times of up to four hours were investigated. Superparamagnetic nanoparticles were covalently attached to the chain end. Membrane performance was determined using bovine serum albumin and dextran as model solutes. Increasing the grafted polymer chain density and length led to a decrease in the permeate flux and an increase in the apparent rejection coefficient. In an oscillating magnetic field, movement of the grafted polymer chains led to a decrease in the permeate flux, as well as an increase in the apparent rejection coefficient of the model solutes.

To quench the thirst of ever-increasing demand for high energy and low-Co lithium-ion batteries (LIB), LiMn0.5Ni0.5O2 has received considerable attention as a promising alternative cathode. However, it has been plagued by the structural failure driven by the irreversible phase change upon subsequent cycling and the structural degradation caused by the unavoidable Li/Ni exchange.[i] This brings the importance of understanding the relation with lithium local environments and domains on overall electrochemical properties of materials. In this study, we have focused on two different samples, prepared by different annealing times (150 vs. 15 hours) to elucidate the change of local lithium surroundings and its sensitivity to the annealing time. We use a combination of 6Li solid-state magic angle spinning (MAS) nuclear magnetic resonance (NMR)[ii] and density functional theory (DFT)[iii] techniques to illuminate the impact of annealing time to the local lithium environment of LiMn0.5Ni0.5O2. Examination of NMR spectra reveals peak shift and intensity change, which is scrutinized by the assistance of DFT that is capable of deconvoluting the NMR spectra and obtain the corresponding local lithium environment. We compare the NMR spectra of the previously reported transition metal arrangements such as a zigzag, row, and honeycomb structures and describe the influence of Li/Ni exchange on the shape of the spectra. Overall, we combine the various computed-NMR spectra that show in close proximity to the experimental spectra, which provides new insights to understand the correlation between annealing time and local lithium environment for a promising LIB cathode design. [i] Ceder, G. et al., Phase Transitions in the LiNi0.5Mn0.5O2 System, Chem. Mater. 2007, 19, 7, 1790–1800 [ii] Grey, C. P. et al., NMR Studies of Cathode Materials for Lithium-Ion Rechargeable Batteries, Chem. Rev. 2004, 104, 4493−4512 [iii] Casas-Cabanas, M. et al., DFT-Assisted Solid-State NMR Characterization of Defects in Li2MnO3, Inorg. Chem. 2019, 58, 8347−8356

The effect of formation protocol was determined in tests using small pouch cells containing silicon-graphite/Li(Ni0.5Mn0.3Co0.2)O2 chemistry. The time for the formation protocol was either 13.2 or 186 h for the tested cells. It is demonstrated that the "fast" formation protocol produces cells with similar performance characteristics to that of the "slow" protocol. In addition, the solid-electrolyte interface layers from both formation protocols are stable and function analogously, albeit with different chemistry. The fast formation protocol may thus provide a more economical route to cell fabrication.

Membrane-based processes are attractive for treating oily wastewaters. However, membrane fouling due to the deposition of oil droplets on the membrane surface compromises performance. Here, real-time observation of the deposition of oil droplets by direct confocal microscopy was conducted. Experiments were conducted in dead-end and crossflow modes. Base NF 270 nanofiltration membranes as well as membranes modified by grafting poly(N-isopropylacrylamide) chains from the membrane surface using atom transfer radical polymerization were investigated. By using feed streams containing low and high NaCl concentrations, the grafted polymer chains could be induced to switch conformation from a hydrated to a dehydrated state, as the lower critical solution temperature for the grafted polymer chains moved above and below the room temperature, respectively. For the modified membrane, it was shown that switching conformation of the grafted polymer chains led to the partial release of adsorbed oil. The results also indicate that, unlike particles such as polystyrene beads, adsorption of oil droplets can lead to coalescence of the adsorbed oil droplets on the membrane surface. The results provide further evidence of the importance of membrane properties, feed solution characteristics, and operating mode and conditions on membrane fouling.

Large-scale production of biomass-derived fuels and chemicals requires the economical and efficient depolymerization of lignocellulosic biomass into sugars and fuels. Catalytic hydrolysis of raw wheat straw for the production of glucose was conducted using a designed porous membrane-based polymeric solid acid catalyst consisting of poly (ionic liquid) and polysulfonic acid chains. The catalyst demonstrated superior activity and selectivity with glucose yield reached over 50% from the un-pretreated raw straw. Under the optimal conditions, over 80% of cellulose and over 90% of xylan were converted to soluble sugars and furans with over 60% glucose or xylose yields reached respectively from pretreated straw biomass. Our catalyst demonstrates high glucose and total reducing sugar (TRS) yields from lignocellulosic biomass with promising application for the future lignocellulosic biorefinery.

The activators generated electron transfer (AGET) method coupled with atom transfer radical polymerization (ATRP) is shown to be a simple and well controlled approach for surface-initiated polymerization of 2-hydro-xyethyl methacrylate (HEMA) on regenerated cellulose (RC) membranes. The AGET-ATRP method has been optimized with respect to the initiator concentration, the polymerization reaction time and the reducing agent (activator) concentration. Control of polymer grafting on the external membrane surface versus the internal pore surface of RC ultrafiltration membranes was investigated using different pore filling solvents having a wide range of viscosity and reactivity during ATRP initiator immobilization via acylation of RC hydroxyl groups. The effectiveness of the pore filling solvent in limiting grafting inside the membrane pores was found to depend on both its viscosity and reactivity. Rejection of BSA and dextran was used to probe changes in pore size. Glycerol was found to be the most effective pore filling solvent, indicated by a significant degree of modification of the membrane surface with grafted polyHEMA but only a very minor increase in solute rejection.

Lignocellulosic biomass fractionation has been conducted using a synthetic polymeric solid acid catalyst consisting of dual polymer chains. The acidic polymeric chain, poly(styrene sulfonic acid) (PSSA) catalyzes biomass hydrolysis. A neighboring poly(vinyl imidazolium chloride) (PIL) chain helps solubilize lignocellulosic biomass and enhance the catalytic activity. Hydrolysis was conducted for crystalline cellulose and acid, base or steam pretreated corn stover samples in ionic liquids (IL) and mixtures of IL with H2O or gamma-valerolactone (GVL) or other organic solvents. Near quantitative total reducing sugar (TRS) yields for cellulose hydrolysis as well as pretreated corn stover biomass were achieved at mild conditions and in less than 12 h. Our designed polymeric solid acid catalysts are superior to cellulases as they can be operated at a higher temperature and at a much higher hydrolysis rate. These catalysts are stable and maintain high catalytic activity after repeated runs. Moreover, they can be easily regenerated and are environmental friendly.