Alloy anodes present promising alternatives to alkali metals in solid-state batteries but still face morphological instability upon cycling. Unlike conventional batteries using liquid electrolytes, interfacial evolution between solid-state electrolytes and alloy anodes is determined by interfacial electrochemistry and mechanics. Here, we adapt a classical chemomechanical model for Li metal to apply to alloy anodes. This allows generalizing a principle, namely, the hard and soft electrolytes and alloy anodes pairing principle, to guide improving morphological stability. Specifically, "hard" (high-shear-modulus) ceramic electrolytes should be paired with "harder" alloys, while "soft" (low-shear-modulus) polymer electrolytes favor "softer" alloys. We examine the chemomechanical properties of several Li-M alloys (M = Al, Mg, In, Sn, and Sb). Consistent with the principle, the "harder" Li-Sn anode exhibits a flattened morphology with the "hard" Li6PS5Cl electrolyte after cycling. Conversely, the "softer" Li-In anode evolves extremely rough, indicating Li-In dendrite formation. Our work underscores the significance of tuning alloy anode mechanical properties, incorporating well-established rules in traditional metallurgy.

Dendrite formation, contact loss, and continuous formation of the solid electrolyte interphase (SEI) preclude the practical use of the energy-dense lithium (Li) metal. Li–Ag alloys have the potential to address these issues due to their exceptional lithiophilicity, outstanding mechanical stability, and moderate chemical stability. This study evaluates all phases in the Li–Ag phase diagram based on lithiation capacity, Li insertion, mechanical property, and chemical stability. Our findings suggest that Li4Ag is the most promising phase, and the Gibbs free energy of nucleation (∆Gnucle) for Li–Ag alloys is 3 to 5 orders of magnitude smaller compared to pure Li, resulting in uniform nucleation and deposition behavior. We proposed practical applications within the Li4Ag phases or from the Li9Ag4 to the Li4Ag phases, which may provide a usable capacity of 409 to 696 mAh/g, respectively. Experiments indicate that Li4Ag exhibits not only the smallest impedance but also the highest capacity retention compared to Li9Ag4 and pure Li. The study provides valuable guidance for the selection and application of Li-containing alloys in future battery development.

Although hard carbon anodes are known to outperform alloys in conventional sodium-ion batteries, this trend is reversed in solid-state sodium batteries due to the different underlying sodiation processes. Whereas the sodiation of hard carbon is triggered by Na cation (Na+) adsorption onto electrochemically active sites, that of alloys is driven by solid-state diffusion of Na+ and successive Na-alloy phase transformations. Thus, sodiation processes critically depend upon the chemical nature of Na+, which is solvated in liquids but is bonded at lattice sites in solid electrolytes. In addition, elucidating charge-transport and charge-transfer processes as well as electromechanical coupling at solid/solid interfaces (for solid-state batteries) remains an unresolved challenge. The transition in knowledge from well-investigated solid/liquid interfaces to solid-state sodium batteries is not straightforward. The exploration of hard carbon, alloys, and their composites requires further advancement. This perspective aids in streamlining the research efforts of battery communities, thereby accelerating the development of solid-state sodium batteries.

Lithium (Li) metal batteries though with high energy density are still facing issues like Li dendrite growth, dead Li formation, and thick solid electrolyte interphase (SEI) formation, hindering their long-term stability. Recently, Li-Ag alloys have been reported to potentially address these challenges possibly due to their superior conductivity, lithiophilicity, and mechanical stability. In the pursuit of high-energy-density batteries, Li-Ag alloys typically employ a high Li content phase (γ1). In this study, we applied density functional theory (DFT) calculations to compare the thermodynamic stability, Li adsorption, and Li diffusion of Ag-rich Li-Ag alloy within the γ1 phase (AR-γ1), Ag-poor Li-Ag alloy within the γ1 phase (AP-γ1), and pure Li. AR-γ1 showed better thermodynamic stability and improved Li adsorption and diffusion properties compared to AP-γ1 and pure Li. Electrochemical tests further confirmed the advantages of AR-γ1 in terms of electrode kinetics and cell stability compared to AP-γ1 and pure Li. Our study offers guidance for the selection of the most suitable Li-Ag alloys that can be utilized in high-energy-density lithium batteries.

Resource‐ and energy‐efficient biomass exploitation for green graphite production is one of the most effective strategies for satisfying graphite demand while minimizing energy consumption and carbon emissions. This study investigated green graphite production from biomass waste and its applications to establish a green graphite industry. Biomass pyrolysis and catalytic graphitization of biochar were studied first to produce green graphite. The optimized green graphite exhibited a reversible capacity of 264 mA h/g and 97% capacity retention over 100 cycles in a half‐cell. Green graphite electrodes with a resistivity lower than 5 μΩ m were fabricated by using organic fraction bio‐oil as a green binder. Other green graphite applications, including printing, conductive printing, pencils, and refractories, were also achieved. The overall process of graphite anode and electrode synthesis from biomass waste and short‐rotation energy crops was modeled. Approx. 95 kg of battery graphite or 109 kg of metallurgical graphite electrodes can be produced per ton of biomass with low primary energy consumption and carbon footprint. Prominently, the modeling result and life cycle assessment demonstrated that, for the production of battery graphite from biomass waste, net‐negative‐CO 2 emissions (−0.57 kg CO 2 ‐eq/kg graphite powders) with net‐negative‐primary energy consumption (−28.31 MJ/kg graphite powders) was achieved.

Solid polymer electrolytes (SPE) have attracted a great deal of interest; however, their poor room temperature ionic conductivities still impede their practical application in lithium-ion batteries. Although the polymer blend is considered to be an effective strategy to improve ionic conductivity of SPEs, no quantitative model describing the ion conduction mechanism in polymer blends has yet been identified, and the interplay between the components has not been well elucidated. In this work, we focus on poly(ethylene oxide) (PEO)-based electrolytes blended with poly(methyl methacrylate) (PMMA) or poly(vinylidene fluoride) (PVDF) with systematically changed component ratios. A maximum ionic conductivity of 1.4 x 10(-4) S/cm at 30 degrees C is achieved by accelerated interfacial and segmental dynamics, together with decreased charge-concentrated layers, which promote ion concentration. We demonstrate that both segmental motion and interfacial polarization quantitatively determine ion conduction in polymer blends. Flory-Huggins interaction parameters unveil the thermodynamic interaction between the components and are directly related to the ionic conductivity of polymer blend electrolytes. Furthermore, the polymer blend enables viable applications of the SPE with fairly good ionic conductivity and allows the LFP||Li cell to deliver a discharge-specific capacity of similar to 113.5 mAh/g at 1 C and a capacity retention of similar to 70% after 100 cycles.

The global Sustainable Development Goals highlight the necessity for affordable and clean energy, designated as SDG7. A sustainable and feasible biorefinery concept is proposed for the carbon-negative utilization of biomass waste for affordable H2 and battery anode material production. Specifically, an innovative tandem biocarbon + NiAlO + biocarbon catalyst strategy is constructed to realize a complete reforming of biomass pyro-vapors into H2+CO (as a mixture). The solid residues from pyrolysis are upgraded into high-quality hard carbon (HCs), demonstrating potential as sodium ion battery (SIBs) anodes. The product, HC -16006h, exhibited great electrochemical performance when employed as (SIBs) anodes (full cell: 263 Wh/kg with ICE of 89%). Ultimately, a comprehensive process is designed, simulated, and evaluated. The process yields 75 kg H2, 169 kg HCs, and 891 kg captured CO2 per ton of biomass achieving approx. 100% carbon and hydrogen utilization efficiencies. A life cycle assessment estimates a biomass valorization process with negative-emissions (-0.81 kg CO2/ kg-biomass, reliant on Sweden wind electricity). A techno-economic assessment forecasts a notably profitable process capable of co-producing affordable H2 and hard carbon battery anodes. The payback period of the process is projected to fall within two years, assuming reference prices of 13.7 euro/kg for HCs and 5 euro/kg for H2. The process contributes to a novel business paradigm for sustainable and commercially viable biorefinery process, achieving carbon-negative valorization of biomass waste into affordable energy and materials.(c) 2023 The Author(s). Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC. This is an open access article under the CC BY license (http://creativecommons.org/ licenses/by/4.0/).

Solid-state lithium-metal batteries possess intrinsic advantages in terms of both safety and energy density. However, the fundamental origin of electrochemical lithium deposition heterogeneity in solid-state batteries is much less understood than that in lithium-metal batteries using a liquid electrolyte, partly due to the difficulties of directly mapping lithium-deposition reaction fronts and the associated changes in local stress of the solid-state electrolyte. Here, we trace the evolution of three-dimensional microscopic stress and demonstrate that the stress distribution is rather broad in a garnet solid-state electrolyte during processing and battery cycling using confocal Raman spectroscopy. We further discuss the effect of local stress variations on the overpotential of lithium deposition as the most likely origin of lithium-deposition heterogeneity in garnet systems. The ex situ stress-mapping tool developed in this work provides a strong basis for understanding the electromechanical effects, a prerequisite to fully unlock the potential of solid-state lithium-metal batteries.

The practical energy density of solid-state batteries remains limited, partly because of the lack of a general method to fabricate thin membranes for solid-state electrolytes with high ionic conductivity and low area-specific resistance (ASR). Herein, we use an ultrahigh concentration of a ceramic ion conductor (Na3SbS4) to build an ion-conduction “highway”, and a polymer (polyethylene oxide, 2 ​wt%) as a flexible host to prepare a polymer-in-ceramic ion-conducting membrane of approximately 40 ​μm. Without the use of any salt (e.g., NaPF6), the resulting membrane exhibits a threefold increase in electronic ASR and a twofold decrease in ionic ASR compared with a pure ceramic counterpart. The activation energy for sodium-ion transport is only 190 ​meV in the membrane, similar to that in pure ceramic, suggesting ion transport predominantly occurs through a percolated network of ion-conducting ceramic particles. The salt-free design also provides an opportunity to suppress dendritic metal electrodeposits, according to a recently refined chemomechanical model of metal deposition. Our work suggests that salt is not always necessary in composite solid-state electrolytes, which broadens the choice of polymers to allow the optimization of other desired attributes, such as mechanical strength, chemical/electrochemical stability, and cost.