Interface Engineering via Manipulating Solvation Chemistry for Liquid Lithium-Ion Batteries Operated ≥ 100 °C.

High-performance and temperature-resistant lithium-ion batteries (LIBs), which are able to operate at elevated temperatures (i.e., >60 °C) are highly demanded in various fields, especially in military or aerospace exploration. However, their applications were  impeded by the poor electrochemical performance and unsatisfying safety issues, which was induced by the severe side reactions between electrolytes and electrodes at high temperatures. Herein, with the synergetic effects of solvation chemistry and functional additive in the elaborately designed weakly solvating electrolyte, a unique robust organic/inorganic hetero-interphase, composed of gradient F, B-rich inorganic components and homogeneously distributed Si-rich organic components, was successfully constructed on both cathodes and anodes, which would effectively inhibit the constant decomposition of electrolytes and dissolution of transition metal ions. As a result, both cathodes and anodes, without compromising their low-temperature performance, operate at temperatures ≥100 ℃, with excellent capacity retentions of 96.1 % after 500 cycles and 93.5% after ≥200 cycles, respectively, at 80 ℃. Ah-level LiCoO2||graphite full cells with a cut-off voltage of 4.3 V also exhibited superior temperature-resistance with a capacity retention of 89.9% at temperature as high as 120 ℃. Moreover, the fully charged pouch cells exhibited highly enhanced safety, demonstrating their potentials in practical applications at ultrahigh temperatures.

Upgrading the Separators Integrated with Desolvation and Selective Deposition toward the Stable Lithium Metal Batteries.

A practical and effective approach to improve the cycle stability of high-energy density lithium metal batteries (LMBs) is to selectively regulate the growth of the lithium anode. The design of desolvation and lithiophilic structure have proved to be significant means to regulate the lithium deposition process. Here, a fluorinated polymer lithiophilic separator (LS) loaded with a metal-organic framework (MOF801) is designed, which facilitates the rapid transfer of Li+ within the separator owing to the MOF801-anchored PF6 - from the electrolyte, Li deposition is confined in the plane resulting from the polymer fiber layer rich in lithiophilic groups (C─F). The numerical simulation results confirm that LS induces a uniform electric field and Li+ concentration distribution. Visualization technology records the behavior of regular Li deposition in Li||Li and Li||Cu cells equipping LS. Therefore, LS exhibits an ultrahigh Li+ transference number (tLi + = 0.80) and a large exchange current density (j0 = 1.963 mA cm-2). LS guarantees the stable operation of Li||Li cells for over 1000 h. In addition, the LiNi0.8Co0.1Mn0.1O2||Li cell equipped with LS exhibits superior rate and cycle performances owing to the formation of LiF-rich robust SEI layers. This study provides a way forward for dendrite-free Li anodes from the perspective of separator engineering.

Insights into the solvation chemistry in liquid electrolytes for lithium-based rechargeable batteries.

Lithium-based rechargeable batteries have dominated the energy storage field and attracted considerable research interest due to their excellent electrochemical performance. As indispensable and ubiquitous components, electrolytes play a pivotal role in not only transporting lithium ions, but also expanding the electrochemical stable potential window, suppressing the side reactions, and manipulating the redox mechanism, all of which are closely associated with the behavior of solvation chemistry in electrolytes. Thus, comprehensively understanding the solvation chemistry in electrolytes is of significant importance. Here we critically reviewed the development of electrolytes in various lithium-based rechargeable batteries including lithium-metal batteries (LMBs), nonaqueous lithium-ion batteries (LIBs), lithium-sulfur batteries (LSBs), lithium-oxygen batteries (LOBs), and aqueous lithium-ion batteries (ALIBs), and emphasized the effects of interactions between cations, anions, and solvents on solvation chemistry, and functions of solvation chemistry in different types of electrolytes (strong solvating electrolytes, moderate solvating electrolytes, and weak solvating electrolytes) on the electrochemical performance and redox mechanism in the abovementioned rechargeable batteries. Specifically, the significant effects of solvation chemistry on the stability of electrode-electrolyte interphases, suppression of lithium dendrites in LMBs, inhibition of the co-intercalation of solvents in LIBs, improvement of anodic stability at high cut-off voltages in LMBs, LIBs and ALIBs, regulation of redox pathways in LSBs and LOBs, and inhibition of hydrogen/oxygen evolution reactions in LOBs are thoroughly summarized. Finally, the review concludes with a prospective outlook, where practical issues of electrolytes, advanced in situ/operando techniques to illustrate the mechanism of solvation chemistry, and advanced theoretical calculation and simulation techniques such as "material knowledge informed machine learning" and "artificial intelligence (AI) + big data" driven strategies for high-performance electrolytes have been proposed.

Graphitic Carbon Quantum Dots Modified Nickel Cobalt Sulfide as Cathode Materials for Alkaline Aqueous Batteries.

Carbon quantum dots (CQDs) as a new class of emerging materials have gradually drawn researchers' concern in recent years. In this work, the graphitic CQDs are prepared through a scalable approach, achieving a high yield with more than 50%. The obtained CQDs are further used as structure-directing and conductive agents to synthesize novel N,S-CQDs/NiCo2S4 composite cathode materials, manifesting the enhanced electrochemical properties resulted from the synergistic effect of highly conductive N,S-codoped CQDs offering fast electronic transport and unique micro-/nanostructured NiCo2S4 microspheres with Faradaic redox characteristic contributing large capacity. Moreover, the nitrogen-doped reduced graphene oxide (N-rGO)/Fe2O3 composite anode materials exhibit ultrahigh specific capacity as well as significantly improved rate property and cycle performance originating from the high-capacity prism-like Fe2O3 hexahedrons tightly wrapped by highly conductive N-rGO. A novel alkaline aqueous battery assembled by these materials displays a specific energy (50.2 Wh kg-1), ultrahigh specific power (9.7 kW kg-1) and excellent cycling performance with 91.5% of capacity retention at 3 A g-1 for 5000 cycles. The present research offers a valuable guidance for the exploitation of advanced energy storage devices by the rational design and selection of battery/capacitive composite materials.

Porous Fe2O3 Modified by Nitrogen-Doped Carbon Quantum Dots/Reduced Graphene Oxide Composite Aerogel as a High-Capacity and High-Rate Anode Material for Alkaline Aqueous Batteries.

Carbon quantum dots (CQDs) as novel types of emerging materials have aroused tremendous attention in recent years. Herein, we report for the first time a new application of 3D CQD-based composite aerogels as excellent electrode materials for alkaline aqueous batteries. The scalable graphitic CQDs are prepared with high yields (>40%) and further utilized to fabricate the novel nitrogen-doped CQDs/reduced graphene oxide/porous Fe2O3 (N-CQDs/rGO/Fe2O3) composite aerogels with different contents of Fe2O3. Benefiting from the unique 3D network composite aerogel structure with a high surface area and hierarchical porous structure as well as the synergistic effect of high-capacity Fe2O3 and highly conductive and stable N-CQDs/rGO, the composite aerogels achieve enhanced electrochemical properties with ultrahigh specific capacity, admirable rate property, and superior cycling performance. Furthermore, the N-CQDs/rGO/Fe2O3-1 electrode (Fe2O3, 34.9 wt %) exhibits the best rate capability (72.1, 58.9, and 46.2% capacity retention at 5, 50, and 100 A g-1, respectively) and cycle performance (80.4% capacity retention at 3 A g-1 over 5000 cycles), while the N-CQDs/rGO/Fe2O3-3 electrode (Fe2O3, 62.3 wt %) displays the highest specific capacity (274.1 mA h g-1 at 1 A g-1). The current research provides a valuable guidance for developing high-performance 3D CQD-based composite aerogels for application in energy storage systems.

Facile synthesis of crystalline RuSe2 nanoparticles as a novel pseudocapacitive electrode material for supercapacitors.

Crystalline RuSe2 nanoparticles were prepared by a facile hydrothermal approach followed by thermal treatment, and utilized as a pseudocapacitive electrode material for supercapacitors for the first time, which exhibited a specific capacitance of 100.8 F g-1 at 0.2 A g-1 with good rate performance and superior cycle stability.