Expired milk powder emulsion-derived carbonaceous framework/Si composite as efficient anode for lithium-ion batteries.

Anodes based on silicon/carbon composites promise their commercial prospects for next-generation lithium ion batteries owing to their merits of high specific capacity, enhanced ionic and electronic conductivity, and excellent compatibility. Herein, a series of carbonaceous framework/Si composites are designed and prepared by rational waste utilization. N, P codoped foam-like porous carbon/Si composites (FPC@Si) and N, P codoped carbon coated Si composites (NPC@Si) are fabricated by utilizing expired milk powder as a carbon source with facile treatment methods. The results indicate that the porous carbon skeleton and carbon shell can improve the conductivity of Si and stabilize the solid electrolyte interfaces to avoid direct contact between active material and electrolyte. Moreover, the influence of drastic volume expansion of Si on the anode can be efficiently alleviated during charge/discharge processes. Therefore, the Si/C composite electrodes present excellent long-term cycling stability and rate capability. The electrochemical performance shows that the reversible capacity of FPC@Si and NPC@Si can be respectively maintained at 587.3 and 731.2 mAh g-1 after 1000 charge/discharge cycles under 400 mA g-1. Most significantly, the optimized Si/C composite electrodes exhibit outstanding performance in the full cell tests, promising them great potential for practical applications. This study not only provides a valuable guidance for recycling of waste resources, but also supports a rational design strategy of advanced composite materials for high-performance energy storage devices.

Less is More: Trace Amount of a Cyclic Sulfate Electrolyte Additive Enable Ultra-Stable Graphite Anode for High-Performance Potassium-Ion Batteries.

Graphite can be successfully used as an anode for potassium-ion batteries (PIBs), while its conversion to KC8 leads to huge volume expansion, destruction of solid electrolyte interphase (SEI), and thus poor cycling stability. Incorporating additives into electrolytes is an economical and effective way to construct robust SEI for high-performance PIBs. Herein, we developed a series of sulfur-containing additives for PIB graphite anodes, and the impacts of their molecular structure and contents on the SEI are also systematically investigated. Compared with butylene sulfites and 1,3-propane sultone, the 1,3,2-dioxathiolane 2,2-dioxide (DTD) additive endows the graphite electrode (GE) with a higher reversible capacity, and better cycling stability in both the dilute potassium bis(fluorosulfonyl)imide (KFSI)- and potassium hexafluorophosphate (KPF6)-based carbonate electrolyte, as a result of a thinner and sulfate-enriched SEI. Moreover, the addition of a trace amount (0.2 wt %) DTD to the electrolyte can effectively protect the GE running over 800 cycles at 1 C. Excessive additives in the electrolyte will induce continuous SEI growth and render a rapid capacity fading of the GE. This strategy using the electrolyte additive paves the way for the design of novel PIB electrolytes and thus provides a great opportunity for commercial PIBs.

Metal-Organic Framework Confined Solvent Ionic Liquid Enables Long Cycling Life Quasi-Solid-State Lithium Battery in Wide Temperature Range.

Solid-state Li batteries are receiving increasing attention as a prospective energy storage system due to the high energy density and improved safety. However, the high interfacial resistance between solid-state electrolyte and electrode results in sluggish Li+ transport kinetics. To tackle the interfacial problem and prolong the cycle life of solid-state Li batteries, a quasi-solid-state electrolyte (QSSE) based on a solvate ionic liquid (SIL) space-restricted in nanocages of UIO-66 (SIL/UIO-66) is prepared in this study. Benefiting from the effective spatial confinement of the TFSI- by the pore UIO-66 and the strong chemical interactions between the SIL and metal atoms, SIL/UIO-66 QSSE exhibits high ionic conductivity and good compatibility with electrodes. As a result, Li|QSSE|LFP cells demonstrate excellent rate capability and cycle stability in a wide temperature range of 25-90 °C. This study provides a realistic strategy for the fabrication of safe solid electrolytes with excellent compatibility and long cycle life for high-performance QSSE Li-ion batteries.

Nitrogen-Doped Highly Photoluminescent Carbon Dots Derived from Citric Acid and Guanidine Carbonate.

A facile one-pot hydrothermal method for fabricating nitrogen-doped carbon dots (N-CDs) was developed by using citric acid as a carbon source and guanidine carbonate as a nitrogen and carbon source. X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectra indicated that the N-CDs were rich in elemental nitrogen. They had excellent stability in the presence of various salt concentrations and under UV irradiation. The N-CDs exhibited high quantum yields (52%), as well as down-conversion and up-conversion photoluminescence. The N-CD photoluminescence was quenched in the presence of Hg2+, while nearly no intensity changes were observed when in the presence of Na+, Mg2+, Mn2+, Zn2+, Ni2+, Cu2+, Ba2+, Cd2+ or Ca2+. The binding constant (KSV) and detection limit were also determined.

Nitrogen and sulfur co-doped graphene aerogel for high performance supercapacitors.

The development of high energy density and power density supercapacitors is very necessary in energy storage and application fields. A key factor of such devices is high-performance electrode materials. In this work, nitrogen and sulfur co-doped graphene aerogels (N/S-GA) were synthesized using graphene oxide as the precursor and 2-mercapto-1-methylimidazole as both the reducing agent and the N/S doping agent. The pore size distribution of the as-prepared N/S-GA was measured and the N/S-GA possesses a hierarchical porous structure. As an electrode material of supercapacitors, the N/S-GA could provide a suitable structure for charge accommodation and a short distance for ion transport. When 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF4) ionic liquid was used as the electrolyte, the specific capacitance of the N/S-GA electrode material reached 212 F g-1 and 162 F g-1 at the current densities of 1 A g-1 and 10 A g-1, respectively. And the energy density and average power density of the N/S-GA based supercapacitor could reach 117 W h kg-1 and 1.0 kW kg-1 at 1 A g-1, 82 W h kg-1 and 9.5 kW kg-1 at 10 A g-1, respectively. It is believed that the N/S-GA material can be used in high-performance supercapacitors.