understanding of the material synthesis/ fabrication, interfacial behavior, and thermal-chemical stabilities are vital. [3] With electronic appliances requiring stable voltage delivery, the current LIBs employ graphite or mixtures with soft carbons (carbon black) to achieve stable performance at discharge curves. [4] Since 1991, various forms of ordered and disordered (i.e., soft and hard) carbon have been primarily used as anode materials. [5] With graphitic carbon, a compromise was identified, which delivered a theoretical maximum capacity of 372 mAh g −1 , while maintaining stability and cycling characteristics. This stability comes at a cost of battery capacity, as it takes six carbon atoms to bind a single lithium ion (LiC 6 ) during charging process. [6] By contrast, alternative anode materials such as silicon, can bind about four lithium atoms (SiLi 4.4 ), improving energy densities by an order of magnitude. [7] Silicon anodes have garnered huge attention as they provide over ten times more theoretical capacity (3579 mAh g −1 ) than graphite anode. Problematically, the intercalated Si, Li 3.75 Si, swells in volume by about 320% during charging. Such huge volumetric expansion causes large material stresses, resulting in anode cracking, fracturing, loss of electrical contact (delamination), unstable solid electrolyte interface (SEI) and even catastrophic cell failure. [8][9][10][11] Naturally, this is unacceptable for practical and industrial applications. To overcome the capacity limitations of carbon, and the mechanical limitations of silicon, manufacturers have moved into composite materials-with the primary structure consisting of graphitic carbon, with silicon nanoparticles implanted within. First reported by Yoshio and co-workers in 2002, the C/Si composites did improve capacity, but the silicon nanoparticles were difficult to merge with the carbon bulk. [12,13] After repeated cycling, it was found that the particles separate and capacity drops. [14] Li et al. reported fabrication of graphite-Si composite using polymer blends of poly(diallyl dimethyl-ammonium chloride) and poly(sodium 4-styrenesulfonate) to obtain capacity of 450 mAh g −1 with 95% capacity retention after 200 cycles. [15] Zhang et al. prepared core-shell structure (Si@C) using silicon nanoparticles (Si-NPs) and emulsion polymerization of acrylonitrile, followed by pyrolysis. [16] The composite [15] retained A composite anode material synthesized using silicon nanoparticles, micrometer sized graphite particles, and starch-derived amorphous carbon (GCSi) offers scalability and enhanced electrochemical performance when compared to existing graphite anodes. Mechanistic elucidation of the formation steps of tailored GCSi composite are achieved with environmental transmission electron microscopy (ETEM) and thermal safety aspects of the composite anode are studied for the first time using specially designed multimode calorimetry for coin cell studies. Electrochemical analysis of the composite anode demonstrates a high initial discharge capaci...

No abstract

Temperature rise in Lithium-ion batteries (LIBs) due to solid electrolyte interfaces breakdown, uncontrollable exothermic reactions in electrodes and Joule heating can result in the catastrophic failures such as thermal runaway, which is calling for reliable real-time electrode temperature monitoring. Here, we present a customized LIB setup developed for early detection of electrode temperature rise during simulated thermal runaway tests incorporating a modern additive manufacturing-supported resistance temperature detector (RTD). An advanced RTD is embedded in a 3D printed polymeric substrate and placed behind the electrode current collector of CR2032 coin cells that can sustain harsh electrochemical operational environments (acidic electrolyte without Redox, short-circuiting, leakage etc.) without participating in electrochemical reactions. The internal RTD measured an average 5.8 °C higher temperature inside the cells than the external RTD with almost 10 times faster detection ability, prohibiting thermal runaway events without interfering in the LIBs’ operation. A temperature prediction model is developed to forecast battery surface temperature rise stemming from measured internal and external RTD temperature signatures.

In situ replenishment of formation cycle lithium-ion loss is considered for the development of longer-lasting rechargeable batteries, containing a thin lithium reservoir-electrode to mitigate the formation cycle capacity loss. Synchronized lithium and lithium-ion batteries (SLLIB) deliver specific charge-discharge capacities of 147/145 mAh g-1 for mesocarbon microbeads (MCMB) versus LiFePO 4 and 186/171 mAh g-1 for C-Si versus LiNi 1/3 Mn 1/3 Co 1/3 O 2 at 0.2 C. The energy-reduced cells (due to solid electrolyte interface (SEI) formation) are replenished and achieved an increased energy density of

The 11B—19F spin–spin coupling constant in AgBF4 is shown to have an opposite sign in water from that found in a number of organic solvents. Application of the hypothesis of Bell and Danyluk indicates that it has a positive sign in water. Evidence is presented for association, probably in the form of solvent-separated ion pairs, in aqueous LiBF4 and NaBF4 solutions, and for the formation of more tightly bound ion pairs in solvents of lower dielectric constant. In contrast, there apparently is no solute association in AgBF4 solutions in water, DMSO, DMF, or acetonitrile. The pronounced changes observed in the 11B—19F coupling constant support the postulate that its small size is a result of near cancellation of large opposing terms.The collapse of the 10B—11B isotope shift at high temperatures in the 19F spectra of solutions of AgBF4 in acetonitrile and in acetone provides evidence for exchange of fluorine among boron atoms; a mechanism is proposed for this process.

This work provides an alternative solution to the challenge of battery recycling via the upcycling of spent lithium cobalt oxide (LCO) as a new promising solid lubricant additive. An advanced solid lubricant mixture of graphene, Aremco binder, and recycled LCO was formulated into a spray with the use of excess volatile organic solvent. Numerous flat steel disks were spray-coated with the new lubricant formulation and naturally dried followed by curing at 180 °C. When tested on a ball-on-disk up to 230 m in distance, the composite new solid lubricant reduced the coefficient of friction (COF) by 85% between two steel surfaces compared to unlubricated surfaces under a constant 1 GPa Hertzian pressure in an ambient environment. The tribofilm composition, particle size, and type of contact are identified as important parameters in the improvement of the COF. Scanning electron microscopy was used to study its morphology, and energy dispersive X-ray spectroscopy was used to analyze the composition of pristine and tested tribofilms. Upcycled spent low value LCO powder was used as a lubricant additive in tribology for the first time with exceptional lubricious properties.

Thermal safety is of prime importance for any energy-storage system. For lithium-ion batteries (LIBs), numerous safety incidences have been roadblocks on the path toward realizing high-energy-density next-generation batteries. Solutions, viz. electrolyte additives, shut-off separators, and exotic coatings, have limited scope in their operating voltage window, response time, and performance. Various temperature monitoring devices have been tested out with their limitations. Here, we report in situ sensing of thermal signatures from the anode of a typical LIB using an internal resistance temperature detector (RTD). Solid electrolyte interface (SEI) comprised of ROCO 2 Li, (CH 2 OCO 2 Li) 2 and ROLi is formed on the surface of a graphite anode, and its decomposition releases enormous heat during thermal runway events. Sensing the temperature from the anode gives direct access to the heat liberated in thermal runaway, including SEI decomposition related heat generation. External short circuit (ESC) and overcharge tests were conducted to trigger the thermal runaway event, and temperature of 36.4 and 48.4 °C were recorded using internal RTDs, which were 9 and 20 °C higher than with external RTD, respectively. Interestingly, internal RTD has detection ability for 90% temperature rise 14 times faster than compared to the external RTD. Modeling of simulated tests explained the occurrence of different regimes during thermal runaway events initialed by ESC and overcharge. Furthermore, multimode calorimetry (MMC) for LIB with internal RTD yielded more endothermic peaks beyond 150 °C due to the presence of three-dimensional (3D)-printed polylactic acid (PLA) support. Overall 1.75 kJ g −1 of generated heat was measured using MMC, which is significantly lower than LIB without an RTD sensor. The RTD-embedded assembly acts as a passive safety device while stationed inside the battery. Using thermal signatures from RTD, an advanced battery management system can lead to a conducive LIB, which would be a safer powerhouse for high-energy-density applications such as in the automotive industry and high-energy grid storage.

No abstract