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Silicon (Si) anodes suffer from huge volume changes leading to cracking and pulverization impacting the battery life. To deliver high energy and long-term stability, we present a unique and facile prelithiated silicon nano alloy (SiNA) material with lithium stearate as reagent. Structurally controlled SiNA (in this work Si -iron (Fe)-manganese (Mn) combination) design with active Si surrounded by inactive buffer matrix to reduce mechanical deterioration during expansions was synthesized using a low-cost and low-temperature process relying on mechanical milling. Prelithiation was accomplished to compensate for the initial irreversible loss by pre-feeding with the lithium reagent to form a protective artificial solid electrolyte interphase (SEI) and prefill the mechanical crack voids of the SiNA to improve the mechanical properties necessary for long-term cyclability. The approach was to mechanically mix SiNA with lithium stearate followed by heat treatment above the melting point of lithium stearate to allow its easy diffusion with the surface and mechanical voids of the SiNA. Prelithiated SiNA exhibited enhanced physicochemical properties and featured boosted mechanical integrity characterized by nanoindentation. In overall, prelithiated SiNA revealed excellent electrochemical properties and long-term cycling stability addressed at significantly high loading (∼2 mg cm−2) and over 250 cycles, demonstrating its transformable potential to high energy applications.

The electrochemical performance of a battery is considered to be primarily dependent on the electrode material. However, engineering and optimization of electrodes also play a crucial role, and the same electrode material can be designed to offer significantly improved batteries. In this work, Si–Fe–Mn nanomaterial alloy (Si/alloy) and graphite composite electrodes were densified at different calendering conditions of 3, 5, and 8 tons, and its influence on electrode porosity, electrolyte wettability, and long-term cycling was investigated. The active material loading was maintained very high (~2 mg cm−2) to implement electrode engineering close to commercial loading scales. The densification was optimized to balance between the electrode thickness and wettability to enable the best electrochemical properties of the Si/alloy anodes. In this case, engineering and optimizing the Si/alloy composite electrodes to 3 ton calendering (electrode densification from 0.39 to 0.48 g cm−3) showed enhanced cycling stability with a high capacity retention of ~100% over 100 cycles.

Solid polymer electrolytes (SPE) have gained a lot of attention recently due to their lower interfacial resistance with electrodes and high processability. However, these electrolytes still suffer from low ionic conductivity at room temperature. The lithium ion transfer within the polymer electrolyte is heavily dependent on polymer chain mobility, and one of the most efficient ways to enhance its ionic conductivity is by an addition of a filler that would prevent the polymer from crystallizing. In this work, we utilize nanoporous electrospun Li7La3Zr2O12 (LLZO) as fillers in polyethylene oxide(PEO)/bis(trifluoromethane)sulfonimide lithium (LiTFSI) polymer electrolyte. Nanoporous LLZO was synthesized by electrospinning LLZO precursor fibers followed by calcination. LLZO is one of the most popular inorganic solid electrolytes (ISE) due to its great electrochemical stability and high ionic conductivity. LLZO serves a multifunctional role of inhibiting polymer crystallinity as well as of providing an additional lithium ion transfer mechanism. The ultra-fine nanoporous particle morphology enhances the polymer chain mobility which has the potential to significantly improve the ionic conductivity of hybrid polymer electrolyte (HPE).

To enable the futuristic applications of Li-ion batteries, significant boost in energy density and tremendous improvement in safety is required. Ceramic solid state electrolytes (SSE) with fast Li-ion diffusion are a promising class of materials that can potentially change the scenario because of their superior thermal and chemical stabilities and a wider operational temperature window. Among the numerous different solid-state oxide materials, Li7La3Zr2O12(LLZO) has gained significant interest due to its high ionic conductivity, good compatibility with lithium metal and stability in air. The preparation of LLZO is mostly based on the conventional solid state syntheses or sol-gel method, in which powders are calcined usually at temperatures above 850 °C. These current synthesis routes generally require higher calcination temperatures and longer heating duration. In this work, we have reported spray-dried LLZO particles for the first time via a low-temperature calcination. Spray drying has allowed us to achieve a nanoporous LLZO precursor which was later calcined only at 450 °C for 4 hours to obtain the LLZO particles. The nanoporous spray-dried particles have aided in the sintering process because of higher surface energy, and thus has significantly reduced the calcination time and temperature. LLZO Pellets were prepared for further physical-chemical characterization. Electrochemical performance evaluation is also in order.

Flexible, portable electronics and wearable devices are on emergence in the market and are anticipated to be the next generation of electronics advancement. To embrace the device flexibility requirement, the demand for high energy density flexible batteries itself are heavily considered. In this work, structurally controlled and highly engineered Silicon-Iron metal alloy (Si Alloy) was designed as the core chemistry materials for high energy and cycle life, and hosted on flexible substrates to support bending without mechanical degradations. This design integration into a pouch cell confirmed excellent flexible anode properties delivering significantly high capacity and stable cycle life. The battery pouch was bend to ~1.7 cm radius position and over, and was still able to to easily light up different Light-Emitting Diodes (LEDs) ranging from 2 V (Red LED) – 3 V (Blue LED) showcasing its flexibility and bendability features. The results spectacle an enormous potential for high energy ultrathin flexible batteries design and project the capability of great technical innovation. Figure 1

The ever-growing demand for high capacity cathode materials is on the rise since the futuristic applications are knocking on the door. Conventional approach to developing such cathode relies on the lithium-excess materials to operate the cathode at high voltage and extract more lithium-ion. Yet, they fail to satiate the needs because of their unresolved issues upon cycling such as, for lithium manganese-rich layered oxides—their voltage fading, and for as nickel-based layered oxides—the structural transition. Here, in contrast, lithium-deficient ratio is demonstrated as a new approach to attain high capacity at high voltage for layered oxide cathodes. Rapid and cost effective lithiation of a porous hydroxide precursor with lithium deficient ratio is acted as a driving force to partially convert the layered material to spinel phase yielding in a multiphase structure (MPS) cathode material. Upon cycling, MPS reveals structural stability at high voltage and high temperature and results in fast lithium-ion diffusion by providing a distinctive solid electrolyte interface (SEI) chemistry—MPS displays minimum lithium loss in SEI and forms a thinner SEI. MPS thus offers high energy and high power applications and provides a new perspective compared to the conventional layered cathode materials denying the focus for lithium excess material.

A lignin/polyvinyl alcohol (lignin/PVA) composite membrane has been prepared as a separator for lithium-ion batteries (LIBs) using a simple, low-cost, environment-friendly, water-based method. Lignin is a low-cost, naturally occurring, widely abundant, sustainable, biodegradable, and biocompatible material. Polyvinyl alcohol (PVA) has good hydrophilicity, biocompatibility, chemical and thermal stability, mechanical strength, and abrasion resistance. PVA can serve as a host skeleton to draw fibers out of the lignin/PVA composite using a spinning method. In this work, Lignin and polyvinyl alcohol (PVA) were dissolved in water separately, and the water-based solution was mixed together to make the dope – from where the electrospun fibers were drawn to form a non-woven lignin/PVA membrane. A highly porous interpenetrating network structure resulted, which was revealed by scanning electron microscopy. Electrolyte compatibility, uptake tests, and contact angle measurements were examined with three different electrolytes focusing different anodes and supercapacitors, and they all showed favorable results. Thermal shrinkage test and thermogravimetric analysis showed high thermal stability and good flame retardant properties of the membrane. Electrochemical cycling performances were investigated comparing to commercial Celgard separator, using Li/Li(Ni1/3Mn1/3Co1/3)O2 electrodes, and they showed good results for lignin/PVA membrane. Rate performance and electrochemical impedance spectroscopy revealed high rate performance using the lignin/PVA membrane that is caused by its high ionic transport property. The lignin/PVA composite separator showed enhanced physical, thermal and electrochemical properties, and can be considered as a suitable separator for LIBs with graphite or silicon anodes, as well as for supercapacitors.

In this work, silicon alloy (Si-Fe-Mn) was pretreated with a number of lithium compounds and investigated on improvements in electrochemical properties for high efficiency and better capacity retention. The motivation was to prefill the cracks and any voids of the silicon alloy with lithium-based compounds, to avoid unnecessary solid electrolyte interface (SEI) reformations, and thus to dodge the capacity drains to a certain extent. Prelithiation was performed by simply heat treating the grounded mixture of silicon alloy and lithium compounds. The temperature for heat treatment was maintained slightly above the melting point of the lithium compound to allow diffusion into the cracks and voids of silicon alloy. Lithium stearate (C18H35LiO2), lithium carbonate (Li2CO3), lithium tetrafluoroborate (LiBF4), and lithium nitride (Li3N) were chosen for prelithiation. Investigations were performed by changing the chemicals and amount of the materials, heat treatment temperature, and the order of the processes. Out of which, silicon alloy with 5 wt.% lithium stearate treated at 300°C for 4 hours demonstrated the best electrochemical performance.

A high-performance lithium deficient Lix(Ni1/3Mn1/3Co1/3)O2 (xx(Ni1/3Mn1/3Co1/3)O2 cathode material. Energy dispersive spectroscopy and inductive coupled plasma – optical emission spectroscopy results confirmed the metal ratios and composition. High-resolution transmission electron microscopy and selective area electron diffraction data, from the cross section of the particle after focused ion beam milling, revealed the formation of a layered structure (space group: R-3m) in the core, and a mixed structure consist of spinel (space group: Fd-3m) and layered structure at the surface. Half cells (2032-type coin cell) made with commercial Lix(Ni1/3Mn1/3Co1/3)O2 (x>1.0, Umicore) (hereafter LPC) and MPC showed very high improvement in the rate capability and cycle performance for MPC which is attributed to the high voltage structural stability of the multiphase structure.