Edoardo Barcaro

Silicon-based anode offers a practical pathway to increase the energy density of the lithium-ion battery, yet substantial volume change during cycling necessitates a mechanical buffer to allow its use. Here, we systematically investigate the electrochemical compatibility of a CO2-derived crosslinked poly(carbonate-ether) solid polymer electrolyte with Si/C composite anode in solid-state battery. The CP-SPE achieves relevant mechanical strength, with maximum stress of 0.44 MPa and elongation at break of 95%, while maintaining an ionic conductivity of 0.5×10−4 S cm⁻1 at 60°C. Both differential capacity (dQ/dV) analysis and ex-situ X-ray diffraction (XRD) confirm the lithiation of the active material structure, with the apparent Li+ diffusion coefficient in the CP-SPE ranging from 10−17 to 10−10 cm2 s⁻1. We demonstrate that this elastomeric CP-SPE is compatible with silicon/carbon (Si/C) composite anode, delivering ~350 mAh g−1 in half cell with Coulombic efficiency (CE) exceeding 99.5% after 100 cycles at 60°C, and preserved electrode structural integrity as confirmed by post-cycling SEM. Building on this, a pre-lithiated Si/C is coupled with LiFePO4 (LFP) in a full-cell with N/P ratio of 1.07 that sustains operation from 0.05C to 0.3C at 60°C over 100 cycles. This work establishes the optimized CP-SPE as a viable elastomeric solid polymer electrolyte for silicon-based solid-state lithium-ion batteries, opening a route toward practical full-cell configurations.

The present battery technology includes fluorine in electrodes and electrolytes, which is one of the most challenging environmental issues, possibly leading to polyfluoroalkyl substances (PFAS) pollution. Herein, we investigate the features of a fully fluorine‐free battery using lithium iron phosphate (LiFePO ₄ , LFP) electrode, polyethylene oxide (PEO) binder, and lithium bis(oxalate)borate (LiBOB) salt. The salt is incorporated both in the electrode by environmental friendly aqueous processing, and in the electrolyte exploiting a glyme solvent. The electrolyte reveals conductivity higher than 1 × 10 ⁻³ S cm ⁻¹ from 60 to −2°C, lithium transference number ( t _{Li +} ) of 0.57, electrochemical stability extending from 0 to 4.3 V versus Li ⁺ /Li, low stripping/deposition polarization and interphase resistance. The electrode shows high crystallinity, adequate morphology and thickness, low tortuosity, and enhanced Li ⁺ ‐percolation, decreasing the cell polarization. Furthermore, the PEO binder and the absence of organic solvents during electrode preparation enable LFP loading as high as 13.6 mg cm ⁻² , with maximum discharge capacity at 3.5 V of ~160 mAh g ⁻¹ (2.15 mAh cm ⁻² ). Therefore, this work presents a viable design of new fluorine‐free water‐processed electrodes and boron‐based glyme electrolyte solutions, which are essential for the development of high‐performing rechargeable Li‐metal batteries (LMBs) having a low environmental impact.

A lithium battery benefits from the conversion reaction of a soluble polysulfide and a sulfur-based electrode. The battery with S-content from 4.5 to 6.5 mg cm⁻² achieves exceptional energy and power, from 700 W h kg_S ⁻¹ and 100 W kg_S ⁻¹ at 0.1C to 100 W h kg_S ⁻¹ and 35 kW kg_S ⁻¹ at 50C over 500 cycles.

Alternative configuration of lithium cell exploits electrode and polymer electrolyte cast all‐in‐one to form a membrane electrode assembly (MEA), in analogy to fuel cell technology. The electrolyte is based on polyethylene oxide (PEO), lithium bis‐trifluoromethane sulfonyl imide (LiTFSI) conducting salt, LiNO₃ sacrificial film‐forming agent to stabilize the lithium metal, and fumed silica (SiO₂) to increase the polymer amorphous degree. The membrane has conductivity ranging from ~5×10⁻⁴ S cm⁻¹ at 90 °C to 1×10⁻⁴ S cm⁻¹ at 50 °C, lithium transference number of ~0.4, and relevant interphase stability. The MEA including LiFePO₄ (LFP) cathode is cycled in polymer lithium cells operating at 3.4 V and 70 °C, with specific capacity of ~155 mAh g⁻¹ (1 C=170 mA g_LFP⁻¹) for over 100 cycles, without signs of decay or dendrite formation. The cell exploiting the MEA shows enhanced electrochemical performance as compared with the one using simple polymeric membrane stacked between cathode and anode. Furthermore, the MEA reveals the key advantage of possible scalability and applicability in roll‐to‐roll systems for achieving high‐energy lithium metal battery, as demonstrated by pouch‐cell application. These data may trigger new interest on this challenging battery exploiting the polymer configuration for achieving environmentally/economically sustainable, and safe energy storage.

A Li‐ion battery combines a cathode benefitting from Sn and MnO₂ with high sulfur content, and a lithiated anode including fumed silica, few layer graphene (FLG) and amorphous carbon. This battery is considered a scalable version of the system based on lithium‐sulfur (Li−S) conversion, since it exploits at the anode the Li‐ion electrochemistry instead of Li‐metal stripping/deposition. Sn and MnO₂ are used as cathode additives to improve the electrochemical process, increase sulfur utilization, while mitigating the polysulfides loss typical of Li−S devices. The cathode demonstrates in half‐cell a maximum capacity of ~1170 mAh g_S⁻¹, rate performance extended over 1 C, and retention of 250 cycles. The anode undergoes Li‐(de)alloying with silicon, Li‐(de)insertion into amorphous carbon, and Li‐(de)intercalation through FLG, with capacity of 500 mAh g⁻¹ in half‐cell, completely retained over 400 cycles. The full‐cells are assembled by combining a sulfur cathode with active material loading up to 3 mg cm⁻² and lithiated version of the anode, achieved either using an electrochemical pathway or a chemical one. The cells deliver at C/5 initial capacity higher than 1000 mAh g_S⁻¹, retained for over ~40 % upon 400 cycles. The battery is considered a promising energy storage system for possible scaling‐up in pouch or cylindrical cells.

Glyme‐based electrolytes for sodium‐sulfur (Na–S) batteries are proposed for advanced cell configuration. Solutions of NaClO₄ or NaCF₃SO₃ in tetraglyme are investigated in terms of thermal stability, ionic conductivity, Na⁺‐transference number, electrochemical stability, stripping‐deposition ability, and chemical stability in Na‐cells. Subsequently, versions of the electrolytes doped with fluoroethylene carbonate (FEC) are prepared using 0.5, 1, 2, or 3% additive weight concentrations, and evaluated by adopting the same approach used for the bare solutions. Scanning electron microscopy (SEM) provides morphological details of the passivation layer formed on the Na electrodes, while X‐ray photoelectron spectroscopy (XPS) sheds light on its composition. The most relevant achievement of the FEC‐added electrolyte is the suppression of the polysulfide shuttle in Na–S cells using a cathode with 70 wt.% of sulfur in the composite. This result appears even more notable considering the low amount of the additive requested for enabling the reversible cell operation. The solutions using 1% of FEC show the best compromise between cell performance and stability. Cyclic voltammetry (CV) displays the potential region related to the FEC electrochemical process responsible for Na–S cell operation. The understanding of the electrolyte features enables additional cycling tests using sulfur cathode with an optimized current collector, increased specific capacity, and coulombic efficiency.

A solid polymer electrolyte has been developed and employed in lithium‐metal batteries of relevant interest. The material includes crystalline poly(ethylene glycol)dimethyl ether (PEGDME), LiTFSI and LiNO₃ salts, and a SiO₂ ceramic filler. The electrolyte shows ionic conductivity more than 10⁻⁴ S cm⁻¹ at room temperature and approaching 10⁻³ S cm⁻¹ at 60 °C, a Li⁺‐transference number exceeding 0.3, electrochemical stability from 0 to 4.4 V vs. Li⁺/Li, lithium stripping/deposition overvoltage below 0.08 V, and electrode/electrolyte interphase resistance of 400 Ω. Thermogravimetry indicates that the electrolyte stands up to 200 °C without significant weight loss, while FTIR spectroscopy suggests that the LiTFSI conducting salt dissolves in the polymer. The electrolyte is used in solid‐state cells with various cathodes, including LiFePO₄ olivine exploiting the Li‐insertion, sulfur–carbon composite operating through Li conversion, and an oxygen electrode in which reduction and evolution reactions (i. e., ORR/OER) evolve on a carbon‐coated gas diffusion layer (GDL). The cells operate reversibly at room temperature with a capacity of 140 mA h g⁻¹ at 3.4 V for LiFePO₄, 400 mA h g⁻¹ at 2 V for sulfur electrode, and 500 mA h g⁻¹ at 2.5 V for oxygen. The results suggest that the electrolyte could be applied in room‐temperature solid polymer cells.