Xiaoya Wang

Fluorinated-ethers are recognized as promising electrolyte solvents for high-voltage lithium metal batteries (HV-LMBs) due to their exceptional oxidation resistance and high reductive stability on anode. However, their oxidative and chemical stability are strongly influenced by the fluorination degree and α-hydrogen reactivity, which can easily be attacked by active oxygen species. Herein, a series of methyl-modified fluorinated-ethers on the acetal structure motif were designed and synthesized, and the fluorinated-ether featuring simultaneous trifluoromethyl and methyl substitution delivered outstanding electrochemical performances. With the designed fluorinated-ether of 1,1,1-trifluoro-2-(1-(2,2,2-trifluoroethoxy) ethoxy) ethane (TFEE), the electrolyte enabled highly reversible Li deposition/stripping, achieving an average Coulombic efficiency of 98.5% over 455 cycles. Li||LiNi0.8Co0.1Mn0.1O2 cells maintained 79.2% capacity retention after 410 cycles under 4.5 V, exceeding those containing non-methylated or monofluorinated ether analogs. Li||LiNi0.8Co0.1Mn0.1O2 pouch cell with 1 Ah theoretical capacity could stably cycle for 80 cycles with 79.6% capacity retention. This molecular design strategy provides new insights for developing advanced high-voltage electrolytes for next-generation LMBs.

Heterostructured cathodes are widely credited with accelerating conversion kinetics in magnesium/lithium hybrid-ion batteries (MLHBs). Here, we construct a Cu7S4/CuCo2S4 heterostructure in a single hydrothermal process, in which the two phases sharing a common Cu–S sublattice form a coherent interface within individual particles. By fixing the phase ratio independently through Rietveld refinement and benchmarking against both phase-pure constituents under identical conditions, we show that the composite exceeds the composition-weighted rule-of-mixtures prediction by a factor of 3.4 at 0.3 A g–1. Because the constituents exhibit closely comparable charge–discharge profiles, the redox chemistry itself is unchanged, and this strongly super-additive response can primarily originate from the interface rather than from composition. Elemental mapping and surface-sensitive XPS, together with the coexistence of Li2S and MgS in in situ XRD, further reveal that storage is spatially partitioned: Li+ converts the particle interior while Mg2+ reacts predominantly in the near-surface region, so that the two carriers occupy complementary regions of the same particle. Comparing APC-LiCl with APC-LiTFSI at matched salt concentration, and identical in every other respect, localizes the electrolyte effect to the electrode interface, where the chloride-containing system suppresses the progressive Mg-surface passivation that drives continuous overpotential growth in the TFSI– system. The resulting cell delivers 400 mAh g–1 at 0.3 A g–1 and retains 152.56 mAh g–1 after 330 cycles at 1.0 A g–1 at ∼100% Coulombic efficiency. DFT calculations indicate increased states near the Fermi level and a localized interfacial electrostatic gradient consistent with the measured kinetics.

Lithium-ion batteries (LIBs) with high energy density, as emerging energy-storage systems, rely on high-capacity electrode to drive the energy transition. Silicon (Si) has been considered as a promising alternative to graphite anodes due to its exceptional theoretical capacity, exhibiting enormous potential to meet the demand for high-energy-density energy storage. However, Si anodes are constrained by substantial volume expansion during lithiation, unstable solid electrolyte interphase (SEI), and poor electrical conductivity. To address these challenges, researchers have integrated the advantages of different materials to develop silicon/carbon (Si@C) composites as LIBs anodes, which offer a unique balance between structural toughness and electrochemical performance. Nevertheless, Si@C materials still face unsatisfactory structural stability, interfacial compatibility, and electrochemical kinetics during electrochemical cycling. Combined with recent research advances, this review summarizes and comparatively analyzes the mainstream preparation methods of Si@C composites. Based on the lithium storage mechanism of silicon, the multi-dimensional failure mechanisms of Si@C anodes are systematically clarified. Focusing on the key bottlenecks, including structural degradation, interfacial instability, inferior intrinsic conductivity, and industrial application limitations, current modification strategies are comprehensively reviewed and critically compared. Furthermore, the cutting-edge development trends of Si@C anodes are prospected, providing systematic theoretical support and technical guidance for future mechanism exploration, process optimization, and large-scale industrial applications.

Developing high-capacity and fast reaction kinetic sodium-ion (Na-ion) battery anodes still remains a big challenge. Here, a ternary heterostructure composite of NiS2/CoS2/CuS2 with hollow cubic structure configuration is developed by sulfurizing a NiCoCu-based prussian blue analog precursor. The ternary sulfides synergistically enhance electron/ion transport, while the hollow cubic morphology improves structural stability during cycling which is confirmed through in situ studies such as in situ Raman and X-ray diffraction. The NiS2/CoS2/CuS2 anode delivers a high capacity of 671 mAh g–1 after cycling 250 times under 0.5 A g–1, and it maintains 417 mAh g–1 after 900 cycles at 1 A g–1. The NiS2/CoS2/CuS2 anode-based full cell when paired with a NVP cathode achieves 310 mAh g–1 after 1000 cycles under 0.5 A g–1, displaying a good applicability potential. It is expected these findings are of great significance to develop long-life, high-capacity Na-ion batteries.

Layered oxides for sodium-ion batteries have attracted extensive attention from researchers due to their distinctive advantages. Nevertheless, for O3-type layered oxides with a high initial capacity, critical issues including excessive surface residual sodium, sluggish reaction kinetics, and poor long-term cycling stability remain to be urgently addressed. Herein, a novel wet in situ coating strategy using ammonium phosphomolybdate is proposed. The NFM@NH-Mo material derived from the coating modification of NaNi₁/₃Fe₁/₃Mn₁/₃O₂ (NFM) is endowed with a sodium-ion conductor group (SCG) coating layer. Various kinetic tests demonstrate that the SCG coating layer significantly facilitates the deintercalation and intercalation of Na⁺, leading to an approximate one-order-of-magnitude enhancement in the Na⁺ diffusion coefficient compared with pristine NFM. In addition, the consumption of surface residual sodium on NFM during the formation of the SCG coating layer effectively reduces the polarization of NFM@NH-Mo. Combined with the electrochemical performance of NFM@NH-Mo at 55 °C, which delivers a capacity retention of 83.10% after 100 cycles against only 70.51% for NFM, the SCG coating layer is proven to suppress the anisotropic stress variation of the NFM material and the side reactions between the active material and electrolyte, thus endowing the modified material with excellent cycling stability at elevated temperatures.