Interfacial self-healing polymer electrolytes for Long-Cycle silicon anodes in High-Performance solid-state lithium batteries.

For all-solid-state lithium-ion batteries (ASSLIBs), silicon (Si) stands out as an appealing anodes material due to its high energy density and improved safety compared to lithium metal. However, the substantial volume changes during cycling result in poor solid-state physical contact and electrolyte-electrode interface issues, leading to unsatisfactory electrochemical performance. In this study, we employed in-situ polymerization to construct an integrated Si anodes/self-healing polymer electrolyte for ASSLIBs. The polymer chain reorganization stems from numerous dynamic bonds in the constructed self-healing dynamic supermolecular elastomer electrolyte (SHDSE) molecular structure. Notably, SHDSE also serves as a Si anodes binder with enhanced adhesive capability. As a result, the well-structured Li|SHDSE|Si-SHDSE cell generates subtle electrolyte-electrode interface contacts at the molecular level, which can offer a continuous and stable Li+ transport pathway, reduce Si particle displacement, and mitigate electrode volume expansion. This further enhances cyclic stability (>500 cycles with 68.1 % capacity retention and >99.8 % Coulombic efficiency). More practically, the 2.0 Ah wave-shaped Si||LiCoO2 soft-pack battery with in-situ cured SHDSE exhibits strongly stabilized electrochemical performance (1.68 Ah after 700 cycles, 86.2 % capacity retention) in spite of a high operating temperatures up to 100 °C and in various bending tests. This represents a groundbreaking report in flexible solid-state soft-pack batteries containing Si anodes.

Steric molecular combing effect enables Self-Healing binder for silicon anodes in Lithium-Ion batteries.

Silicon is a promising anode material for lithium-ion batteries with its superior capacity. However, the volume change of the silicon anode seriously affects the electrode integrity and cycle stability. The waterborne guar gum (GG) binder has been regarded as one of the most promising binders for Si anodes. Here, a unique steric molecular combing approach based on guar gum, glycerol, and citric acid is proposed to develop a self-healing binder GGC, which would boost the structural stability of electrode materials. The GGC binder is mainly designed to weaken van der Waals' forces between polymers through the plasticizing effect of glycerol, combing and straightening the guar molecular chain of GG, and exposing the guar hydroxyl sites of GG and the carboxyl groups of citric acid. The condensation reaction between the hydroxyl sites of GG and the carboxyl groups of citric acid forms stronger hydrogen bonds, which can help achieve self-healing effect to cope with the severe volume expansion effect of silicone-based materials. Silicon electrode lithium-ion batteries prepared with GGC binders exhibit outstanding electrochemical performance, with a discharge capacity of up to 1579 mAh/g for 1200 cycles at 1 A/g, providing a high capacity retention rate of 96%. This paper demostrates the great potential of GGC binders in realizing electrochemical performance enhancement of silicon anode.

Design of a Dual-Electrolyte Battery System Based on a High-Energy NCM811-Si/C Full Battery Electrode-Compatible Electrolyte.

Rechargeable lithium-ion batteries using high-capacity anodes and high-voltage cathodes can deliver the highest possible energy densities among all electrochemical devices. However, there is no single electrolyte with a wide and stable electrochemical window that can accommodate both a high-voltage cathode and a low-voltage anode so far. Here, we propose that a strategy of using a hybrid electrolyte should be applied to realize the full potential of a Ni-rich LiNi0.8Co0.1Mn0.1O2 (NCM811)-silicon/carbon (Si/C) full cell by simultaneously achieving optimal redox chemistry at both the NCM811 cathode and the Si/C anode. The hybrid-electrolyte design spatially separates the cathodic electrolytes from anodic electrolytes by a Nafion-based separator. The ionic liquid electrolyte (LiTFSI-Pyr13TFSI) on the cathode side can stand high work potentials and form a stable cathodic electrolyte intermediate (CEI) on NCM811. Meanwhile, a stable solid electrolyte intermediate (SEI) and high cycling stability can also be achieved on the anode side, enabled by a localized high concentration of ether-based electrolytes (LiTFSI-DME/HFE). The decoupled NCM811-Si/C full cell exhibits excellent long-term cycling performance with ultrahigh capacity retention for over 1000 cycles, thanks to the synergy of the cathode-side and anode-side electrolytes. This hybrid-electrolyte strategy has been proven to be applicable for other high-performance battery systems such as dual-ion batteries (DIB).

Oxygen Defect Hydrated Vanadium Dioxide/Graphene as a Superior Cathode for Aqueous Zn Batteries.

Zinc ion batteries have become a new type of energy storage device because of the low cost and high safety. Among the various cathode materials, vanadium-oxygen compounds stand out due to their high theoretical capacity and variable chemistry valence state. Here, we construct a 3D spongy hydrated vanadium dioxide composite (Od-HVO/rG) with abundant oxygen vacancy defects and graphene modifications. Thanks to the stable structure and abundant active sites, Od-HVO/rG exhibits superior electrochemical properties. In aqueous electrolyte, the Od-HVO/rG cathode provides high initial charging capacity (428.6 mAh/g at 0.1 A/g), impressive rate performance (186 mAh/g even at 20 A/g), and cycling stability, which can still maintain 197.5 mAh/g after 2000 cycles at 10 A/g. Also, the superior specific energy of 245.3 Wh/kg and specific power of 14142.7 W/kg are achieved. In addition, MXene/Od-HVO/rG cathode materials are prepared and PAM/ZnSO4 hydrogel electrolytes are applied to assemble flexible soft pack quasi-solid-state zinc ion batteries, which also exhibit excellent flexibility and cycling stability (206.6 mAh/g after 2000 cycles). This work lays the foundation for advances in rechargeable aqueous zinc ion batteries, while revealing the potential for practical applications of flexible energy storage devices.