Chloride-Reinforced Solid Polymer Electrolyte for High-Performance Lithium Metal Batteries

In Situ-Polymerized High-Entropy-Driven Solid Polymer Electrolyte for Safer Solid-State Lithium Metal Batteries

The most promising way to achieve scaled-up solid-state battery production is to use the in situ polymerization process, which inherits excellent interfacial contact and is compatible with existing battery manufacturing processes. However, the resulting solid polymer electrolytes suffer from poor oxidation stability and, thus, cannot match mainstream high-voltage cathodes. Herein, in situ-polymerized high-entropy-driven solid polymer electrolytes based on five cyclic ether structured monomers are designed for safer high-voltage solid-state lithium metal batteries. The constructed disordered alkyl chain with weakened solvation ability can effectively improve the voltage tolerance to 5.2 V and accelerate the segment motion of polymer chains, which induces the formation of an anion-derived LiBr-rich organic-inorganic hybrid passivation layer, achieving long-term cycling stability over 1000 h and deep cycling under 6.45 mA cm-2. The cells paired with polyanionic compounds or high-voltage layered oxides demonstrate excellent rate performance when charging to 100% state of charge in 7.5 min and long-term cycling stability for more than 700 cycles. A 287.13 W h kg-1 solid-state lithium metal pouch cell was fabricated with a capacity retention of 98.67% for 100 cycles, which provides an innovative strategy to realize large-scale application of safer solid-state batteries.

Phase-Transition-Promoted Interfacial Anchoring of Sulfide Solid Electrolyte Membranes for High-Performance All-Solid-State Lithium Battery

Solvent-free manufacturing is crucial for fabricating high-performance sulfide-electrolyte-based all-solid-state lithium batteries (ASSLBs), with advantages including side reaction inhibition, less contamination, and practical scalability. However, the fabricated sulfide electrolytes commonly suffer from brittleness, limited ion transport, and unsatisfactory interfacial stability due to the uncontrolled dispersion of the sulfide particles within the polymer binder matrix. Herein, a "solid-to-liquid" phase transition strategy is reported to fabricate flexible Li6PS5Cl (LPSCl) electrolytes. The polycaprolactone (PCL)-based binder (PLI) with phase-transition characteristics fills the gap of LPSCl particles and tightly grafts on the particle surface via ion-dipole interaction, bringing a thin and compact electrolyte membrane (80 µm). The simultaneously high Li-ion conducting and electron insulating nature of PLI binder facilitates Li-ion transport and ensures good interfacial stability between electrolyte and anode. Consequently, the sulfide electrolyte membrane exhibits high ionic conductivity (8.5 × 10-4 S cm-1), enabling symmetric and full cells with 10 and 2.5 times longer cycling life compared with that of the cells with pristine LPSCl electrolyte, respectively. The demonstrated strategy is versatile and can be extended to ethylene vinyl acetate copolymer (EVA) that also brings enhanced electrochemical performance. The thin sulfide electrolyte with high interfacial stability potentially facilitates dendrite-free ASSLBs with high energy density.

Polydopamine-Induced Metal-Organic Framework Network-Enhanced High-Performance Composite Solid-State Electrolytes for Dendrite-Free Lithium Metal Batteries

Due to the high safety, flexibility, and excellent compatibility with lithium metals, composite solid-state electrolytes (CSEs) are the best candidates for next-generation lithium metal batteries, and the construction of fast and uniform Li+ transport is a critical part of the development of CSEs. In this paper, a stable three-dimensional metal-organic framework (MOF) network was obtained using polydopamine as a medium, and a high-performance CSE reinforced by the three-dimensional MOF network was constructed, which not only provides a continuous channel for Li+ transport but also restricts large anions and releases more mobile Li+ through a Lewis acid-base interaction. This strategy endows our CSEs with an ionic conductivity (7.1 × 10-4 S cm-1 at 60 °C), a wide electrochemical window (5.0 V), and a higher Li+ transfer number (0.54). At the same time, the lithium symmetric batteries can be stably cycled for 2000 h at 0.1 mA cm-2, exhibiting excellent electrochemical stability. The LiFePO4/Li cells have a high initial discharge specific capacity of 153.9 mAh g-1 at 1C, with a capacity retention of 80% after 915 cycles. This paper proposes an approach for constructing three-dimensional MOF network-enhanced CSEs, which provides insights into the design and development of MOFs for the positive effects of high-performance CSEs.