Synthetic-Clay-Assisted Carrier Transport in Solid Polymer Electrolytes for Enhanced All-Solid-State Lithium Metal Batteries.

As a potential alternative to liquid organic electrolytes, solid polymer electrolytes provide good processability and interfacial properties. However, insufficient ionic conductivity limits its further development. To overcome these challenges, we propose the solution of synthetic clay Laponite as a filler in this work. Specifically, the ionic conductivity increases to 1.71×10-4  S cm-1 (60 °C) after adding 5 wt.% of Laponite to the PEO-LiClO4 system. The Laponite surface's negative charge enhances lithium ions dissociation and transport in the electrolyte: the lithium-ion transference number increases from 0.17 to 0.34, and the exchange current density increases from 46.84 µA cm-2 to 83.68 µA cm-2 . The improved electrochemical properties of composite electrolytes improve the symmetric cell's stability to at least 600 h. Meanwhile, the Li||LiFePO4 cells' rate and long-cycle performance are also significantly enhanced. This work's concept of Laponite filler demonstrates a novel strategy to enhance ion transport in polymer-based electrolytes for solid-state batteries.

Isolated Metalloid Tellurium Atomic Cluster on Nitrogen-Doped Carbon Nanosheet for High-Capacity Rechargeable Lithium-CO2 Battery.

Rechargeable Li-CO2 battery represents a sustainable technology by virtue of CO2 recyclability and energy storage capability. Unfortunately, the sluggish mass transport and electron transfer in bulky high-crystalline discharge product of Li2 CO3 , severely hinder its practical capacity and rechargeability. Herein, a heterostructure of isolated metalloid Te atomic cluster anchored on N-doped carbon nanosheets is designed (TeAC @NCNS) as a metal-free cathode for Li-CO2 battery. X-ray absorption spectroscopy analysis demonstrates that the abundant and dispersed Te active centers can be stabilized by C atoms in form of the covalent bond. The fabricated battery shows an unprecedented full-discharge capacity of 28.35 mAh cm-2 at 0.05 mA cm-2 and long-term cycle life of up to 1000 h even at a high cut-off capacity of 1 mAh cm-2 . A series of ex situ characterizations combined with theoretical calculations demonstrate that the abundant Te atomic clusters acting as active centers can drive the electron redistribution of carbonate via forming TeO bonds, giving rise to poor-crystalline Li2 CO3 film during the discharge process. Moreover, the efficient electron transfer between the Te centers and intermediate species is energetically beneficial for nucleation and accelerates the decomposition of Li2 CO3 on the TeAC @NCNS during the discharge/charge process.

Phase-locked constructing dynamic supramolecular ionic conductive elastomers with superior toughness, autonomous self-healing and recyclability.

Stretchable ionic conductors are considerable to be the most attractive candidate for next-generation flexible ionotronic devices. Nevertheless, high ionic conductivity, excellent mechanical properties, good self-healing capacity and recyclability are necessary but can be rarely satisfied in one material. Herein, we propose an ionic conductor design, dynamic supramolecular ionic conductive elastomers (DSICE), via phase-locked strategy, wherein locking soft phase polyether backbone conducts lithium-ion (Li+) transport and the combination of dynamic disulfide metathesis and stronger supramolecular quadruple hydrogen bonds in the hard domains contributes to the self-healing capacity and mechanical versatility. The dual-phase design performs its own functions and the conflict among ionic conductivity, self-healing capability, and mechanical compatibility can be thus defeated. The well-designed DSICE exhibits high ionic conductivity (3.77 × 10-3 S m-1 at 30 °C), high transparency (92.3%), superior stretchability (2615.17% elongation), strength (27.83 MPa) and toughness (164.36 MJ m-3), excellent self-healing capability (~99% at room temperature) and favorable recyclability. This work provides an interesting strategy for designing the advanced ionic conductors and offers promise for flexible ionotronic devices or solid-state batteries.

Expanding the active charge carriers of polymer electrolytes in lithium-based batteries using an anion-hosting cathode.

Ionic-conductive polymers are appealing electrolyte materials for solid-state lithium-based batteries. However, these polymers are detrimentally affected by the electrochemically-inactive anion migration that limits the ionic conductivity and accelerates cell failure. To circumvent this issue, we propose the use of polyvinyl ferrocene (PVF) as positive electrode active material. The PVF acts as an anion-acceptor during redox processes, thus simultaneously setting anions and lithium ions as effective charge carriers. We report the testing of various Li||PVF lab-scale cells using polyethylene oxide (PEO) matrix and Li-containing salts with different anions. Interestingly, the cells using the PEO-lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) solid electrolyte deliver an initial capacity of 108 mAh g-1 at 100 µA cm-2 and 60 °C, and a discharge capacity retention of 70% (i.e., 70 mAh g-1) after 2800 cycles at 300 µA cm-2 and 60 °C. The Li|PEO-LiTFSI|PVF cells tested at 50 µA cm-2 and 30 °C can also deliver an initial discharge capacity of around 98 mAh g-1 with an electrolyte ionic conductivity in the order of 10-5 S cm-1.

Understanding the Dual-Phase Synergy Mechanism in Mn2O3-Mn3O4 Catalyst for Efficient Li-CO2 Batteries.

Rechargeable Li-CO2 batteries have been receiving intense interest because of their high theoretical energy density and environmentally friendly CO2 fixation ability. However, due to the sluggish CO2 reduction/evolution reaction (CRR/CER) kinetics, the current Li-CO2 batteries still suffer from severe polarization and poor cycling stability. Herein, we designed and in situ synthesized sea urchinlike Mn2O3-Mn3O4 nanocomposite and explored the synergistic effect between Mn2O3 and Mn3O4 during charge-discharge process in Li-CO2 batteries. It is found that Mn3O4 can effectively promote the kinetics of CRR process, and Mn2O3 can induce the nucleation of Li2CO3 and promote its decomposition (CER). Benefiting from the dual-phase synergy, the Mn2O3-Mn3O4 cathode combines the respective catalytic advantages of the both and delivers a high full discharge capacity of 19 024 mAh g-1, a low potential gap of 1.24 V, and durable cycling stability (1380 h) at a current density of 100 mA g-1. Moreover, based on experimental results and density functional theory (DFT) calculations, a charge-discharge process model of the Mn2O3-Mn3O4 cathode was established to display the electrochemical reaction mechanism. We hope that this design strategy can encourage further studies for efficient cathode catalysts to accelerate the practical application of Li-CO2 batteries and even the metal-air batteries.