Intrinsic Self-Healing Chemistry for Next-Generation Flexible Energy Storage Devices.

The booming wearable/portable electronic devices industry has stimulated the progress of supporting flexible energy storage devices. Excellent performance of flexible devices not only requires the component units of each device to maintain the original performance under external forces, but also demands the overall device to be flexible in response to external fields. However, flexible energy storage devices inevitably occur mechanical damages (extrusion, impact, vibration)/electrical damages (overcharge, over-discharge, external short circuit) during long-term complex deformation conditions, causing serious performance degradation and safety risks. Inspired by the healing phenomenon of nature, endowing energy storage devices with self-healing capability has become a promising strategy to effectively improve the durability and functionality of devices. Herein, this review systematically summarizes the latest progress in intrinsic self-healing chemistry for energy storage devices. Firstly, the main intrinsic self-healing mechanism is introduced. Then, the research situation of electrodes, electrolytes, artificial interface layers and integrated devices based on intrinsic self-healing and advanced characterization technology is reviewed. Finally, the current challenges and perspective are provided. We believe this critical review will contribute to the development of intrinsic self-healing chemistry in the flexible energy storage field.

Reversible Silicon Anodes with Long Cycles by Multifunctional Volumetric Buffer Layers.

Establishing a stable, stress-relieving configuration is imperative to achieve a reversible silicon anode for high energy density lithium-ion batteries. Herein, we propose a silicon composite anode (denoted as T-Si@C), which integrates free space and mixed carbon shells doped with rigid TiO2/Ti5Si3 nanoparticles. In this configuration, the free space accommodates the silicon volume fluctuation during battery operation. The carbon shells with embedded TiO2/Ti5Si3 nanoparticles maintain the structural stability of the anode while accelerating the lithium-ion diffusion kinetics and mitigating interfacial side reactions. Based on these advantages, T-Si@C anodes demonstrate an outstanding lithium storage performance with impressive long-term cycling reversibility and good rate capability. Additionally, T-Si@C//LiFePO4 full cells show superior electrochemical reversibility. This work highlights the importance of rational structural manipulation of silicon anodes and affords fresh insights into achieving advanced silicon anodes with long life.

Insights into interfacial effect and local lithium-ion transport in polycrystalline cathodes of solid-state batteries.

Interfacial issues commonly exist in solid-state batteries, and the microstructural complexity combines with the chemical heterogeneity to govern the local interfacial chemistry. The conventional wisdom suggests that "point-to-point" ion diffusion at the interface determines the ion transport kinetics. Here, we show that solid-solid ion transport kinetics are not only impacted by the physical interfacial contact but are also closely associated with the interior local environments within polycrystalline particles. In spite of the initial discrete interfacial contact, solid-state batteries may still display homogeneous lithium-ion transportation owing to the chemical potential force to achieve an ionic-electronic equilibrium. Nevertheless, once the interior local environment within secondary particle is disrupted upon cycling, it triggers charge distribution from homogeneity to heterogeneity and leads to fast capacity fading. Our work highlights the importance of interior local environment within polycrystalline particles for electrochemical reactions in solid-state batteries and provides crucial insights into underlying mechanism in interfacial transport.

Scalable submicron/micron silicon particles stabilized in a robust graphite-carbon architecture for enhanced lithium storage.

Silicon-carbon composite is recognized as one of the most promising next-generation anodes for high-energy lithium-ion batteries, especially silicon-graphite composites. Herein, cost-efficient and scalable submicron/micron silicon particles are stabilized in a robust graphite-carbon architecture by solid-phase ball milling and liquid-phase coating methods. The obtained silicon-graphite-carbon composite with a stable encapsulated sandwich-like architecture exhibits impressive lithium storage performance, including high initial Coulombic efficiency of 83.7%, outstanding cycle stability and remarkable rate capability. Even at high loadings of 4 mg cm-2, it still exhibits great reversible capacity with 620 mA h g-1 after 100 cycles at 0.2 C. Furthermore, 8 wt% silicon-graphite-carbon composites as additives are applied into the full cell with a designed capacity of 1000 mA h, and the full cell displays superior cycle stability with high capacity retention of 85% after 100 cycles. In addition, the scalable and low-cost preparation makes it enormous application value and huge commercial prospect.