| Rechargeable lithium ion batteries (LIBs), as one of the most important electrochemical energy storage (EES) devices, currently provide the dominant power source for a range of devices including portable electronic devices and electric vehicles due to their high energy and power densities. The interest in exploring new electrode materials for LIBs has been drastically increasing due to the surging demands for clean energy. However, the challenging issues essential to the development of electrode materials are their low lithium capacity, poor rate ability and low cycling stability, strongly limiting their practical applications. Recent remarkable advances in material sciences and nanotechnology enable rational design of heterostructured nanomaterials with optimized composition and fine nanostructure, providing new opportunities for enhancing electrochemical performance. Herein we propose the Nanoscale Engineering of Transition--Metal Chalcogenides/Hydroxides for Boosting Electrochemical Energy Storage. This dissertation provides some successful examples in designing new electrode materials for boosting EES. It puts special emphasis on the design and engineering of novel heterostructured electrode materials with reduced size, large surfaces area, excellent electrical conductivity, structural stability, fast electron and ion transport, which necessarily lead to enhanced EES performance in terms of high capacity, long cycling lifespan, and high rate durability. These engineered nanomaterials mainly take advantages of (1) novel uninstructive and morphology with large surface area, short ion diffusion path such as Fe3O4 and Fe2O3 nanoparticles (Chapter 2 and 3), Co-Ni oxide or hydroxide nanosheets (Chapter 4 and 5), and MoS2 nanosheets assembly (Chapter 6); (2) supporting carbon materials with intrinsic high electronic conductivity, high stability, tunable carbon porosity such as Fe 3O4 embedded in carbon matrix (Chapter 2), rGO wrapped Fe 2O3 nanoparticles (Chapter 3) and porous carbon bridged MoS 2 nanosheets (Chapter 6); (3) conducting polymer featuring with feasibility, light weight, large capacitance, good electric conductivity, ease of synthesis and low cost (Chapter 3); (4) special hybrid transition-metal compounds with synergistic effect from both components and offering better electrochemical properties over their single counterpart (Chapter 4). Nevertheless, these strategies may at the same time suffer from certain drawbacks pointed out in different chapters, bringing us with sophisticated challenges. |
