高比容量负极/正极材料炭载体在锂/钠离子电池研究进展

Recent progress in the carbon-based frameworks for high specific capacity anodes/cathode in lithium/sodium ion batteries

  • 摘要: 随着对清洁能源需求的不断增加,二次离子电池已成为研究热点,开发具有高比容量的负极/正极材料尤为重要。合金化反应机制的硅、磷、锗、锡负极和硫正极材料存在较高的体积膨胀率,其中磷和硫较差的导电性以及可溶性中间产物的穿梭效应限制了实际应用。沉积/溶解机制的金属负极枝晶问题使其不能单独作为负极材料使用。炭材料由于其来源广泛以及优异的导电性常作为高比容量负极/正极材料的载体。本文从炭载体的比表面积、孔/空结构,电子/离子电导率、界面修饰和表面化学修饰的角度出发,综述了其在硅、磷、锗、锡、金属锂、金属钠负极,以及硫正极中的研究进展。

     

    Abstract: Secondary-ion batteries, such as lithium-ion (LIBs) and sodium-ion batteries (SIBs), have become a hot research topic owing to their high safety and long cycling life. The electrode materials for LIB/SIBs need to be further developed to achieve high energy and power densities. Anode/cathode active materials based on their alloying/dealloying with lithium, such as the anode materials of silicon, phosphorus, germanium and tin, and the cathode material of sulfur, have a high specific capacity. However, their large volume changes during charging/discharging, the insulating nature of phosphorus and sulfur, as well as the shuttling of polysulfides in a battery with a sulfur cathode decrease their specific capacity and cycling performance. The formation of dendrites in anodes during the deposition/dissolution of Li and Na leads to severe safety issue and hinders their practical use. Carbon materials produced from abundant natural resources have a variety of structures and excellent conductivity making them suitable host frameworks for loading high specific capacity anode/cathode materials. Recent progress in this area is reviewed with a focus on the factors affecting their electrochemical performance as the hosts of active materials. It is found that the mass loading of the active materials and the energy density of the batteries can be enhanced by increasing the specific surface area and pore volume of the carbon frameworks. Large volume changes can be efficiently accommodated using high pore volume carbon frameworks and a moderate loading of the active material. Suppression of the shuttling of polysulfides and therefore a long cycling life can be achieved by increasing the number of binding sites and their binding affinity with polysulfides by surface modification of the carbon frameworks. Dendrite growth can be inhibited by a combination of a high specific surface area and appropriate interface modification. Rate performance can be improved by designing the pore structure to shorten Li+/Na+ diffusion paths and increasing the electrical conductivity of the carbon frameworks. DFT calculations and simulations can be used to design the structures of carbon frameworks and predict their electrochemical performance.

     

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