含天然模板生物质制备多孔炭材料及其在高能锂电池中的应用

Rechargeable lithium sulfur battery and rechargeable lithium air (oxgen) battery, which are environmental friendly high energy batteries, have wide application prospects. The main challenges are their poor cycle life. Designing and preparing the porous carbon matrix, and then using them to fabricate highly effective reaction interface constitutes will play an important role to improve cell performance. In this study, based on the perfect structure of the biomass with natural templates, we are going to focus on developing novel porous carbons with favorable pore structure and surface composition which are effective for redox reaction in cathodes of lithium sulfur battery and rechargeable lithium air (oxgen) battery, revealing the forming process and mechanism of pore structure and surface functional groups, further developing the pore-creating model of the carbon materials using biomass with natural templates as precursor and establishing the theory in terms of this carbon microstructure formation. Influence of the specific energy, specific power, cycle life of lithium sulfur battery or lithium air battery on pore structure, degree of graphitization, functional groups of the carbon materials will be studied, and its energy storage behavior and mechanism will be revealed. Stable sulfur cathode and air cathode will be fabricated using these new carbon materials, by providing perfect interfaces of the electrochemical reaction in these two rechargeable batteries. Novel way to improve cycle performance of the lithium battery (lithium sulfur battery or lithium air battery) and its mechanism should be discovered. Through this item, a kind of novel materials for high energy lithium battery will be developed, and a new application field of the biomass (such as animal bone and scale) will be opened up.

锂硫和锂空（氧）气二次电池作为环境友好的新型高能电池体系，无疑具有广阔的应用潜力。目前它们实用化亟待解决的共性问题是循环稳定性差。通过新型炭材料的制备，构建出有利于高能锂电池（锂硫和锂空（氧）气电池）正极电化学反应的界面是提高锂电池性能的关键。本研究借助含天然模板生物质结构的优势，研究制备具有有效孔结构和高电化学活性表面组成的新型炭材料，揭示其孔结构和表面官能团的形成过程与机制，发展新型含天然模板生物质制备炭材料造孔过程模型和微观结构形成理论；研究锂硫电池和锂空（氧）气电池比能量、比功率和循环寿命与炭材料的孔结构、石墨化程度和表面官能团等物化性能之间关联规律，阐明其储能行为和炭材料作用机制；并以分别其制备出高能锂硫电池和锂空（氧）气正极，为其电化学反应构建新型优化界面，探求提高其循环性能新方法，揭示其机理。为高能锂二次电池正极开发新材料，为含天然模板生物质（动物骨和鳞等）开拓新的应用领域。

在高比能电池研究领域， 具有分级孔结构的炭材料优势显著，已成为目前研究热点。本项目采用食品加工废弃物鱼鳞等生物质为原料，借助其结构和组成的优势设计制备出具有分级孔结构炭材料，并用其改善了高比能电池电化学性能。具体工作包括：.第一，用含天然模板生物质（鱼鳞）制备了多孔炭材料，并对其炭化机制进行了研究。结果表明，碳化温度和活化剂用量对炭材料的孔结构和组成影响显著。所制炭材料比表面积可高达2732m2/g，且具有多级孔分布；同时可以实现N，S，O的掺杂。因此该方法可实现炭材料组成和结构的可控制备。.第二，用生物质设计制备了锂硫电池用高性能多孔炭及其复合材料。借助电化学测试、紫外分光光谱、X射线能量色散谱分析等手段，研究了不同结构和组成的多孔炭对硫正极动力学的影响及充放电反应机制。结果表明，应用所制备多孔炭添加到硫正极可实现首放容量为1612mAh g-1（0.1C），经50次循环后，容量保持率为73.6%。用该多孔炭设计制备非对称硫正极，在1C下，首放容量为 1426 mAh g-1；100次循环后，比容量仍保持990 mAh g-1，库仑效率高达97%。凭借蟹壳的组成和结构的优势，以蟹壳为原料，制备了Ca(OH)2/炭复合物，并以此改性了锂硫电池隔膜，有效地抑制了多硫化物溶解，提高了锂硫电池电化学性能。在1C倍率下，经200次循环，比容量仍保持在780 mAhg-1。.第三，采用含天然模板生物质蟹壳和鱼鳞制备了锂空电池正极用微孔炭材料，将它们与商用norit微孔炭材料进行了对比研究。结果表明，由于蟹壳基介孔炭丰富的介孔结构，为Li2O2的生成提供了充足的反应界面，从而显著提高了空气电极性能。蟹壳基介孔碳正极在100mA g-1恒流放电下，首次放电容量达6600 mAhg-1，且展示了小的电化学极化。较鱼鳞基炭材料及商用Norit炭材料优势显著。.这些研究结果为高比能锂电池开发新材料提供了理论依据，也将为含天然模板生物质有效利用开发新途径。.