Improving accessible Li-ion cathode capacity through morphological control

在氧化物合成的许多领域，包括锂离子和钠离子领域的阴极材料中，已经成功地利用了形态-功能关系。尽管它的发展相对较晚，但NMC811已经通过各种方法合成，包括水热和溶胶-凝胶。虽然这些方法对颗粒大小有一定的控制，但它们不能控制晶体形状，这可以用来帮助Li （de）相互作用，并且容易产生严重团聚的颗粒。这些阴极可能会出现裂纹和无法进入的锂区域，因此通过控制晶体形状来减少这些影响，这些类型的阴极还有改进的空间。生物模板，利用生物衍生的长链聚合物来控制煅烧过程中的结晶，是一种能够控制形态的技术。该技术已成功地用于在各种氧化物中创建纳米和微米级结构。它已被证明可以控制颗粒形状，同时减少生产所需的能量，尽管这没有目标形状控制。该项目将利用生物模板和类似技术，通过有针对性地控制NMC811和相关材料的晶体形态，寻求提高比容量和机械稳定性。具体的形状，如纳米线或空心多晶球将被合成和表征。FutureCat的WP1和3将提供材料的范围，并将与WP5的新型电极制造联系起来，WP5将寻求可扩展的初级或次级颗粒原料，以适应循环过程中的体积变化。这也与CatMat和NEXGENNa等其他项目相联系，在这些项目中，类似的阴极材料也可以从这些类型的合成方法中受益。我们将使用材料部门和谢菲尔德罗伊斯公司提供的合成、粉末放大和表征设施。

Morphology-function relationships have been successfully exploited in many areas of oxide synthesis, including for cathode materials across the Li and Na-ion fields. Despite its relatively recent development, NMC811 has been synthesised by a variety of methods including hydrothermal and sol-gel. Although these methods give some control over particle size, they offer no control of crystal shape, which could be exploited to aid Li (de)intercalaction, and tend to produce heavily agglomerated particles. These can suffer from cracking and areas of inaccessible Li, and so there is space for improvement of these types of cathode through control of crystallite shape to minimise these effects.Biotemplating, the use of biologically derived long-chain polymers to control crystallisation during calcination, is a technique which enables such control of morphology. The technique has been successfully used to create nano- and micron-scale structures in a wide variety of oxides. It has been shown to control particle shape whilst reducing the energy required for production, although this was without targeted shape control.This project will seek to improve specific capacity and mechanical stability through targeted control of crystallite morphology in NMC811 and related materials using biotemplating and similar techniques. Specific shapes e.g. nanowires or hollow polycrystalline spheres will be synthesised and characterised. There will be scope for materials to be informed by WP1 and 3 of FutureCat, and will link well into the novel manufacturing of electrodes in WP5 which will seek scalable primary or secondary particle feedstocks which can accommodate volume changes during cycling. This also links into other projects such as CatMat and NEXGENNa, where similar cathode materials could benefit from these types of synthesis methods. We will use the synthesis, powder scale-up and characterisation facilities available in the Materials department and the Royce at Sheffield.