Improving accessible Li-ion cathode capacity through morphological control

形态-功能关系已被成功地用于氧化物合成的许多领域，包括用于锂离子和钠离子领域的阴极材料。尽管NMC811的合成相对较新，但已有多种方法合成NMC811，包括水热法和溶胶凝胶法。虽然这些方法提供了一些对颗粒大小的控制，但它们没有提供对晶体形状的控制，这可以被用来帮助锂(脱)层，并倾向于产生严重团聚的颗粒。它们可能会出现破裂和无法接触到锂的区域，因此有空间通过控制微晶形状来改进这些类型的阴极，以将这些影响降至最低。生物模板，即使用生物衍生的长链聚合物来控制焙烧过程中的结晶，是一种能够实现这种形态控制的技术。这项技术已经成功地用于在各种氧化物中创建纳米和微米级结构。已经证明它可以控制颗粒形状，同时减少生产所需的能量，尽管这是没有针对性的形状控制。该项目将寻求通过使用生物模板和类似技术对NMC811和相关材料的微晶形态进行有针对性的控制来提高比容量和机械稳定性。特定的形状，如纳米线或中空多晶球体将被合成和表征。FutureCat的WP1和W3将为材料提供信息，并将很好地与WP5中电极的新制造相结合，该电极将寻找可扩展的一次或二次颗粒原料，以适应循环期间的体积变化。这也链接到其他项目，如CatMat和NEXGENNa，在这些项目中，类似的正极材料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的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.