论文标题
高尼克利阳性电极的降解模型：活性材料损失和可环锂对容量褪色的影响
Degradation model of high-nickel positive electrodes: Effects of loss of active material and cyclable lithium on capacity fade
论文作者
论文摘要
富含镍的分层氧化物已被广泛用作高能密度锂离子电池的正电极材料，但它们的降解严重影响了细胞性能，尤其是在高压和温度下。然而，由于复杂性和缺乏预测模型，尚未充分理解潜在的降解机制。在这里，我们在粒子水平上提出了一个模型，以描述相变为活性材料丢失（LAM），锂库存丢失（LLI）（LLI）（LLI）（LLI）（LLI）和抵抗力增加而引起的结构降解。然后将粒子降解模型纳入细胞级P2D模型中，以探索LAM和LLI对循环老化测试中容量褪色的影响。据预测，可环锂的损失（被困在降解的壳中）会导致负电极的化学计量范围的变化，但并不直接导致容量损失，而正阳性电极活性材料的损失则占据了可用细胞容量的淡出。通过退化的壳层的额外电阻进一步降低了给定电流速率的可用容量。电荷曲线的变化模式比常规容量效果曲线提供了更大维的信息，这有助于诊断降解模式。该模型已实施到Pybamm中，并作为开源代码提供。
Nickel-rich layered oxides have been widely used as positive electrode materials for high-energy-density lithium-ion batteries, but their degradation has severely affected cell performance, in particular at a high voltage and temperature. However, the underlying degradation mechanisms have not been well understood due to the complexity and lack of predictive models.Here we present a model at the particle level to describe the structural degradation caused by phase transition in terms of loss of active material (LAM), loss of lithium inventory (LLI), and resistance increase. The particle degradation model is then incorporated into a cell-level P2D model to explore the effects of LAM and LLI on capacity fade in cyclic ageing tests. It is predicted that the loss of cyclable lithium (trapped in the degraded shell) leads to a shift in the stoichiometry range of the negative electrode but does not directly contribute to the capacity loss, and that the loss of positive electrode active materials dominates the fade of usable cell capacity in discharge. The available capacity at a given current rate is further decreased by the additional resistance of the degraded shell layer. The change pattern of the state-of-charge curve provides information of more dimensions than the conventional capacity-fade curve, beneficial to the diagnosis of degradation modes. The model has been implemented into PyBaMM and made available as open source codes.
