The effects of external compression on the performance and ageing of NMC(1/3)/Graphite single-layer Li-ion pouch cells are investigated using a spring-loaded fixture. The influence of pressure (0.66, 0.99, 1.32, and 1.98 MPa) on impedance is characterized in fresh cells that are subsequently cycled at the given pressure levels. The aged cells are analyzed for capacity fade and impedance rise at the cell and electrode level. The effect of pressure distribution that may occur in large-format cells or in a battery pack is simulated using parallel connected cells. The results show that the kinetic and mass transport resistance increases with pressure in a fresh cell. An optimum pressure around 1.3 MPa is shown to be beneficial to reduce cyclable-lithium loss during cycling. The minor active mass losses observed in the electrodes are independent of the ageing pressure, whereas ageing pressure affects the charge transfer resistance of both NMC and graphite electrodes and the ohmic resistance of the cell. Pressure distribution induces current distribution but the enhanced current throughput at lower pressures cell does not accelerate its ageing. Conclusions from this work can explain some of the discrepancies in non-uniform ageing reported in the literature and indicate coupling between electrochemistry and mechanics.

使用弹簧夹具研究了外部压缩对NMC（1/3）/石墨单层锂离子袋式电池性能和老化的影响。在新电池中表征了压力（0.66、0.99、1.32和1.98 MPa）对阻抗的影响，这些新鲜电池随后在给定的压力水平下循环。分析老化的电池在电池和电极水平的容量衰减和阻抗上升。使用并联的电池模拟在大型电池或电池组中可能发生的压力分布的影响。结果表明，动力学和传质阻力随新鲜电池中的压力而增加。已显示约1.3 MPa的最佳压力有利于减少循环过程中可循环锂的损失。在电极中观察到的较小的活性质量损失与老化压力无关，而老化压力会影响NMC和石墨电极的电荷转移电阻以及电池的欧姆电阻。压力分布会引起电流分布，但是在较低压力的电池中增强的电流通过量并不会加速其老化。这项工作的结论可以解释文献中报道的不均匀老化的一些差异，并表明电化学和力学之间的耦合。