In this study, quantitative measurements of lithium ion concentrations in an operating lithium-ion battery (LIB) with a graphite anode were achieved using low-energy X-ray microscopy and nuclear magnetic resonance (NMR) spectroscopy. The concentration distributions of lithium ions inside the graphite anode and the separator were able to be investigated quantitatively. Higher discharge rates produced steep ion concentration gradients inside of the LIB. At a 3C discharge rate, the ion concentration reached 2.5 M inside the anode. However, it was observed that the lithium ion was depleted near the cathode and that the discharge stopped because of an increase of overvoltage. To investigate the validity of the measurement, the diffusion coefficient of ions was measured by NMR, and the lithium-ion flux was calculated from the concentration gradient. The results showed good agreement with the theoretical values obtained from the discharge rate, which indicates that ion transport phenomena in the electrodes of operating LIBs can be evaluated quantitatively with this combination of low-energy X-ray microscopy and NMR.

在这项研究中，使用低能X射线显微镜和核磁共振（NMR）光谱技术对带有石墨阳极的锂离子电池（LIB）的锂离子浓度进行了定量测量。可以定量研究石墨阳极和隔板内部锂离子的浓度分布。较高的放电速率会在LIB内部产生陡峭的离子浓度梯度。在3C的放电速率下，阳极内部的离子浓度达到2.5M。但是，观察到锂离子在阴极附近被耗尽并且由于过电压的增加而停止了放电。为了研究该测量的有效性，通过NMR测量离子的扩散系数，并从浓度梯度计算锂离子通量。