基于开尔文探针技术的磷酸铁锂表面势研究

依托新颖的表面表征技术开尔文探针力显微镜（KPFM）获悉磷酸铁锂表面势的情况，以期深入研究锂离子在磷酸铁锂表面的动力学行为。研究结果表明，磷酸铁锂薄膜在常温下的功函数为5.38 eV，并且其功函数随着外界温度的上升而呈现出逐渐下降的趋势，在80 ℃时的功函数为4.69 eV。此现象意味着高温状况下的磷酸铁锂具有较好的电子迁移能力。此外，非原位的开尔文探针检测发现不同电压平衡状态下的磷酸铁锂具有不同的表面功函数。充电至4.3 V时，磷酸铁锂功函数为4.91 eV，放电至2.5 V时，功函数稳定在5.01 eV。显然，磷酸铁锂的功函数非常敏感于表面的锂离子脱出量。研究从功函数的新角度探究磷酸铁锂表面的锂离子动力学行为，期望能够为其他储能材料的脱锂过程研究提供参考。

Study on surface potential of lithium iron phosphate based on kelvin probe technology

Based on the novel surface characterization technology，Kelvin probe force microscope（KPFM） was used to study the surface potential of lithium iron phosphate in order to further study the dynamic behavior of lithium ions on the surface of lithium iron phosphate.The results showed that the work function of lithium iron phosphate film was 5.38 eV at room temperature，and its work function was gradually decreased with the increase of external temperature，and when the temperature reached 80 ℃，the work function of lithium iron phosphate was 4.69 eV.It represented that lithium iron phosphate at high temperature had good electron mobility.In addition，ex situ Kelvin probe detection found that lithium iron phosphate had different surface work functions under different voltage equilibrium states.When it was charged to 4.3 V，the work function of lithium iron phosphate was 4.91 eV，and when it was discharged to 2.5 V，the work function of material was stable at 5.01 eV.It could be seen that the work function of lithium iron phosphate was very sensitive to the amount of lithium ion on the surface.This study was to explore the lithium ion dynamic behavior on the surface of lithium iron phosphate from a new perspective of work function.It was hoped to provide a reference for the study of lithium removal process of other energy storage materials.