文献中:The working electrode potential is continuously increased from -250 to 1000 mV relative to the open circuit potential (OCP) at a scan rate of 1 mV/s in potentiodynamic tests. 这里面的相对于开路电位是什么意思?是极化曲线上的电压范围是-250 到1000mv 吗?为什么图上的却不是-250到1000呢?新手,求大家帮助。