Posts

Showing posts from March, 2020

Understanding Charging (充電)and Discharging (放電)

Image
Electrochemistry - using electricity to drive chemical reactions and then through chemical reactions to make electricity !!! One of the most difficult concepts I teach for electrochemistry class, is the concept of VOLTAGE, a.k.a. electric potential difference or some old text books call it "an electromotive force". If one considers a generic picture of a battery, consisting a negative electrode, a positive electrode and the electrolyte. Electrons flow (outside the battery) from the cathode (lithium transition metal oxide) to anode (graphite) during the charging of the battery, lithium ions flow from the cathode to the anode INSIDE the battery through the electrolyte. It may be intuitive for people to think the battery as a blackbox storing full of electrons - but such understanding is so conceptually inaccurate. Charging (when you plug in your phone) - you are using the electricity from to make chemical reactions in the battery. (Voltage will be raised during this process