In most types of batteries, primary and secondary, the metallic electrode is the anode, and a non-metal acts as cathode. Or a pure metal is the anode, and the cathode is a metal oxide.

Why is the opposite true in a lithium-ion battery?


This is not entirely true. Wikipedia lists several possible cathode materials and they are oxides. They may be "metallic" is the sense of being metallic conductors (some oxides are so), but they are ceramic compounds.

The anode is typically Li-intercalated carbon (which is also a good conductor). Lithium intercalates readily into carbon, allowing a safer and less side-reaction prone choice than pure lithium, whereas most other metals do not.

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  • $\begingroup$ Perhaps I should have said that the anode in most batteries is 'more metallic' than the cathode, with the opposite being true in a lithium-ion battery..... $\endgroup$ – Kurt Hikes Nov 17 '19 at 19:30
  • $\begingroup$ Then how do you define "more metallic"? $\endgroup$ – Oscar Lanzi Nov 17 '19 at 19:48
  • $\begingroup$ I don't agree that the cathode is more metallic. A Li-ion battery with a lithium metal anode is a common chemistry for primary batteries. $\endgroup$ – Mark Wolfman Jan 23 at 4:41

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