
Better lithium ion batteries, how do they work? Magnets - algirau
http://arstechnica.com/science/2016/07/better-lithium-ion-batteries-how-do-they-work-magnets/
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algirau
Explanation of claim: Magnetization of graphite makes lithium diffusion easier
in anode

Effect: Half-cell data shows energy capacity of anode increase up to 3X

What time means to real people: The anode is roughly 20% of the LiB, thus a 3X
increase in capacity would equate to 3x20% = 60% improvement in capacity of a
real battery.

My take: HORSESHIT

Why???? #1: Half-cell demonstrations, like this one, do not translate well as
the cathode used in pure-lithium metal, essentially providing an infinite
source of lithium. In a full-cell test you use a metal oxide with lithium-ions
pre-intercalated, essentially providing a limited source of lithium.
Unfortunately lithium gets eaten up in side reactions by the electrolyte and
the active material (SEI, solid-electrolyte-interphase). Thus infinite lithium
sources via half-cell testing are not good final test. They are only used for
screening.

Why??? #2: Tortuosity has NOTHING to do, albiet directly, with how much
lithium can intercalate with carbon in graphite. What it effects is the path
that lithium has to diffuse through the electrode - it effects
charge/discharge rates. Essentially, magnetization should charge/discharge
easier (i.e. at lower voltages) because the lithium can navigate easier
through the electrode. Why no reporting on C rate?

My take: I suspect what is happening is that the same charge/discharge rate
can be attained at a lower voltage because magnetization of graphite with iron
oxide additives make it easier for lithium to navigate in the electrode.
Because it is a lower voltage, less lithium is eaten up by electrolytes
breaking down in SEI. However, I'd bet you my mother's rusty ball-sack this
amounts to tiddlywinks when the lithium is limited in a full-cell battery.

Nice try but nothing matters with out full-cell testing, energy density
reporting AND cyclability reporting.

