TE
TechEcho
Home24h TopNewestBestAskShowJobs
GitHubTwitter
Home

TechEcho

A tech news platform built with Next.js, providing global tech news and discussions.

GitHubTwitter

Home

HomeNewestBestAskShowJobs

Resources

HackerNews APIOriginal HackerNewsNext.js

© 2025 TechEcho. All rights reserved.

Better lithium ion batteries, how do they work? Magnets

2 pointsby algiraualmost 9 years ago

1 comment

algiraualmost 9 years ago
Explanation of claim: Magnetization of graphite makes lithium diffusion easier in anode<p>Effect: Half-cell data shows energy capacity of anode increase up to 3X<p>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.<p>My take: HORSESHIT<p>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.<p>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&#x2F;discharge rates. Essentially, magnetization should charge&#x2F;discharge easier (i.e. at lower voltages) because the lithium can navigate easier through the electrode. Why no reporting on C rate?<p>My take: I suspect what is happening is that the same charge&#x2F;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&#x27;d bet you my mother&#x27;s rusty ball-sack this amounts to tiddlywinks when the lithium is limited in a full-cell battery.<p>Nice try but nothing matters with out full-cell testing, energy density reporting AND cyclability reporting.