This post is a detailed review and discussion of the paper “Monte-Carlo simulation combined with density functional theory to investigate the equilibrium thermodynamics of electrode materials: lithium titanates as model compounds” by Ozaki, Tada, and Kiyobayashi, published in 2019.

Lithium-titanate-oxide is an anode material whose open-circuit potential stays almost flat over the entire range of cycleable stoichiometry bounds:

Image from here

The paper answers the question: what is the physical explanation of LTO’s open-circuit voltage plateau?

This page is also a sequel of the page about electrode lithiation stages which focused on graphite anode.

LTO lattice structure

There are two flavours of anode lithium-titanate-oxide: Li_{1–2}Ti_2O_4 and…

We can apply the ideas from “Learning an Accurate Physics Simulator via Adversarial Reinforcement Learning” to cell simulation with electrical cell models, such as Thevenin equivalent circuit model:

  1. Make all model parameters (e. g., resistances and capacitances in an equivalent circuit model (ECM)) learned functions of the state (state-of-charge, temperature, etc.). …

Physical understanding of the open-circuit voltage relationship

When an electrode (graphite anode, in the examples below) has a certain amount of Lithium ions intercalated, they spread in the material in a regular pattern (more on why does this happen below):

Pictures above (adapted from Liu et al. [1]) illustrate graphite (brown lattice) with Lithium atoms (green balls) intercalated into it. At stage k, Lithium atoms are intercalated at every k-th layer of graphite. The left picture is stage 1 (LiC6), the right picture is stage 2 (LiC12).

Notice that at stage 1 (LiC6), not every “honeycomb cell” of the carbon layer has a Lithium atom on top…

This is the second post in a series about open source. The first one was “Capitalistic corporations don’t like diversity”.

Trustworthiness will become much more important than it is today

In 50 years from now, it’s likely that the world’s “economic activity” (I don’t like this term — I would rather call it more generically, “the activity of humans and human-created entities”) will mostly consist of information generation, exchange, and processing.

On the other hand, in the last 10 years, we saw more and more things appeared that undermine our trust in both the information that we receive and in the systems that collect, store, and process our data: deepfakes…

Positions pro and aganst consensus. Analogy between consensus decisions and ensemble learning.

In this post, I aggregate what different people wrote about consensus and compromise decisions.

Pro consensus

In his courses, Earl Beede calls consensus one of the good decision-making processes, alongside delegating decisions to implementers and “decider after a discussion”. Steve McConnell (the author of Code Complete and Software Estimation who works with Earl Beede at Construx Software) also suggests to try to find a “golden mean” third alternative in his paper “Managing Technical Debt” (see summary):

Teams often turn the technical debt decision into a simplistic “two option” decision — good path vs. quick and dirty path. Pushing through to a third…

Note: this article discusses diversity as a system property, and not workplace diversity as the title might also suggest.

Update: the second post in this series is “On trust, information inequality, and open source technology”.

I’m currently writing about my new view on open source. In this post, I discuss the ideas which prelude these views. This might be useful to keep in mind for the context.


Diversity is fundamentally valuable

To me, diversity has intrinsic aesthetic value. Diversity is beautiful.

If it doesn’t seem so to you, you can still appreciate that diversity is really important for sustainability and reliability in the long…

Focus on fast detection and response instead of trying to avoid failure

In a great interview in the Mindscape podcast by Sean Carroll, Niall Ferguson analyses the government response to COVID in the US and in Taiwan and concludes that for a system to be robust, it should rather be generally paranoid than very specifically prepared to particular threats (transcript, 0:33:31.6):

If you were a highly bureaucratic public health system that optimized for central control and risk minimization, as I think CDC, the Centers for Disease Control in the United States, did, your response to the news of a novel pathogen from Wuhan was in fact to make it harder to test…

In response to my article “Blockchain is not decentralised”, Garycris wrote:

While the developer’s are acting in their own best interest, if you buy into the philosophy of cryptocurrency, then your interests are pretty much aligned with them as well. At the end of the day cryptocurrency will not be successful because it is altruistic, it will be successful because it accepts the reality of human nature, which is that we have unlimited wants and limited resources. This results in greed and lack of trust. Cryptocurrency takes the emotion and judgement out of it.

I’m shocked and terrified by this…

I keep hearing an opinion that “Bitcoin (or any cryptocurrency, or blockchain in general) is decentralised”. It is presented as a “good” property of cryptocurrencies that distinguishes it from older fiat money such as US dollar. Most recently, by Balaji S. Srinivasan:

The people who complain most about filter bubbles are complaining about the plural: there was just one filter bubble they controlled, and now they’re annoyed there’s more than one. The complaint isn’t about filter bubbles, it’s about competing filter bubbles.

The answer isn’t reform, it’s radical decentralization. One component is citizen journalism, where everyone is a journalist, as…

In this post, I want to discuss some of David Deutsch’s positions from “The Beginning of Inifinity”.

“The Beginning of Infinity” is a bold, extremely optimistic hymn to science, and to the growth of human knowledge in general. In fact, one of the key propositions of the book is that the paradigm of seeking good explanations through creativity and criticism (which humanity has used in science since the Enlightenment with astonishing success) applies to art, philosophy, and history as well.

“The Beginning of Infinity” is a rare kind of book which I disagreed a lot with yet wanted to read…

Roman Leventov

Software engineer and designer, author. Working at Northvolt.

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