The heating triangle: A quantitative review of self-heating methods for lithium-ion batteries at low temperatures

Haijun Ruan, Jorge Varela Barreras, Marco Steinhardt, Andreas Jossen, Gregory J. Offer, Billy Wu

Research output: Contribution to journalReview articlepeer-review

3 Citations (Scopus)
9 Downloads (Pure)


Lithium-ion batteries at low temperatures have slow recharge times alongside reduced available power and energy. Battery heating is a viable way to address this issue, and self-heating techniques are appealing due to acceptable efficiency and speed. However, there are a lack of studies quantitatively comparing self-heating methods rather than qualitatively, because of the existence of many different batteries with varied heating parameters. In this work, we review the current state-of-the-art self-heating methods and propose the heating triangle as a new quantitative indicator for comparing self-heating methods, towards identifying/developing effective heating approaches. We define the heating triangle which considers three fundamental metrics: the specific heating rate (°C·g·J−1), coefficient of performance (COP) (−), and specific temperature difference (°C·hr), enabling a quantitative assessment of self-heating methods using data reported in the literature. Our analysis demonstrates that very similar metrics are observed for the same type of self-heating method, irrespective of the study case, supporting the universality of the proposed indicator. With the comparison insights, we identify research gaps and new avenues for developing advanced self-heating methods. This work demonstrates the value of the proposed heating triangle as a standardised approach to compare heating methods and drive innovation.

Original languageEnglish
Article number233484
Number of pages16
JournalJournal of Power Sources
Early online date22 Aug 2023
Publication statusPublished - 15 Oct 2023

Bibliographical note

This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (,
which permits unrestricted use, distribution, and reproduction in any medium,
provided the original work is properly cited.


This work was kindly supported by the Faraday Institution's Industrial Fellowship ( FIIF-013 ), the EPSRC Impact Acceleration Award ( EP/X52556X/1 ), the EPSRC Faraday Institution's Multi-Scale Modelling Project ( EP/S003053/1 , grant number FIRG003 ), the EPSRC Joint UK-India Clean Energy Centre (JUICE) ( EP/P003605/1 ), the EPSRC Integrated Development of Low-Carbon Energy Systems (IDLES) project ( EP/R045518/1 ), and by the German Federal Ministry for Economic Affairs and Energy (BMWi) ( 03 ET6153C iMoBatt ).


  • lithium-ion battery
  • Low temperature
  • Metrics
  • Preheating
  • Self-heating
  • Thermal management

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Physical and Theoretical Chemistry
  • Electrical and Electronic Engineering


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