Bipolar Battery

The bipolar battery essentially moves the series connections inside the cell. This brings a number of advantages and significant challenges.

This is shown very clearly in the Toyota battery technology roadmap [1].

Toyota image of a bipolar battery
Current Lithium-Ion cells in series (Monopolar) vs a Bipolar arrangement [1]

The expectation from Toyota is to deliver the following benefits in 2027-2028:

  • 10% cost reduction over a monopolar battery
  • Rapid charging time of 20 minutes or less for 10 – 80% SOC

Gambe et al [2] show the bipolar semi-solid state cell and manufacturered 2 and 3 layer bipolar cells in the lab that operated at 2x and 3x the voltage of the single layer device. Thus showing that it is possible to make asemi-solid state cell with a nominal voltage of ~10V.

bipolar solid state cell

The advantage is that you remove the need for external connections and some of the cell packaging. Reducing cost, package space and mass.

However, the challenges are significant [3, 4]:

  • mechanical sealing
  • electrical connections between bilayers
  • chemical stability
  • state of charge estimation
  • state of charge balance across cells within a bipolar cell
  • uniform temperature

This post has been built based on the support and sponsorship from: Thermo Fisher ScientificEatron TechnologiesAbout:Energy and Quarto Technical Services.


  1. Toyota sets out advanced battery technology roadmap, Toyota Media
  2. Gambe, Y., Sun, Y. & Honma, I. Development of Bipolar All-solid-state Lithium Battery Based on Quasi-solid-state Electrolyte Containing Tetraglyme-LiTFSA Equimolar ComplexSci Rep 5, 8869 (2015)
  3. P. Mohana Sundaram, Chhail Bihari Soni, Sungjemmenla, S.K. Vineeth, C. Sanjaykumar, Vipin Kumar, Reviving bipolar construction to design and develop high-energy sodium-ion batteries, Journal of Energy Storage, Volume 63, 2023
  4. The Breakthrough of Bipolar Batteries and Toyota’s Remarkable Achievement, Dr. Ivana Veljkovic, LinkedIn post

2 thoughts on “Bipolar Battery”

  1. It appears to me, naively, as parallel connection versus series connection of unit cells…if that’s the case, won’t single failure deactive teh entire bipolar assembly?

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