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    Solid-state batteries

    Also known as all-solid-state batteries, ASSB, solid-state lithium-metal batteries

    Solid-state batteries replace the liquid electrolyte of a lithium-ion cell with a solid one, promising higher energy density and better safety.[1] As of October 2026 they are at the pilot-line stage: Toyota, BYD and Samsung SDI target first vehicles or mass production in 2027-28, and QuantumScape opened its Eagle Line pilot in February 2026.[2][3][4]

    Editor reviewedUpdated Batteries and energy storageEnergy and climateScience
    Key facts

    What it is

    A conventional lithium-ion cell moves lithium ions through a liquid electrolyte.[5] A solid-state battery uses a solid electrolyte instead. The solid both conducts ions and acts as a physical barrier against dendrites, the lithium filaments that can short a cell.[1][6] That opens the door to a lithium-metal anode and to higher energy density and better safety than liquid-electrolyte cells.[1] QuantumScape’s design, for example, is a solid-state lithium-metal cell built around a ceramic separator.[7]

    Electrolyte families and their problems

    There are three main families, and each has a weak point. Sulfide electrolytes can still grow dendrites and have a limited electrochemical window. Oxides suffer high interfacial resistance against lithium metal. Polymers have limited ionic conductivity.[8] Toyota and Idemitsu chose sulfides because they are soft and stick well to other materials, which suits mass production.[9]

    Who is building them

    • Toyota and Idemitsu. In 2023 the two companies agreed to develop mass production of sulfide electrolytes, aiming to commercialise solid-state cars in 2027-28.[10] In early 2026 Idemitsu began building a pilot plant at Chiba with capacity of several hundred tons a year, due for completion at the end of 2027.[11]
    • BYD. BYD plans to sell its first all-solid-state EV from 2027 and to begin mass production from 2030.[2]
    • Samsung SDI. Samsung SDI targets mass production in the second half of 2027.[3]
    • QuantumScape. QuantumScape inaugurated its Eagle Line pilot on 4 February 2026. It also widened its licensing deal with PowerCo, Volkswagen Group’s battery company, and signed two further automakers.[4][12]

    Naming and standards

    In 2026 China’s National Automotive Standardization Technical Committee prepared a standard that separates liquid, hybrid solid-liquid and all-solid-state EV batteries, scheduled for July 2026.[13] The open questions are covered in the readiness debate.

    Questions readers ask

    What makes a battery "solid-state"?

    Its electrolyte, the material that carries ions between the electrodes, is a solid rather than a liquid. Researchers expect this to raise energy density and safety.[1]

    Why are they so hard to make?

    Each electrolyte family has a weakness. Sulfides can form dendrites and have a limited electrochemical window, oxides have high interfacial resistance with lithium metal, and polymers conduct ions poorly.[8]

    When will cars use them?

    Toyota plans its first all-solid-state vehicle by 2028, BYD plans one from 2027, and Samsung SDI targets mass production in the second half of 2027.[2][3]

    Are "semi-solid" batteries the same thing?

    No. China's 2026 standard separates hybrid solid-liquid batteries from all-solid-state ones.[13]

    Sources

    Each numbered claim is a statement we checked against the sources listed with it. Status shows how well established it is.

    1. [1]

      All-solid-state lithium batteries promise higher energy density and better safety than batteries with liquid electrolytes, partly because the solid electrolyte can act as a physical barrier to dendrites. confirmedas of 2024-04-01

    2. [2]

      The IEA reports that Toyota plans its first all-solid-state battery vehicle by 2028, and BYD plans to sell its first all-solid-state EV from 2027 with mass production from 2030. confirmedas of 2026-10-10

    3. [3]

      Samsung SDI targets mass production of all-solid-state batteries in the second half of 2027. reportedas of 2026-07-02

    4. [4]

      QuantumScape inaugurated its Eagle Line pilot production line, which uses its Cobra separator process, on 4 February 2026. confirmedas of 2026-02-11

    5. [5]

      During discharge, lithium atoms in the anode give up their electrons, and the lithium ions travel through the electrolyte to the cathode, where they recombine with electrons. confirmedas of 2026-10-10

    6. [6]

      Lithium-based batteries often fail because root-like dendrites of lithium metal grow on the anode, which stands in the way of combining high energy density with long cycle life in advanced designs such as lithium-sulfur. confirmedas of 2026-10-10

    7. [7]

      QuantumScape develops solid-state lithium-metal battery technology built around a proprietary ceramic separator. confirmedas of 2026-02-11

    8. [8]

      Each solid electrolyte family has a hurdle - sulfides suffer dendrite formation and a limited electrochemical window, oxides have interfacial resistance with lithium metal, and polymers have limited ionic conductivity. confirmedas of 2024-04-01

    9. [9]

      Idemitsu and Toyota chose sulfide solid electrolytes because their softness and adhesiveness to other materials suit mass production. confirmedas of 2023-10-12

    10. [10]

      In October 2023 Idemitsu Kosan and Toyota agreed to develop mass production of sulfide solid electrolytes, aiming to commercialise all-solid-state batteries for battery-electric vehicles in 2027-28. confirmedas of 2023-10-12

    11. [11]

      In early 2026 Idemitsu began building a solid electrolyte pilot plant at its Chiba site with capacity of several hundred tons a year, due for completion at the end of 2027. reportedas of 2026-02-03

    12. [12]

      QuantumScape expanded its collaboration and licensing arrangement with PowerCo, Volkswagen Group's battery company, and added two more global automakers under joint development agreements. confirmedas of 2026-02-11

    13. [13]

      China's National Automotive Standardization Technical Committee prepared a standard on solid-state EV battery terms and classification, separating liquid, hybrid solid-liquid and all-solid-state batteries, for release in July 2026. reportedas of 2026-02-11

    14. [14]

      The first sodium-ion battery electric car was introduced in China in late 2023, and the technology is now being scaled up. confirmedas of 2026-10-10

    15. [15]

      The University of Washington's Clean Energy Institute notes that multiplying today's battery deployments 100-fold would strain supplies of lithium, nickel and cobalt. confirmedas of 2026-10-10

    16. [16]

      According to SNE Research, CATL's share of global EV battery installations rose from 38.0% in 2024 to 39.2% in 2025, on 464.7 gigawatt-hours. confirmedas of 2026-02-04

    Revision history (1)
    1. Page created.

    Created Oct 10, 2026. Last reviewed by an editor on Oct 10, 2026. Next scheduled review: Jan 10, 2027.

    Cite this page

    "Solid-state batteries." ContentLora, updated Oct 10, 2026. https://contentlora.com/wiki/solid-state-batteries

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