The global automotive industry is currently undergoing a significant structural change where traditional internal combustion engines are slowly being replaced by more energy efficient and environmentally friendly electric powdered new energy vehicles consisting of pure battery electric vehicles plug-in hybrid vehicles, and hybrid vehicles commonly referred to as electric vehicles. By 2030, it is estimated global auto sales will exceed 125 million vehicles, of which EV global production will account for 30 million vehicles, representing a 23.8% market share.

One of the major material components used in the manufacturing of an EV is its power stack which acts as the unit drive train which powers the vehicle motion. The power stack is generally made up of a group of lithium-ion batteries as the main power source. Traditional liquid lithium-ion batteries are made up of several components, namely a cathode (positive electrode), anode (negative electrode) and separator. The separator is typically a polymeric membrane saturated with a liquid electrolyte that enables lithium ion transport but prevents direct contact between the electrodes.

There are several factors that affect the health and lifespan of Li-ion batteries. The performance degradation of Li-ion batteries can be characterised by the loss of either capacity (i.e., available energy) or power (i.e., reaction rate). Overheating of the batteries can lead to thermal runaway potentially causing fire and loss of life or property. Violent external collisions or squeezing of the battery could result in the liquid electrolyte leaking, leading to a short circuit with the battery cell.

The energy density of lithium-ion batteries is typically within the range of 100-265 Wh/kg. However traditional Li-ion batteries may not be able to satisfy the rising demand of high energy density for EV-Type Li-ion battery. According to China’s "Energy Conservation and New Energy Vehicle Technology Roadmap", the energy density targets for 2020, 2025, and 2030 are 300Wh/kg, 400Wh/kg, and 500Wh/kg, respectively. Japan, the United States, and other countries have EV-Type Li-ion battery energy density targets of 350Wh/kg or close to the limit energy density of liquid electrolyte Li-ion batteries.

As such, EV-Type Li-ion battery component companies are pushing towards next generation solid-state technology to improve safety, increase energy density, reduce the amount of raw materials required and reduce the battery cost.

Solid-State lithium-ion Battery

A solid-state lithium-ion battery uses a solid-state material as the electrolyte portion of the battery replacing the traditional liquid electrolyte.  All solid-state lithium-ion batteries are defined by a solid-state electrolyte and its anode material, which is commonly a solid lithium ion anode or solid lithium metal.

In terms of safety, solid-state Li-ion batteries are based on solid materials that are non-flammable, non-corrosive, non-volatile and free from leakage problems. In terms of energy density, solid-state batteries under conventional cathode and anode electrode systems are similar to that of traditional liquid Li-ion batteries. However, the compatibility potential of solid-state lithium batteries for high-capacity and high-voltage cathode and anode materials can make the electrochemical window reach more than 5V and potentially increase energy density up to 500Wh/kg.

Furthermore, without the requirement for liquid electrolyte and a separator, the internal space of the battery and battery weight are both reduced. The liquid electrolyte and a separator together occupy nearly 40% of the volume and 25% of the mass of traditional lithium-ion batteries. In addition, the battery case and cooling system modules can be simplified, further reducing the weight of the battery.

Solid-state Li-ion batteries can be divided into three types based on the electrolyte materials, namely polymers, oxides and sulfides. Polymers are an organic electrolyte and oxides and sulfides are inorganic electrolytes.

Solid-State Lithium-ion Battery Companies

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  • Executive Summary
  • Introduction
  • Solid-State Lithium-ion Batteries
  • Solid-State Electrolytes
  • Government Development Goals
  • Research and Development
  • Market Size and Potential
  • Global Competitiveness
  • Conclusion
  • Appendix: Solid-State Battery Company Profiles

[83 pages, published March 2020]