From Solid-Solution Electrodes and the Rocking-Chair Concept to Today's Batteries.

Lithium-ion batteries (LIBs) have become ubiquitous power sources for small electronic devices, electric vehicles, and stationary energy storage systems. Despite the success of LIBs which is acknowledged by their increasing commodity market, the historical evolution of the chemistry behind the LIB technologies is laden with obstacles and yet to be unambiguously documented. This Viewpoint outlines chronologically the most essential findings related to today's LIBs, including commercial electrode and electrolyte materials, but furthermore also depicts how the today popular and widely emerging solid-state batteries were instrumental at very early stages in the development of LIBs.

In-Depth Interfacial Chemistry and Reactivity Focused Investigation of Lithium-Imide- and Lithium-Imidazole-Based Electrolytes.

A comparative and in-depth investigation on the reactivity of various Li-based electrolytes and of the solid electrolyte interface (SEI) formed at graphite electrode is carried out using X-ray photoelectron spectroscopy (XPS), chemical simulation test, and differential scanning calorimetry (DSC). The electrolytes investigated include LiX (X = PF6, TFSI, TDI, FSI, and FTFSI), dissolved in EC-DMC. The reactivity and SEI nature of electrolytes containing the relatively new imide (LiFSI and LiFTFSI) and imidazole (LiTDI) salts are evaluated and compared to those of well-researched LiPF6(-) and LiTFSI-based electrolytes.

Comprehensive Insights into the Reactivity of Electrolytes Based on Sodium Ions.

We report a systematic investigation of Na-based electrolytes that comprise various NaX [X=hexafluorophosphate (PF6 ), perchlorate (ClO4 ), bis(trifluoromethanesulfonyl)imide (TFSI), fluorosulfonyl-(trifluoromethanesulfonyl)imide (FTFSI), and bis(fluorosulfonyl)imide (FSI)] salts and solvent mixtures [ethylene carbonate (EC)/dimethyl carbonate (DMC), EC/diethyl carbonate (DEC), and EC/propylene carbonate (PC)] with respect to the Al current collector stability, formation of soluble degradation compounds, reactivity towards sodiated hard carbon (Nax -HC), and solid-electrolyte interphase (SEI) layer formation. Cyclic voltammetry demonstrates that the stability of Al is highly influenced by the nature of the anions, solvents, and additives. GC-MS analysis reveals that the formation of SEI telltales depends on the nature of the linear alkyl carbonates and the battery chemistry (Li(+) vs.

Hindered Glymes for Graphite-Compatible Electrolytes.

Organic carbonate mixtures are used almost exclusively as lithium battery electrolyte solvents. The linear compounds (dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate) act mainly as thinner for the more viscous and high-melting ethylene carbonate but are the least stable component and have low flash points; these are serious handicaps for lifetime and safety. Polyethers (glymes) are useful co-solvents, but all formerly known representatives solvate Li(+) strongly enough to co-intercalate in the graphite negative electrode and exfoliate it.

In-depth safety-focused analysis of solvents used in electrolytes for large scale lithium ion batteries.

To better rule out the complex fire risk related to large format lithium ion cells, a detailed and systematic evaluation, both at component and cell levels, could be an invaluable milestone. Therefore, combustion analysis was conducted for major single organic solvents and their mixtures used in lithium ion battery technology, both in oxygen rich and lean environments using a Tewarson calorimeter. Well controlled test conditions have enabled the determination of key parameters governing the fire induced hazards such as flash point, ease of ignition, heat release rate, effective heat of combustion, specific mass loss rate, as well as the assessment of fire induced toxicity.