Review—Practical Challenges Hindering the Development of Solid State Li Ion Batteries

Abstract

Solid state electrolyte systems boasting Li + conductivity of >10 mS cm −1 at room temperature have opened the potential for developing a solid state battery with power and energy densities that are competitive with conventional liquid electrolyte systems. The primary focus of this review is twofold. First, differences in Li penetration resistance in solid state systems are discussed, and kinetic limitations of the solid state interface are highlighted. Second, technological challenges associated with processing such systems in relevant form factors are elucidated, and architectures needed for cell level devices in the context of product development are reviewed. Specific research vectors that provide high value to advancing solid state batteries are outlined and discussed. Solid state battery systems are of great interest because of potential benefits in gravimetric and volumetric energy density, operable temperature range, and safety in comparison to traditional liquid electrolyte based systems. However, unresolved fundamental issues remain in the quest to fully understand the behavior of all-solid batteries, especially in the area of electrochemical interfaces.1 There are also a number of significant engineering challenges that require methodical effort to enable a tangible product. Some transitions from academic laboratories to entrepreneurial efforts attempting to overcome these challenges remain unsuccessful in efforts to bring a product to the market.2,3 Vital parameters that require robust understanding from a product development standpoint are material cost, cell lifetime and shelf life, cell energy density on a volumetric and gravimetric basis, operable capabilities for given temperature conditions, and safety. The advantage of energy density remains to be realized in solid state electrolytes (SSEs) since most studies to date utilize thick SSEs or cathodes with low active loading compared to liquid counterparts. 4,5 Furthermore, the desire to use SSEs in conjunction with Li metal anodes requires understanding and managing the morphology of Li metal plating, which can impact volumetric energy density. Operation at both higher and lower temperature compared to conventional technologies is a significant potential advantage of SSE systems. However, reports of solid state cells achieving parity with traditional systems at room temperature or any other temperature do not currently exist. The safety, specifically decreased flammability, of SSE systems is another potential advantage but requires ongoing validation and study.6 Unlike current liquid electrolyte systems, 7 the manufacturability and material component costs of SSEs have not been well characterized, and thus the value of these features will need to be weighed accordingly with any added cost. Operating lifetime of SSEs capturing intrinsic materials parameters such as voltage stability, 8 as well as catastrophic failure modes such as shorting, 9 have been briefly investigated, but in the absence of high energy density electrode formulations and appli...

Investigation on the interface between Li10GeP2S12 electrolyte and carbon conductive agents in all-solid-state lithium battery

“…The organic liquid electrolyte used in conventional lithium-ion batteries usually acts as a fuel for the combustion in a thermal-runaway reaction, thereby leading to safety incidents 3 . On the other hand, ASSBs exploit non-flammable solid electrolytes, making them much more tolerant to reactions with such explosive natures, thus are regarded as the promising safe alternative to the current lithium-ion batteries 4–6 . However, employing solid-state electrolyte in the ASSBs accompanies several important technical issues that need to be addressed such as the necessity of finding solid-state fast ionic conductors whose ionic conductivity should be comparable to that of the liquid electrolyte and the careful interface control of the solid-solid contacts among the various components in the battery 7–9 .…”

Diffusion Limitation of Lithium Metal and Li–Mg Alloy Anodes on LLZO Type Solid Electrolytes as a Function of Temperature and Pressure

“…[12,13] In this context, Li 7 La 3 Zr 2 O 12 (LLZO) type garnet SEs [14] have attracted great attention as they combine high ionic conductivity with sufficient electrochemical stability against lithium metal, which prevents fast degradation and growth of a resistive interphase. [17,18] Lithium penetration through garnet-type SEs currently limits the possible charge rates. [17,18] Lithium penetration through garnet-type SEs currently limits the possible charge rates.…”

Synthesis and Properties of NaSICON‐type LATP and LAGP Solid Electrolytes

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Inorganic solid electrolytes, in comparison with their liquid counterparts, have more potential in varioust ypes of batteries due to their dual roles of ion transportation and separation. [7,8] In principle, ideal solid electrolytes are expected to have several features: [9][10][11][12][13][14] 1) fast ion dynamics and negligible electronic conductivity (minimum ionic conductivity of 10 À4 Scm À1 at room temperature for practical consideration);2 )a wide electrochemical potential window for battery cycling;3 )ane xceptional mechanical strength to suppress lithium dendrite growth;4 )excellent thermal stability during the cycling processes;and 5) asimple and low cost synthetic process for large-scale applications.Generally,i norganic lithium superionic conductors are divided into three categories:o xides, sulfides, and phosphates. Moreover,i norganic solid electrolytes are also beneficial for lithium-ion batteries and lithium-air batteries, in which they functiona se ither surface modification layers or lithium-ion conductors.

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