Chemo-mechanical failure mechanisms of the silicon anode in solid-state batteries

Abstract

Silicon is a promising anode material due to its high theoretical specific capacity, low lithiation potential and low lithium dendrite risk. Yet, the electrochemical performance of silicon anodes in solid-state batteries is still poor (for example, low actual specific capacity and fast capacity decay), hindering practical applications. Here the chemo-mechanical failure mechanisms of composite Si/Li6PS5Cl and solid-electrolyte-free silicon anodes are revealed by combining structural and chemical characterizations with theoretical simulations. The growth of the solid electrolyte interphase at the Si|Li6PS5Cl interface causes severe resistance increase in composite anodes, explaining their fast capacity decay. Solid-electrolyte-free silicon anodes show sufficient ionic and electronic conductivities, enabling a high specific capacity. However, microscale void formation during delithiation causes larger mechanical stress at the two-dimensional interfaces of these anodes than in composite anodes. Understanding these chemo-mechanical failure mechanisms of different anode architectures and the role of interphase formation helps to provide guidelines for the design of improved electrode materials.

Polymer design for solid-state batteries and wearable electronics

“…When not well matched, the mechanical stresses that arise from volume changes during cycling and reactive interfaces can also lead to delamination and capacity decay. 27 …”

“…These undergo especially large volume changes of up to 300% during charge–dischargecycles and thus require flexible electrolyte designs. 27 Ultimately, the significant hurdle limiting SPEs is the still struggling ion transport properties. Consequently, constructing composite solid electrolytes integrating polymeric and inorganic components to improve ionic conductivity and selectively is an attractive research direction.…”

Implementation of Different Conversion/Alloy Active Materials as Anodes for Lithium-Based Solid-State Batteries

“…They show that void formation in the μm scale during delithiation causes capacity fading over time. 13 Other emerging anode materials for LIBs are conversion/ alloy active materials (CAAMs, e.g., NiO, 14,15 CuO, 16,17 Fe 3 O 4 , 18,19 ZnO, 20,21 SnO 2 , 22,23 and mixed transition metal (TM) oxides 24−26 ). CAAMs are of particular interest due to their high theoretical capacities (e.g., q th (SnO 2 ) = 1494 mAh g −1 ), high lithium-ion diffusion coefficients, and low materials costs.…”

“…Furthermore, they provide a deep understanding of the chemomechanical failure mechanism of 2D sheet electrodes. They show that void formation in the μm scale during delithiation causes capacity fading over time …”

Intimate Protective Layer via Lithiation Sintering for All-Solid-State Lithium Metal Batteries

“…Lithium-ion batteries (LIBs), composed of graphite anodes and nickel-rich cathodes, have reached their theoretical energy density (250–300 Wh kg –1 ). − In addition, due to the recent fire accidents involving electric vehicles, concerns regarding the safety of flammable liquid electrolytes have emerged. − All-solid-state batteries (ASSBs) offer the potential for both increased energy density and enhanced safety. The solid-state nature of ASSBs has opened new avenues for the utilization of Li metals, which are challenging to employ in liquid electrolytes due to continuous electrolyte decomposition. − Although the solid electrolyte (SE) minimizes the surface area of Li metals for side reactions, repeated plating and stripping processes still generate interfacial voids between the Li metal and SE layers, thereby leading to increased local current densities and accelerated Li dendrite growth. Recent research highlighted that the interface passivation of SEs allows for Li metal plating and stripping in a 2-dimensional mode. − In this respect, the technology of protective layers for stabilizing interfaces has the potential to advance the feasibility of ASSBs paired with Li metal.…”