Engineering a passivating electric double layer for high performance lithium metal batteries

Abstract

In electrochemical devices, such as batteries, traditional electric double layer (EDL) theory holds that cations in the cathode/electrolyte interface will be repelled during charging, leaving a large amount of free solvents. This promotes the continuous anodic decomposition of the electrolyte, leading to a limited operation voltage and cycle life of the devices. In this work, we design a new EDL structure with adaptive and passivating properties. It is enabled by adding functional anionic additives in the electrolyte, which can selectively bind with cations and free solvents, forming unique cation-rich and branch-chain like supramolecular polymer structures with high electrochemical stability in the EDL inner layer. Due to this design, the anodic decomposition of ether-based electrolytes is significantly suppressed in the high voltage cathodes and the battery shows outstanding performances such as super-fast charging/discharging and ultra-low temperature applications, which is extremely hard in conventional electrolyte design principle. This unconventional EDL structure breaks the inherent perception of the classical EDL rearrangement mechanism and greatly improve electrochemical performances of the device.

Designing Anion-Derived Solid Electrolyte Interphase in a Siloxane-Based Electrolyte for Lithium-Metal Batteries

“…In sharp contrast, only Li 2 SO x components are found in the outer layer of the CEI formed in SiBE with LiNO 3 . After the addition of LiNO 3 , SiBE forms a stable CEI toward the LFP cathode, which demonstrates that LiNO 3 is capable of affecting the decomposition of electrolytes and improving the composition of the CEI to passivate it under high voltage. , …”

“…After the addition of LiNO 3 , SiBE forms a stable CEI toward the LFP cathode, which demonstrates that LiNO 3 is capable of affecting the decomposition of electrolytes and improving the composition of the CEI to passivate it under high voltage. 55,56 The stable and highly Li + -conductive inorganic SEI and CEI formed in SiBE also make it promising for practical Li||LFP batteries. Both large-excess Li-metal anodes and limited-excess Li-metal anodes were used to assemble the Li||LFP full cells.…”

Regulating Lithium Ion Transport by a Highly Stretchable Interface for Dendrite-Free Lithium Metal Batteries

“…Recently, numerous researchers are devoted to solving the lithium dendrite issues to enable the commercial application of LMBs. Effective strategies reported in the studies include the artificial solid–electrolyte interphase (ASEI), − Li metal hosts, − and liquid electrolyte engineering. − Among these approaches, the ASEI method has received great attention due to its tunability and effectiveness in performance improvement . Recently, the mechanical stability and chemical passivation of the ASEI have been studied extensively, which enables the ASEI to tolerate the volume change during cycling and reduce the risk of electron penetration to some extent .…”

Self-Healing Silicon Anode via the Addition of GaInSn-Encapsulated Microcapsules

“…For instance, a porous Si/C core–shell composite synthesized via self-corrosion reaction, rational annealing, and etching treatments delivers a reversible capacity of 1027.8 mAh g –1 after 500 cycles at 1 A g –1 . However, in the as-reported Si/C composite materials, the constructed electric diffusion channel may be broken once cracking and exfoliation occur. , Besides, these methods involve complicated processes, consume more energy, and are environmentally unfriendly − as they involve chemical vapor deposition and high carbonization temperatures. − Interestingly, additives, such as lithium difluoro­(oxalato)­borate (LiDFOB) and malonic acid-decorated fullerene (MA-C 60 ), are widely used in high-performance electrolytes to stabilize the electrode/electrolyte interface and prevent the degradation of electrode/electrolyte and finally enable LIBs with superior electrochemical performances. − Based on the beneficial functions of additives that could enhance stability, it is interesting and important to design additives that could tolerate the volume expansion and reform the electrical conduction pathways inside the Si anode.…”