Anode-less all-solid-state batteries: recent advances and future outlook

While all-solid-state batteries have built global consensus with regard to their impact in safety and energy density, their anode-less versions have attracted appreciable attention because of the possibility of further lowering the cell volume and cost. This perspective article summarizes recent research trends in anode-less all-solid-state batteries (ALASSBs) based on different types of solid electrolytes and anticipates future directions these batteries may take. We particularly aim to motivate researchers in the field to challenge remaining issues in ALASSBs by employing advanced materials and cell designs

Rationally Designed Solution-Processible Conductive Carbon Additive Coating for Sulfide-based All-Solid-State Batteries

Sulfide-based all-solid-state batteries (ASSBs) have emerged as promising candidates for next-generation energy storage systems owing to their superior safety and energy density. A conductive agent is necessarily added in the cathode composite of ASSBs to facilitate electron transport therein, but it causes the decomposition of the solid electrolyte and ultimately the shortening of lifetime. To resolve this dilemmatic situation, herein, we report a rationally designed solution-processible coating of zinc oxide (ZnO) onto vapor-grown carbon fiber as a conductive agent to reduce the contact between the carbon additive and the solid electrolyte and still maintain electron pathways to the active material. ASSBs with the carbon additive with an optimal coating of ZnO have markedly improved cycling performance and rate capability compared to those with the bare conductive agent, which can be attributed to hindering the decomposition of the solid electrolytes. The results highlight the usefulness of controlling the interparticle contacts in the composite cathodes in addressing the challenging interfacial degradation of sulfide-based ASSBs and improving their key electrochemical properties

Room-Temperature Anode-Less All-Solid-State Batteries via the Conversion Reaction of Metal Fluorides

All-solid-state batteries (ASSBs) that employ anode-less electrodes have drawn attention from across the battery community because they offer competitive energy densities and a markedly improved cycle life. Nevertheless, the composite matrices of anode-less electrodes impose a substantial barrier for lithium-ion diffusion and inhibit operation at room temperature. To overcome this drawback, here, the conversion reaction of metal fluorides is exploited because metallic nanodomains formed during this reaction induce an alloying reaction with lithium ions for uniform and sustainable lithium (de)plating. Lithium fluoride (LiF), another product of the conversion reaction, prevents the agglomeration of the metallic nanodomains and also protects the electrode from fatal lithium dendrite growth. A systematic analysis identifies silver (I) fluoride (AgF) as the most suitable metal fluoride because the silver nanodomains can accommodate the solid-solution mechanism with a low nucleation overpotential. AgF-based full cells attain reliable cycling at 25 degrees C even with an exceptionally high areal capacity of 9.7 mAh cm(-2) (areal loading of LiNi0.8Co0.1Mn0.1O2 = 50 mg cm(-2)). These results offer useful insights into designing materials for anode-less electrodes for sulfide-based ASSBs.N

Elastic Binder for High-Performance Sulfide-Based All-Solid-State Batteries

Sulfide-based all-solid-state batteries (ASSBs) offer en-hanced safety and potentially high energy density. Particularly, an"anode-less"electrode containing metallic seeds that form a solid-solution with lithium was recently introduced to improve the cycle life ofsulfide-based ASSB cells. However, this anode-less electrode is graduallydestabilized because the metal particles undergo severe volumeexpansion during repeated cycling. Furthermore, the irreversibility ofthe electrode in early cycles impairs the energy density of the cellsignificantly. Herein, we introduce an elastic polymer known as"Spandex"as a binder for the silver-carbon composite. The soft andhard segments of this binder act synergistically in that the former engagesin strong hydrogen bonding with the active material and the latterpromotes elastic adjustment of the binder network. This binder designsignificantly improves the charge-discharge reversibility and long-termcyclability of the anode-less ASSB cell and provides insights into elastic binder systems for high-capacity ASSB anodes thatundergo a large volume expansion.N

Rationally Designed Solution-Processible Conductive Carbon Additive Coating for Sulfide-based All-Solid-State Batteries

Sulfide-based all-solid-state batteries (ASSBs) have emerged as promising candidates for next-generation energy storage systems owing to their superior safety and energy density. A conductive agent is necessarily added in the cathode composite of ASSBs to facilitate electron transport therein, but it causes the decomposition of the solid electrolyte and ultimately the shortening of lifetime. To resolve this dilemmatic situation, herein, we report a rationally designed solution-processible coating of zinc oxide (ZnO) onto vapor-grown carbon fiber as a conductive agent to reduce the contact between the carbon additive and the solid electrolyte and still maintain electron pathways to the active material. ASSBs with the carbon additive with an optimal coating of ZnO have markedly improved cycling performance and rate capability compared to those with the bare conductive agent, which can be attributed to hindering the decomposition of the solid electrolytes. The results highlight the usefulness of controlling the interparticle contacts in the composite cathodes in addressing the challenging interfacial degradation of sulfide-based ASSBs and improving their key electrochemical properties

Anode-Less All-Solid-State Batteries Operating at Room Temperature and Low Pressure

Anode-less all-solid-state batteries (ASSBs) are being targeted for next-generation electric mobility owing to their superior energy density and safety as well as the affordability of their materials. However, because of the anode-less configuration, it is nontrivial to simultaneously operate the cell at room temperature and low pressure as a result of the sluggish reaction kinetics of lithium (de)plating and the formation of interfacial voids. This study overcomes these intrinsic challenges of anode-less ASSBs by introducing a dual thin film consisting of a magnesium upper layer with a Ti3C2Tx MXene buffer layer underneath. The Mg layer enables reversible Li plating and stripping at room temperature by reacting with Li via a (de)alloying reaction with a low reaction barrier. The MXene buffer layer maintains the electrolyte-electrode interface by inhibiting the formation of voids even at low pressure of 2 MPa owing to the high ductility of MXene. This study highlights the importance of a combined chemical and mechanical approach when designing anode-less electrodes for practical adaptation for anode-less ASSBs