No abstract

Electrodeposition of lithium-ion battery cathodes enables ultraflexible, ultrathick, and high-power rechargeable batteries.

Billions of internet connected devices used for medicine, wearables, and robotics require microbattery power sources, but the conflicting scaling laws between electronics and energy storage have led to inadequate power sources that severely limit the performance of these physically small devices. Reported here is a new design paradigm for primary microbatteries that drastically improves energy and power density by eliminating the vast majority of the packaging and through the use of high‐energy‐density anode and cathode materials. These light (50–80 mg) and small (20–40 µL) microbatteries are enabled though the electroplating of 130 µm‐thick 94% dense additive‐free and crystallographically oriented LiCoO2 onto thin metal foils, which also act as the encapsulation layer. These devices have 430 Wh kg−1 and 1050 Wh L−1 energy densities, 4 times the energy density of previous similarly sized microbatteries, opening up the potential to power otherwise unpowerable microdevices.

No abstract

Interfaces play crucial, but still poorly understood roles in the performance of secondary solid-state batteries (SSBs). Using crystallographically oriented and highly faceted thick cathodes, we directly assess the impact of cathode crystallography and morphology on long-term performance of SSBs. The controlled interface crystallography, area, and microstructure of these cathodes enables understanding interface instabilities unknown (hidden) in conventional thin film and composite solid-state electrodes. A generic and direct correlation between cell performance and interface stability is revealed for a variety of both lithium and sodium-based cathodes and solid electrolytes. Our findings highlight that minimizing interfacial area, rather than its expansion as is the case in conventional composite cathode, is key to both understanding the nature of interface instabilities and improving cell performance. Our findings also point to the use of dense and thick cathodes as a new path for increasing the energy density and stability of SSBs.