Electrolyte Stability Determines Scaling Limits for Solid-State 3D Li Ion Batteries

Abstract

Rechargeable, all-solid-state Li ion batteries (LIBs) with high specific capacity and small footprint are highly desirable to power an emerging class of miniature, autonomous microsystems that operate without a hardwire for power or communications. A variety of three-dimensional (3D) LIB architectures that maximize areal energy density has been proposed to address this need. The success of all of these designs depends on an ultrathin, conformal electrolyte layer to electrically isolate the anode and cathode while allowing Li ions to pass through. However, we find that a substantial reduction in the electrolyte thickness, into the nanometer regime, can lead to rapid self-discharge of the battery even when the electrolyte layer is conformal and pinhole free. We demonstrate this by fabricating individual, solid-state nanowire core-multishell LIBs (NWLIBs) and cycling these inside a transmission electron microscope. For nanobatteries with the thinnest electrolyte, ≈110 nm, we observe rapid self-discharge, along with void formation at the electrode/electrolyte interface, indicating electrical and chemical breakdown. With electrolyte thickness increased to 180 nm, the self-discharge rate is reduced substantially, and the NWLIBs maintain a potential above 2 V for over 2 h. Analysis of the nanobatteries' electrical characteristics reveals space-charge limited electronic conduction, which effectively shorts the anode and cathode electrodes directly through the electrolyte. Our study illustrates that, at these nanoscale dimensions, the increased electric field can lead to large electronic current in the electrolyte, effectively shorting the battery. The scaling of this phenomenon provides useful guidelines for the future design of 3D LIBs.

Design Considerations for Unconventional Electrochemical Energy Storage Architectures

“…Researchers in the battery fi eld have realized this fundamental problem and recognized as well that one of the fundamental limitations of the ultrathin-fi lm confi guration is the solid-state electrolyte. [ 338 ] So far, only the solid-state electrolytes comply with the electrochemical and electrical requirements for the realization of sub-micron electrolyte layers in the ultra-thin fi lm battery confi guration. Ultra-high vacuum deposition techniques have been primarily used to coat the solid electrolyte as well as the entire multi-layered thin fi lm battery.…”

“…Reproduced with permission. [ 338 ] Copyright 2012, American Chemical Society. B) Cross-sectional SEM view showing the stacked layers in a thin-fi lm LIB.…”

P3HT:PCBM/nickel-aluminum layered double hydroxide-graphene foam composites for supercapacitor electrodes

“…Supercapacitors (SCs, or ultracapacitors) and hybrid solid-state batteries are but a few examples of the most recent technological innovations in the field of electrical energy storage [1][2][3][4][5][6][7][8][9]. Among the latter, SCs possess higher power density and longer cycle life, but lower energy density.…”

In situ methods for Li-ion battery research: A review of recent developments

“…Ruzmetov and colleagues [54] investigated all-solid-state nano-batteries with a radial geometry, which were fabricated by subsequent (physical vapor) deposition of the various components onto Si nanowires. Based on their currentevoltage characteristics the authors argue that the only 110 and 180 nm thick (LiPON) electrolyte layers were pin-hole free.…”