Direct observation of internal short circuits by lithium dendrites in cross-sectional lithium-ion in situ full cells

Multistep Improvement of Pilot-Scale 21700 Cells for Increased Fast-Charging Capability: Combining Optimized Electrolyte, Cell Design and Fast-Charging Protocol

“…2b), the anode potential drops below 0 V vs Li/Li + already at 2 C. When the anode potential drops below 0 V vs Li/Li + , Li metal deposition becomes thermodynamically possible 3,4,[19][20][21] which can cause irreversible capacity losses due to the reaction of Li metal with the electrolyte and electronically insolated Li ("dead Li"). 3,14,46 Especially for high C-rates (2 C, 3 C, and 4 C), the anode potential already drops below 0 V vs Li/Li + after a SOC of 53%, 30%, and 18% is reached. The occurrence of capacity losses is evident from the reduced capacity retention in the last 0.1 C cycles (cycle 1-3: SOC: 100%; cycle 19-21; SOC: 97%) and the dropping capacity retention values for the consecutive 4 C cycles in Fig.…”

“…The in situ cell set-up and preparation of the cross-sectional cell were developed in our group and are described in detail in our previous publications. 13,14 For these measurements, the anode and cathode had identical dimensions (diameter: 16 mm), and two layers of Celgard 2325 separator (diameter: 18 mm) were used. The electrodes were dried overnight under vacuum conditions at 130 °C, and the separator was dried at 70 °C.…”

“…[10][11][12] Especially at higher charging rates, the transport properties can cause a depletion of Li + in the electrolyte within the parts of the electrode close to the current collector. 8,9 This causes an inhomogeneous lithiation distribution within the electrodes 13,14 which can ultimately lead to faster aging at the electrode surface. 15 Changing the conductive salt concentration 8,16 or the conductive salt itself 17 can improve the mass transport properties and allow higher charging rates.…”

Na metal anodes for liquid and solid-state Na batteries

“…In this regard, optical microscopy (OM) as a common and valuable tool gains considerable attention to studying metallic electrode surface morphologies at the micro-level due to its low cost and convenience of operation. 146,147 The ability to perform in situ observations under operando conditions enables close monitoring and analysis of the dynamic changes occurring on the anode's surface during electrochemical processes. 148,149 As shown in Fig.…”

Wide-temperature-range sodium-metal batteries: from fundamentals and obstacles to optimization

“…492,493 Unfortunately, the low resolution determines that in situ OM can be observed only at the submicron level and is considered a macroscopic characterization technique. 493,494 Fig. 21g shows in situ OM.…”