Grain Boundary Engineering in Ta-Doped Garnet-Type Electrolyte for Lithium Dendrite Suppression

Abstract

Solid-state lithium batteries (SSLBs) based on Ta-doped Li6.5La3Zr1.5Ta0.5O12 (LLZTO) suffer from lithium dendrite growth, which hinders their practical application. Herein, first principles simulations indicate that the Ta element prefers to segregate along grain boundaries in the form of Ta2O5 precipitates due to a high energy difference induced by Ta doping. Grain boundary engineering is employed to regulate the distribution of the Ta element and enhance the density of LLZTO by introducing the La2O3 additive. The sufficient La2O3 additive reacts with the Ta2O5 precipitates, while the residual La2O3 nanoparticles fill up void defects, promoting the homogeneous distribution of the Ta element and improving the relative density to ∼98%. Critical current density of the symmetric Li battery reaches 2.12 mA·cm–2 at room temperature with the solid-state electrolyte (LLZTO + 5 wt % La2O3), which increases by 41% compared to pure LLZTO. SSLBs with the LiFePO4 cathode achieve a stable cycling performance with a discharge capacity of 138.6 mA·h·g–1 after 400 cycles at 0.2 C. This work provides theoretical insights into the distribution of Ta-doped LLZTO and inhibits lithium dendrite growth through grain boundary engineering.

Insight into Dendrites Issue in All Solid‐State Batteries with Inorganic Electrolyte: Mechanism, Detection and Suppression Strategies

“…At the same time, these La 2 O 3 can also fill the internal voids of LLZO to achieve a high density of LLZO. [161] Compared with the process of GB modification using inorganic ceramics, the process of GB engineering using polymers is more straightforward and universal. This is due to the solubility of the polymer in polar solvents.…”

“…At the same time, these La 2 O 3 can also fill the internal voids of LLZO to achieve a high density of LLZO. [ 161 ]…”

Dendrite growth and inhibition in all-solid-state lithium metal batteries: in situ optical observation

“…One is that lithium dendrites directly grow along pre-existing chains of defects such as grain boundaries. 19,[26][27][28][29][30][31][32] Another is that non-uniform lithium deposition at the anode-SSE interface causes accumulation of local stress and crack formation in the SSE layer, which causes further dendrite growth inside the cracks. 16,[33][34][35][36][37] It is important to understand which mechanism plays a key role in dendrite growth that eventually leads to short-circuiting in a LPSC based all-solid-state lithium metal cell.…”

Imperfect Battery Materials: A Closer Look at the Role of Defects in Electrochemical Performance

“…The presence of grain boundaries separating small crystallites or grains prevents the motion of dislocations and hence strengthens the material. For solid-state battery applications, however, electrolytes are often annealed to recrystallize the polycrystalline materials with the aim to favor ionic mobility within the bulk and to avoid Li dendrite propagation within grain boundaries and volume defects such as cracks , voids , and pores . , …”

“…For solid-state battery applications, however, electrolytes are often annealed to recrystallize the polycrystalline materials with the aim to favor ionic mobility within the bulk and to avoid Li dendrite propagation within grain boundaries and volume defects such as cracks, voids, and pores. 11,12 On the other hand, defects have also been repeatedly ignored in the evaluation of structure−property correlations because achieving a complete, quantitative, and accurate description often represents a challenge. This is due to several factors.…”