Within　the　family　of　halide　solid　electrolytes　(SEs),　Li2ZrCl6　demonstrates　high　oxidative　stability,　cost-effectiveness,　and　mechanical　deformability,　positioning　it　as　a　promising　candidate　for　SEs.　However,　the　application　of　Li2ZrCl6　as　a　SEs　was　hindered　by　its　low　ionic　conductivity　at　room　temperature.　Current　strategies　to　enhance　the　ionic　conductivity　of　Li2ZrCl6　primarily　are　focused　on　single　cation　or　anion　sublattice-engineering,　each　with　distinct　advantages　and　limitations.　Here,　we　propose　a　novel　cation　and　anion-sublattice-engineering　strategy,　termed　CASE,　to　increase　the　amorphous　content　and　thus　enhance　ionic　conductivity.　The　incorporation　of　Cu2+　and　O2−　induces　distinctive　structural　modifications　within　Li2ZrCl6.　This　structure　corroborated　through　analytic　data　of　X-ray　absorption　spectroscopy,　the　neutron　diffraction,　and　ab　initio　molecular　dynamics.　Consequently,　the　amorphous　Li2.1Zr0.95Cu0.05Cl4.4O0.8　achieves　an　enhanced　ionic　conductivity　of　2.05 mS　cm−1　at　25 °C.　Furthermore,　all-solid-state　lithium　batteries　utilizing　the　amorphous　Li2.1Zr0.95Cu0.05Cl4.4O0.8　as　an　electrolyte　and　LiNi0.83Co0.11Mn0.06O2　as　a　cathode　exhibit　a　superior　long-term　cycling　stability　retaining　90.3%　of　capacity　after　1000　cycles　at　2　C　under　room　temperature,　which　are　much　higher　than　those　of　Zr-based　halide　electrolytes　in　publications.　Such　a　result　might　stimulate　the　development　of　more　amorphous　structures　with　high　ionic　conductivity　in　the　CASE　strategy.　©　2025　Wiley-VCH　GmbH.