High-Nickel Battery Electrolyte for Capacity Retention Stability
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face a reduction in capacity retention ratio when the cobalt content in the composite oxide is lowered, leading to instability in the crystal structure and reduced lithium ion absorption and release capabilities.
Innovation Solution
Incorporating specific cations (Na+, K+, Rb+, Cs+, Fr+, Mg2+, Ca2+, Sr2+, Ba2+, Al3+) and oxalate complex anions into the liquid electrolyte, forming a fluoride surface film on the positive electrode to stabilize the composite oxide structure, thereby maintaining high capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the cobalt content in the composite oxide is lowered to reduce cost, then the battery capacity increases due to higher nickel content, but the capacity retention ratio deteriorates due to crystal structure instability
Solution Approach 1:
Alkali metal salts (LiClO4, LiPF6, LiBF4, LiCF3SO3) and alkaline earth metal salts (Mg(ClO4)2, Ca(ClO4)2, Sr(ClO4)2, Ba(ClO4)2) are introduced as intermediary substances in the electrolyte. These salts form protective surface films on the composite oxide particles, acting as intermediaries that stabilize the crystal structure during charge-discharge cycles, thereby improving capacity retention ratio while maintaining high nickel content
Solution Approach 2:
The invention changes the chemical composition parameters of the electrolyte by specifically controlling the concentration ranges of alkali metal salts (0.01-1.0 mol/L) and alkaline earth metal salts (0.01-0.5 mol/L). This parameter optimization enables the formation of stable surface films that protect the composite oxide structure, resolving the capacity retention issue without sacrificing battery capacity
2Use of energy by moving object
If the nickel content in the composite oxide is increased to achieve high capacity, then the battery energy density improves, but the crystal structure stability deteriorates leading to reduced lithium ion absorption and release
Solution Approach 1:
Alkali and alkaline earth metal salts serve as intermediary substances that form stable surface films on high-nickel composite oxide particles. These intermediary layers protect the underlying unstable crystal structure from degradation during electrochemical cycling, enabling high nickel content (90-99 mol%) to be maintained while preserving crystal structure stability
Solution Approach 2:
The electrolyte containing alkali and alkaline earth metal salts performs preliminary action by forming protective surface films on the composite oxide particles before they are exposed to harsh electrochemical conditions. This pre-formed protection layer prevents crystal structure transformation and maintains stability throughout the battery's operational life
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution effectively suppresses the reduction in capacity retention ratio by stabilizing the composite oxide structure, ensuring high lithium ion migration and maintaining battery performance.
Implementation Method 1
the liquid electrolyte contains at least one cation X selected from the group consisting of Na +, K +, Rb +, Cs +, Fr +, Mg 2+, Ca 2+, Sr 2+, Ba 2+, Al 3+ and at least one anion Y selected from the group consisting of BF 4 -, CF 3 SO 3 -, C 2 O 4 -, B(C 2 O 4) 2 -, and B(C 2 O 4 )(H 2 O) 3 -
Data Source
Figure 1
AI summary
A non-aqueous electrolyte secondary battery including a positive electrode, a separator, a negative electrode facing the positive electrode, with the separator interposed; and a liquid electrolyte. The positive electrode includes a composite oxide containing lithium as a first metal, and a second metal other than lithium. In the composite oxide, the second metal contains Ni, a content of Ni in the second metal is 90 at% or more, and a content of Co in the second metal is 10 at% or less. The liquid electrolyte contains at least one cation X selected from the group consisting of Na+, K+, Rb+, Cs+, Fr+, Mg2+, Ca2+, Sr2+, Ba2+, and Al3+, and an oxalate complex anion Y.