Boron-Graded High-Nickel Cathode Material for Hot-Cycle Capacity

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Solution Overview

Problem

Existing non-aqueous electrolyte secondary batteries with lithium-transition metal composite oxides face challenges in maintaining battery capacity and rate characteristics when charged and discharged at high temperatures, due to issues like secondary particle cracking and increased resistance.

Innovation Solution

A positive electrode active material is developed, comprising lithium-transition metal composite oxide with 80 mol% or more Ni content, where boron (B) is present on the particle surface, and the mole fraction of B is higher in larger particles than in smaller particles, optimizing the distribution to inhibit secondary particle cracking and resistance increase.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If boric acid compound is adhered onto particle surface of lithium-transition metal composite oxide, then decrease in battery capacity at high temperature is inhibited, but resistance value increases and rate characteristics decrease

Engineering Contradiction:

Improvebattery capacity retention at high temperatureVSAvoidrate characteristics

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies different mole fractions of boron to different particle size regions. Larger particles (first particles with diameter > D70) have a higher mole fraction of B (0.003-0.02) compared to smaller particles (second particles with diameter < D30) with mole fraction of B (0.001-0.01). This local differentiation allows larger particles to benefit from better capacity retention while smaller particles maintain lower resistance, resolving the contradiction between high-temperature stability and rate characteristics.

Inventive Principle:

Principle #3Local quality

2Use of energy by moving object

If high Ni content (80 mol% or more) is used in lithium-transition metal composite oxide, then energy density increases, but secondary particle cracking occurs at high temperature

Engineering Contradiction:

Improveenergy densityVSAvoidparticle structure stability at high temperature

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The patent changes the chemical composition parameter by incorporating boron into the lithium-transition metal composite oxide with high Ni content (80 mol% or more). The boron forms a protective layer or modifies the crystal structure, preventing secondary particle cracking during high-temperature charging and discharging while maintaining the high energy density provided by the high Ni content.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12300815B2Positive electrode active material for nonaqueous electrolyte secondary batteries, and nonaqueous electrolyte secondary battery

Publication Date: 2025.05.13 PANASONIC HOLDINGS CORP

AI summary

This positive electrode active material for nonaqueous electrolyte secondary batteries is a positive electrode active material that comprises a lithium transition metal composite oxide containing at least 80 mol % Ni with reference to the total number of moles of metal elements excluding Li, and that has B present on the particle surface of at least this composite oxide. Assuming that a particle having a particle diameter larger than the 70% volume-based particle diameter (D70) is denoted as a first particle and a particle having a particle diameter smaller than the 30% volume-based particle diameter (D30) is denoted as a second particle, the mole fraction of B, with reference to the total number of moles of metal elements excluding Li, in the first particle is larger than the mole fraction of B, with reference to the total number of moles of metal elements excluding Li, in the second particle.